Probiotic and milk technological properties of Lactobacillus brevis

Synthesis of potential prebiotic oligosaccharides with diverse glycosidic linkages from corn stover via simultaneous hydrolysis and glycosylation

This study presents the synthesis of potential prebiotic oligosaccharides directly from corn stover using concentrated sulfuric acid as both solvent and catalyst under mild conditions. The process involves dissolving corn stover at 20 °C for 1 h, followed by simultaneous hydrolysis of cellulose and hemicellulose and glycosylation of the resulting mono- and oligo-saccharides at 50 °C for 10 min in 80 wt% H2SO4. A yield of 48.8 % of corn stover-derived oligosaccharides (CS-OS) was achieved, nearing the theoretical yield. Structural analysis revealed that CS-OS were primarily gluco-oligosaccharides (average degree of polymerization (DP) 4.3) and xylo-oligosaccharides (average DP 3.6) with diverse α/β-(1→6/4/3/2/1) glycosidic bonds. Preliminary in vitro evaluation demonstrated that CS-OS effectively supported the growth of three probiotic strains (Lactobacillus and Pediococcus), outperforming commercial prebiotic isomalto-oligosaccharides and matching commercial prebiotic xylo-oligosaccharides. This study offers a valuable method to convert agricultural waste lignocellulosic biomass into valuable prebiotic oligosaccharides.

Crystal structure of the C1 domain of the surface-layer protein SlpM from Lactobacillus brevis: a module involved in protein self-assembly

Surface-layer proteins (SLPs) play a crucial role in the self-assembly of bacterial surface layers, yet the structural details of their assembly domains remain largely unexplored. Here, we report the crystal structure of SlpM_C1, a structural module within the self-assembly domain of SlpM from Lactobacillus brevis. SlpM_C1 adopts a β-grasp fold, a conserved structural motif found in diverse protein families. Structural comparisons with ubiquitin and the SlpA_II domain from L. acidophilus reveal both shared and distinct features, highlighting elements of structural convergence despite sequence divergence. Furthermore, the dimerization patterns of SlpM_C1 and SlpA_II are compared and discussed. These findings provide new insights into the architecture and evolutionary adaptability of SLPs in Lactobacillus species.

Exploring sub-species variation in food microbiomes: a roadmap to reveal hidden diversity and functional potential

Within-species diversity of microorganisms in food systems significantly shapes community function. While next-generation sequencing (NGS) methods have advanced our understanding of microbiomes at the community level, it is essential to recognize the importance of within-species variation for understanding and predicting the functional activities of these communities. This review highlights the substantial variation observed among microbial species in food systems and its implications for their functionality. We discuss a selection of key species in fermented foods and food systems, highlighting examples of strain-level variation and its influence on quality and safety. We present a comprehensive roadmap of methodologies aimed at uncovering this often overlooked underlying diversity. Technologies like long-read marker-gene or shotgun metagenome sequencing offer enhanced resolution of microbial communities and insights into the functional potential of individual strains and should be integrated with techniques such as metabolomics, metatranscriptomics, and metaproteomics to link strain-level microbial community structure to functional activities. Furthermore, the interactions between viruses and microbes that contribute to strain diversity and community stability are also critical to consider. This article highlights existing research and emphasizes the importance of incorporating within-species diversity in microbial community studies to harness their full potential, advance fundamental science, and foster innovation.

Cytoprotective Nanoencapsulation of Probiotic Cells within Fe3+-Phytic Acid Nanoshells

Probiotic oral delivery is challenged by harsh gastrointestinal conditions and environmental stressors in the body. This study presents the construction of durable nanoshells composed of an Fe3+-phytic acid metal-organic complex around individual probiotic cells, providing exceptional cytoprotective properties, in single-cell nanoencapsulation. Nanoencapsulated Levilactobacillus brevis maintains high viability under simulated gastric fluid and the antibiotic tetracycline. The Fe3+-phytic acid nanoshells provide an effective platform for improving the viability and functionality of probiotics in therapeutic and nutritional applications.

Acetolactate Decarboxylase as an Important Regulator of Intracellular Acidification, Morphological Features, and Antagonism Properties in the Probiotic Lactobacillus reuteri

SCORE

This study identifies the coding gene (aldB) of acetolactate decarboxylase (ALDC) as an important regulatory gene of the intracellular pH in Lactobacillus reuteri (L. reuteri), uncovering the important role of ALDC in regulating intracellular pH, morphological features, and antagonism properties in the probiotic organism L. reuteri.

METHODS AND RESULTS

The aldB mutant (ΔaldB) of L. reuteri is established using the homologous recombination method. Compare to the wild-type (WT) strain, the ΔaldB strain shows a smaller body size, grows more slowly, and contains more acid in the cell cytoplasm. The survival rate of the ΔaldB strain is much lower in low pH and simulated gastric fluid (SGF) than that of the WT strain, but higher in simulated intestinal fluid (SIF). The antagonism test demonstrates the ΔaldB strain can inhibit Listeria monocytogenes (L. monocytogenes) and Salmonella more effectively than the WT strain. Additionally, there is a dramatic decrease in the adhesion rate of Salmonella to Caco-2 and HT-29 cells in the presence of the ΔaldB strain compared to the WT strain. Simultaneously analyze, the auto-aggregation, co-aggregation, cell surface hydrophobicity (CSH), hemolytic, temperature, NaCl, oxidative stress, and antibiotic susceptibility of the ΔaldB strain are consistent with the features of probiotics.

CONCLUSION

This study highlights that the aldB gene plays a significant role in the growth and antibacterial properties of L. reuteri.

Antibacterial potential of commercial and wild lactic acid bacteria strains isolated from ovine and caprine raw milk against Mycoplasma agalactiae

Introduction

The complexity of fighting contagious agalactia (CA) has raised the necessity of alternative antimicrobial therapies, such as probiotics. Lactic acid bacteria (LAB) are present in the mammary gland of small ruminants and their antimicrobial effect have been previously described against species like Mycoplasma bovis but never against Mycoplasma agalactiae (Ma). This in vitro study aims to evaluate the antimicrobial activity against Ma of ovine and caprine LAB strains and a human commercial probiotic (L2) of Lactobacillus spp.

Methods

A total of 63 possible LAB strains were isolated from nine ovine and caprine farms in Spain, three isolates (33B, 248D, and 120B) from the 63 strains were selected, based on their capacity to grow in a specific medium in vitro, for an in vitro experiment to assess their antimicrobial activity against Ma in Ultra High Temperature (UHT) processed goat milk (GM). A women commercial vaginal probiotic was also included in the study. The inoculum of L2 was prepared at a concentration of 3.24 × 10⁸  CFU/mL and the average concentration of the inoculum of the wild LAB varied from 7.9 × 10⁷ to 8.4 × 10⁸  CFU/mL.

Results

The commercial probiotic L2 significantly reduced the concentration of Ma to 0.000 log CFU/mL (p < 0.001), strain 33B reduced it from 7.185 to 1.279 log CFU/mL (p < 0.001), and 120B from 6.825 to 6.466 log CFU/mL (p < 0.05). Strain 248D presented a bacteriostatic effect in GM. Moreover, the three wild strains and the commercial probiotic produced a significative reduction of the pH (p < 0.001).

Discussion

This is the first in vivo report of the antimicrobial potential of LAB strains against Ma and its interaction. Our results support possible future alternative strategies to antibiotic therapy, previously not contemplated, to fight CA in small ruminants. Further studies are necessary to elucidate the action mechanisms through which these LAB are able to inhibit Ma and to assess the safety of using these strains in possible in vivo studies.

Assessing the protection mechanisms against Enterobacter aerogenes by analyzing aggregation, adherence, antagonistic activity, and safety properties of potentially probiotic strain Lactobacillus brevis G145

The aim of this study was to evaluate the probiotic potential of Lactobacillus brevis G145 isolated from traditional Khiki cheese, analyzing pH and bile resistance, physicochemical properties of the strain (hydrophobicity, auto- and co-aggregation), cholesterol removal, hydroxyl radical scavenging activity, adhesion ability to Caco-2 cells monolayer, and adhesion competition on Enterobacter aerogenes (competition, inhibition and replacement assays). Also, DNase, haemolytic activity, biogenic amine production and antibiotic susceptibility was investigated. L. brevis G145 was resistant to acidic pHs, bile salts, and simulated gastrointestinal conditions, and showed remarkable cell surface hydrophobicity (49.56%), co-aggregation (28.90%), auto-aggregation (34.10%), adhesion (9.40%), cholesterol removal (45.50%), and antioxidant (52.19%) properties. According to the results of well diffusion agar and disc diffusion agar tests, the highest and lowest inhibition zones were accounted for Staphylococcus aureus and Enterobacter aerogenes, respectively. The isolate did not show haemolytic, DNAse, and biogenic amine production properties. It was sensitive to antibiotics erythromycin, ciprofloxacin, and chloramphenicol, and semi-sensitive to imipenem, ampicillin, nalidixic acid, and nitrofurantoin. According to the findings of probiotic tests L. brevis G145 can be used as a in the food industry.

Green removal of unpleasant volatiles from soapberry (Sapindus mukorossi) extracts by two-phase microbial fermentation fortified with pomelo peel waste

Soapberry (Sapindus mukorossi Gaertn) is a popular woody plant in Vietnam, often used as a cleaning product due to its ability to wash, foam and emulsify due to high saponin content. In this study, the performance of fermentation by two microbial strains, namely Saccharomyces cerevisiae active dry yeast (ADY) and Levilactobacillus brevis lactic acid bacteria (LB) along with the addition of pomelo peel (flavedo) was evaluated during 15 days in terms of sugar removal, antioxidant and antibacterial activities, foaming power, volatile composition, and sensory acceptability. The results showed that the soluble solid content of original extracts experienced a significant decrease from 14.5% to a stable range of 9.4-11.0% until day 15 for all fermented samples, which correlated with a reduction by approximately 60% in reducing sugars (from 12.52 g L-1 to 4.77-6.56 g L-1). In addition, the saponin content of fermented extracts was in the range of 118.2-145.0 mg L-1 while antioxidant activities were extremely reduced after 15 days of fermentation. Increases in pomelo peel imparted fermented extracts with greater antibacterial activity against Staphylococcus aureus ATCC 6538, Proteus mirabilis ATCC 25933, and Candida albicans ATCC 10231, and LB had higher activity than ADY overall. Regarding the volatile profiles, two main compounds in the original extracts, including trilaurin (75.02%) and 1-dodecanoyl-3-myristoyl glycerol (24.85%), were completely removed and replaced by new alkanes, alkenes, alcohols, esters, and organic acids, and particularly d-limonene (86.34-95.31%) upon pomelo addition. Additionally, the foaming ability and stability of fermented extracts were also enhanced and there was clear distinction between fermented and unfermented samples using principal component analysis based on sensory liking data which showed consumers' preference towards fermented samples with a high percentage of pomelo peel.

Gamma-Aminobutyric Acid-Producing Levilactobacillus brevis Strains as Probiotics in Litchi Juice Fermentation

Levilactobacillus brevis strains can be isolated from traditional Chinese pickles and used as the starter cultures to improve the nutritional profiles of fermented juices. Three L. brevis strains (LBG-29, LBG-24, LBD−14) that produce high levels of gamma-aminobutyric acid (GABA; >300 mg/L) were isolated from traditional Chinese pickles. The strains showed tolerance to low pH and high bile salts and exhibited safety in vitro. Litchi juice was fermented using each strain at 37 °C for 48 h. The litchi juice was determined to be a good substrate for fermentation as the process enhanced its functional profile. Overall, cell vitality increased (above 8.7 log10 CFU/mL), the antioxidant activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric ion-reducing antioxidant power (FRAP) were significantly increased, and the antioxidant capacity of the 2,2′-amino-di(3-ethyl-benzothiazoline sulphonic acid-6)ammonium salt (ABTS) was decreased. There was also a significant increase in the GABA and acetic acid content after LBG-29 and LBG-24 fermentation. It was thus determined that the LBG-29 and LBG-24 strains could be used to improve beverage functionality and aid in the development of new products. This is the first report of litchi fermentation using L. brevis as a starter culture. Further research is required to elucidate the functional benefits for the human body and the nutritional and functional properties during its shelf life.

Antibacterial and antibiofilm activity of Lactobacillus strains secretome and extraction against Escherichia coli isolated from urinary tract infection

The purpose of this study was to antibacterial, and antibiofilm activity of two Lactobacillus strains secretome and extraction against E. coli isolated from women with urinary tract infection (UTI). We isolated 100 E. coli samples from women with UTI. Lactobacillus acidophilus and Lactobacillus casei characteristics were evaluated, and their secretome and extraction were prepared. The antibacterial and antibiofilm activity of secretome and extraction of both Lactobacillus strains were evaluated against isolated E. coli samples. L. acidophilus and L. casei were able to tolerate pH 3, bile salts, and pancreatic enzymes. Both probiotics were not resistant to antibiotics and demonstrated an appropriate ability to adhere to the intestinal epithelial cells. Secretome and extraction of L. acidophilus and L. casei strains showed a good antibacterial and antibiofilm against E. coli isolates. Generally, present study suggested that the secretome and extraction of L. acidophilus and L. casei strains exhibits a good antimicrobial activity.

Growth studies of dominant lactic acid bacteria in orange juice and selection of strains to ferment citric fruit juices with probiotic potential

The study aimed to evaluate the ability of dominant lactic acid bacteria (LAB) in orange juice to growth on N-depleted MRS medium supplemented or not with cysteine (mMRS), then to select the most nutritionally promising strains for growth assays in the food matrix and evaluation of beneficial attributes for fruit juice fermentation. Levilactobacillus brevis and Lactiplantibacillus plantarum were dominant species among the total of 103 LAB isolates as confirmed by multiplex PCR and/or 16 s rDNA sequence analysis. Based on growing lower than 20% and higher than 70% in mMRS (1.0 g/l meat extract, without peptone and yeast extract) with and without cysteine requirement, one L. brevis (JNB23) and two L. plantarum (JNB21 and JNB25) were selected. These bacteria and the L. plantarum strains N4 and N8 (previously isolated from oranges peel) when inoculated in orange juice grew up to 1.0 log cfu/ml for 24 h incubation at 30 °C and mainly produced lactic acid, with strains JNB25 and JNB23 reaching the highest and lowest cell densities in agreement with their nutritional exigency. In addition, all L. plantarum strains exhibited antagonistic activity against the majority of tested bacterial pathogens (in opposition to L. brevis), ability to grow or survive to pH 3.0 for 3 h, to grow with 0.5% sodium taurocholate, and a decrease after simulated gastrointestinal digestion assay which did not exceed 1.0 or 2.0 log units, depending on the strain. Thus, autochthonous L. plantarum strains with ability for overcoming nutritional limitations and beneficial attributes are promising candidates for further investigations as novel probiotic and/or preservative starters to ferment citric fruit juices.

Surface Layer Protein Pattern of Levilactobacillus brevis Strains Investigated by Proteomics

The outermost constituent of many bacterial cells is represented by an S-layer, i.e., a semiporous lattice-like layer composed of self-assembling protein subunits called S-layer proteins (Slps). These proteins are involved in several processes, such as protecting against environmental stresses, mediating bacterial adhesion to host cells, and modulating gut immune response. Slps may also act as a scaffold for the external display of additional cell surface proteins also named S-layer associated proteins (SLAPs). Levilactobacillus brevis is an S-layer forming lactic acid bacterium present in many different environments, such as sourdough, milk, cheese, and the intestinal tract of humans and animals. This microorganism exhibits probiotic features including the inhibition of bacterial infection and the improvement of human immune function. The potential role of Slps in its probiotic and biotechnological features was documented. A shotgun proteomic approach was applied to identify in a single experiment both the Slps and the SLAPs pattern of five different L. brevis strains isolated from traditional sourdoughs of the Southern Italian region. This study reveals that these closely related strains expressed a specific pattern of surface proteins, possibly affecting their peculiar properties.

Probiotication of Nutritious Fruit and Vegetable Juices: An Alternative to Dairy-Based Probiotic Functional Products

Fruits and vegetables are widely known to be rich in nutrients, antioxidants, vitamins, dietary fiber, minerals, and a bioactive molecule, making them an essential component of a balanced diet with multiple documented positive effects on human health. The probiotication of plant-based juices for the production of functional and nutraceutical food serves as a healthy alternative to dairy probiotics. They are cholesterol free, lack several dairy allergens, and also encourage ingestion for people with lactose intolerance. This review highlights valuable claims regarding the efficacy of different probiotic strains on various diseases. A comprehensive nutrition comparison and the preference of plant-based over dairy probiotic drinks is also discussed, supported with updated market trends of probiotic drinks (dairy and non-dairy based). An extensive compilation of current plant-based probiotic drinks that are available in markets around the world is listed as a reference. The fermentability of carbon sources by probiotic microorganisms is crucial in addressing the development of plant-based drinks. Therefore, the pathway involved in metabolism of sucrose, glucose, fructose, and galactose in fruit and vegetable juice was also underlined. Finally, the key factors in monitoring the quality of probiotic products such as total soluble solids, sugar consumption, titratable acidity, pH, and stability at low storage temperatures were outlined.

Lacticaseibacillus rhamnosus: A Suitable Candidate for the Construction of Novel Bioengineered Probiotic Strains for Targeted Pathogen Control

Probiotics, with their associated beneficial effects, have gained popularity for the control of foodborne pathogens. Various sources are explored with the intent to isolate novel robust probiotic strains with a broad range of health benefits due to, among other mechanisms, the production of an array of antimicrobial compounds. One of the shortcomings of these wild-type probiotics is their non-specificity. A pursuit to circumvent this limitation led to the advent of the field of pathobiotechnology. In this discipline, specific pathogen gene(s) are cloned and expressed into a given probiotic to yield a novel pathogen-specific strain. The resultant recombinant probiotic strain will exhibit enhanced species-specific inhibition of the pathogen and its associated infection. Such probiotics are also used as vehicles to deliver therapeutic agents. As fascinating as this approach is, coupled with the availability of numerous probiotics, it brings a challenge with regard to deciding which of the probiotics to use. Nonetheless, it is indisputable that an ideal candidate must fulfil the probiotic selection criteria. This review aims to show how Lacticaseibacillus rhamnosus, a clinically best-studied probiotic, presents as such a candidate. The objective is to spark researchers’ interest to conduct further probiotic-engineering studies using L. rhamnosus, with prospects for the successful development of novel probiotic strains with enhanced beneficial attributes.

Anti-Osteoporotic Effect of Lactobacillus brevis AR281 in an Ovariectomized Mouse Model Mediated by Inhibition of Osteoclast Differentiation

Osteoporosis is a global disease characterized by weakened bone microarchitecture, leading to osteoporotic fractures. Estrogen replacement therapy is the traditional treatment for osteoporosis but carries with it an increased risk of cardiac events. In search of a safe and effective treatment, we used Lactobacillus brevis AR281, which has anti-inflammatory properties, to conduct a 7-week experiment, investigating its inhibitory effects on osteoporosis in an ovariectomized (ovx) mouse model. The results demonstrated that AR281 significantly improved bone microarchitecture and biomechanical strength in ovx mice by attenuating bone resorption. AR281 significantly decreased the critical osteoclast activator, the ratio of the receptor activator for nuclear factor kappa B (NF-κB) ligand (RANKL) to osteoprotegerin, and pro-inflammatory osteoclastogenic mediators, such as IL-1, IL-6, and IL-17, which can increase the RANKL expression. Moreover, AR281 modulated intestinal microbiota in ovx mice increased the abundance of Akkermansia, which is responsible for the improvement of gut epithelial barrier integrity. In an in vitro trial, AR281 suppressed the number of osteoclasts differentiated from the osteoclast precursor RAW264.7 cells caused by RANKL through the tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6)/NF-κB/nuclear factor of activated T cells c1 (NFATc1) pathway. Therefore, AR281 may be a natural alternative for combating osteoporosis.

Lactobacillus plantarum and Lactobacillus brevis Alleviate Intestinal Inflammation and Microbial Disorder Induced by ETEC in a Murine Model

The purpose of this research is to explore the positive effects of Lactobacillus plantarum and Lactobacillus brevis on the tissue damage and microbial community in mice challenged by Enterotoxigenic Escherichia coli (ETEC). Twenty-four mice were divided into four groups randomly: the CON group, ETEC group, LP-ETEC group and LB-ETEC group. Our results demonstrated that, compared with the ETEC group, the LP-ETEC and LB-ETEC groups experienced less weight loss and morphological damage of the jejunum. We measured proinflammatory factors of colonic tissue and found that L. plantarum and L. brevis inhibited the expression of proinflammatory factors such as IL-β, TNF-α, and IL-6 and promoted that of the tight junction protein such as claudin-1, occludin, and ZO-1. Additionally, L. plantarum and L. brevis altered the impact of ETEC on the intestinal microbial community of mice, significantly increased the abundance of probiotics such as Lactobacillus, and reduced that of pathogenic bacteria such as Proteobacteria, Clostridia, Epsilonproteobacteria, and Helicobacter. Therefore, we believe that L. plantarum and L. brevis can stabilize the intestinal microbiota and inhibit the growth of pathogenic bacteria, thus protecting mice from the gut inflammation induced by ETEC.

Investigation of Antibacterial Activity and Probiotic Properties of Strains Belonging to Lactobacillus and Bifidobacterium Genera for Their Potential Application in Functional Food and Feed Products

For novel food/feed product formulation, the selection of the right culture with probiotic properties is essential. The purpose of this research was to evaluate antibacterial activity and probiotic features of Lactobacillus and Bifidobacterium spp. for its potential application in functional food/feed products as supplement. The evaluation of antibacterial activities was carried out by agar diffusion assay and broth inhibition assay methods against twelve pathogenic strains belonging to Staphylococcus aureus, Escherichia coli, Staphylococcus chromogenes, and Staphylococcus hyicus species. Metabolites produced by Lactobacillus paracasei subsp. paracasei DSM 20020, L. paracasei subsp. paracasei DSM 4905, and L. gasseri DSM 20077 inhibited the growth of all tested pathogens. The strains were characterized in vitro for their probiotic characteristics such as resistance to low pH and bile salts, antibiotic sensitivity by gradient diffusion using MIC Test Strips, autoaggregation and coaggregation assay with E. coli DSM 27503, and antioxidant activity by 1-diphenyl-2-picrylhydrazyl (DPPH) and 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging assays. The results demonstrated that tested probiotic properties varied among the strains. Lactobacillus spp. tolerated pH 3 for 4 h, while 8 of 14 strains survived 4 h in pH 2. Most of tested strains were able to tolerate 0.3% bile salts for 4 h. All tested strains were sensitive to ampicillin. No gelatinase and hemolytic activities were detected. These results suggest Lactobacillus acidophilus DSM 20079, Bifidobacterium pseudolongum DSM 20099, and Bifidobacterium animalis DSM 20105 as probiotic candidates for the development of functional food/feed.

Isolation of Bile Salt Hydrolase and Uricase Producing Lactobacillus brevis SF121 from Pak Sian Dong (Fermented Spider Plant) for using as Probiotics

The interesting application of bile salt hydrolase enzyme is reduction of cholesterol in serum and amelioration lipid profile. While uricase enzyme can be applied to convert insoluble uric acid to be soluble form and excrete from the body. Probiotics are living organisms with generally know that they can provide beneficial effects to their host. Several reports show that probiotic bacteria with bile salt hydrolase and uricase can improve hypercholesterolemia and hyperuricemia patient. The novel isolate of Lactobacillus from Pak Sian Dong in this study is identified as L. brevis SF121 and probably use as probiotic bacteria in the future. However, this isolate still need further experiments to investigate and improve properties of probiotics. Moreover, this finding suggests that Pak Sian Dong or fermented spider plant can be designated as a good source for probiotic screening and also defines as health-promoting diet.

Isolation and characterization of lactic acid bacteria from human milk

Human milk is the main source of nutrition for infants and the transmission of various microorganisms. The lactic acid bacteria (LAB) in breast milk allow for the establishment of the gut microflora of infants. In this study, we aimed to assess the probiotic potential of LAB strains isolated from breast milk of healthy Chinese women. Two strains, Lacticaseibacillus rhamnosus (formerly Lactobacillus rhamnosus) LHL6 and LHL7, were selected and identified through morphology observation, Gram staining, and 16S rDNA phylogenetic analysis. Using Limosilactobacillus fermentum (formerly Lactobacillus fermentum) CECT5716 as the standard reference strain, the screened strains were characterized for aspects of growth, production of lactic acid and H₂O₂, antibiotic susceptibility, survival under simulated gastrointestinal conditions, and tolerance to cadmium (Cd). In de Man, Rogosa, and Sharpe (MRS) broth, LHL6 and LHL7 showed longer lag phases than CECT5716 but higher specific growth rates. For the production of lactic acid and H₂O₂, LHL7 performed better than LHL6 and CECT5716, indicating better antimicrobial ability. Strain LHL7 generated 9.99 mg/L H₂O₂, considerably higher than 1.25 mg/L for LHL6 and 2.33 mg/L for CECT5716. According to European Food Safety Authority minimum inhibitory concentrations, all of the investigated strains were resistant to chloramphenicol, streptomycin, and kanamycin. However, unlike LHL6 and CECT5716, LHL7 was susceptible to ampicillin and resistant to tetracycline. Resistance to azithromycin, cephalexin, and penicillin G were similar for all 3 strains, whereas CECT5716 was resistant to a higher concentration of roxithromycin. All 3 strains were able to survive in a simulated gastric-like solution, but a low percentage survived in the presence of 0.4% bile salt and 7% pancreatin. Encapsulation with protectants may enhance the survival rate. All 3 strains were tolerant to 500 mg/L Cd in MRS broth and to 1,000 mg/L Cd on MRS agar medium. In summary, 2 novel strains of LAB were obtained that have similar characteristics to the reference strain CECT5716. This work identified potential probiotic candidates for application in the food and pharmaceutical industries and facilitated identification of further probiotics.

Tracking of deliberately inoculated Leuconostoc mesenteroides and Lactobacillus brevis in kimchi

The objective of this study was to track intentionally inoculated Leuconostoc mesenteroides (11251) and Lactobacillus brevis (B151) strains in kimchi using random amplified polymorphic DNA (RAPD), repetitive element palindromic PCR (rep-PCR), and comparative housekeeping gene sequences analysis. The 16S rRNA gene provided species-level information for 30 colonies randomly picked from kimchi inoculated with strains 11251 and B151. Out of 30 colonies, one colony was matched to strain 11251, and two colonies were found identical to strain B151 reference strain in inoculated kimchi. Notably, among the three tools, strain 11251 was best tracked by comparative gene sequence analysis, while strain B151 tracked by all three tools. Our results suggest that the gene sequence analysis is a more reliable tool for tracking of desired strains than RAPD and rep-PCR. Based on the findings, it is recommended that gene sequence analysis could be used to avoid misuse of industrially useful strains within the growing food industry.

Administration of Metabiotics Extracted From Probiotic Lactobacillus rhamnosus MD 14 Inhibit Experimental Colorectal Carcinogenesis by Targeting Wnt/β-Catenin Pathway

Background and Objective: The cellular microenvironment, diet, and lifestyle play a key role in the occurrence of colorectal cancer. Due to its rising trend, attempts are being made to devise novel biointerventions as adjunct to conventional therapies to prevent this deadly disease. "Metabiotics," the beneficial metabolic signatures of probiotics are emerging as potential anticancer agent due to their ability to alter metabolic processes in the gut lumen and reduce the severity of colon carcinogenesis. Although beneficial attributes of metabiotics have been elucidated in vitro, yet their anticancer mechanism in vivo needs to be explored. Thus, the present study was performed to envisage anticancer potential of metabiotic extract obtained from indigenous probiotic, Lactobacillus rhamnosus MD 14, in early experimental colon carcinogenesis. Materials and Methods: Sprague-Dawley rats were daily administered with low, medium, and high dose of metabiotic extract orally along with a single dose of weekly intraperitoneal injection of 1,2-dimethylhydrazine up to 6 weeks and monitored for the markers of early colon carcinogenesis. Results: It was observed that the medium dose of metabiotic extract attenuated early colon carcinogenesis by reducing fecal procarcinogenic enzymes, oxidants, aberrant crypt foci, vis-à-vis downregulating oncogenes [K-ras, β-catenin, Cox-2, nuclear factor kappa B (NF-κB)] and upregulating tumor suppressor p53 gene leading to almost normal colon histology. Conclusions: It can be suggested that metabiotics modulate experimental colorectal cancer and could be used as a promising alternative of probiotics, particularly in immunocompromised individuals.

The potential role of interventions impacting on gut-microbiota in epilepsy

INTRODUCTION

The gut microbiota seems to be implicated in the functioning and development of basic physiological processes and might also influence central neural processes, through the microbiota-gut-brain (MGB) axis. Pre- and clinical studies support the role of the microbiome in seizure modulation and in the pathogenesis of epilepsy. Acting through different interventions (e.g. diet, supplementations, drugs) could perturb directly and indirectly the MGB axis. Investigating the effects of these interventions might possibly allow better understanding of epilepsy itself, identify biomarkers, or providing new therapeutic options.

AREAS COVERED

PubMed and Google Scholar searches were used to compile a list of relevant publications until January 2020, using data from preclinical studies and clinical trials and gut microbiome/microbiota projects. Furthermore, we evaluate the impact of the antiepileptic drugs on gut microbiota and the influence of intestinal alterations on seizures occurrence.

EXPERT OPINION

Investigating the MGB axis and the role of gut supplementation in epilepsy is challenging due to the numerous potential pathways and variables involved. Few studies have been performed so far and all have been limited making speculation still premature. Studies designed with the similar strictness of pharmaceutical drug development trials, performing taxa, and metabolomic analyses with standard methodologies are needed.

A LAPS-Based Differential Sensor for Parallelized Metabolism Monitoring of Various Bacteria

Monitoring the cellular metabolism of bacteria in (bio)fermentation processes is crucial to control and steer them, and to prevent undesired disturbances linked to metabolically inactive microorganisms. In this context, cell-based biosensors can play an important role to improve the quality and increase the yield of such processes. This work describes the simultaneous analysis of the metabolic behavior of three different types of bacteria by means of a differential light-addressable potentiometric sensor (LAPS) set-up. The study includes Lactobacillus brevis, Corynebacterium glutamicum, and Escherichia coli, which are often applied in fermentation processes in bioreactors. Differential measurements were carried out to compensate undesirable influences such as sensor signal drift, and pH value variation during the measurements. Furthermore, calibration curves of the cellular metabolism were established as a function of the glucose concentration or cell number variation with all three model microorganisms. In this context, simultaneous (bio)sensing with the multi-organism LAPS-based set-up can open new possibilities for a cost-effective, rapid detection of the extracellular acidification of bacteria on a single sensor chip. It can be applied to evaluate the metabolic response of bacteria populations in a (bio)fermentation process, for instance, in the biogas fermentation process.

Inhibition of Clostridium difficile in Mice Using a Mixture of Potential Probiotic Strains Enterococcus faecalis NM815, E. faecalis NM915, and E. faecium NM1015: Novel Candidates to Control C. difficile Infection (CDI)

This study is aimed at the isolation, identification, and characterization of potential probiotic strains capable of inhibiting Clostridium difficile in vitro and in vivo. Twenty isolates were isolated from infant fecal samples and screened against C. difficile using their cell-free supernatant. Only three isolates showed maximum inhibition from 56.05 to 60.60%, thus they were characterized for probiotic properties and safety. The results obtained approved their tolerance to the gastrointestinal tract conditions and safety profile. They were identified by sequencing 16S rRNA as Enterococcus faecalis NM815, E. faecalis NM915, and Enterococcus faecium NM1015. For in vivo evaluation, a viable mixture of these three strains (10⁹ CFU/mL) was administrated to a group of mice (treated group) in daily dose for 14 days, then followed by challenge with viable C. difficile (10⁵ CFU/mL) in daily dose for 7 days, then a second administration of a viable mixture of the three strains was done daily for 7 days. In addition, the control group was administered PBS buffer only and the untreated group received PBS buffer instead of the probiotic mixture before and after the challenge with C. difficile. The results obtained from histological analysis confirmed the effectiveness of our three potential probiotic strains which expressed inhibition of C. difficile and maintained the structural integrity of the liver and intestinal cells.

Fermented Portulaca oleracea L. Juice: A Novel Functional Beverage with Potential Ameliorating Effects on the Intestinal Inflammation and Epithelial Injury

P. oleracea L. contains high level of nutrients and biologically active compounds. Recently, lactic fermentation has been proposed as a biotechnological option to enrich the profile of biogenic compounds of Portulaca oleracea L. puree. This study investigated the capability of fermentation by selected lactic acid bacteria to enhance the restoring features of Portulaca oleracea juice towards intestinal inflammation and epithelial injury. Lactic acid fermentation markedly increased the total antioxidant capacity of P. oleracea juice, preserved the inherent levels of vitamins C, A, and E, and increased the bioavailability of the level of vitamin B₂ and that of phenolics. The effects of fermented P. oleracea juice on a Caco-2 cell line were investigated using an in vitro model closest to the in vivo conditions. Fermented P. oleracea juice strongly decreased the levels of pro-inflammatory mediators and reactive oxygen species. It also counteracted the disruption of the Caco-2 cell monolayers treated with the inflammatory stimulus. We used a diversified spectrum of lactic acid bacteria species, and some effects appeared to be strains- or species-specific. Fermentation with Lactobacillus kunkeei B7 ensured the best combination for the content of bioactive compounds and the ability to counteract the intestinal inflammation and epithelial injury.

Physiological Characteristics and Anti-obesity Effect of Lactobacillus plantarum K10

This study aimed to investigate the physiological characteristics and anti-obesity effects of Lactobacillus plantarum K10. The α-amylase inhibitory activity, α-glucosidase inhibitory activity, and lipase inhibitory activity of L. plantarum K10 was 94.66±4.34%, 99.78±0.12%, and 87.40±1.41%, respectively. Moreover, the strain inhibited the adipocyte differentiation of 3T3-L1 cells (32.61±8.32%) at a concentration of 100 µg/mL. In order to determine its potential for use as a probiotic, we investigated the physiological characteristics of L. plantarum K10. L. plantarum K10 was resistant to gentamycin, kanamycin, streptomycin, ampicillin, ciprofloxacin, tetracycline, vancomycin, and chloramphenicol. It also showed higher Leucine arylamidase, Valine arylamidase, and β-galactosidase activities. Moreover, it was comparatively tolerant to bile juice and acid, exhibiting resistance to Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus with rates of 90.71%, 11.86%, 14.19%, and 23.08%, respectively. The strain did not produce biogenic amines and showed higher adhesion to HT-29 cells compared to L. rhamnosus GG. As a result of the animal study, L. plantarum K10 showed significantly lower body weight compared to the high-fat diet group. The administration of L. plantarum K10 resulted in a reduction of subcutaneous fat mass and mesenteric fat mass compared to the high-fat diet (HFD) group. L. plantarum K10 also showed improvement in gut permeability compared to the HFD positive control group. These results demonstrate that L. plantarum K10 has potential as a probiotic with anti-obesity effects.

Characterization and screening of the potential probiotic lactic acid bacteria and Bifidobacterium strains isolated of different biotopes

The use of lactic acid bacteria (LAB) and bifidobacteria species as probiotics may help to reduce antibiotic use for therapeutic, prophylactic and growth promotion in animal husbandry. The choice of the starter cultures has a critical impact on the palatability, processability and nutritional attributes of fermented products. In our research, the aim of this study was to screen and select potent probiotic LAB and Bifidobacterium strains isolated from different niches and to evaluate their characteristic features. A total of fourteen LAB and fifty-four Bifidobacterium were isolated from four fresh cows and camel’s milk, and twenty stool samples of healthy new born infants were identified and characterized by morphology and biochemical tests in order to select most suitable strains according to their technological characteristics including probiotic proprieties, antibiotics resistance and in vitro antagonism against food-poisoning bacteria. When the results of tolerance to both gastric and bile juices are taken together it appears that between fourteen LAB and forty-five, the strain B. longum BHI 07 has significantly the highest ability to survive during gastrointestinal transit (P < 0.05). Therefore, the mixed cultures of Bf. longum strains with LAB strains were more active against pathogenic bacteria than the pure one. These results show that bifidobacteria isolated from infants may be useful for improving probiotic formulae with respect to protection against pathogenic bacteria responsible of infection.

A Controlled Fermented Samjunghwan Herbal Formula Ameliorates Non-alcoholic Hepatosteatosis in HepG2 Cells and OLETF Rats

Hepatosteatosis (HS), a clinical feature of fatty liver with the excessive intracellular accumulation of triglyceride in hepatocytes, is manifested by perturbation of the maintenance of liver lipid homeostasis. Samjunghwan (SJH) is an herbal formula used mostly in Korean traditional medicine that is effective against a number of metabolic diseases, including obesity. Herbal drugs, enriched with numerous bioactive substances, possess health-protective benefits. Meanwhile, fermented herbal products enriched with probiotics are known to improve metabolic processes. Additionally, current lines of evidence indicate that probiotics-derived metabolites, termed as postbiotics, produce the same beneficial effects as their precursors. Herein, the anti-HS effects of 5-weeks naturally fermented SJH (FSJH) was investigated with FSJH-mixed chow diet in vivo using Otsuka Long-Evans Tokushima Fatty (OLETF) and Long-Evans Tokushima Otsuka (LETO) rats as animal models of HS and controls, respectively. In parallel, the anti-HS effects of postbiotic-metabolites of three bacterial strains [Lactobacillus brevis (LBB), Lactococcus lactis (LCL) and Lactobacillus plantarum (LBP)] isolated from FSJH were also evaluated in vitro using the FFAs-induced HepG2 cells. Feeding OLETF rats with FSJH-diet effectively reduced body, liver, and visceral adipose tissue (VAT) weights, produced marked hypolipidemic effects on serum and hepatic lipid parameters, decreased serum AST and ALT levels, and upregulated the HMGCOR, SREBP, and ACC, and downregulated the AMPK and LDLR gene expressions levels. Additionally, exposure of FFAs-induced HepG2 cells to postbiotic metabolic media (PMM) of bacterial strains also produced marked hypolipidemic effects on intracellular lipid contents and significantly unregulated the HMGCOR, SREBP, and ACC, and downregulated the AMPK and LDLR genes expressions levels. Overall, our results indicate that FSJH enriched with fermented metabolites could be an effective anti-HS formulation.

Probiotic and anti-inflammatory potential of Lactobacillus rhamnosus 4B15 and Lactobacillus gasseri 4M13 isolated from infant feces

A total of 22 Lactobacillus strains, which were isolated from infant feces were evaluated for their probiotic potential along with resistance to low pH and bile salts. Eight isolates (L. reuteri 3M02 and 3M03, L. gasseri 4M13, 4R22, 5R01, 5R02, and 5R13, and L. rhamnosus 4B15) with high tolerance to acid and bile salts, and ability to adhere to the intestine were screened from 22 strains. Further, functional properties of 8 Lactobacillus strains, such as anti-oxidation, inhibition of α-glucosidase activity, cholesterol-lowering, and anti-inflammation were evaluated. The properties were strain-specific. Particularly, two strains of L. rhamnosus, 4B15 (4B15) and L. gasseri 4M13 (4M13) showed considerably higher anti-oxidation, inhibition of α-glucosidase activity, and cholesterol-lowering, and greater inhibition of nitric oxide production than other strains. Moreover, the two selected strains substantially inhibited the release of inflammatory mediators such as TNF-α, IL-6, IL-1β, and IL-10 stimulated the treatment of RAW 264.7 macrophages with LPS. In addition, whole genome sequencing and comparative genomic analysis of 4B15 and 4M13 indicated them as novel genomic strains. These results suggested that 4B15 and 4M13 showed the highest probiotic potential and have an impact on immune health by modulating pro-inflammatory cytokines.

Molecular typing of Lactobacillus brevis isolates from Korean food using repetitive element-polymerase chain reaction

Lactobacillus brevis is a part of a large family of lactic acid bacteria that are present in cheese, sauerkraut, sourdough, silage, cow manure, feces, and the intestinal tract of humans and rats. It finds its use in food fermentation, and so is considered a "generally regarded as safe" organism. L. brevis strains are extensively used as probiotics and hence, there is a need for identifying and characterizing these strains. For identification and discrimination of the bacterial species at the subspecific level, repetitive element-polymerase chain reaction method is a reliable genomic fingerprinting tool. The objective of the present study was to characterize 13 strains of L. brevis isolated from various fermented foods using repetitive element-polymerase chain reaction. Repetitive element-polymerase chain reaction was performed using three primer sets, REP, Enterobacterial Repetitive Intergenic Consensus (ERIC), and (GTG)₅, which produced different fingerprinting patterns that enable us to distinguish between the closely related strains. Fingerprinting patterns generated band range in between 150 and 5000 bp with REP, 200-7500 bp with ERIC, and 250-2000 bp with (GTG)₅ primers, respectively. The Jaccard's dissimilarity matrices were used to obtain dendrograms by the unweighted neighbor-joining method using genetic dissimilarities based on repetitive element-polymerase chain reaction fingerprinting data. Repetitive element-polymerase chain reaction proved to be a rapid and easy method that can produce reliable results in L. brevis species.

Characterization of a Potential Probiotic Lactobacillus brevis RK03 and Efficient Production of γ-Aminobutyric Acid in Batch Fermentation

Lactic acid bacteria were isolated from fish and evaluated for their γ-aminobutyric acid (GABA)-producing abilities. Out of thirty-two isolates, Lactobacillus brevis RK03 showed the highest GABA production ability. The effects of various fermentation parameters including initial glutamic acid level, culture temperature, initial pH, and incubation time on GABA production were investigated via a singleparameter optimization strategy. For industrial large-scale production, a low-cost GABA producing medium (GM) broth was developed for fermentation with L. brevis RK03. We found that an optimized GM broth recipe of 1% glucose; 2.5% yeast extract; 2 ppm each of CaCO₃, MnSO₄, and Tween 80; and 10 μM pyridoxal phosphate (PLP) resulted in a maximum GABA yield of 62,523 mg/L after 88 h following the addition of 650 mM monosodium glutamate (MSG), for a conversion rate of 93.28%. Our data provide a practical approach for the highly efficient and economic production of GABA. In addition, L. brevis RK03 is highly resistant to gastric acid and bovine bile salt. Thus, the discovery of Lactobacillus strains with the ability to synthesize GABA may offer new opportunities in the design of improved health-promoting functional foods.

Potential Probiotic Microorganisms in Kefir

Probiotic microorganisms are defined as living microorganisms that provide health benefits on the host when administered in adequate amounts. The benefits include improvement of microbial balance immune system and oral health, provision of cholesterol-lowering effect, and antimicrobial activity against a wide variety of bacteria and some fungi. Kefir microbiota contains active living microorganisms. Many researches were carried out that potential probiotic bacteria such as Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus kefir, Lactobacillus kefiranofaciens, Leuconostoc mesenteroides, or yeasts like microorganisms such as Saccharomyces cerevisiae, Kluyveromyces lactis, and Kluyveromyces marxianus were isolated from kefir grains. This chapter presents the data both on the probiotic bacteria isolated from kefir grains or kefir and the probiotic properties of kefir produced with these microorganisms.

Selection of autochthonous lactic acid bacteria from goat dairies and their addition to evaluate the inhibition of Salmonella typhi in artisanal cheese

This study aimed to select autochthonous lactic acid bacteria (LAB) with probiotic and functional properties from goat dairies and test their addition to artisanal cheese for the inhibition of Salmonella typhi. In vitro tests, including survival in the gastrointestinal tract (GIT), auto- and co-aggregation, the hemolytic test, DNase activity, antimicrobial susceptibility, antibacterial activity, tolerance to NaCl and exopolysaccharide (EPS), gas and diacetyl production were conducted for sixty isolates. Based on these tests, four LAB isolates (UNIVASF CAP 16, 45, 84 and 279) were selected and identified. Additional tests, such as production of lactic and citric acids by UNIVASF CAP isolates were performed in addition to assays of bile salt hydrolase (BSH), β-galactosidase and decarboxylase activity. The four selected LAB produced high lactic acid (>17 g/L) and low citric acid (0.2 g/L) concentrations. All selected strains showed BSH and β-galactosidase activity and none showed decarboxylase activity. Three goat cheeses (1, 2 and control) were produced and evaluated for the inhibitory action of selected LAB against Salmonella typhi. The cheese inoculated with LAB (cheese 2) decreased 0.38 log10 CFU/g of S. Typhy population while in the cheese without LAB inoculation (cheese 1) the pathogen population increased by 0.29 log units. Further, the pH value increased linearly over time, by 0.004 units per day in cheese 1. In the cheese 2, the pH value decreased linearly over time, by 0.066 units per day. The cocktail containing selected Lactobacillus strains with potential probiotic and technological properties showed antibacterial activity against S. typhi in vitro and in artisanal goat cheese. Thus, goat milk is important source of potential probiotic LAB which may be used to inhibit the growth of Salmonella population in cheese goat, contributing to safety and functional value of the product.

Isolation of Enterococcus faecium NM113, Enterococcus faecium NM213 and Lactobacillus casei NM512 as novel probiotics with immunomodulatory properties

Probiotics, defined as living bacteria that are beneficial for human health, mainly function through their immunomodulatory abilities. Hence, these microorganisms have proven successful for treating diseases resulting from immune deregulation. The aim of this study was to find novel candidates to improve on and complement current probiotic treatment strategies. Of 60 lactic acid bacterial strains that were isolated from fecal samples of healthy, full-term, breast-fed infants, three were chosen because of their ability to activate human immune cells. These candidates were then tested with regard to immunomodulatory properties, antimicrobial effects on pathogens, required pharmacological properties and their safety profiles. To identify the immunomodulatory structures of the selected isolates, activation of specific innate immune receptors was studied. The three candidates for probiotic treatment were assigned Enterococcus faecium NM113, Enterococcus faecium NM213 and Lactobacillus casei NM512. Compared with the established allergy-protective strain Lactococcus lactis G121, these isolates induced release of similar amounts of IL-12, a potent inducer of T helper 1 cells. In addition, all three neonatal isolates had antimicrobial activity against pathogens. Analysis of pharmacological suitability showed high tolerance of low pH, bile salts and pancreatic enzymes. In terms of safe application in humans, the isolates were sensitive to three antibiotics (chloramphenicol, tetracycline and erythromycin). In addition, the Enterococcus isolates were free from the four major virulence genes (cylA, agg, efaAfs and ccf). Moreover, the isolates strongly activated Toll-like receptor 2, which suggests lipopeptides as their active immunomodulatory structure. Thus, three novel bacterial strains with great potential as probiotic candidates and promising immunomodulatory properties have here been identified and characterized.

Safety, beneficial and technological properties of Enterococcus faecium isolated from Brazilian cheeses

This study aimed to characterize the safety and technological properties of Enterococcus faecium strains isolated from Brazilian Coalho cheeses. High levels of co-aggregation were observed between Enterococcus faecium strains EM485 and EM925 and both Escherichia coli and Clostridium perfringens . Both strains presented low levels of hydrophobicity. E. faecium EM485 and EM925 were both able to grow in the presence of 0.5% of the sodium salts of taurocholic acid (TC), taurodeoxycholic acid (TDC), glycocholic acid (GC), and glycodeoxycholic acid (GDC), although they showed the ability to deconjugate only GDC and TDC. Both strains showed good survival when exposed to conditions simulating the gastro intestinal tract (GIT). When tested for the presence of virulence genes, only tyrosine decarboxylase and vancomycin B generated positive PCR results.

Probiotic potential of Lactobacillus strains with antimicrobial activity against some human pathogenic strains

The objective of this study was to isolate, identify, and characterize some lactic acid bacterial strains from human milk, infant feces, and fermented grapes and dates, as potential probiotics with antimicrobial activity against some human pathogenic strains. One hundred and forty bacterial strains were isolated and, after initial identification and a preliminary screening for acid and bile tolerance, nine of the best isolates were selected and further identified using 16 S rRNA gene sequences. The nine selected isolates were then characterized in vitro for their probiotic characteristics and their antimicrobial activities against some human pathogens. Results showed that all nine isolates belonged to the genus Lactobacillus. They were able to tolerate pH 3 for 3 h, 0.3% bile salts for 4 h, and 1.9 mg/mL pancreatic enzymes for 3 h. They exhibited good ability to attach to intestinal epithelial cells and were not resistant to the tested antibiotics. They also showed good antimicrobial activities against the tested pathogenic strains of humans, and most of them exhibited stronger antimicrobial activity than the reference strain L. casei Shirota. Thus, the nine Lactobacillus strains could be considered as potential antimicrobial probiotic strains against human pathogens and should be further studied for their human health benefits.

Cellular fatty acid composition and exopolysaccharide contribute to bile tolerance in Lactobacillus brevis strains isolated from fermented Japanese pickles

Bile tolerance is a fundamental ability of probiotic bacteria. We examined this property in 56 Lactobacillus brevis strains isolated from Japanese pickles and also evaluated cellular fatty acid composition and cell-bound exopolysaccharide (EPS-b) production. The bile tolerance of these strains was significantly lower in modified de Man – Rogosa – Sharpe (MRS) medium (without Tween 80 or sodium acetate) than in standard MRS medium. Aggregating strains showed significantly higher bile tolerance than nonaggregating strains in MRS medium, but there was no significant difference in the modified MRS media. The relative octadecenoic acid (C18:1) content of the 3 most tolerant aggregating and nonaggregating strains was significantly higher when bile was added to MRS. In MRS without Tween 80, the relative C18:1 content was only marginally affected by addition of bile. In MRS without sodium acetate, only the 3 most tolerant nonaggregating strains increased their relative C18:1 content in the presence of bile. Meanwhile, culture in MRS without sodium acetate reduced EPS-b production in aggregating strains. In conclusion, both EPS-b and cellular fatty acid composition play important roles in bile tolerance of pickle-derived L. brevis.