1,720,965 research outputs found
Valutazione tecnologica e probiotica mediante approcci fisiologici e molecolari di nuovi batteri lattici isolati da alimenti fermentati tradizionali
Get PDFIn primo luogo, è stata studiata la diversità microbica e le proprietà nutrizionali della "Yellow Curd" (Kashk zard) un alimento fermentato tradizionale persiano, utilizzando approcci microbiologici classici e analisi del metabarcoding dell'rRNA 16S. L'analisi metagenomica ha rivelato che i batteri lattici, in particolare i generi Lactobacillus, Pediococcus e Streptococcus, erano dominanti in Yellow Curd. Inoltre, sono stati effettuati l'isolamento, la caratterizzazione e l'identificazione di nuovi LAB con potenziale tecnologico e proprietà probiotiche, nonché la preparazione e caratterizzazione di alimenti funzionali. I risultati hanno rivelato che i ceppi di Pediococcus acidilactici IRZ12A e IRZ12B isolati dal cibo fermentato tradizionale persiano erano sicuri e dotati di proprietà probiotiche come la resistenza a condizioni gastrointestinali simulate e l'effetto ipocolesterolemizzante. Il genoma completo di questo promettente ceppo di P. acidilactici IRZ12B con il miglior effetto ipocolesterolemizzante è stato sequenziato e l'analisi in silico ha evidenziato l'assenza di plasmidi, geni di resistenza agli antibiotici trasmissibili e fattori di virulenza. Pertanto, abbiamo cercato di utilizzare P. acidilactici IRZ12B con tre piante officinali, ovvero Malva, Calendula ed Echinacea, per prove di fermentazione e, al fine di verificare la possibile produzione di alimenti funzionali. Le piante fermentate con P. acidilactici IRZ12B sono state utilizzate per studiarne la funzionalità su cellule sane e cancerose. I risultati hanno mostrato che le erbe fermentate con il ceppo probiotico non hanno avuto alcun effetto citotossico sulle cellule intestinali umane sane (Caco-2 differenziato) e potrebbero invece ridurre significativamente la vitalità cellulare sulle cellule del cancro al seno (MCF-7).
Successivamente, dato che alcuni ceppi probiotici non hanno tollerato la condizione di conservazione e il passaggio gastrointestinale umano, in questa tesi, per la prima volta, abbiamo valutato l'uso della molecola di 2′-fucosillattosio in microincapsulazione e l'abbiamo confrontata con altre molecole note, come la gelatina e l'inulina. Le microcapsule, ottenute con la tecnica dell'estrusione, sono state valutate in termini di efficienza di incapsulamento, stabilità di conservazione, resistenza alle condizioni gastrointestinali e cinetica di rilascio cellulare. Le microcapsule a base di alginato hanno mostrato caratteristiche interessanti, inclusa la buona capacità di proteggere le cellule batteriche dalle difficili condizioni gastrointestinali simulate. Rispetto ad altre molecole utilizzate in microincapsulazione insieme all'alginato, come la gelatina e l'inulina, il 2'-fucosillattosio ha evidenziato un rilascio estremamente rapido e abbondante di cellule batteriche dalle capsule all'interno di un fluido intestinale simulato.
Infine, sono state studiate le proprietà tecnologiche di un LAB isolato da un tradizionale alimento indiano fermentato (Dahi). Si è rilevato che il ceppo Limosilactobacillus fermentum ING8 possiede proprietà tecnologiche molto interessanti, come la capacitò di utilizzo del galattosio, l'attività antimicrobica, la produzione di esopolisaccaridi e la capacità di sopravvivenza alla conservazione a lungo termine a temperatura di refrigerazione. La valutazione completa del genoma di questo promettente ceppo ha confermato l'assenza di possibili elementi deleteri, come geni acquisiti di resistenza agli antibiotici, geni di virulenza o geni correlati all'emolisi, mentre sono stati rilevati tutti i geni strutturali correlati all'operone galattosio e alla produzione di EPS.Firstly, we have studied the microbial diversity and nutritional properties of “Yellow Curd” (Kashk zard) a traditional Persian fermented food, using classical microbiology approaches and 16S rRNA metabarcoding analysis. The metagenomics analysis revealed that lactic acid bacteria, particularly the genera Lactobacillus, Pediococcus and Streptococcus, were dominant in Yellow Curd. In addition, isolation, characterization and identification of new LAB with technological potential and probiotic properties, as well as functional foods preparation and characterization, have been carried out. The outcomes revealed that Pediococcus acidilactici strains IRZ12A and IRZ12B isolated from traditional Persian fermented food were safe and endowed with probiotic properties such as resistance to simulated gastrointestinal conditions and hypocholesterolemic effect. The complete genome of this promising P. acidilactici IRZ12B strain with the best cholesterol-lowering effect was sequenced, and the in-silico analysis evidenced the absence of plasmids, transmissible antibiotic resistance genes and virulence factors. Therefore, we tried to use P. acidilactici IRZ12B and three officinal plants, namely Malva, Calendula and Echinacea, for fermentation trials and consequently, possible functional food production. The fermented herbs with P. acidilactici IRZ12B were used to study their functionality on healthy and cancer cells. Results showed that fermented herbs with the probiotic strain did not have any cytotoxic effect on healthy human intestinal cells (differentiated Caco-2); however, they could significantly reduce cell viability on breast cancer cells (MCF-7).
Secondly, some beneficial strains did not tolerate the storage condition and the human gastrointestinal passage. In this thesis, for the first time, we evaluated the use of 2′-fucosyllactose molecule in microencapsulation, and compared it with other known molecules, such as gelatin and inulin. Microcapsules, obtained by the extrusion technique, were evaluated in terms of encapsulation efficiency, storage stability, gastrointestinal condition resistance, and cell release kinetics. The alginate-based microcapsules showed interesting features, including the good capability to protect bacterial cells from harsh simulated gastrointestinal conditions. Compared to other molecules used in microencapsulation together with alginate, such as gelatin and inulin, 2’-fucosyllactose evidenced an extremely quick and abundant release of bacterial cells from the capsules inside a simulated intestinal fluid.
Lastly, we have studied the technological properties of LAB isolated from a traditional fermented Indian food (Dahi). As a result, strain Limosilactobacillus fermentum ING8 was found to possess a safe status with very interesting technological properties, such as galactose utilization, antimicrobial activity, exopolysaccharide production and survivability to long-term storage at refrigeration temperature. The complete genome evaluation of this promising strain confirmed the absence of possible deleterious elements, such as acquired antibiotic resistance genes, virulence genes, or hemolytic-related genes. However, all structural genes related to galactose operon and EPS production have been detected
Whole-genome sequence and comparative genome analysis of Lactobacillus paracasei DTA93, a promising probiotic lactic acid bacterium
No full textThe complete genome sequence of Lactobacillus paracasei DTA93, isolated from healthy infant feces is reported, along with in silico genetic analyses of its main features. The 3.02 Mb sequenced genome possesses 2990 protein-coding sequences distributed on 341 SEED subsystems. In previous in vitro studies, this strain demonstrated interesting probiotic properties, anti-cancer activity, and anti-bacterial activity. The whole-genome sequencing allowed to identify DTA93 as L. paracasei and to precisely place it within the L. casei group, since it shows the highest number of orthologous genes/proteins in common with the type strain L. paracasei ATCC 25302T. In silico analyses revealed the absence of potentially negative traits, such as presence of prophages, transmissible antibiotic resistance and virulence factors. The results provided here considerably increased the amount of information available on DTA93 in favor of its possible use in food products as health-promoting culture. The complete genome data have been deposited in GenBank under the accession number VTYT00000000
Lactic Acid Bacteria in Dairy Foods: Prime Sources of Antimicrobial Compounds
Get PDFhis review presents an in-depth examination of fermented dairy products, highlighting their significance as rich sources of antimicrobial agents. Through a comprehensive study of microbial activities during fermentation, we identify and discuss the rise of bioactive elements with antimicrobial characteristics. Bacteriocins such as nisin and pediocin play a significant role, as do organic acids such as lactic and acetic acid in providing antimicrobial activity. Challenges, including the enzymes, heat and pH sensitivity of certain compounds, are also touched upon, emphasizing the need for stable delivery for consistent efficacy. Our discussion covers various compounds, including bacteriocins, organic acids, and bioactive peptides, detailing their functions, action mechanisms, and potential applications. Moreover, this review discusses the emerging role of genetic engineering in optimizing lactic acid bacteria strains and exploring the potential of genetically modified organisms in improving the production and efficacy of antimicrobial compounds in dairy products. Additionally, we emphasize the interaction between beneficial microbes and their antimicrobial byproducts and discuss strategies for enhancing the synthesis of these antimicrobial compounds. The review highlights the nutritional significance of fermented dairy items and their potential as a rich source of compounds crucial for improving food safety. Additionally, the review explores challenges and potential solutions related to the stability of these compounds, ensuring their consistent efficacy and contribution to overall well-being
Complete Genome Sequence and Carbohydrates-Active EnZymes (CAZymes) Analysis of Lactobacillus paracasei DTA72, a Potential Probiotic Strain with Strong Capability to Use Inulin
No full textThe whole genome sequence of Lactobacillus paracasei DTA72, isolated from healthy infant feces, is reported, along with the Carbohydrates-Active enZymes (CAZymes) analysis and an in silico safety assessment. Strain DTA72 had previously demonstrated some interesting potential probiotic features, such as a good resistance to gastrointestinal conditions and an anti-Listeria activity. The 3.1 Mb sequenced genome consists of 3116 protein-coding sequences distributed on 340 SEED subsystems. In the present study, we analyzed the fermentation capability of strain DTA72 on six different carbohydrate sources, namely, glucose, fructose, lactose, galactose, xylose, and inulin by using phenotypical and genomic approaches. Interestingly, L. paracasei DTA72 evidenced the best growth performances on inulin with a much shorter lag phase and higher number of cells at the stationary phase in comparison with all the sugars tested. The CAZyme analysis using the predicted amino acid sequences detected 80 enzymes, distributed into the five CAZymes classes. Moreover, the in silico analysis revealed the absence of blood hemolytic genes, transmissible antibiotic resistances, and plasmids in DTA72. The results described in this study, together with those previously reported and particularly the strong capability to utilize inulin as energy source, make DTA72 a very interesting potential probiotic strain to be considered for the production of synbiotic foods. The complete genome data have been deposited in GenBank under the accession number WUJH00000000. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
A critical issue on microbiological cut-off value of ampicillin resistance in Lactiplantibacillus plantarum
No full textAim Comprehensive evaluation of antibiotic susceptibility patterns in Lactiplantibacillus plantarum strains isolated from grape marc, based on genomic and phenotypic assessment. Methods and results We assessed the antibiotic resistance-susceptibility patterns of 20 L. plantarum strains for 16 antibiotics. Genomes of relevant strains were sequenced for in silico assessment and comparative genomic analysis. Results showed high MIC values for spectinomycin, vancomycin, and carbenicillin, indicating natural resistance to these antibiotics. Besides, these strains revealed MIC values for ampicillin higher than previously established by the EFSA, indicating the possible presence of acquired resistance genes in the genomes. However, genomic analysis by complete genome sequencing did not reveal presence of ampicillin resistance genes. Conclusion Comparative genomic analysis between our strains and other L. plantarum genomes present in the literature showed several substantial genomic differences, and suggested the need to adjust the cut-off value for ampicillin in L. plantarum. However, further sequence analysis will reveal how these strains have acquired antibiotic resistance
Genomic and phenotypic assessments of safety and probiotic properties of Streptococcus macedonicus strains of dairy origin
No full textIn this work, we studied the genomes and characterized some probiotic features of four S. macedonicus strains isolated from dairy environments in Italy that already had indicated some technological potential. The genomes of these strains were sequenced and used for genomic in silico studies. All strains were also evaluated for hemolytic activity, susceptibility to most commonly used antibiotics and probiotic potential, such as resistance to simulated gastrointestinal conditions, bile salts hydrolytic activity and adhesion ability to HT-29 human colorectal adenocarcinoma cells. Results revealed that one strain, namely S. macedonicus 211MA, was found to possess probiotic properties, such as resistance to simulated gastrointestinal conditions as well as adherence capability to human epithelial cells. In silico analyses revealed that S. macedonicus 211MA displayed the least number of single copy genes, genomic islands regions and gene content classified as virulence factors when compared to other S. macedonicus and S. gallolyticus strains. Moreover, the maximum gene content associated with bacterial stress response category and the presence of the opuCABCD operon, not detected in the other strains, were correlated with S. macedonicus 211MA capability to resist to low pH and to show higher adhesion to HT-29 human cells. This is the first report on the presence of opuCABCD operon in S. macedonicus and its possible relation with attachment ability and stress response. © 2019 Elsevier Lt
Comparative evaluation of cheese whey microbial composition from four Italian cheese factories by viable counts and 16S rRNA gene amplicon sequencing
Get PDFThe microbiota of cheese whey from four dairy companies located in the North-East of Italy was evaluated during winter and spring using both culture-dependent and culture-independent methods. Although no significant differences were observed (p > 0.05) for any of the six microbial categories analysed by plate counting among the dairy companies, significant differences at the family and genus level were revealed by linear discriminant analysis (LDA). In particular, variations in the abundance of the families Pseudomonadaceae and Enterobacteriaceae, as well as of the genus Acinetobacter were observed and positively correlated with plate count results (p < 0.05). The combined use of culture-dependent and culture-independent approaches gave a better description of the hygienic conditions and food safety aspects and could therefore be suggested as a useful integrated approach. © 2020 Elsevier Lt
New insights into the raw milk microbiota diversity from animals with a different genetic predisposition for feed efficiency and resilience to mastitis
Get PDFThe main objective of this study was to assess the microbiota diversity in milk samples collected from Holstein cows with different estimated breeding values for predicted feed efficiency, milk coagulation, resilience to mastitis, and consequently, to study its effects on milk quality. One hundred and twenty milk samples were collected in two seasons (summer and winter) from different commercial dairy farms in the Nord-east of Italy. For each trait, 20 animals divided into two groups of the high (10 cows) and the low (10 cows) were selected to study the microbiota profile using 16S rRNA metabarcoding sequencing. The alpha and beta diversity analysis revealed significant differences between the high and the low groups for feed efficiency and resilience to mastitis, while no significant difference was detected for milk coagulation. Moreover, remarkable differences among the taxa were detected between the two seasons, where the winter was more diverse than summer when applied the Chao1 index. Lastly, the linear discriminant analysis (LDA) effect size (LEfSe) indicated Aerococcus, Corynebacterium, Facklamia, and Psychrobacter taxa with more abundance in the high group of feed efficiency, whereas, in resilience to mastitis, only two genera of Mycoplana and Rhodococcus were more abundant in the low group. In addition, LEfSe analysis between the seasons showed significant differences in the abundance of Bacteroides, Lactobacillus, Corynebacterium, Escherichia, Citrobacter, Pantoea, Pseudomonas, and Stenotrophomonas. These findings indicate that the different genetic predisposition for feed efficiency and resilience to mastitis could affect the raw milk microbiota and, consequently, its quality. Moreover, we found more abundance of mastitis-associated bacteria in the milk of dairy cows with a higher feed efficiency index
Microbial Diversity and Nutritional Properties of Persian "Yellow Curd" (Kashk Zard), a Promising Functional Fermented Food
No full text"Yellow curd" (YC) is one of the most popular homemade Persian fermented foods and is consumed by many people. Notwithstanding, no studies are available to date on its nutritional and microbiological composition. In this study, we examined YC samples obtained from different local markets of Sistan and Baluchestan province, Iran. The results of the chemical analyses revealed a homogenous content of protein (13.71% ± 1.07), lipids (4.09% ± 0.73), and carbohydrates (61% ± 2.13) among the samples. By comparing the average mineral content of YC with yogurt, many relevant differences were detected. Apart from the calcium content, which was similar on average to that of YC, all other minerals tested are present in higher amounts in YC than in yogurt. The analysis of the main sugars present (i.e., lactose, galactose and glucose) highlighted relevant differences among samples, indicating that different YC samples contain natural strains with different capabilities to metabolize sugars. The concentration of galactose in YC samples should be taken into consideration by galactose intolerant people. From the microbiological perspective, the metagenomics analysis revealed that lactic acid bacteria, and particularly the genera Lactobacillus, Pediococcus, and Streptococcus, were dominant in YC. The information provided shows that YC is an interesting base for the preparation of novel functional foods with a good content of beneficial bacteria
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