Determining probiotic potential of exopolysaccharide producing lactic acid bacteria isolated from vegetables and traditional Indian fermented food products

The composition of Tibetan kefir grain TKG-Y and the antibacterial potential and milk fermentation ability of S. warneri KYS-164 screened from TKG-Y

This study utilized high-throughput sequencing and SEM observation to elucidate the microbial composition of a Tibetan herder's homemade kefir grain named TKG-Y. Subsequently, S. warneri KYS-164 was isolated from TKG-Y, which can produce mixed protein substances with antibacterial activity, namely bacteriocin-like inhibitory substances (BLIS). BLIS can significantly reduce the growth rate of Escherichia coli 366-a, Staphylococcus aureus CICC 10384 and mixed strains at low concentrations (1 × MIC). The presence of the warnericin-centered gene cluster in KYS-164 may explain the antibacterial properties of the BLIS. Pepsin and an acidic environment can reduce the number of colonies of KYS-164 by 2.5 Log10 CFU mL-1 within 1 h, and reduce the antibacterial activity of BLIS by 21.48%. S. warneri KYS-164 showed no antibiotic resistance and biological toxicity after 80 subcultures, while BLIS produced by 40 generations of the strain retained their inhibitory efficacy against pathogenic bacteria. After 48-hour fermentation of milk with KYS-164, volatile compounds such as aldehydes, phenols, esters, and alcohols, giving it a floral, fruity, milky, oily, and nutty aroma, were released, enriching the sensory characteristics of dairy products. This study not only revealed the bacterial colony composition information of home-made kefir grain TKG-Y but also discovered and proved that S. warneri KYS-164 has the potential to inhibit bacteria and ferment dairy products. This will provide a basis for subsequent applied research on KYS-164.

Evaluation of Probiotic Properties and Safety of Lactobacillus helveticus LH10 Derived from Vinegar through Comprehensive Analysis of Genotype and Phenotype

The probiotic potential of Lactobacillus helveticus LH10, derived from vinegar Pei, a brewing mixture, was assessed through genotype and phenotype analyses. The assembled genome was comprised of 1,810,276 bp and predicted a total of 2044 coding sequences (CDSs). Based on the whole genome sequence analysis, two bacteriocin gene clusters were identified, while no pathogenic genes were detected. In in vitro experiments, L. helveticus LH10 exhibited excellent tolerance to simulated gastrointestinal fluid, a positive hydrophobic interaction with xylene, and good auto-aggregation properties. Additionally, this strain demonstrated varying degrees of resistance to five antibiotics, strong antagonistic activity against four tested pathogens, and no hemolytic activity. Therefore, L. helveticus LH10 holds great promise as a potential probiotic candidate deserving further investigation for its beneficial effects on human health.

Fermented foods and gastrointestinal health: underlying mechanisms

Although fermentation probably originally developed as a means of preserving food substrates, many fermented foods (FFs), and components therein, are thought to have a beneficial effect on various aspects of human health, and gastrointestinal health in particular. It is important that any such perceived benefits are underpinned by rigorous scientific research to understand the associated mechanisms of action. Here, we review in vitro, ex vivo and in vivo studies that have provided insights into the ways in which the specific food components, including FF microorganisms and a variety of bioactives, can contribute to health-promoting activities. More specifically, we draw on representative examples of FFs to discuss the mechanisms through which functional components are produced or enriched during fermentation (such as bioactive peptides and exopolysaccharides), potentially toxic or harmful compounds (such as phytic acid, mycotoxins and lactose) are removed from the food substrate, and how the introduction of fermentation-associated live or dead microorganisms, or components thereof, to the gut can convey health benefits. These studies, combined with a deeper understanding of the microbial composition of a wider variety of modern and traditional FFs, can facilitate the future optimization of FFs, and associated microorganisms, to retain and maximize beneficial effects in the gut.

Nanoformulated meloxicam and rifampin: inhibiting quorum sensing and biofilm formation in Pseudomonas aeruginosa

Background: We aimed to investigate the simultaneous effects of meloxicam and rifampin nanoformulations with solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) substrates on inhibiting the quorum-sensing system of Pseudomonas aeruginosa and preventing biofilm formation by this bacterium. Methods: Antimicrobial activity of rifampin and meloxicam encapsulated with SLNs and NLCs against P. aeruginosa PAO1 was assessed by disk diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results: The SLN formulation was associated with lower doses for the MIC and minimum bactericidal concentration in comparison to NLC. Moreover, our results demonstrated that both nanoformulations were able to produce 100% inhibition of the biofilm formation of P. aeruginosa PAO1. Conclusion: All these findings suggest that meloxicam and rifampin encapsulated with SLNs could be the most effective formulation against P. aeruginosa.

Tracing probiotic producing bacterial species from gut of buffalo (Bubalus bubalis), South-East-Asia

Abstract Due to extensive application of antibiotics as growth promoters in animal feed, antimicrobial resistance has been increased. To overcome this challenge, rumen microbiologists search for new probiotics to improve the rate of livestock production. The present study was aimed to isolate and evaluate breed-specific lactic acid bacteria (LAB) as potential animal probiotics. The current study was conducted during 10 months from July 2020 to April 2021, in which a total of n=12 strains were isolated from different samples including milk, rumen, and feces of Nilli Ravi Buffaloes. These isolates were evaluated for their antimicrobial potential against common animal pathogens (Bacillus spp., E. coli, Staphylococcus aureus, Salmonella spp., Listeria spp.). All the isolates were identified using 16S rRNA gene sequencing and the phylogenetic analyses inferred that these strains showed close relations to the species of various genera; Enterococcus lactis, Pediococcus pentosaceus, Bacillus subtilis Weissella cibaria, Weissella soli, Bacillus tequilensis, Weissella bombi, Bacillus licheniformis, Lactococcus lactis, Bacillus megaterium, Lactobacillus ruminis, and Lactococcus lactis. NMCC-Ru2 has exhibited the enormous potential of antimicrobial activity, 28 mm, for Salmonella typhimurium;23 mm for Listeria monocytogenes 21 mm for E.coil. Highest resistance was seen in NMCC-Ru2 agasint test antbiotic, like 25.5 mm for Tetracycline. Overall results revesl that the probiotic profile of isolates was achieved using standard criteria, particularly with animal probiotic properties

Safety aspects, probiotic potentials of yeast and lactobacillus isolated from fermented foods in North-Eastern India, and its anti-inflammatory activity

Lactobacillus and yeast obtained from fermented foods in North-East India were tested for safety and probiotic properties. All the lactobacilli and yeast tested negative for the catalase, indole, urease, phenylalanine, hemolysis, gelatin hydrolysis, and biogenic amine production tests, indicating that they are safe to use as probiotics in food supplements. Lactiplantibacillus plantarum KGL3A (accession no. MG722814) was capable of resisting the replicated gastric fluid (pH 2) till 2 h of exposure, whereas both KGL3A and Lacticaseibacillus rhamnosus K4E (accession no. KX950834.1) strains were able to resist pH 3 till 2 h of exposure with a reduction in overall viable cell count from 7.48 log CFU/mL to 1.09 log CFU/mL and 7.77 log CFU/mL to 0.83 log CFU/mL, respectively. In vitro gastric juice simulation conditions were tolerated by the yeast Saccharomyces cerevisiae WBS2A. The cell surface hydrophobicity (CSH) towards hydrocarbons (n-hexadecane) was seen highest in L. plantarum KGL3A (77.16± 0.84%) and Limosilactobacillus fermentum KGL4 accession no. MF951099 (72.60 ± 2.33%). The percentage auto-aggregation ranged from 8.70 to 25.53 after 2 h, which significantly increased to 10.50 to 26.94 during the fifth hour for cultures. Also, a higher percentage of co-aggregation was found for the culture L. rhamnosus K4E with S. typhi (34.18 ± 0.03%), E. coli (32.97 ± 0.02 %) and S. aureus (26.33 ± 0.06 %) and for the yeast S. cerevisiae WBS2A, a higher percentage of co-aggregation was found with Listeria monocytogenes (25.77 ± 0.22%). The antioxidant activity and proteolytic activity were found to be higher for Lactobacillus helveticus K14 and L. rhamnosus K4E. The proportion of decreased cholesterol was noticeably higher in KGL4 (29.65 ± 4.30%). β glucosidase activity was significantly higher in the L. fermentum KGL4 strain (0.359 ± 0.002), and α galactosidase activity was significantly higher in the L. rhamnosus K4E strain (0.415 ± 0.016). MTT assays suggested that KGL4 and WBS2A at a lower dose did not exhibit cytotoxicity.

Analysing the dynamics of the bacterial community in pozol, a Mexican fermented corn dough

Pozol is a traditional prehispanic Mexican beverage made from fermented nixtamal dough; it is still part of everyday life in many communities due to its nutritional properties. It is the product of spontaneous fermentation and has a complex microbiota composed primarily of lactic acid bacteria (LAB). Although this is a beverage that has been used for centuries, the microbial processes that participate in this fermented beverage are not well understood. We fermented corn dough to produce pozol and sampled it at four key times to follow the community and metabolic changes (0, 9 24 and 48 h) by shotgun metagenomic sequencing to determine structural changes in the bacterial community, as well as metabolic genes used for substrate fermentation, nutritional properties and product safety. We found a core of 25 abundant genera throughout the 4 key fermentation times, with the genus Streptococcus being the most prevalent throughout fermentation. We also performed an analysis focused on metagenomic assembled genomes (MAGs) to identify species from the most abundant genera. Genes involving starch, plant cell wall (PCW), fructan and sucrose degradation were found throughout fermentation and in MAGs, indicating the metabolic potential of the pozol microbiota to degrade these carbohydrates. Complete metabolic modules responsible for amino acid and vitamin biosynthesis increased considerably during fermentation, and were also found to be abundant in MAG, highlighting the bacterial contribution to the well-known nutritional properties attributed to pozol. Further, clusters of genes containing CAZymes (CGCs) and essential amino acids and vitamins were found in the reconstructed MAGs for abundant species in pozol. The results of this study contribute to our understanding of the metabolic role of micro-organisms in the transformation of corn to produce this traditional beverage and their contribution to the nutritional impact that pozol has had for centuries in the traditional cuisine of southeast Mexico.

Probiotic Potential and Safety Assessment of Type Strains of Weissella and Periweissella Species

Although numerous strains belonging to the Weissella genus have been described in the last decades for their probiotic and biotechnological potential, others are known to be opportunistic pathogens of humans and animals. Here, we investigated the probiotic potential of two Weissella and four Periweissella type strains belonging to the species Weissella diestrammenae, Weissella uvarum, Periweissella beninensis, Periweissella fabalis, Periweissella fabaria, and Periweissella ghanensis by genomic and phenotypic analyses, and performed a safety assessment of these strains. Based on the results of the survival to simulated gastrointestinal transit, autoaggregation and hydrophobicity characteristics, as well as adhesion to Caco-2 cells, we showed that the P. beninensis, P. fabalis, P. fabaria, P. ghanensis, and W. uvarum type strains exhibited a high probiotic potential. The safety assessment, based on the genomic analysis, performed by searching for virulence and antibiotic resistance genes, as well as on the phenotypic evaluation, by testing hemolytic activity and antibiotic susceptibility, allowed us to identify the P. beninensis type strain as a safe potential probiotic microorganism. IMPORTANCE A comprehensive analysis of safety and functional features of six Weissella and Periweissella type strains was performed. Our data demonstrated the probiotic potential of these species, indicating the P. beninensis type strain as the best candidate based on its potential probiotic features and the safety assessment. The presence of different antimicrobial resistance profiles in the analyzed strains highlighted the need to establish cutoff values to perform a standardized safety evaluation of these species, which, in our opinion, should be mandatory on a strain-specific basis.

Soy yoghurts produced with efficient GABA (γ-aminobutyric acid)-producing Lactiplantibacillus plantarum ameliorate hyperglycaemia and re-establish gut microbiota in streptozotocin (STZ)-induced diabetic mice

Soy yogurt has been gaining popularity as a vegan food produced simply by soymilk fermentation with proper microbial manipulation. It is well known that soy containing rich isoflavones is beneficial for ameliorating hyperglycaemic disorders. Soy fermentation can improve the bioavailability of these precious nutrients. Lactiplantibacillus plantarum is one of the most abundant and frequently isolated species in soymilk manufacturing. Soy yogurts produced with efficient GABA (γ-aminobutyric acid)-producing L. plantarum and the deglycosylating activity of L. plantarum were functionally assessed in a STZ-induced hyperglycaemic mouse model. Hyperglycaemic mice were assigned into groups and treated with daily gavage of either dH₂O, soymilk, soy yoghurts produced with high GABA-producing L. plantarum GA30 (LPGA30), low GABA-producing L. plantarum PV30 (LPPV30) or the soy yoghurts fortified with additional 30 mg g^-1 GABA counterparts (GA + GABA and PV + GABA groups). Except the dH₂O group, all soy yoghurt groups retained body weight with improved glucose homeostasis, glucose tolerance test results and renal tissue integrity, while the soymilk group shows partial benefits. Plasma GABA concentrations in the daily soy yoghurt-supplemented groups (LPGA30 and LPPV30) plateaued at 5 times higher than the average 0.5 μM in dH₂O and soymilk groups, and their GABA-fortified soy yoghurt counterparts (GA + GABA and PV + GABA) groups were accountable for the restored plasma insulin levels. Gut microbiome analysis revealed dysbiosis in STZ-induced hyperglycemic mice of the dH₂O group with breached out facultative anaerobic Proteobacteria over the normal phyla Firmicutes and Bacteroidetes. Restored gut microbiota with transitionally populated Actinobacteria was demonstrated in the LPGA30 group but not in the LPPV30 group. Soy yoghurts produced with efficient GABA-producing L. plantarum GA30 showed exceptional benefits in modulating gut microbiota with dominant genera of Enterococcus, Lactobacillus and Bifidobacterium, and the presence of some minor beneficial microbial communities including Akkermansia muciniphila, Butyricicoccus pullicaecorum, Corynebacterium spp. and Adlercreutzia spp. Efficient GABA-producing L. plantarum GA30 fermented soymilk to produce soy yoghurts that exhibit profound synergistic protections over rich soy isoflavones to restore pancreatic β-cell functions for insulin production in STZ-induced hyperglycaemic mice. Additionally, the probiotic role of GABA-producing L. plantarum in re-establishing healthy gut microbiota in hyperglycaemic mice implies a possible symbiotic relationship, awaiting further exploration.

Production and Characterization of Exopolysaccharide From Newly Isolated Marine Probiotic Lactiplantibacillus plantarum EI6 With in vitro Wound Healing Activity

Because of its safety, biological activities, and unique properties, exopolysaccharide (EPS) from lactic acid bacteria (LAB) has been developed as a potential biopolymer. A few studies have investigated the EPS produced by marine LAB. This study reports the wound healing activity of an EPS produced by a marine isolate identified as Lactiplantibacillus plantarum EI6, in addition to assessing L. plantarum EI6's probiotic properties. EI6 demonstrated promising antimicrobial activity against different pathogenic bacteria, as well as the ability to withstand stomach pH 3, tolerate 0.3% bile salt concentration, and exhibit no signs of hemolysis. Furthermore, EI6 was able to produce 270 mg/L of EPS upon growth for 48 h at 37°C in an MRS medium enriched with 1.0% of sucrose. The chemical features of the novel EI6-EPS were investigated: the UV-vis estimated a high carbohydrate content of ~91.5%, and the FTIR emphasized its polysaccharide nature by the characteristic hydroxyl, amide I, II, & III, and glycosidic linkage regions. The GC-MS and NMR analyses revealed the existence of five monosaccharides, namely, rhamnose, galactose, mannose, glucose, and arabinose, existing mainly in the pyranose form and linked together by α- and β-glycosidic linkages. EI6-EPS was found to be safe (IC50 > 100 μg/ml) and induced human skin fibroblasts (HSF) proliferation and migration. These findings imply that EI6 can be used as a safe source of bioactive polymer in wound care.

Antimicrobial activity and safety features assessment of Weissella spp. from environmental sources

Weissella strains have been reported to be useful in biotechnological and probiotic determinations, and some of them are considered opportunistic pathogens. Given the widespread interest about antimicrobial susceptibilities, transmission of resistances, and virulence factors, there is little research available on such topics for Weissella. The aim of this study was to assess the safety aspects and antimicrobial potential of 54 Weissella spp. strains from different environmental sources. Antibiotic susceptibility, hemolytic activity, horizontal transfer, and antibacterial activity were studied, as well as the detection of biogenic amine BA production on decarboxylase medium and PCR was performed. All the strains were nonhemolytic and sensitive to chloramphenicol and ampicillin. Several strains were classified as resistant to fusidic acid, and very low resistance rates were detected to ciprofloxacin, tetracycline, streptomycin, lincomycin, erythromycin, and rifampicin, although all strains had intrinsic resistance to vancomycin, nalidixic acid, kanamycin, and teicoplanin. Two BA‐producing strains (W. halotolerans FAS30 and FAS29) exhibited tyrosine decarboxylase activity, and just one W. confusa FS077 produced both tyramine and histamine, and their genetic determinants were identified. Ornithine decarboxylase/odc gene was found in 16 of the Weissella strains, although 3 of them synthesize putrescine. Interestingly, eight strains with good properties displayed antibacterial activity. Conjugation frequencies of erythromycin from Bacillus to Weissella spp. varied in the average of 3 × 10⁻⁹ transconjugants/recipient. However, no tetracycline‐resistant transconjugant was obtained with Enterococcus faecalis JH2‐2 as recipient. The obtained results support the safe status of Weissella strains, derived from environmental sources, when used as probiotics in animal feed.

Functional and health-promoting properties of probiotics' exopolysaccharides; isolation, characterization, and applications in the food industry

Exopolysaccharides (EPS) are extracellular sugar metabolites/polymers of some slim microorganisms and, a wide variety of probiotics have been broadly investigated for their ability to produce EPS. EPS originated from probiotics have potential applications in food, pharmaceutical, cosmetology, wastewater treatment, and textiles industries, nevertheless slight is recognized about their function. The present review purposes to comprehensively discuss the structure, classification, biosynthesis, extraction, purification, sources, health-promoting properties, techno-functional benefits, application in the food industry, safety, toxicology, analysis, and characterization methods of EPS originated from probiotic microorganisms. Various studies have shown that probiotic EPS used as stabilizers, emulsifiers, gelling agents, viscosifiers, and prebiotics can alter the nutritional, texture, and rheological characteristics of food and beverages and play a major role in improving the quality of these products. Numerous studies have also proven the beneficial health effects of probiotic EPS, including antioxidant, antimicrobial, anti-inflammatory, immunomodulatory, anticancer, antidiabetic, antibiofilm, antiulcer, and antitoxin activities. Although the use of probiotic EPS has health effects and improves the organoleptic and textural properties of food and pharmaceutical products and there is a high tendency for their use in related industries, the production yield of these products is low and requires basic studies to support their products in large scale.

Bacterial Communities in Lanna Phak-Gard-Dong (Pickled Mustard Green) from Three Different Ethnolinguistic Groups in Northern Thailand

The Lanna region, the main part of northern Thailand, is a place of ethnic diversity. In this study, we investigated phak-gard-dong (PGD), or pickled mustard green (Brassica juncea L. Czern.), for its beneficial bacteria content and to analyse the variations in bacterial compositions among the PGD of three different ethnolinguistic groups, the Karen, Lawa, and Shan. DNA was extracted from the PGD pickled brine, and 16S rRNA gene Illumina sequencing was performed. Metagenomic data were analysed and the results demonstrated that the dominant bacterial species were Weissella (54.2%, 65.0%, and 10.0%) and Lactobacillus (17.5%, 5.6%, and 79.1%) in the PGD of the Karen, Lawa, and Shan, respectively. Pediococcus was found only in the PGD of the Karen and Shan. Bacterial communities in PGD of the Lawa were distinctive from the other ethnic groups, both in the alpha and beta diversity, as well as the predicted functions of the bacterial communities. In addition, overall network analysis results were correlated to bacterial proportions in every ethnic PGD. We suggest that all ethnic PGDs have the potential to be a good source of beneficial bacteria, warranting its conservation and further development into health food products.

Potential Probiotic Enterococcus faecium OV3-6 and Its Bioactive Peptide as Alternative Bio-Preservation

Probiotic Enterococcus faecium OV3-6 and its secreted active peptide were characterized and investigated. The strain survived in simulated gastric and small intestinal conditions at 88.16% and 94.33%, respectively. The safety assessment revealed that the strain was shown α-hemolysis and susceptible to most clinically relevant antibiotics, but intermediate sensitivity to erythromycin and kanamycin was found. It does not harbor any virulence genes except for the efaA_fm gene. Both of its living cells and the cell-free supernatants (CFS) of the strain significantly reduced the adhesion of E. coli and S. Typhi on Caco-2 cells. The strain can regulate the secretion of pro and inflammatory cytokines, IL-6 and IL-12 and induce the secretion of anti-inflammatory IL-10 of the Caco-2 cell. The strain can prevent the growth of Gram-positive strains belonging to the genera Bacillus, Carnobacterium, Listeria, and Staphylococcus. It also presented the entP gene that involves the production of bacteriocin named enterocin P. The antimicrobial peptide was matched 40% with 50S ribosomal proteins L29 (7.325 kDa), as revealed by LC-MS/MS. This active peptide exhibits heat stability, is stable over a wide pH range of 2−10, and maintains its activity at −20 and 4 °C for 12 weeks of storage. Altogether, E. faecium OV3-6 thus has potential for consideration as a probiotic and bio-preservative for applied use as a fermented food starter culture and in functional food or feed industries.

Probiotic and Antioxidant Properties of Lactic Acid Bacteria Isolated from Indigenous Fermented Tea Leaves (Miang) of North Thailand and Promising Application in Synbiotic Formulation

Miang, a traditional fermented tea from Northern Thailand, potentially hosts beneficial probiotic bacteria. A total of 133 isolates of lactic acid bacteria (LAB) isolated from Miang were evaluated for probiotic potential. Among them, 5 strains showed high tolerance to bile and acidic conditions and were selected for further evaluation. All selected strains showed inhibitory activity against human pathogens, including Bacillus cereus, Staphylococcus aureus, and Salmonella ser. Typhimurium. Nucleotide sequences analysis of the 16S rRNA gene revealed that 3 isolates were identified as Lactobacillus pentosus; the remaining were L. plantarum and Pediococcus pentosaceus, respectively. All 5 strains showed a high survival rate of more than 90% when exposed to simulated gastrointestinal conditions and were also susceptible to antibiotics such as erythromycin, tetracycline, and gentamycin, and resistant to vancomycin, streptomycin, and polymycin. In addition, the selected isolates exhibited different degrees of cell surface hydrophobicity (58.3–92.9%) and auto-aggregation (38.9–46.0%). The antioxidant activity reflected in DPPH scavenging activities of viable cells and their cell-free culture supernatants (CFCS) were also found in selected LAB isolates. Moreover, selected LAB isolates showed ability to grow on commercial prebiotics (GOS, FOS or XOS). The preliminary study of spray-drying using cyclodextrin as thermoprotectant suggested that all strains can be designed as a powdered formulation. L. pentosus A14-6 was the best strain, with high tolerance against simulated gastrointestinal conditions, high cell surface hydrophobicity, effective response to tested commercial oligosaccharides, especially XOS, and the highest cell antioxidant properties. L. pentosus A14-6 was therefore targeted for further applications in food and synbiotic applications.

Probiotic Potential of Bacillus Strains Isolated from an Acidic Fermented Food Idli

Present study is intended to assess the probiotic properties of Bacillus spp. isolated from idli batter, a traditional fermented food of Southern India and Sri Lanka. A total of 32 isolates were screened for potential pathogenic behaviour through haemolysis assay, DNase activity and antibiotics sensitivity. Two of the isolates were found to be potentially safe and identified as Bacillus spp. These strains were characterized for in vitro probiotic attributes and antioxidant activity. Both the strains showed strong acid and bile tolerance, transit tolerance, lysozyme tolerance, cell surface hydrophobicity, auto-aggregation, co-aggregation, biofilm formation potential and adhesion to human colon adenocarcinoma (HT 29) cell line demonstrating potential probiotic ability. These strains also exhibited considerable cholesterol binding, thermostability, β-galactosidase production, proteolytic, amylolytic and lipolytic activity. Cell-free supernatant inhibited the biofilm formation by Pseudomonas aeruginosa (KT266804) to 90%. Intact cells showed significant DPPH (41%), hydroxyl (31%), radical scavenging activity and lipid peroxidation inhibition (20.38%), while cell-free extracts exhibited significant superoxide anion radical scavenging activity (16.25%). Results revealed that isolates could be potential probiotic candidate after further assessment of in vivo probiotic properties and safety evaluation and could be utilised as starter cultures in functional foods.

Diversity and Antimicrobial Activity towards Listeria spp. and Escherichia coli among Lactic Acid Bacteria Isolated from Ready-to-Eat Seafood

Biopreservation is a food preservation technology using microorganisms and/or their inherent antimicrobial metabolites to inhibit undesirable microorganisms. The aim of the present study was to explore the diversity and antimicrobial activity of lactic acid bacteria (LAB) strains (n = 99) isolated from ready-to-eat (RTE) seafood (cold-smoked salmon (CSS), gravlax, and sushi) towards two strains of Listeria monocytogenes (CCUG 15527, F11), Listeria innocua (CCUG 15531) and Escherichia coli (CCUG 38079). The LAB strains were assigned to five different genera (Carnobacterium spp., Lactobacillus spp., Leuconostoc spp., Weissella spp., and Enterococcus sp.) by sequencing a 1150 bp stretch of the 16S rRNA gene. A significant association between the seafood source and the distribution of LAB genera was found (p < 0.001), of which Leuconostoc spp. were most prevalent in sushi and Carnobacterium sp. and Lactobacillus sp. were most frequently isolated from CSS and gravlax. Antimicrobial activity among the LAB was significantly affected by LAB genera (F= 117.91, p < 0.001, one-way ANOVA), product of origin (F = 3.47, p < 0.05), and target (F = 4.64, p = 0.003). LAB isolated from sushi demonstrated a significantly higher antimicrobial effect than LAB from CSS and gravlax (p < 0.05). In general, a significantly higher antimicrobial activity was found towards Listeria spp. than E. coli (p < 0.05). However, Leuconostoc spp. demonstrated similar antimicrobial effects towards E. coli and Listeria spp., except for L. monocytogenes F11 being more sensitive (p < 0.05). This study suggested that seafood-derived LAB strains could be selected for technological application in RTE seafood systems.

Usage of in situ exopolysaccharide-forming lactic acid bacteria in food production: Meat products-A new field of application?

In the meat industry, hydrocolloids and phosphates are used to improve the quality attributes of meat products. However, latest research results revealed that the usage of exopolysaccharide (EPS)-forming lactic acid bacteria (LAB), which are able to produce EPS in situ during processing could be an interesting alternative. The current review aims to give a better understanding of bacterial EPS production in food matrices with a special focus on meat products. This includes an introduction to microbial EPS production (homopolysaccharides as well as heteropolysaccharides) and an overview of parameters affecting EPS formation and yield depending on LAB used. This is followed by a summary of methods to detect and characterize EPS to facilitate a rational selection of starter cultures and fermentation conditions based on desired structure-function relationships in different food matrices. The mechanism of action of in situ generated EPS is then highlighted with an emphasis on different meat products. In the process, this review also highlights food additives currently used in meat production that could in the future be replaced by in situ EPS-forming LAB.

Probiotic potential of lactic acid bacteria obtained from fermented curly kale juice

The aim of the paper was to analyse changes in lactic acid bacteria (LAB) populations during spontaneous fermentation of green curly kale juice (Brasicca oleracea L. var. acephala L.) and to determine the probiotic potential of LAB isolates. The analyses revealed that changes in LAB populations were specific for spontaneously fermented vegetable juices. The initial microbiota, composed mostly of Leuconostoc mesenteroides bacteria, was gradually replaced by Lactobacillus species, mainly Lactobacillus plantarum, Lactobacillus sakei, and Lactobacillus coryniformis. Screening tests for the antimicrobial properties and antibiotic susceptibility of isolates allowed for the selection of 12 strains with desirable characteristics. L. plantarum isolates were characterized by the widest spectrum of antimicrobial interactions, both towards Gram-positive and Gram-negative bacteria. Also, L. plantarum strains exhibited the best growth abilities under low pH conditions, and at different NaCl and bile salt concentrations. All strains showed different levels of antibiotic sensitivity, although they were resistant to vancomycin and kanamycin. The present study has shown that bacterial isolates obtained from spontaneously fermented kale juice could constitute valuable probiotic starter cultures, which may be used in fermentation industry.

Integrated Phenotypic-Genotypic Analysis of Candidate Probiotic Weissella Cibaria Strains Isolated from Dairy Cows in Kuwait

Probiotics represent a possible strategy for controlling intestinal infections in livestock. Members of the Weissella genus are increasingly being studied for health-related applications in animals and humans. Here we investigated the functional properties of two Weissella cibaria strains isolated from cows reared in Kuwait breeding facilities by combining phenotypic with genomic analyses. W. cibaria SP7 and SP19 exhibited good growth in vitro under acidic conditions and in the presence of bile salts compared to the reference probiotic Lacticaseibacillus (formerly Lactobacillus) rhamnosus GG. Both strains were able to adhere to Caco-2 and HT-29 cell lines, as well as to mucin. The cell-free supernatants of the two isolates exhibited inhibitory activity towards Escherichia coli ATCC 25,922 and Salmonella enterica UC3605, which was ultimately due to the low pH of supernatants. W. cibaria SP19 showed a co-aggregation ability similar to that of L. rhamnosus GG when incubated with S. enterica. Whole genome sequencing and analysis revealed that both strains harbored several genes involved in carbohydrate metabolism and general stress responses, indicating bacterial adaptation to the gastrointestinal environment. We also detected genes involved in the adhesion to host epithelial cells or extracellular matrix. No evidence of acquired antibiotic resistance or hemolytic activity was found in either strain. These findings shed light on the potential of W. cibaria for probiotic use in livestock and on the mechanisms underlying host-microbe interaction in the gut. W. cibaria` strain SP19 exhibited the best combination of in vitro probiotic properties and genetic markers, and is a promising candidate for further investigation.

Characterization of robust Lactobacillus plantarum and Lactobacillus pentosus starter cultures for environmentally friendly low-salt cucumber fermentations

Seven candidates for starter cultures for cucumber fermentations belonging to the Lactobacillus pentosus and Lactobacillus plantarum species were characterized based on physiological features desired for pickling. The isolates presented variable carbohydrate utilization profile on API^® 50CHL test strips. The L. pentosus strains were unable to utilize d-xylose in MRS broth or the M medium. The lactobacilli were unable to produce histamine, tyramine, putrescine, and cadaverine in biogenic amine broth containing the necessary precursors. Production of d-lactic acid by the lactobacilli, detected enzymatically, was stimulated by growth in MRS broth as compared to cucumber juice medium (CJM). The lactobacilli utilized malic acid in the malate decarboxylase medium. Exopolyssacharide biosynthesis related genes were amplified from the lactobacilli. A sugar type-dependent-ropy phenotype was apparent for all the cultures tested in MRS and CJM. The genes associated with bacteriocin production were detected in the lactobacilli, but not the respective phenotypes. The antibiotic susceptibility profile of the lactobacilli mimics that of other L. plantarum starter cultures. It is concluded that the lactobacilli strains studied here are suitable starter cultures for cucumber fermentation. PRACTICAL APPLICATION: The availability of such starter cultures enables the implementation of low salt cucumber fermentations that can generate products with consistent biochemistry and microbiological profile.

Potential Health Benefits of Ropy Exopolysaccharides Produced by Lactobacillus plantarum

The ability of Lactobacillus plantarum to produce exopolysaccharides (EPS) of various structures and properties is effective in showing both starter and probiotic culture qualification. In this study, the potential health promoting functions of the ropy EPS produced by Lactobacillus plantarum strains isolated from tarhana were tested. A stimulation of the pro-inflammatory IL-12 and TNF-α cytokines was observed in the presence of the ropy EPS suggesting an in vitro immune modulation. Similarly, the tested EPS demonstrated promoted the growth of the probiotic strains in fermentation medium. A medium level of radical scavenging activities of ropy EPS was observed whereas the superoxide and hydroxyl scavenging activities were more effective. The ropy EPS also showed α-glucosidase inhibition and cholesterol removal characteristics depending on their concentration. These findings revealed the potential health-promoting functions of ropy EPS from L. plantarum strains and EPS from L. plantarum PFC311 and PFC310 strains demonstrated multiple health-improving effects that can be further evaluated in food and other industries.

Spontaneously fermented traditional beverages as a source of bioactive compounds: an overview

Fermented food has been present throughout history, since fermentation not only helps preserving food, but also provides specific organoleptic characteristics typically associated to these foods. Most of the traditional fermented foods and artisanal beverages are produced by spontaneous generation, meaning no control of the microbiota, or the substrate used. Nevertheless, even not being standardized, they are an important source of bioactive compounds, such as antioxidant compounds, bioactive beeps, short chain fatty acids, amino acids, vitamins, and minerals. This review compiles a list of relevant traditional fermented beverages around the world, aiming to detail the fermentation process itself-including source of microorganisms, substrates, produced metabolites and the operational conditions involved. As well as to list the bioactive compounds present in each fermented food, together with their impact in the human health. Traditional fermented beverages from Mexico will be highlighted. These compounds are of high interest for the food, pharmaceutical and cosmetics industry. To scale-up the home fermentation processes, it is necessary to fully understand the microbiology and biochemistry behind these traditional products. The use of good quality raw materials with standardized methodologies and defined microorganisms, may improve and increase the production of the desirable bioactive compounds and open a market for novel functional products.

Tannin-Tolerant and Extracellular Tannase Producing Bacillus Isolated from Traditional Fermented Tea Leaves and Their Probiotic Functional Properties

A total of 117 Bacillus strains were isolated from Miang, a culture relevant fermented tea of northern Thailand. These strains were collected from 16 sampling sites in north Thailand. In this collection 95 isolates were tannin-tolerant Bacillus capable of growth on nutrient agar supplemented with 0.5% (w/v) total tannins from tea leaves extract (TE). The strains were also positive for pectinase, xylanase and amylase activity, while 91 and 86 isolates were positive for cellulase and β-mannanase, respectively. Only 21 isolates producing extracellular tannase were selected for further characterization. Identification by 16S rRNA gene sequence analysis revealed that more than 50% (11 of 21 isolates) were Bacillustequilensis, whereas the remaining were B. siamensis (3), B. megaterium (3), B. aryabhattai (3) and B. toyonensis (1). B. tequilensis K34.2 produced the highest extracellular tannase activity of 0.60 U/mL after cultivation at 37 °C for 48 h. In addition, all 21 isolates were resistant to 0.3% (w/v) bile salt, sensitive to gentamicin, erythromycin, vancomycin and kanamycin and also tolerant to acidic condition. Cell hydrophobicity varied from 9.4 to 80.4% and neutralized culture supernatants of some Bacillus isolates showed bacteriocin producing potentiality against Samonella enterica serovar Typhimurium TISTR 292. All tested probiotic properties indicated that B. tequilensis K19.3, B. tequilensis K34.2 and B. siamensis K19.1 had high probiotic potential. This is the first report describing tannin-tolerant Bacillus and their extracellular tannase producing capability in Miang, a traditional fermented tea of Thailand.

Characterization of potentially probiotic lactic acid bacteria and bifidobacteria isolated from human colostrum

Breast milk is the main source of nutrition for infants; it contains considerable microflora that can be transmitted to the infant endogenously or by breastfeeding, and it plays an important role in the maturation and development of the immune system. In this study, we isolated and identified lactic acid bacteria (LAB) from human colostrum, and screened 2 strains with probiotic potential. The LAB isolated from 40 human colostrum samples belonged to 5 genera: Lactobacillus, Bifidobacterium, Streptococcus, Enterococcus, and Staphylococcus. We also isolated Propionibacterium and Actinomyces. We identified a total of 197 strains of LAB derived from human colostrum based on their morphology and 16S rRNA sequence, among them 8 strains of Bifidobacterium and 10 strains of Lactobacillus, including 3 Bifidobacterium species and 4 Lactobacillus species. The physiological and biochemical characteristics of strains with good probiotic characteristics were evaluated. The tolerances of some of the Bifidobacterium and Lactobacillus strains to gastrointestinal fluid and bile salts were evaluated in vitro, using the probiotic strains Bifidobacterium lactis BB12 and Lactobacillus rhamnosus GG as controls. Among them, B. lactis Probio-M8 and L. rhamnosus Probio-M9 showed survival rates of 97.25 and 78.33% after digestion for 11 h in artificial gastrointestinal juice, and they exhibited growth delays of 0.95 and 1.87 h, respectively, in 0.3% bile salts. These two strains have the potential for application as probiotics and will facilitate functional studies of probiotics in breast milk and the development of human milk-derived probiotics.

Safety and probiotic functionality of isolated goat milk lactic acid bacteria

Purpose

Lactic acid bacteria (LAB) are traditionally employed in the food industry. LAB strains from goat milk may also present probiotic potential, and it is fundamental to study the safety and functionality aspects which are desirable for their use in food. The objective of this study was to verify the probiotic potential of lactic bacteria isolated from goat milk.

Methods

The presence of safety-related virulence factors (hemolytic activity, gelatinase production, coagulase, and sensitivity to antibiotics) as well as functionality (exopolysaccharide (EPS) production, proteolytic activity, autoaggregation, gas production, survival in the gastrointestinal tract, and antimicrobial activity against bacteria that impair oral health) were determined.

Result

The selected LAB strains are safe against the evaluated parameters and have characteristics of possible probiotic candidates. Especially L. plantarum (DF60Mi) and Lactococcus lactis (DF04Mi) have potential to be added to foods because they have better resistance to simulated gastrointestinal conditions. In addition, they are isolated with already proven antimicrobial activity against Listeria monocytogenes, an important food-borne pathogen. DF60Mi was able to produce EPS (exopolysaccharides). LS2 and DF4Mi strains, both Lactococcus lactis subsp. lactis, demonstrated antimicrobial activity against S. mutans ATCC 25175, a recurrent microorganism in oral pathologies, mainly caries.

Conclusion

This study provides subsidies for future exploration of the potentialities of these LAB strains for both the development of new functional foods and for application in oral health.

Comprehensive Evaluation of Microbiological and Physicochemical Properties of Commercial Drinking Yogurts in Korea

Most consumers consider yogurt to be a healthy food because it contains probiotic microorganisms. Although a plethora of commercially produced yogurts exists, nutritional and functional aspects of the commercial yogurts have not been well characterized. In this study, the microbiological and physicochemical properties of popular drinking yogurts in Korea were extensively characterized. The viability of lactic acid bacteria, including lactobacilli and bifidobacteria, varied between yogurt samples. These lactobacilli and bifidobacteria showed effective antimicrobial activities against foodborne pathogenic bacteria. Unlike the titratable acidity and pH, the soluble solids content varied between yogurt samples. All the yogurt samples contained high levels of potassium (average 143.53 mg/100 g) and calcium (average 133.92 mg/100 g), as well as phosphorus and sodium. Lactose, fructose, and glucose were the major sugar components in most yogurt samples, whereas the levels of sucrose and maltose were relatively low. Among several organic acids analyzed in the yogurt samples, lactic acid (average 767.67 mg/100 g) and citric acid (average 170.91 mg/100 g) were the most predominant. Taken together, this study provides preliminary information about the nutritional and functional characteristics of commercially available drinking yogurts.

Genetic and technological characterization of lactic acid bacteria isolated from tropically grown fruits and vegetables

Phyllosphere microorganisms are common contaminants of fruit or vegetable containing foods. The aim of this study was to identify and characterize lactic acid bacteria isolated from fruits and vegetables from Reunion Island, regarding possible application in food. Among 77 isolates, a large diversity of species was observed, with isolates belonging to Lactobacillus plantarum (3 isolates), other species of Lactobacillus (3), Lactococcus lactis (13), Leuconostoc pseudomesenteroides (25), Leuconostoc lactis (1), Leuconostoc mesenteroides (7), Leuconostoc citreum (14), Weissella cibaria (4), Weissella confusa (4), other species of Weissella (2) and Fructobacillus tropaeoli (1). Several of these species, although belonging to lactic acid bacteria, are poorly characterized, because of their low occurrence in dairy products. Lactobacillus, Lactococcus, Leuconostoc and Weissella isolates were classified by (GTG)₅ fingerprinting in 3, 6, 21 and 10 genetic groups, respectively, suggesting a large intra-species diversity. Several Weissella and Lactobacillus isolates were particularly tolerant to acid and osmotic stress, whereas Lc. pseudomesenteroides 60 was highly tolerant to oxidative stress. Isolates of Weissella 30, 64 and 58, Leuconostoc 60 and 12b, Lactobacillus 75 and Fructobacillus 77 present relevant characteristics for their use as starters or as preservative cultures for fruits and vegetables.

Production, partial characterization and antioxidant properties of exopolysaccharide α-d-glucan produced by Leuconostoc lactis KC117496 isolated from an idli batter

Exopolysaccharide (EPS) produced from Leuconostoc lactis KC117496 isolated from the naturally fermented idli batter has been reported earlier. Here, study aimed to optimize the carbon source to enhance the yield of EPS production, partial characterization and antioxidant activity of α-d-glucan EPS. Among different disaccharides (sucrose, maltose, lactose) and monosaccharides (glucose, galactose and fructose), combination of sucrose and glucose at 2% showed highest EPS production of 4.55 g/L in MRS medium. The molecular weight was identified as ~ 4.428 × 103 kDa with MALDI-TOF mass spectroscopy. 1D and 2D NMR results exhibited the presence of α-1-6 and α-1-3 linked glucose revealed EPS as a glucan. Antioxidant properties of glucan (500 µg/mL) revealed the significant oxidation alleviation potential such as DPPH (74%) and Hydroxyl radical activity (97.8%), whereas metal chelating activity (70%) was lower as compare to control standard. These characteristics of glucan EPS reveals its potential application in food and pharmaceutical industry.

Antagonistic Activities and Probiotic Potential of Lactic Acid Bacteria Derived From a Plant-Based Fermented Food

In this study, antagonistic activities and probiotic potential of lactic acid bacteria (LAB) derived from a plant-based fermented food, kimchi, were demonstrated. The cell free supernatants (CFS) from Lactobacillus curvatus KCCM 43119, Leuconostoc mesenteroides KCCM 43060, Weissella cibaria KCTC 3746, and W. koreensis KCCM 41517 completely inhibited the growth of foodborne pathogenic bacteria, while neutralized CFS (pH 6.5) partially inhibited the growth. The competition, exclusion, and displacement of foodborne pathogenic bacteria by the LAB strains from adhesion to HT-29 cells were investigated. The LAB strains were able to compete with, exclude, and displace the foodborne pathogenic bacteria. However, the degree of inhibition due to the adhesion was found to be a LAB strain-dependent phenomenon. The LAB strains showed high coaggregation with foodborne pathogenic bacteria, and they also exhibited high resistance to acidic condition. Except W. cibaria KCTC 3746, all LAB strains were capable of surviving in the presence of bile salts. Furthermore, while all LAB strains were resistant to chloramphenicol, kanamycin, streptomycin, gentamicin, and erythromycin, only W. cibaria KCTC 3746 and W. koreensis KCCM 41517 displayed resistance to vancomycin. These results suggest that the LAB strains derived from kimchi exerted antagonistic activities against foodborne pathogenic bacteria with probiotic potential.

Enzymes and Dairy Products

The use of enzymes in food production, including dairy products, is below expected due the high costs associated with their production and purification. Microbial enzymes have great potential for industrial applications since they can be produced via large-scale fermentation and they are easily expressed by cloning in well-known cultivated microorganisms. The combination of different procedures such as over-expression techniques and the use of low costs induction sources has resulted in the production of enzymes to be used in high added-value dairy products. The addition of glucose oxidase to probiotic yogurts has been indicated as an alternative to the maintenance of probiotic functionality. Bile salt hydrolase contributes to prevention of hypercholesterolemia which is interesting to produce new functional dairy products. This chapter discusses enzyme sources and their relevance in dairy products, the production of enzymes using cloning and super-expression techniques, as well as enzymes related to functional dairy products.

Why Are Weissella spp. Not Used as Commercial Starter Cultures for Food Fermentation?

Among other fermentation processes, lactic acid fermentation is a valuable process which enhances the safety, nutritional and sensory properties of food. The use of starters is recommended compared to spontaneous fermentation, from a safety point of view but also to ensure a better control of product functional and sensory properties. Starters are used for dairy products, sourdough, wine, meat, sauerkraut and homemade foods and beverages from dairy or vegetal origin. Among lactic acid bacteria, Lactobacillus, Lactococcus, Leuconostoc, Streptococcus and Pediococcus are the majors genera used as starters whereas Weissella is not. Weissella spp. are frequently isolated from spontaneous fermented foods and participate to the characteristics of the fermented product. They possess a large set of functional and technological properties, which can enhance safety, nutritional and sensory characteristics of food. Particularly, Weissella cibaria and Weissella confusa have been described as high producers of exo-polysaccharides, which exhibit texturizing properties. Numerous bacteriocins have been purified from Weissella hellenica strains and may be used as bio-preservative. Some Weissella strains are able to decarboxylate polymeric phenolic compounds resulting in a better bioavailability. Other Weissella strains showed resistance to low pH and bile salts and were isolated from healthy human feces, suggesting their potential as probiotics. Despite all these features, the use of Weissella spp. as commercial starters remained non-investigated. Potential biogenic amine production, antibiotic resistance pattern or infection hazard partly explains this neglecting. Besides, Weissella spp. are not recognized as GRAS (Generally Recognized As Safe). However, Weissella spp. are potential powerful starters for food fermentation as well as Lactococcus, Leuconostoc or Lactobacillus species.

Fermented Aloreña Table Olives as a Source of Potential Probiotic Lactobacillus pentosus Strains

A collection of 31 Lactobacillus pentosus strains isolated from naturally fermented Aloreña green table olives were screened in depth in the present study for their probiotic potential. Several strains could be considered promising probiotic candidates since they showed good growth capacity and survival under simulated gastro-intestinal conditions (acidic pH of 1.5, up to 4% of bile salts and 5 mM of nitrate), good ability to auto-aggregate which may facilitate their adhesion to host cells as multiple aggregates and the subsequent displacement of pathogens. Moreover, co-aggregation of lactobacilli with pathogenic bacteria was shown with Listeria innocua, Staphylococcus aureus, Escherichia coli, and Salmonella Enteritidis as good defense strategy against gut and food pathogens. Furthermore, they exhibited adherence to intestinal and vaginal cell lines, such property could be reinforced by their capacity of biofilm formation which is also important in food matrices such as the olive surface. Their antagonistic activity against pathogenic bacteria by means of acids and plantaricins, and also their different functional properties may determine their efficacy not only in the gastro-intestinal tract but also in food matrices. Besides their ability to ferment several prebiotics, the new evidence in the present study was their capacity to ferment lactose which reinforces their use in different food matrices including dairy as a dietary adjunct to improve lactose digestibility. Lactobacillus pentosus CF2-10N was selected to have the best probiotic profile being of great interest in further studies. In conclusion, spontaneous fermented Aloreña table olives are considered a natural source of potential probiotic L. pentosus to be included as adjunct functional cultures in different fermented foods.

Probiotic isolates from unconventional sources: a review

The use of probiotics for human and animal health is continuously increasing. The probiotics used in humans commonly come from dairy foods, whereas the sources of probiotics used in animals are often the animals’ own digestive tracts. Increasingly, probiotics from sources other than milk products are being selected for use in people who are lactose intolerant. These sources are non-dairy fermented foods and beverages, non-dairy and non-fermented foods such as fresh fruits and vegetables, feces of breast-fed infants and human breast milk. The probiotics that are used in both humans and animals are selected in stages; after the initial isolation of the appropriate culture medium, the probiotics must meet important qualifications, including being non-pathogenic acid and bile-tolerant strains that possess the ability to act against pathogens in the gastrointestinal tract and the safety-enhancing property of not being able to transfer any antibiotic resistance genes to other bacteria. The final stages of selection involve the accurate identification of the probiotic species.

Functional Properties of Microorganisms in Fermented Foods

Fermented foods have unique functional properties imparting some health benefits to consumers due to presence of functional microorganisms, which possess probiotics properties, antimicrobial, antioxidant, peptide production, etc. Health benefits of some global fermented foods are synthesis of nutrients, prevention of cardiovascular disease, prevention of cancer, gastrointestinal disorders, allergic reactions, diabetes, among others. The present paper is aimed to review the information on some functional properties of the microorganisms associated with fermented foods and beverages, and their health-promoting benefits to consumers.