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مدلسازی انفجار مخازن سوخت گندلهسازی با استفاده از نرمافزار PHAST
No full textBackground and Aim: This descriptive cross-sectional study was conducted in 2024 to model the consequences of accidents in the diesel tank and provide corrective and control measures in Gol Gohar Industrial and Mining Company, pellet factory using PHAST software.
Methods: In the first step, information about the reservoirs such as the operational and physical conditions of the reservoirs, geographical and climatic information, location and site plan of the reservoirs, and process maps were collected. In the next step, possible scenarios were identified and after modeling and evaluation of the consequences using the software, the outputs were analyzed to provide appropriate control measures.
Results: Findings and Conclusion: In examining the scenario related to the leakage of 10 mm and 100 mm in the diesel tank the minimum dangerous distance observed in the 10 mm leakage is 21.94 meters and the maximum dangerous distance is 49.24 meters, considering the weather condition of Sirjan city. Also, in the scenario of 100 mm leakage, the lowest dangerous distance is 16.16 meters and the highest dangerous distance is 275.67 meters from the diesel storage tank. In the explosion scenario, the minimum and maximum dangerous distance was 590.51 meters and 1053.87 meters respectively, which is the highest damage related to this scenario.
Conclusion: Therefore, it is suggested that the surroundings of these tanks be declared free of personnel up to a radius of at least 590.51 meters, and a safe gathering place should be considered at a distance of 1060 meters to protect the personnel from possible injuries.
Please cite this article as:
Khoshmanesh B, Razavian F, Bakhtiari N. Consequences of the Explosion and Fire of Pelletizing Fuel Tanks using PHAST Software. Irtiqa Imini Pishgiri Masdumiyat .2024;12(4):234-247. https://doi.org/10.22037/iipm.v11i3.47473سابقه و هدف: این مطالعه توصیفی - مقطعی در سال 1403 با هدف مدلسازی پیامد حوادث در مخزن گازوئیل و ارائه اقدامات اصلاحی و کنترلی در شرکت صنعتی و معدنی گل گهر، کارخانه گندله سازی با استفاده از نرم افزار PHAST انجام گرفت.
روش کار: در گام اول اطلاعات مربوط به مخازن از قبیل شرایط عملیاتی و فیزیکی مخازن، اطلاعات جغرافیایی و آبوهوایی، جانمایی و سایت پلان مخازن و نقشههای فرایندی جمعآوری گردید و در گام بعدی سه سناریو شناسایی و مورد تحلیل قرار گرفت.
یافته ها: نشت گازوئیل از مخزن به قطر 10 میلیمتر به عنوان سناریوی اول، نشت گازوئیل از مخزن به قطر 100 میلیمتر به عنوان سناریوی دوم و انفجار ناگهانی مخزن به عنوان سناریو سوم شبیه سازی گردید و پیامدهای ناشی از سناریوهای ذکر شده شامل آتش استخری، آتش فورانی و آتش ناگهانی مشخص گردید. در بررسی سناریو مربوط به نشتی 10 میلیمتر و 100 میلیمتر در مخزن گازوئیل در شرایط آب و هوایی شهرستان سیرجان، حداقل فاصله خطرناکی که در نشتی 10 میلیمتر مشاهده گردید 21.94 متر و حداکثر فاصله خطرناک 49.24 متر است. همچنین در سناریو مربوط به نشتی 100 میلیمتر، کمترین فاصله خطرناک در 16.16 متر و بیشترین فاصله خطرناک در275.67متر از مخزن ذخیره گازوئیل میباشد. در سناریو انفجار به ترتیب حداقل و حداکثر فاصله خطرناک در 590.51 متر و 1053.87متر از مخزن ذخیره گازوئیل بود که بالاترین میزان خسارت مربوط به این سناریو میباشد.
نتیجه گیری: باتوجهبه شرایط موجود پیشنهاد میگردد اطراف این مخازن حداقل تا شعاع 51/590 متر خالی از پرسنل اعلام گردد و جهت جانمایی مکان تجمع ایمن، فاصله بیش از 1060 متر لحاظ شود تا پرسنل از آسیبهای احتمالی محافظت گردند.
به این مقاله، به صورت زیر استناد کنید:
Khoshmanesh B, Razavian F, Bakhtiari N. Consequences of the Explosion and Fire of Pelletizing Fuel Tanks using PHAST Software. Irtiqa Imini Pishgiri Masdumiyat .2024;12(4):234-247. https://doi.org/10.22037/iipm.v11i3.4747
Correction to: Therapeutic Effects of Photobiomodulation Therapy on Multiple Sclerosis by Regulating the Inflammatory Process and Controlling Immune Cell Activity: A Novel Promising Treatment Target
Full text linkIn the article titled “Therapeutic Effects of Photobiomodulation Therapy on Multiple Sclerosis by Regulating the Inflammatory Process and Controlling Immune Cell Activity: A Novel Promising Treatment Target” published in J Lasers Med Sci 2022;13:e32 (doi: 10.34172/jlms.2022.32), there was an error in the Ethical approval section.
The ethics approval code was incorrectly reported as: “All protocols were confirmed by the Ethics Committee of Shahid Beheshti University of Medical Sciences (IR.SBMU.RETECH. REC.1400.009).”
The correct ethics approval code is:
IR.SBMU.REC.1400.009
The corrected sentence should read: “All protocols were confirmed by the Ethics Committee of Shahid Beheshti University of Medical Sciences (IR.SBMU.REC.1400.009 ).”
This correction has now been updated in both the PDF and HTML versions of the article
Navigating Success and Challenges in Arteriovenous Fistulain Pediatrics: A Retrospective Observational Study: Navigating Success in Arteriovenous Fistula
No full textBackground and Aim: Arteriovenous fistula (AVF) is an essential surgery for youngpatients who need long-term access to hemodialysis (HD). Despite the widespread use ofAVFs in adult populations, there is a lack of research on their utilization and outcomes inpediatric patients. The purpose of this study was to assess the outcomes of AVF developmentin children, including the factors that affect success rates, complications, and long-termoutcomes.Methods: This study was a retrospective cohort of patients with end-stage renal disease(ESRD) who were aged under 18 years old and underwent an AVF surgery at our centerbetween December 2021 and January 2023. We collected demographic data from patients andfollow-up data at 1 week, 6 weeks, 6 months, 12 months, and 18 months. Details, such as thetype of access, its anatomical location, and complications, were also documented.Results: During the study period, a total of 47 AVFs were created. We created brachiocephalicAVF in 63.83% of cases (n=30), radiocephalic AVF in 14.89% (n=07), and brachiobasilictransposition in 21.28% (n=10). The overall primary patency rate at 12 months was78.72%. The median survival of the brachiocephalic fistula was much greater than that ofthe radiocephalic and brachiobasilic fistulas (BBF). The primary patency rates at 1 week, 6weeks, 6 months, 12 months, and 18 months were 87.23%, 85.11%, 82.97% and 74.47%,and 66%, respectively.Conclusion: AVF provides effective long-term HD access in the pediatric population withESRD. Thromosis was identified as the main cause of failure, underscoring the importance ofproactive monitoring and interventions to improve outcomes.
An anthropological-cultural analysis of nutritional barriers and social health: a mixed-methods study across generations of urban households in Iran
Full text linkBackground: Healthy nutrition and social health are key components of sustainable community development. However, cultural and economic barriers, along with generational differences, can significantly affect dietary patterns and levels of social health in urban Iranian households. This study aimed to provide an anthropological-cultural analysis of nutritional barriers and their relationship with social health across different generations.
Methods: This mixed-method study included both quantitative and qualitative approaches. The quantitative phase involved a survey of 400 individuals from urban households representing three age groups (youth, middle-aged, and elderly). The qualitative phase included semi-structured interviews with 20 participants. The number of interviewees was determined based on the principle of data saturation, whereby new interviews no longer produced additional themes or insights. Saturation was reached after approximately 17 interviews, and three further interviews were conducted to confirm this point. Participants were selected purposefully to ensure diversity in age, gender, and socio-economic background. Data were analysed using regression analysis in the quantitative phase and thematic analysis in the qualitative phase.
Results: The findings showed that cultural barriers (β = -0.42, p < 0.001) and economic barriers (β =-0.38, p=0.004) had significant negative effects on social health. In addition, the generational variable was positively associated with social health (β = 0.21, p = 0.026). The qualitative analysis supported these results, indicating that older generations maintained stronger adherence to traditional dietary patterns and family interactions, whereas younger generations demonstrated a tendency toward fast food consumption and individualistic lifestyles.
Conclusion: The results highlight the need for urban health policies to focus on nutrition education, revitalization of family-oriented food culture, and reduction of cultural and economic barriers to healthy eating. Considering generational differences is essential in designing effective interventions
بررسی میزان استرس دانشجویان دندانپزشکی شهرکرد در دوران پاندمی کووید-19
No full textBackground and Aims: The present study aimed to assess the level of stress among dental students in Shahrekord during the COVID-19 pandemic.
Materials and Methods: In this descriptive cross-sectional study, a total of 122 dental students participated in 2021. Participants completed a two-part questionnaire consisting of demographic information and dental environment stress. Data were analyzed using SPSS software version 22. Ethical considerations were observed at all stages of the study.
Results: The mean dental environment stress score was 75.67 ± 1.16. The highest score was related to the academic factors dimension, with a mean of 56.5 ± 1.6. Significant differences were observed between students’ year of entry and the level of stress in certain dimensions of the Dental Environment Stress (DES) scale including academic performance, patient treatment, academic factors, and clinical training. The indices measured were considerably lower in first-year students compared to those in higher years.
Conclusion: The dental environment stress among the students studied was at a moderate level, with the highest stress observed in the academic factors dimension. By providing effective strategies during critical situations, such as the COVID-19 pandemic, it is possible to reduce students’ stress, anxiety, and depression through necessary training, identification of at-risk individuals, and offering counseling, thereby preventing the occurrence of related complications and problems.زمینه و اهداف: مطالعه حاضر با هدف بررسی میزان استرس دانشجویان دندانپزشکی شهرکرد در دوران پاندمی کووید-19 صورت گرفت.
مواد و روشها: در این مطالعه مقطعی- توصیفی، تعداد 122 دانشجوی رشته دندانپزشکی در سال 1400 وارد مطالعه شدند و پرسشنامه 2 قسمتی شامل اطلاعات جمعیتشناختی و استرس محیط دندانپزشکی را تکمیل کردند. دادهها توسط نرمافزار SPSS 22 تجزیه و تحلیل شد. رعایت ملاحظات اخلاقی در تمام مراحل اجرای مطالعه درنظر گرفته شد.
یافتهها: میانگین نمره استرس محیط دندانپزشکی 1/16±75/67 بود. بیشترین نمره نیز مربوط به بعد عوامل دانشگاهی با میانگین نمره 1/6±5/65 بود. بین برخی از ابعاد مقیاس استرس محیط دندانپزشکی شامل بعد کارایی دانشگاهی، بعد درمان بیماران، بعد عوامل دانشگاهی و بعد آموزش بالینی مقیاس DES اختلاف معناداری بین سال ورودی دانشجویان و میزان اختلالات مشاهده گردید و میزان شاخصهای مورد بررسی در دانشجویان سال اول به مراتب کمتر از دانشجویان با مقاطع بالاتر بود.
نتیجهگیری: استرس محیط دندانپزشکی برای دانشجویان مورد بررسی در حد متوسط بود که بیشترین میزان آن مربوط به بعد عوامل دانشگاهی میباشد. با ارائه راهکارهایی مفید در شرایط بحرانی مانند دوران پاندمی کووید- 19، در کاهش میزان استرس، اضطراب و افسردگی دانشجویان از طریق ارائه آموزشهای لازم و شناسایی افراد در معرض خطر و ارائه مشاوره برای آنها از بروز عوارض و مشکلات ناشی از آن جلوگیری شود
بررسی عوامل موثر بر طول مدت شیردهی در مادران بر اساس تئوری رفتار برنامهریزی شده
No full textBackground and Aims: The importance of breastfeeding for the growth, development, and survival of infants, as well as its beneficial effects on the health of mothers, families, and society has always been emphasized.
Materials and Methods: This cross-sectional study with a descriptive-analytical approach was conducted on 200 mothers of children aged 24 months who attended comprehensive health service centers in 2024. Data were collected using a researcher-designed questionnaire consisting of two sections, demographic questions and constructs of the theory of planned behavior. Data analysis was performed using simple linear regression, Pearson correlation, and independent t-tests. Ethical considerations were observed at all stages of the study.
Results: The mean age of the mothers was 28.64±4.68 years. The mean age at the introduction of complementary feeding was 6.28±1.71 months. Significant associations were observed between breastfeeding duration and mothers’ education (P=0.005), occupation (P=0.012), type of milk consumed (P=0.05), and mode of delivery, either cesarean or natural (P=0.016). Self-efficacy (β=0.404) and attitude (β=0.225) were identified as the strongest predictors of mothers’ intention to breastfeed.
Conclusion: In the present study, mothers’ education, occupation, mode of delivery, and perceived self-efficacy were identified as the most important predictors of breastfeeding duration. Therefore, by providing necessary education—particularly to mothers with low awareness of the benefits of breastfeeding—promoting natural delivery, enhancing mothers’ self-efficacy and offering appropriate support, healthcare professionals and policymakers can help promote widespread exclusive breastfeeding practices, thereby improving the health and well-being of both mothers and infants.زمینه و اهداف: اهمیت تغذیه با شیر مادر در رشد، تکامل و بقای شیرخوار و اثرات مفید آن در حفظ سلامت مادر، خانواده و اجتماع همواره مورد تاکید قرار گرفته است.
مواد و روشها: این مطالعه از نوع مقطعی با رویکرد توصیفی- تحلیلی میباشد که روی 200 نفر از مادران دارای کودکان 24 ماه مراجعهکننده به مراکز خدمات جامع سلامت در سال 1403 انجام شد. ابزار جمعآوری اطلاعات شامل پرسشنامه محقق ساخته که از دو بخش سوالات جمعیتشناختی و سازههای تئوری رفتار برنامهریزی شده بود. برای تحلیل دادهها از رگرسیون خطی ساده، همبستگی پیرسون و آزمون تی مستقل استفاده شد. رعایت ملاحظات اخلاقی در تمام مراحل اجرای مطالعه درنظر گرفته شد.
یافتهها: میانگین سن مادران 4/68 ±28/64 سال بود. سن شروع تغذیه کمکی 1/71 ±6/28 ماه بود. بین تحصیلات مادران (0/005=P)، شغل (0/012=P) و نوع شیر مصرفی (0/05=P) و نوع زایمان به روش سزارین و طبیعی (0/016=P) با طول مدت شیردهی نیز ارتباط آماری معنیداری وجود داشت. سازه خودکارآمدی (0/404=β) و نگرش (0/225=β) به ترتیب به عنوان قویترین پیشبینیکنندههای قصد مادران برای شیردهی مشخص شدند.
نتیجهگیری: در مطالعه حاضر تحصیلات، شغل، نوع زایمان و خودکارآمدی درک شده مادران از مهمترین پیشبینیکنندههای طول مدت شیردهی بودند. بنابراین ارائه آموزشهای لازم به مادران بهویژه مادرانی که آگاهی پایینی در خصوص فواید مصرف شیر مادر دارند و همچنین ترویج به زایمان طبیعی و در نهایت افزایش خودکارامدی آنها و همچنین ارائه حمایتهای لازم از آنها، متخصصان مراقبتهای بهداشتی و سیاستگذاران میتوانند به ترویج شیوههای گسترده شیردهی انحصاری با شیر مادر کمک کنند و به نوبه خود، سلامت و رفاه مادران و نوزادان را افزایش دهند
Antidiabetic Bioactive Peptides from A2 Milk Fermented by Lacticaseibacillus rhamnosus: Enzyme Inhibition and Docking Insights
Full text linkBackground and Objective: Diabetes mellitus is a long-term disorder characterized by the body’s inability to regulate excessive blood glucose levels. The incidence of diabetes mellitus worldwide has significantly increased in recent decades. In addition to careful regulation of food quantities, improving food quality through the consumption of functional foods that do not trigger glucose spikes is also recommended. Accordingly, the aim of this research is to determine the potency of antidiabetic functional food derived from the fermentation of A2 cow's milk with higher β-casein content using Lacticaseibacillus rhamnosus RAL43.
Material and Methods: This study involved in vitro assays to test the inhibitory activity against diabetes-related enzymes, namely α-glucosidase, α-amylase, and dipeptidyl peptidase-4 (DPP4), followed by molecular docking simulations.
Results and Conclusion: The results of the study showed inhibitory activity against enzymes that trigger blood glucose spikes, namely 66.35% against α-glucosidase, 68.87% against α-amylase, and 10.69% against DPP4. The results of the analysis showed an increase in the quantity of peptides after fermentation, along with the results of the analysis of L. rhamnosus RAL43 which showed high proteolytic activity during fermentation. After ultrafiltration, it was found that the greatest inhibitory activity came from protein with molecular weight (MW) larger than 10 kDa. The amino acid sequencing process with high-resolution liquid chromatography-mass spectrometry then showed bioactive peptides, including VLVLDTDYK which was previously reported to show DPP4 inhibitory activity, along with many other peptides that display various specific bioactivities. The VLVLDTDYK peptide fragment was successfully docked and positioned in the DPP4 molecule through molecular docking simulations. This study concluded that A2 milk can be a functional substrate to produce specific bioactive peptides that inhibit enzymes that trigger blood glucose spikes that have a negative impact on diabetes. L. rhamnosus RAL43 can be developed as a proteolytic isolate and starter culture to produce foods with functional properties that can aid in blood glucose regulation.
Keywords: Bioactive Peptides, A2 Milk, Antidiabetic, Molecular Docking
Introduction
Diabetes mellitus (DM) has emerged as a significant global health issue. It is a persistent condition marked by increased blood glucose levels, typically above 180 mg.dL-1. Under normal circumstances, the hormone insulin regulates blood glucose levels by converting glucose into energy for cells. However, in individuals with diabetes, the body either does not produce enough insulin or cannot use it effectively to control blood glucose levels. According to data released by the International Diabetes Federation, Type 2 Diabetes Mellitus (T2DM) is the most common form globally and continues to increase significantly each year. The primary causes of T2DM include being overweight and obese, often due to an unbalanced diet and lack of physical activity. T2DM typically does not exhibit critical symptoms in its early stages, causing many individuals to remain unaware of their condition. Chatterjee et al. [1] and Antar et al. [2] identified a prediabetic phase that precedes full-blown diabetes. With proper prevention and management during the prediabetic phase, T2DM can still be avoided. In principle, individuals with T2DM must consistently avoid high blood glucose levels, particularly postprandial spikes [1,2]. Besides careful control of dietary quantity, improving diet quality through the consumption of functional foods that do not trigger glucose spikes is also recommended. Foods or beverages that offer health benefits are referred to as functional foods. Antidiabetic functional foods have been reported to originate from fermented products containing probiotics and/or bioactive compounds that inhibit digestive enzymes involved in carbohydrate breakdown into glucose, including α-amylase, α-glucosidase, and dipeptidyl peptidase-4 (DPP4) [3-5]. Functional foods with antidia-betic activity are considered a promising alternative for managing T2DM without the side effects often associated with pharmaceutical treatments [6].
Digestive enzyme inhibitors operate through various mechanisms. The enzymes α-amylase and α-glucosidase break down complex carbohydrates into simple sugars for absorption in the intestines. Inhibiting these enzymes helps slow glucose absorption and prevents postprandial blood glucose spikes [7]. Meanwhile, the DPP4 enzyme plays a critical role in blood glucose regulation by degrading incretin hormones such as GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). This degradation can suppress insulin secretion and burden the pancreas. DPP4 inhibitors are thought to prevent incretin breakdown, thereby maintaining normal glucose levels and enhancing insulin sensitivity [8]. Enzyme inhibitors targeting α-amylase, α-glucosidase, and DPP4 have been reported in the form of short-chain peptide fragments produced through proteolytic processes, either via enzy-matic hydrolysis or microbial fermentation [9-11]. These peptide-based inhibitors are thought to function as competitive inhibitors by attaching to the enzyme’s active site, preventing substrate binding, and thereby slowing down the buildup of glucose in the blood [12]. Other reported types of enzyme inhibitors include flavonoids, terpenoids, phenolic acids, tannins, alkaloids, and xanthones [10,13]. However, this study will focus specifically on exploring peptide-based inhibitors produced through fermentation by lactic acid bacteria (LAB) isolates.
Once the bioactivity data are obtained and the peptide sequences with potential inhibitory effects are identified, the next step is to perform molecular docking. Molecular docking is a crucial and efficient method for exploring the potential bioactivity of inhibitory peptides. It provides a strong scientific basis prior to biological testing, accelerates the screening process, and helps focus the research on the most promising peptide candidates [14]. This computational approach allows for the modeling and prediction of molec-ular interactions between candidate peptides and target enzymes. In this study, molecular docking is used to generate preliminary data supporting the hypothesis that the identified peptides may possess inhibitory activity against the target enzyme.
Fermented dairy products using LAB have been reported to exhibit antidiabetic potential [3,15,16]. Although not classified as therapeutic drugs, these products are considered effective as functional foods for diabetes preven-tion and management [7,17]. LAB have a significant advantage due to their proteolytic activity, enabling the breakdown of proteins into short-chain peptides. Dairy products fermented with LAB are well recognized as rich sources of bioactive peptides that exhibit antidiabetic, antioxidant, antihypertensive, cholesterol-lowering, and various other functional effects [18-20]. In this study, three lactic acid bacteria isolates (Lacticaseibacillus (L.) rhamnosus RAL27, Limosilactobacillus fermentum RAL29, and L. rhamnosus RAL43) previously isolated from Indonesian kefir grains [21], will be used to ferment A2-type cow’s milk. In recent years, A2 milk has been introduced. This type of milk was first commercialized in New Zealand and has since been marketed in several countries [22]. The main differences between A1 and A2 milk lie in the amino acid composition and β-casein. A1 β-casein contains histidine at position 67, while A2 β-casein contains proline at the same position [23]. These subtle differences can affect human digestion and metabolism. Some studies suggest that A1 milk may be associated with gastrointestinal discomfort and symptoms similar to lactose intolerance. A study by Choi et al. [24] found that participants consuming A1 milk reported more bloating and abdominal pain compared to those consuming A2 milk. The release of β-casomorphin-7 (BCM-7), a peptide derived from A1 β-casein during digestion, is thought to contribute to these symptoms. Some epidemiological studies suggest that A1 milk may be correlated with an increased risk of heart disease due to its inflammatory effects [23]. Conver-sely, A2 milk may offer cardioprotective effects, although further clinical trials are needed to validate these findings. A possible link between A1 milk consumption and the onset of type 1 diabetes has been proposed. A study by Kay et al. [23] suggests that early exposure to A1 milk may be associated with an increased risk of developing autoimmune conditions, possibly due to an immune response triggered by β-casomorphin-7 (BCM-7). With increasing health and wellness awareness, consumer demand for A2 milk has increased significantly. Many dairy companies have begun marketing A2 milk as a healthier alternative to A1 milk, capitalizing on its perceived benefits. This shift reflects a broader trend toward personalized nutrition and the importance of understanding genetic variation in food choices.The fermentation of A2 milk is expected to generate a new and unique peptide profile. Digestive conditions can influence the stability and absorption of peptides produced by A2 milk fermentation. Many peptides are biodegradable, so only peptides of a certain size or structure are retained. Smaller peptides may persist, while larger ones tend to break into fragments. Some bioactive peptides (e.g., DPP4 or α-glucosidase inhibitors) have been shown to remain active even after simulated in vitro digestion, but their persistence varies depending on sequence and structure [7,25]. However, not all peptides identified in vitro will persist into the systemic circulation. However, local activity in, for example, (α-glucosidase inhibition) is expected to remain relevant, even if the peptide is not absorbed in large quantities from the gut. Therefore, this study aims to determine the potential of antidiabetic functional food derived from the fermentation of A2 cow’s milk using lactic acid bacteria isolates, and to evaluate it through in vitro inhibitory activity tests against key diabetes-related enzymes: α-glucosidase, α-amylase, and DPP4, followed by binding simulation analysis.
Materials and Methods
2.1. Material
This study used three isolates from Indonesian kefir grains: L. rhamnosus strain RAL27, Limosilactobacillus fermentum strain RAL29, and L. rhamnosus strain RAL43. The A2 milk (KIN Fresh Milk, Jakarta, Indonesia) and Mann Rogosa Sharpe broth (Himedia) were used as growth media. The chemicals used included α-glucosidase from Saccaromyces cerevisiae (Sigma-Aldrich Co.), α-amylase from from porcine pancreas (Sigma-Aldrich Co.), DPP4 inhibitor screening kit (Sigma-Aldrich Co.) included DPP4 enzyme from human, o-phthalaldehyde (Sigma-Aldrich Co.), p-Nitrophenyl α-D-glucopyranoside (PNPG; Sigma-Aldrich Co.), phenolphthalein (Himedia), Folin-Ciocalteu reagent (Sigma-Aldrich Co.), trichloroacetic acid (Himed-ia), methanol (Himedia), ethanol (Merck), sodium carbonate (Himedia), sodium pyrophosphate (Himedia), β-mercapto-ethanol (Merck), acarbose (Merck), Sitagliptin (Sigma-Aldrich Co.), phosphoric acid (Himedia), phosphate buffer saline (PBS; Himedia), 0.22µM filter membrane (Aijiren), and membrane filter 3.000 and 10.000 Da (Spin-X® UF Concentrators, Corning).
2.2 Isolates preparation
Isolates of L. rhamnosus strain RAL27, L. fermentum strain RAL29, and L. rhamnosus strain RAL43 were refreshed in Mann Rogosa Sharpe broth (MRSB) and incubated at 37oC for 48 h. Cultivation in MRSB was carried out 2 times and then the three isolates were adapted to A2 milk, by inoculating the isolates as much as 2% into A2 milk, then incubated at 37oC for 48 h. This process was also carried out 2 times.
2.3 Fermentation process
The fermentation process refers to the research of Yusuf et al. [26]. The isolate was inoculated to A2 milk at concen-tration of 2% from 5 log CFU.mL-1 starter. Incubation was conducted aerobically at 37°C for 24 h. The fermented milk obtained was characterized by assessing the total viability of LAB, pH value, acidity, aromatic profile, and coagulation properties. Subsequently, the fermented milk was centr-ifuged at 8000×g for 5 min at 4°C, leading to the separation of curd and whey. The whey, located in the upper layer, was carefully collected and subjected to a second centrifugation at the same conditions. The whey was subsequently passed through a 0.22 µm membrane filter to prepare it for further analysis.
2.4 Acidy analysis of fermented A2 milk product
The sample’s pH was determined with a pH meter (Laqua pH1100, Horiba Scientific, Kyoto, Japan). The pH meter was calibrated with buffer solutions of pH 4.0 and 7.0. The acidity measurement using the acid-base titration method. Total of 1 mL sample diluted with 10 mL of sterile water. Afterward, 13 drops of phenolphthalein indicator were added, followed by titration of the sample with 0.05 N NaOH solution. The titration's end point was indicated by the development of a consistent pink color. Total acid was calculated according to the Eq.1.
Total acid (% lactic acid) =
[ Eq.1
2.5 Proteolytic activity assay
Proteolytic activity testing refers to the report of Celik et al. [27] with modifications. The isolate was first cultured in MRSB and incubated at 37 °C for 24 h. Cells were harvested by centrifugation (5000×g, 5 min), washed twice with phosphate-buffered saline, and adjusted to an OD600 of 0.1 ± 0.005. The resulting suspension was inoculated into 5 mL of sterile A2 milk and incubated at 37 °C for another 24 h. Following incubation, the sample was mixed with 10 mL of 0.72 N trichloroacetic acid and 1 mL of distilled water, allowed to stand for 10 min, and then filtered through Whatman No. 1 paper. From the filtrate, 5 mL was combined with 10 mL of Na2CO3–Na4P2O7 solution, after which 3 mL of diluted Folin–Ciocalteu reagent was added. The mixture was stirred until a blue color appeared, centrifuged (3000×g, 3 min), and the clear supernatant was analyzed spectrophotometrically at 650 nm. Tyrosine served as the standard for constructing the calibration curve to determine proteolytic activity.
2.6 Preparation of whey fraction by ultrafiltration
Purification using ultrafiltration refers to Yusuf et al. [26]. Whey was fractionated using a centrifugal tube containing 3 and 10 kDa filter membranes. Treatment carried out: 15 mL of supernatant was put into a 10 kDa centrifuge tube, then centrifuged (8000×g; 5 min). From this process, 2 parts of the solution will be obtained, namely those that pass the filter and those that do not pass the filter. The solution that passes the filter will contain molecules measuring ≤10 kDa and those that do not pass the filter will contain Protein with molecular weight >10 kDa. For the solution that passes the filter, it is put into a 3 kDa centrifuge tube and centrifuged again. So that 3 solutions are obtained: (1) supernatant contains molecules measuring >10 kDa, (2) supernatant contains molecules measuring ≤10 to >3kDa, and (3) supernatant contains molecules measuring ≤3 kDa. All solutions are added with distilled water up to 15 mL according to the initial volume. After that it is ready for further analysis.
2.7 The α-glucosidase inhibitor assay
The α-glucosidase inhibitor assay refers to the study of Son et al. [28]. The reaction mixture in this assay consisted of a blank control (B0), a blank (B1), a sample control (S0), and a sample solution (S1). The S1 solution was prepared by combining 150 µL of PBS (pH 7.4), 75 µL of 20 mM p-nitrophenyl α-D-glucopyranoside, and 25 µL of sample, followed by incubation at 37 °C for 10 min. Subsequently, 50 µL of 0.2 U.mL-1 α-glucosidase enzyme was added and the mixture was incubated again at 37 °C for 10 min. In contrast, the S0 solution was prepared without the addition of the α-glucosidase enzyme. To terminate the reaction, 1 mL of 0.1 M Na2CO3 was added to each mixture. The absorbance of all solutions was then recorded at 405 nm using a microplate reader (iMark, Bio-Rad Co.). After the absorbance value was obtained, the percentage of α-glucosidase inhibitor activity was calculated according to the Eq.2.
α-glucosidase inhibitor activity (%) =
Eq. 2
where B0 is blank control solution, B1 is blank solution, S0 is sample control solution, and S1 is sample solution.
2.8 The α-amylase inhibitor assay
The α-amylase inhibitory assay was performed following the method of Sato et al. [29]. Briefly, 50 µL of sample was mixed with 50 µL of α-amylase solution (1 mg.mL-1) and incubated at 25 °C for 10 min. Next, 50 µL of starch solution (20 mg.mL-1 in PBS) was added and the mixture was incubated at 37 °C for another 10 min. Subsequently, 100 µL of 3, 5-dinitrosalicylic acid was added, and the mixture was heated at 95 °C for 5 min. After cooling, 1500 µL of distilled water was added, and the mixture was centrifuged at 5000×g. An aliquot of 200 µL was transferred into a 96-well plate, and absorbance was measured at 540 nm. Acarbose at 50 ppm served as the positive control. The percentage of α-amylase inhibitory activity was then calculated using the Eq.3.
α-amylase inhibitor activity (%) =
[(Ac - (As - Ab)) ÷ Ac] × 100% Eq. 3
where As is the absorbance of the sample. Ab is the absorbance of the blank. Ac is the absorbance of the acarbose (control).
2.9 The DPP4 inhibitor assay
The DPP4 inhibitory activity was assessed using a modified version of the method described by Yan et al. [5]. In a 96-well microplate, 25 µL of gly-pro-p-nitroanilide (0.2 mM) was combined with either 25 µL of bacterial sample, PBS (as control), or sitagliptin (as reference inhibitor), followed by preincubation at 37 °C for 10 min. Subsequently, 50 µL of DPP4 enzyme (0.01 U.mL-1) was added, and the mixture was incubated at 37 °C for 60 min. The reaction was terminated by adding 100 µL of sodium acetate buffer (1 M, pH 4.0). Fluorescence intensity was then recorded using a microplate reader (Varioskan™ LUX, Thermo Fisher, Massachusetts, USA) at an excitation wavelength of 360 nm and an emission wavelength of 460 nm. All measurements were performed in triplicate, and absorbance values were corrected against blanks prepared by substituting DPP4 with Tris–HCl buffer (100 mM, pH 8.0). Negative controls (without DPP4 activity) and positive controls (DPP4 activity without inhibitor) were also included, using Tris–HCl buffer in place of the sample or the enzyme, respectively. The percentage inhibition of DPP4 activity was then calculated using the Eq. 4.
DPP4 inhibitor activity (%) =
[ Eq. 4
2.10. Identification of peptides
The method used refers to Yusuf et al. [26] with modifications. Identification using Thermo Scientific™ Dionex™ Ultimate 3000 RSLCnano UHPLC coupled with Thermo Scientific™ Q Exactive™ High Resolution Mass Spectrometer. Nano Pump: A= Water + 0.1% Formic Acid and B= Acetonitrile + 0.1% Formic acid. Analytical Column: EASY-Spray column, 15 cm × 75 μM ID, PepMap C18, 3 μm. Flow: 100 µL.min-1. Injection volume: 5 µL. Run time: 60 minutes gradient. Full MS at 70,000 FWHM Resolution. Data Dependent MS2 at 17,500 FWHM. Easy Nano Spray Ionization and positive mode. Protein identification by Thermo Scientific™ Proteome Discoverer 2.2 Software.
2.11 Molecular docking simulation and binding site
Molecular docking analysis was performed using the ClusPro webserver, which provides a dedicated peptide-protein docking feature. In this study, DPP4 was designated as the receptor protein, while the peptide VLVLDTDYK functioned as the ligand. The peptide-protein complex was selected based on the largest cluster generated by ClusPro’s docking algorithm [30]. The resulting complex structure was visualized using PyMOL and LigPlot+, and the binding affinity was evaluated using the PRODIGY webserver [31,32].
2.12 Statistical analysis
Each analysis was conducted in triplicate, and the results are presented as mean ± standard deviation. Data were statistically analyzed using SPSS software (SPSS Inc.) through one-way analysis of variance (ANOVA) followed by Duncan’s multiple range test (DMRT). A p-value of less than 0.05 (P < 0.05) was considered statistically significant.
Results and Discussion
3.1 Profile of pH value and total acidity
The strains L. rhamnosus RAL27, Limosilactobacillus fermentum RAL29, and L. rhamnosus RAL43, when inoculated into A2 milk, exhibited normal growth. This was evidenced by their viability, which ranged from 8.68 to 9.11 log CFU.mL-1, post-fermentation pH values ranging from 4.43 to 4.66, pH changes (ΔpH) between 2.14 and 1.37, and titratable acidity between 0.65% and 0.74% (Table 1). All of these parameters are consistent with typical characteristics of fermented milk products. Comparison with previous studies [26,32,33] revealed no significant differences, with pH values after 24 hours of LAB incubation typically ranging from 3.8 to 4.8 and titratable acidity from 0.6% to 1.6%. These results confirm that A2 milk serves as an appropriate substrate for the growth of all three LAB isolates and holds potential as a starter culture for producing fermented milk or yogurt-like functional products. To assess whether the three LAB i
Cutting-Edge Cheese Crafting: Exploring the Benefits of Postbiotics Coating in Pasteurized Cheese Production
Full text linkBackground and Objective: Cheese is one of the major dairy products with high nutritional value, but its susceptibility to microbial growth and early spoilage remains a challenge for the dairy industry. While chemical additives are widely applied to control microbial contamination, increasing awareness of the potential hazards of synthetic preservatives has led to a growing demand for natural alternatives. This study was designed to evaluate the antimicrobial potential of postbiotics derived from lactiplantibacillus plantarum and Lacticaseibacillus casei against common spoilage and pathogenic microorganisms in cheese, as well as to investigate their impact on the microbiological and chemical properties of cheese during storage.
Material and Methods: Postbiotics were extracted from cultures of L. plantarum and L. casei and their antimicrobial activities were tested using standard microbiological assays against Gram-positive and Gram-negative bacteria. To assess practical application, the postbiotics were applied as coatings on cheese samples either alone or in combination with whey protein concentrate (WPC). Microbiological counts, chemical parameters, and sensory evaluation were performed throughout storage. Data were analyzed to determine the comparative effectiveness of treatments.
Results and Conclusion: The findings showed that the postbiotic derived from L. plantarum demonstrated stronger antimicrobial effects, particularly against Gram-positive bacteria, compared to that from L. casei. However, when combined with WPC, the antimicrobial activity of both postbiotics declined. Despite this limitation, postbiotics applied alone significantly reduced microbial counts during storage without altering the main chemical properties of the cheese. Sensory evaluation confirmed the overall acceptability of postbiotic and postbiotic-WPC treated samples. In conclusion, postbiotics can serve as promising natural antimicrobial agents in cheese preservation, though further optimization is required to enhance their activity when combined with protein-based carriers such as WPC.
Keywords: Antimicrobial activity, Cell-free supernatant, Cheese, Lactic acid bacteria, Postbiotic
Introduction
The food industry consistently faces substantial challenges from pathogenic and spoilage microorganisms, which are major drivers of foodborne diseases (FBDs), product quality degradation, and significant economic losses [1]. Globally, FBDs remain a pressing public health issue, with more than 600 million cases and nearly 420,000 deaths reported annually due to contaminated food and water [2,3]. These statistics have reinforced the urgency of strengthening food safety measures and minimizing contamination throughout production, processing, and storage stages [4,5]. At the same time, consumer concerns over the potential health risks associated with chemical preservatives, alongside the increasing demand for minimally processed foods, have fueled interest in natural preservation strategies [6,7]. Such approaches not only lessen dependence on artificial additives but also align with the growing trend toward clean-label products.
In this regard, biological protection has emerged as a promising strategy, harnessing beneficial microorganisms and their antimicrobial metabolites to suppress the proliferation of spoilage and pathogenic organisms [4]. Probiotics, especially lactic acid bacteria (LAB), have drawn considerable attention for their ability to generate bioactive substances such as organic acids, hydrogen peroxide, diacetyl, and bacteriocins [8]. Among these, LAB species such as Lactobacillus and Bifidobacterium are generally recognized as safe (GRAS) and have been widely employed for decades in the fermentation of diverse foods, including dairy products, cereals, and vegetables [9]. More recently, growing attention has been directed toward postbiotics, defined as non-viable microbial cells, cellular components, or metabolites that provide functional health benefits [10]. Compared with probiotics, postbiotics present notable practical advantages: they are independent of cell viability, exhibit greater stability under processing and storage conditions, and pose a lower risk of antibiotic resistance or incompatibility with food matrices. Additionally, postbiotics retain antimicrobial activity across a wide range of pH and temperature conditions, are capable of disrupting pathogenic biofilms, and can neutralize harmful contaminants such as pesticides and mycotoxins. In food systems, they have been investigated both as direct additives and as functional components of active packaging technologies, thereby overcoming limitations associated with the use of live microbial cultures [4].
Cheese provides a particularly critical application, as it is highly vulnerable to microbial contamination during both processing and storage. Among potential threats, Listeria monocytogenes is of significant concern due to its ability to withstand stress conditions and its high fatality rate in human infections [11,12]. Epidemiological evidence has repeatedly linked outbreaks of listeriosis to cheeses manufactured from raw or inadequately pasteurized milk [13], underscoring the urgent demand for innovative, safe, and effective antimicrobial approaches in dairy preservation.
Recent investigations have demonstrated that postbiotics and bacteriocin-like compounds derived from lactic acid bacteria (LAB) are capable of inhibiting pathogenic bacteria across diverse food matrices, including meat, seafood, and dairy products [14–19].
In parallel, whey protein, a major by-product of cheese production, has attracted considerable interest as a functional material for edible coatings and packaging, owing to its excellent barrier properties and strong film-forming capacity [11]. Incorporating antimicrobial postbiotics into whey protein systems may therefore offer dual advantages: enhancing microbial safety and prolonging shelf life while preserving desirable sensory characteristics.
Although evidence supporting postbiotics as natural preservatives is growing, relatively few studies have systematically assessed their performance in real cheese systems, particularly when combined with whey protein–based coatings. This gap in knowledge constrains a comprehensive understanding of their effectiveness under practical conditions.
The present study aims to bridge this gap by examining the antimicrobial activity of postbiotics derived from lactiplantibacillus plantarum and Lacticaseibacillus casei against key dairy pathogens, while also evaluating the microbial and chemical quality of cheese coated with whey protein concentrate (WPC) enriched with these postbiotics. This integrated strategy offers a novel, effective, and sustainable approach to improving food safety and preservation in dairy products.
Materials and Methods
2.1 Study design
This descriptive-analytical study was conducted between 22 November 2022 and 15 September 2023. The study protocol was reviewed and approved by the Medical Ethics Committee of Gonabad University of Medical Sciences (IR.GMU.REC.1401.073).
2.2 Bacterial strains
Three lactiplantibacillus plantarum strains were isolated from traditional Iranian cheeses [20]. In addition, one Lacticaseibacillus casei strain (1608 PTCC, IBRC of Iran), Listeria monocytogenes (7644 ATCC), Escherichia coli (1338 PTCC), and Staphylococcus aureus (1431 PTCC) were obtained from the Laboratory of Specialization in Nutrition, Mashhad University of Medical Sciences.
2.3 Postbiotic preparation
Each lactic acid bacterial strain was cultured separately in MRS broth medium and incubated under anaerobic conditions at 37 °C for 24 hours. The cultures were then centrifuged at 6000 rpm for 10 minutes at 4 °C. The resulting cell-free supernatants were filtered through a 0.4 µm membrane filter and subsequently freeze-dried (freezing temperature −83 °C, pump pressure 0.0026 mBar, storage temperature −60 °C) for use in subsequent experiments [21].
2.4 Chemical analysis of cell-free supernatants of Lactobacillus sp.
The chemical compounds of postbiotics were identified following the method described by Ryan et al. (2009), with minor modifications. For derivatization, 1 mL of the supernatant was mixed with 10 mL of absolute ethanol and 15 drops of sulfuric acid (97%), and the mixture was stirred at 80 °C for one hour. After cooling, 20 mL of distilled water was added, and extraction was performed five times with 50 mL of dichloromethane, collecting the lower phase each time. The pooled extracts were combined with 50 g of sodium sulfate and passed through filter paper. The solvent was then removed using a vacuum evaporator at 50 °C, and the remaining residue was injected into the gas chromatography–mass spectrometry (GC–MS) system.
The chemical composition of the derivatized postbiotics was analyzed using a GC instrument (Agilent HP-6890, Agilent Technologies, Palo Alto, CA, USA) operated with Agilent GC/MS Mass Hunter Acquisition software. The GC system was equipped with an Agilent HP-5ms column (30 m length, 0.25 mm inner diameter, 0.25 μm film thickness). Helium was used as the carrier gas at a flow rate of 1 mL/min. The oven temperature was programmed to increase from 110 °C to 240 °C at a rate of 4 °C/min with no hold time. A 10 μL sample was injected with a 5:1 split ratio [22].
2.5 Antimicrobial Activity In-vitro
2.5.1 Agar-well diffusion
Three pathogens (L. monocytogenes, E. coli, and S. aureus) were inoculated separately at a concentration of 5 log10 CFU/mL onto the surface of Muller Hinton Agar (MHA) plates. Wells with an 8 mm diameter were then created in the agar, and 100 µL of postbiotic suspensions at concentrations of 5%, 10%, and 20% were added to the wells. Plates were incubated aerobically at 37 °C for 24–48 hours. Nisin (625 IU/mL) and sterile distilled water served as the positive and negative controls, respectively. Antimicrobial activity was expressed as the mean diameter (mm) of inhibition zones, measured as the clear areas surrounding the wells. Each assay was performed in triplicate [23].
2.5.2 Determination of minimum inhibitory concentra-tion (MIC) and minimum bactericidal concentration (MBC) by the microdilution method
MIC and MBC values were determined according to the Clinical and Laboratory Standards Institute (CLSI, 2017) guidelines. After 24 hours of aerobic incubation at 37 °C, the wells were examined for turbidity. To determine the MBC, 10 µL samples from wells without turbidity (corresponding to MIC and higher concentrations) were streaked onto MHA plates in triplicate and incubated under the same conditions [24].
2.5.3 Anti-listeria activity of coatings containing postbiotics
To prepare the coating solution, 50 mL of deionized water was heated to 90 °C in a bain-marie, and 4.34 g of whey protein concentrate (WPC; protein 81.2%, lactose 7.4%, fat 6%, moisture 5%, ash 4%, pH 6.1; Alinda, Greece) was fully dissolved. The solution was maintained at this temperature for 45–60 minutes, during which 2.71 g of glycerol and 0.081 g of Tween 80 were added. After cooling, cell-free supernatants (CFS) were incorporated at concentrations corresponding to MIC and MBC [25]. The anti-listeria activity of coatings containing postbiotics was then evaluated using the agar-well diffusion method. CFS without coating, at equivalent concentrations, was included as a positive control [26].
2.6 Inoculation and coating of cheese samples
A pasteurized traditional cheese, commercially available in local markets, was selected for this study. The cheeses analyzed were pasteurized varieties inoculated with a fungal starter culture. Four treatment groups were prepared to evaluate microbial and chemical characteristics over storage on days 0, 1, 2, 4, 6, 8, and 10 (Table 1).
Cheese pieces of approximately 10 g (3 × 3 × 1 cm) were inoculated with L. monocytogenes at a level of 1 × 10⁵ CFU/g by spreading 1 mL of an appropriately diluted suspension onto the surface [18]. Samples were then allowed to stabilize to ensure bacterial adherence. The treatments were as follows:
Inoculated cheese without further treatment,
Cheese immersed in CFS solution at the designated concentration,
Cheese coated with WPC solution without CFS, and
Cheese coated with WPC solution containing CFS (immersion for 4–5 minutes).
All samples were stored at 4 °C until further analysis.
2.7 Microbial analyses in-situ
monocytogenes, total viable microorganisms, molds, and yeasts were enumerated using Palcam Agar, PCA, and SDA media, respectively. Palcam and PCA plates were incubated at 37 °C for 48 hours, while SDA plates were incubated at 25 °C for 3–5 days [26]. The enumeration of molds and yeasts was carried out according to the Iranian National Standard No. 2406: Microbiology of milk and milk products — Specifications and test methods [27].
2.8 Chemical analyses
The pH of cheese samples was measured using a pre-calibrated pH meter, and moisture content was determined by the gravimetric method on the designated sampling days [17,21].
2.9 Sensory analyses
Cheese slices coated with cell-free supernatants, free of L. monocytogenes, were evaluated for taste, color, aroma, texture, and overall acceptability by a panel of 10 semi-trained assessors using a 5-point hedonic scale [15]. All participants were adults above the legal age and voluntarily provided written informed consent in compliance with ethical standards for human subject research. Evaluations were conducted under identical environmental and temporal conditions to ensure consistency.
2.10 Statistical analyses
Statistical analyses were performed using SPSS software version 26. Mean values from three independent replicates were compared between two groups using the independent t-test, while comparisons among more than two independent groups were carried out using one-way ANOVA. Changes in data trends over the 10-day storage period were analyzed using one-way repeated measures ANOVA. A p-value of <0.05 was considered statistically significant.
Results and Discussion
3.1 Antimicrobial activity of postbiotics
Postbiotics derived from both Lactobacillus species demonstrated inhibitory effects against the three tested pathogens, with higher postbiotic concentrations corresponding to stronger antimicrobial activity (Fig. 1).
Fig. 1. Antimicrobial activity of postbiotics against L. monocytogenes evaluated by the agar-well diffusion method.
The greatest inhibition was observed with the postbiotic from L. plantarum at a 20% concentration against L. monocytogenes, producing an inhibition zone of 30.67 ± 0.57 mm. In contrast, the weakest inhibition was observed with the postbiotic from L. casei at a 5% concentration against S. aureus, yielding an inhibition zone of 8.63 ± 0.55 mm. Across all concentrations, the postbiotic of L. plantarum exhibited significantly stronger inhibitory activity against L. monocytogenes and S. aureus compared to that of L. casei (p < 0.05) (Tables 2–4). For E. coli, no significant differences were detected between the two postbiotics except at the 10% concentration (Table 3). These findings suggest that postbiotics from L. plantarum are more effective against Gram-positive pathogens than those from L. casei.
Overall, the results indicate that L. plantarum postbiotics exert stronger antimicrobial effects against Gram-positive bacteria, with the most consistent reductions achieved through the “CFS only” treatment rather than the CFS–WPC combination. The maximum reduction compared to control (~0.80 log CFU/g for L. monocytogenes at day 2) declined over subsequent storage days, while pH, moisture, and sensory acceptability remained unaffected. This strain- and target-dependent pattern is consistent with previous evidence showing that LAB-derived cell-free supernatants inhibit Gram-positive pathogens primarily through organic acids and bacteriocin-like metabolites, mechanisms that involve pH reduction and disruption of microbial membranes [4,6,9,28–30]. Arena et al. also reported strong anti-pathogen activity of L. plantarum supernatants, with acidification identified as a major contributing factor [31,32]. The reduced inhibitory effect observed when CFS was incorporated into a whey protein carrier is consistent with the well-documented “matrix effects” described in the literature. Previous studies have shown that interactions between proteins and bioactive metabolites, along with the barrier properties of protein films, can delay the release and reduce the bioavailability of antimicrobial compounds [11,26,33–36]. Similar patterns of initial but transient inhibition, followed by partial recovery of pathogen populations, have been reported in fresh cheese, meat, and fish products treated with CFS- or bacteriocin-based films [15–17,19].
In agreement with these findings, the present study demonstrated that chemical attributes (pH and moisture) and sensory acceptance were not adversely affected, supporting the feasibility of integrating postbiotics into dairy preservation systems. However, further optimization of carrier composition and release kinetics is required to maximize antimicrobial effectiveness [37].
The MIC and MBC values of L. plantarum postbiotics against the three tested pathogens were determined as 31.25 mg/mL and 62.5 mg/mL, respectively, for Gram-positive bacteria, and 125 mg/mL for E. coli. These results highlight a greater inhibitory effect against Gram-positive bacteria at lower concentrations (Table 5).
The postbiotic of L. casei exhibited a comparable inhibitory effect against L. monocytogenes to that of L. plantarum, except at the 5% concentration, where a difference was observed in comparison with E. coli (Table 6). No significant differences were detected in the inhibition of S. aureus and E. coli (p > 0.05) (Table 7).
The MIC of L. casei postbiotics against L. monocytogenes was higher (62.5 mg/mL) than that observed for L. plantarum, although both species showed identical MBC values. For E. coli, the MBC of L. casei postbiotics was lower than that of L. plantarum. In contrast, for S. aureus, the MIC and MBC values were the same for both postbiotics.
Arrioja et al. (2020) similarly reported that CFS derived from L. plantarum exhibited stronger inhibitory activity against most pathogens compared with CFS from L. casei [33]. Arena et al. (2016) further demonstrated variability in inhibition zones and MICs among different L. plantarum strains against various pathogens, with generally greater effects observed against Gram-positive bacteria [31]. Consistent with the present findings, Tenea and Barrigas (2018) showed that bacteriocin-containing supernatants from L. plantarum (Cys5-4) exhibited variable inhibitory effects against two E. coli strains [7]. Koohestani et al. (2018) also reported that CFS from L. casei 431 produced an inhibition zone of 13 mm against S. aureus, which closely aligns with the current results [23]. In contrast, Yordshahi et al. (2020) documented smaller inhibition zones for L. plantarum postbiotics against L. monocyte-genes compared with those observed in this study [21].
The antimicrobial activity of lactic acid bacteria has been attributed to a range of metabolites, including organic acids, polyamines, proteases, and bacteriocins. The effectiveness of postbiotics depends on multiple factors such as bacterial strain, metabolite composition and concentration, preparation method, and pathogen type. Numerous studies have confirmed that Gram-positive bacteria are generally more susceptible to the antagonistic compounds in postbiotics than Gram-negative bacteria, consistent with the findings of the present work [38].
Results from the agar-well diffusion assays indicated that postbiotics incorporated into WPC coating solutions at MBC concentrations generally exhibited reduced inhibition against L. monocytogenes compared to postbiotics applied alone (Table 8). However, the combination of L. plantarum postbiotics with WPC coatings produced greater inhibition than L. casei postbiotics at equivalent concentrations.
Based on the in-vitro assays, the L. plantarum postbiotic at twice the MBC concentration was identified as the most effective formulation and was subsequently selected for testing in the food model.
3.2 Identification of chemical compounds of extracted CFS
The chemical compounds identified in the postbiotics derived from L. plantarum and L. casei are presented in their respective chromatograms (Figs. 2 and 3).
Sezen Özcelik et al. (2016) reported that LAB strains are particularly efficient producers of succinic acid, especially when cultivated in MRS broth. Succinic acid serves as a key intermediate in the Krebs cycle and a common fermentation byproduct, reflecting the strong metabolic capacity of LABs. The quantity and composition of organic acids produced by LABs vary considerably across strains and culture media, with pH and temperature exerting significant influence [28]. Similarly, Iqbal Hossain et al. (2021) identified nine distinct organic acids, including succinic acid, in several LAB strains such as L. plantarum, highlighting the diverse metabolite production potential of these bacteria [29]. In the present study, the derivatization technique applied proved particularly effective in detecting compounds such as esters and alkanes.
Shehata et al. demonstrated that LABs synthesize antifungal metabolites that differ across strains, with organic acids and hydrogen peroxide serving as the primary contributors to antifungal activity. Their study identified compounds such as pentadecane and 2,4-di-tert-butylphenol, both known to inhibit foodborne pathogens and fungi. Additionally, antimicrobial compounds including 6-octadecenoic acid methyl ester and hexadecanoic acid methyl ester—also de
Laparoscopic Approach to Impalpable Undescended Testes: A Single-Centre Evaluation: Laparoscopic Approach to Impalpable Undescended Testes
No full textIntroduction: Undescended testes (UDT) is the congenital anomaly affecting children and is one of the most common anomaly. The failure of the testes either unilateral or bilateral to reach the processus vaginalis or scrotum 10-12 weeks after birth is termed as undescended testes or cryptorchidism. Impalpable undescended testes presents diagnostic and management challenges in the pediatric population.
AIM: Evaluating the role of laparoscopy in managing impalpable undescended testes.
Materials and methods: The observational prospective study, conducted in the Department of General Surgery between January 2021 and December 2023. Patients who complained of absent or impalpable testes were clinically assessed and those with impalpable testes were included. Depending on the findings of diagnostic laparoscopy, testes were either brought down to the scrotum in the single- or two-staged procedure (Stephen Fowler) or removed.
Results: 25 patients with impalpable undescended testes were included, and 28 procedures were performed. Of the 25 patients, 14 had right-sided UDT, eight had left-sided UDT, and three had bilateral UDT. All the patients underwent diagnostic laparoscopy. Fourteen (50%) had high intra-abdominal testes, 10(35.7%) had low intra-abdominal testes, 3(10.7%) entered the deep ring with vas and vessels, and one patient had nubbin testis. Fifteen patients underwent single-stage laparoscopic orchidopexy, 7patients underwent two-staged procedures, three patients had vas and vessels entering the deep ring and underwent open inguinal orchidopexy, while three patients underwent orchidectomy.
Conclusion: Ultrasonography (USG) and magnetic resonance imaging (MRI), are the imaging modalities which play a crucial role in localization of impalpable testes. However, laparoscopy provides the most accurate interventional option by demonstrating anatomy.
Adjunctive Treatment of Periodontal Defects Using Fibroblast Growth Factor 2: A Review of Case Reports with Long-term Follow-up
Full text linkObjective(s): Application of fibroblast growth factor 2 (FGF2) as an adjunctive treatment in periodontal regeneration is a treatment modality. Several recent case reports describe the application of FGF-2 in different periodontal defects with detailed information and long-term follow-ups. The aim of this review was to assess the effect of FGF-2 on periodontal regeneration and patient quality of life in cases with long-term follow-up. Methods: An electronic search was performed in PubMed Central, Scopus, and web of science databases from 1990 until December 2023. The search included all case reports in which FGF2 was used for periodontal defect treatment with long-term follow-up. Case series which described detailed data of their cases were also evaluated. Ten articles including 12 patients, 23 teeth, and 25 defects were included in the study. Results: Most of the treated defects were infrabony defects (84%), followed by furcation defects (12%). Probing depth (PD) reduction and clinical attachment loss (CAL) gain were seen in all defects and evidence of bone fill was documented. All cases had a follow-up duration of at least 12 months, with the greatest follow-up time of 9 years. Conclusion: Adjunctive treatment of periodontal defects using FGF-2 is an effective and stable treatment modality that provides patients’ satisfaction. However, more studies in this field are recommended