1,721,009 research outputs found
Microbiological and molecular characterization of commercially available probiotics containing Bacillus clausii from India and Pakistan
No full textProbiotics are actively used for treatment of diarrhoea, respiratory infections, and prevention of infectious gastrointestinal diseases. The efficacy of probiotics is due to strain-specific features and the number of viable cells; however, several reports of deviations from the label in the actual content of strains in probiotic products are a matter of concern. Most of the available data on quality focuses on probiotic products containing lactobacilli and/or bifidobacteria, while very few data are available on spore-forming probiotics. The present study evaluates the label claims for spore count and species identification in five commercial probiotic products marketed in India and Pakistan that claim to contain Bacillus clausii: Tufpro, Ecogro, Enterogermina, Entromax, and Ospor. Bacterial enumeration from three batches was done by microbiological plating methods by two independent operators. Species identification was done using PCR amplification and sequence analysis of the 16S rRNA gene, and determination of the total amount of species present in the products was done using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) analysis followed by DNA sequencing of the excised bands. Plate count methods demonstrated poor correlations between quantitative label indications and bacteria recovered from plates for Tufpro, Ecogro, and Ospor. The 16S rRNA analysis performed on bacteria isolated from plate counts showed that only Enterogermina and Ospor contained homogenous B. clausii. PCR-DGGE analysis revealed that only Enterogermina had a homogenous B. clausii population while other products had mixed bacterial populations. In conclusion, the current analysis clearly demonstrates that of the five analysed commercial probiotics, only Enterogermina followed the label claims
Microbiological Cutoff Values: A Critical Issue in Phenotypic Antibiotic Resistance Assessment of Lactobacilli and Bifidobacteria
No full textThe purpose of this study was to assess the antimicrobial resistance profiles of several strains of Lactobacillus and Bifidobacterium spp. of probiotic interest. The International Organization for Standardization method was used to determine the minimal inhibitory concentrations of the antibiotics recommended by the European Food Safety Authority (EFSA). As a result, some of the tested microorganisms showed a visible growth up to the microbiological cutoff values indicated by EFSA guidelines in 2012. We were not able to categorize these strains as susceptible or resistant on the basis of antimicrobial resistance phenotypic testing as EFSA document does not explicitly deal with such a phenotypic condition where strains grow at antibiotic concentrations up to the established cutoff value. Although a few strains have been analyzed for this study, our findings highlight a potential challenge in accurately determining the antibiotic resistance in specific strains relevant for human and animal health
QUALITATIVE AND QUANTITATIVE EVALUATION OF GUT MICROBIAL POPULATIONS IN SEVERELY OBESE PATIENTS FOLLOWING BILIO-INTESTINAL BYPASS
No full textBackground and aim: Several recent studies showed that the altered gastrointestinal
microbiota linked to obesity changes after gastric bypass in humans
and rats, and it has been suggested that these changes may underlie some of
the beneficial effects of bariatric surgery.
Material and methods: To deeply characterize the impact of weight-loss
surgery on gut microbial ecology, we collected fecal samples from severely
obese patients (n=11) before and six months after bilio-intestinal bypass.
Gut microbial populations were qualitatively and quantitatively evaluated by
Denaturing Gel Gradient Electrophoresis (DGGE), 16S ribosomal RNA gene
sequencing and real-time PCR.
Results: Obese individuals were found to harbor a distinctive community
dominated at the genus/species level by members of the clostridial clusters IV
and XIVa, specifically Roseburia/E. rectale spp, Blautia spp, Ruminococcus
spp, Dorealongicatena. Compared to pre-operative levels, the fecal microbial
profiles of patients revealed a significant increase in the proportion of Lactobacillus
crispatus, a major lactate producer, and in the population related to
Megasphaer aelsdenii, which is known to be an efficient lactate-utilizer. At
high taxonomic level, the BIBP individuals exhibited reduced Bacteroides-
Prevotella, major genera of the Bacteroidetes phylum, but no significant
differences in the relative abundance of Firmicutes in comparison with obese
patients prior to surgery.
Conclusions: The compositional shifts of the fecal microbial community
observed in this study suggest a reprogramming of the bacterial fermentation
routes in the gut following bilio-intestinal bypass. Further research is therefore
called for to understand the implications on host energy homeostasis and
support a possible contribution of gut bacteria in substantial weight loss and
metabolic improvement after bariatric surgery
Detailed analyses of the bacterial populations in processed cocoa beans of different geographic origin, subject to varied fermentation conditions
No full textThe quality of chocolate is influenced by several parameters, one of which is bacterial diversity during fermentation and drying; a crucial factor for the generation of the optimal cocoa flavor precursors. Our understanding of the bacterial populations involved in chocolate fermentation can be improved by the use of high-throughput sequencing technologies (HTS), combined with PCR amplification of the 16S rRNA subunit. Here, we have conducted a high-throughput assessment of bacterial diversity in four processed samples of cocoa beans from different geographic origins. As part of this study, we also assessed whether different DNA extraction methods could affect the quality of our data. The dynamics of microbial populations were analyzed postharvest (fermentation and sun drying) and shipment, before entry to the industrial process. A total of 691,867 high quality sequences were obtained by Illumina MiSeq sequencing of the two bacterial 16S rRNA hypervariable regions, V3 and V4, following paired-read assembly of the raw reads. Manual curation of the 16S database allowed us to assign the correct taxonomic classifications, at species level, for 83.8% of those reads. This approach revealed a limited biodiversity and population dynamics for both the lactic acid bacteria (LAB) and acetic acid bacteria (AAB), both of which are key players during the acetification and lactic acid fermentation phases. Among the LAB, the most abundant species were Lactobacillus fermentum, Enterococcus casseliflavus, Weissella paramesenteroides, and Lactobacillus plantarum/paraplantarum. Among the AAB, Acetobacter syzygii, was most abundant, then Acetobacter senegalensis and Acetobacter pasteriuanus. Our results indicate that HTS approach has the ability to provide a comprehensive view of the cocoa bean microbiota at the species level
Probiotic Microorganisms for Shaping the Human Gut Microbiota - Mechanisms and Efficacy into the Future
No full textSummary
The use of bacteria as beneficial biological agents to be used as food ingredients or as active components of food supplements dates back to the early 1900’s.
These bacteria must reach the human gut in a viable form and in numbers sufficiently high to attain a substantial presence amongst the thousands of bacteria inhabiting the gut; they have also to exert some beneficial action.
These beneficial actions have been supported by hundreds of papers, the vast majority of them dealing with subjects in which the ratio among the different bacterial groups of the gut were altered by pathological conditions; the administration of probiotic bacteria are able to restore the function of the gut microbiota.
In healthy people the action of probiotics is possibly related to different mechanisms, linked to strain-specific action of probiotics and relying on the replacement of some autochthonous bacteria with specifically selected probiotic strains
Exploring the bioaccessibility of polyphenols and glucosinolates from Brassicaceae microgreens by combining metabolomics profiling and computational chemometrics
No full textMicrogreens constitute natural -based foods with health -promoting properties mediated by the accumulation of glucosinolates (GLs) and phenolic compounds (PCs), although their bioaccessibility may limit their nutritional potential. This work subjected eight Brassicaceae microgreens to in vitro gastrointestinal digestion and large intestine fermentation before the metabolomics profiling of PCs and GLs. The application of multivariate statistics effectively discriminated among species and their interaction with in vitro digestion phases. The flavonoids associated with arugula and the aliphatic GLs related to red cabbage and cauliflower were identified as discriminant markers among microgreen species. The multi-omics integration along in vitro digestion and fermentation predicted bioaccessible markers, featuring potential candidates that may eventually be responsible for these functional foods' nutritional properties. This combined analytical and computational framework provided a promising platform to predict the nutritional metabolome-wide outcome of functional food consumption, as in the case of microgreens
Biodiversity and technological-functional potential of lactic acid bacteria isolated from pseudocereals and hemp seeds
No full textPseudocereals as Quinoa (Chenopodium quinoa), Chia (Salvia hispanica), Amaranth (Amaranthus caudatus), Buckwheat (Polygonum fagopyrum) and Hemp (Canapa sativa) produce seeds with high protein and essential amino-acid content. Moreover they are considered a good source of fiber, minerals, polyphenolic compounds, omega-3 and omega-6 fatty acids. In addition, the lack of gluten makes these seeds suitable for new consumers and celiac subjects. The use of these flours is limited due to the low baking and sensory quality of the final products, however strategies such as fermentation could improve both characteristics. The aim of this study was to identify and characterize lactic acid bacteria (LAB) communities present in these seeds in view to design novel functional starter cultures for these flours. Identification and intra-species differentiation allowed to group 66 isolates within five LAB species: Pediococcus pentosaceus (dominant in Buckwheat, Chia and Hemp) Lactobacillus paracasei (prevalent in Amaranth), Leuconostoc mesenteroides and Enterococcus mundtii (common in Quinoa) and Enterococcus faecium. The characterization of 19 representative LAB strains was focused on the technological properties (acidification, proteolytic and amylolytic activities) and the safety characteristics (biogenic amines production, antimicrobial activity against Listeria innocua and Listeria monocytogenes and antibiotic susceptibility) by both traditional and molecular approaches. All strains were able to acidify the medium to pH 4.2 - 4.5 after 24 h except for enterococci. No strain showed amylolytic and amino-acid decarboxylase activities, whereas some proteolytic activity was found in all lactobacilli strains. Three strains of L. paracasei were susceptible to all assayed antibiotics, while most of the strains displayed a double resistance pattern (Kanamycin and Tetracycline). Interestingly, two strains of pediococci exhibited antagonistic activity against Listeria.
All these data allowed the selection of one Lactobacillus paracasei and two Pediococcus pentosaceus strains as good candidates to be evaluated as starter cultures for the production of gluten-free fermented foods
The addition of polysaccharide gums to Aronia melanocarpa purees modulates the bioaccessibility of phenolic compounds and gut microbiota: A multiomics data fusion approach following in vitro digestion and fermentation
Full text linkThis study aimed to determine how the addition of gellan, guar, locust bean, and xanthan gums affected the polyphenol profile of Aronia melanocarpa puree and the human gut microbiota after in vitro gastrointestinal digestion and large intestine fermentation. The different gums distinctively affected the content and bioaccessibility of phenolics in Aronia puree, as outlined by untargeted metabolomics. The addition of locust bean gum increased the levels of low -molecular -weight phenolics and phenolic acids after digestion. Gellan and guar gums enhanced phenolic acids' bioaccessibility after fermentation. Interactions between digestion products and fecal bacteria altered the composition of the microbiota, with the greatest impact of xanthan. Locust bean gum promoted the accumulation of different taxa with health -promoting properties. Our findings shed light on the added -value properties of commercial gums as food additives, promoting a distinctive increase of polyphenol bioaccessibility and shifting the gut microbiota distribution, depending on their composition and structural features
Effects of geographic area, feedstock, temperature, and operating time on microbial communities of six full-scale biogas plants
Full text linkThe objective of this study was to investigate the effect of different animal feedings operated in two distinct PDO (protected designation of origin) cheese production areas (Parmigiano Reggiano and Grana Padano) on the microbiome of six full-scale biogas plants, by means of Illumina sequencing and qPCR techniques. The effects of feedstock (cattle slurry manure, energy crops, agro-industrial by-products), temperature (mesophilic/thermophilic), and operating time were also examined, as were the relationships between the predominant bacterial and archaeal taxa and process parameters. The different feedstocks and temperatures strongly affected the microbiomes. A more biodiverse archaeal population was highlighted in Parmigiano Reggiano area plants, suggesting an influence of the different animal feedings. Methanosarcina and Methanosaeta showed an opposite distribution among anaerobic plants, with the former found to be related to ammonium concentration. The Methanoculleus genus was more abundant in the thermophilic digester whereas representation of the Thermotogales order correlated with hydraulic retention time
Abundance and Diversity of Hydrogenotrophic Microorganisms in the Infant Gut before the Weaning Period Assessed by Denaturing Gradient Gel Electrophoresis and Quantitative PCR
Full text linkDelivery mode (natural vs. cesarean) and feeding type (breast vs. formula feeding) are relevant factors for neonatal gut colonization. Biomolecular methods have shown that the ecological structure of infant microbiota is more complex than previously proposed, suggesting a relevant presence of unculturable bacteria. It has also been postulated that among unculturable bacteria, hydrogenotrophic populations might play a key role in infant health. Sulfate-reducing bacteria (SRB), acetogens, and methanogenic archaea use hydrogenotrophic pathways within the human colon. However, to date, few studies have reported detection of hydrogenotrophic microorganisms in newborns, possibly because of limitations on available group-specific, culture-independent quantification procedures. In the present work, we analyzed 16 fecal samples of healthy babies aged 1–6 months by means of quantitative PCR (qPCR) targeting the 16S rRNA or metabolic functional genes and by denaturing gradient gel electrophoresis (DGGE). qPCR data showed quantifiable levels of methanogens, SRB, and acetogens in all samples, indicating that the relative abundances of these microbial groups were not affected by delivery mode (natural vs. caesarian). DGGE revealed a high prevalence of the Blautia genus within the acetogenic bacteria despite strong interindividual variability. Our preliminary results suggest that hydrogenotrophic microorganisms, which have been a neglected group to date, should be included in future ecological and metabolic studies evaluating the infant intestinal microbiota
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