Comparative genomics of in vitro and in vivo evolution of probiotics reveals energy restriction not the main evolution driving force in short term

Probiotics have attracted much attention because of their health-promoting effects, but little is known about the in vivo evolution of probiotics. This study analyzed the genome adaptation of the probiotic Lactiplantibacillus plantarum P-8 strain cultivated in ordinary and glucose restrictive growth media. Then, this study re-analyzed genomes of P-8 isolates recovered from the gut contents of subjects in two feeding trials (in rat and human). The sampling time points were similar to that of the in vitro evolution experiment, which might give parallel comparison of the in vitro and in vivo evolution processes. Our results showed that intra-individual specific microbial genomic variants of the original strain were detected in all human and some rat subjects. The divergent patterns of evolution within the host gastrointestinal tract suggested intra-individual-specific environmental adaptation. Based on comprehensive analysis of adapted-isolates recovered from these experiments, our results showed that the energy restriction was not the main driving force for evolution of probiotics. The individual-specific adaptation of probiotics might partially explain the varying extent of health effects seen between different individuals after probiotic consumption. In addition, the results suggest that probiotics should not only adapt to the environment of the birth canal, but also adapt to other species in the gut, revealing the Red Queen hypothesis in the process of intestinal flora.     

New perspectives of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> as a probiotic: The gut-heart-brain axis

Lactobacillus plantarum is a non-gas-producing lactic acid bacterium that is generally regarded as safe (GRAS) with Qualified Presumption of Safety (QPS) status. Although traditionally used for dairy, meat and vegetable fermentation, L. plantarum is gaining increasing significance as a probiotic. With the newly acclaimed gut-heart-brain axis, strains of L. plantarum have proven to be a valuable species for the development of probiotics, with various beneficial effects on gut health, metabolic disorders and brain health. In this review, the classification and taxonomy, and the relation of these with safety aspects are introduced. Characteristics of L. plantarum to fulfill the criteria as a probiotic are discussed. Emphasis are also given to the beneficial functions of L. plantarum in gut disorders such as inflammatory bowel diseases, metabolic syndromes, dyslipidemia, hypercholesteromia, obesity, and diabetes, and brain health aspects involving psychological disorders.     

Functional Characterization of Potential Probiotic Lactic Acid Bacteria Isolated from <Emphasis Type="Italic">Kalarei</Emphasis> and Development of Probiotic Fermented Oat Flour

Considerable variations among probiotics with respect to their health benefitting attributes fuel the research on bioprospecting of proficient probiotic strains from various ecological niches especially the poorly unexplored ones. In the current study, kalarei, an indigenous cheese-like fermented milk product, and other dairy-based sources like curd and raw milk were used for isolation of lactic acid bacteria (LAB). Among 34 LAB isolates, 7 that could withstand simulated gastrointestinal (GI) conditions were characterized for functional probiotic attributes, viz. adhesion ability, aggregation and coaggregation, extracellular enzyme producing capability, antibacterial activity against pathogens and antibiotic resistance. The isolate M-13 (from kalarei) which exhibited most of the desirable probiotic functional properties was identified as Lactobacillus plantarum based on 16S ribosomal DNA sequence analysis and designated as L. plantarum M-13. The sequence was submitted to GenBank (accession number KT592509). The study presents the first ever report of isolation of potential probiotic LAB, i.e. L. plantarum M-13 from indigenous food kalarei, and its application for development of potential probiotic fermented oat flour (PFOF). PFOF was analysed for parameters like viability of L. plantarum M-13, acidity and pH. Results show that PFOF serves as a good matrix for potential probiotic L. plantarum M-13 as it supported adequate growth of the organism (14.4 log cfu/ml after 72 h of fermentation). In addition, appreciable acid production by L. plantarum M-13 and consequential pH reduction indicates the vigorous and active metabolic status of the potential probiotic organism in the food matrix. Thus, study shows that fermented oat flour may possibly be developed as a potential probiotic carrier especially in view of the problems associated with dairy products as probiotic vehicles.     

Probiotics Can Generate FoxP3 T-Cell Responses in the Small Intestine and Simultaneously Inducing CD4 and CD8 T Cell Activation in the Large Intestine

Most studies on probiotics aim to restore intestinal homeostasis to reduce immune-pathology in disease. Of equal importance are studies on how probiotics might prevent or delay disease in healthy individuals. However, knowledge on mechanisms of probiotic actions in healthy individuals is scarce. To gain more insight in how different bacterial strains may modulate the healthy intestinal immune system, we investigated the effect of the food derived bacterial strains L. plantarum WCFS1, L. salivarius UCC118, and L. lactis MG1363, on the intestinal regulatory immune phenotype in healthy mice. All three bacterial strains induced an upregulation of activity and numbers of CD11c⁺ MHCII⁺ DCs in the immune-sampling Peyer’s Patches. Only L. salivarius UCC118 skewed towards an immune regulatory phenotype in the small intestinal lamina propria (SILP). The effects were different in the large intestine lamina propria. L. salivarius UCC118 induced activation in both CD4 and CD8 positive T-cells while L. plantarum WCFS1 induced a more regulatory phenotype. Moreover, L. plantarum WCFS1 decreased the Th1/Th2 ratio in the SILP. Also L. lactis MG1363 had immunomodulatory effects. L. lactis MG1363 decreased the expression of the GATA-3 and T-bet in the SILP. As our data show that contradictory effects may occur in different parts of the gut, it is recommended to study effects of probiotic in different sites in the intestine. Our strain-specific results suggest that unspecified application of probiotics may not be very effective. Our data also indicate that selection of specific probiotic strain activities on the basis of responses in healthy mice may be a promising strategy to specifically stimulate or suppress immunity in specific parts of the intestine.     

Effect of Soymilk Fermented with Lactobacillus plantarum P-8 on Lipid Metabolism and Fecal Microbiota in Experimental Hyperlipidemic Rats

We recently identified a novel probiotic strain Lactobacillus plantarum P-8 (L. plantarum P-8), which has been characterized in detail with regard to its probiotic potential. In the present study, soymilk fermented with L. plantarum P-8 was examined for its effects on diet-induced hyperlipidemia in Wistar rats. The experimental animals were divided into four groups: control group (C group), model group (M group), soymilk group (SM group) and fermented soymilk group (FSM group). The serum lipid levels, hepatic fat deposition, serum oxidative stress parameters, hepatic marker enzymes levels, organ indices, gut bacteria and fecal fat contents were analyzed. Fermented soymilk reduced the concentration of total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) in serum, with a significant elevation in high-density lipoprotein cholesterol (HDL) concentration. Our results also suggested the beneficial effects of fermented soymilk on the liver function, hyperlipidemia-induced oxidative stress and intestinal bacteria. Moreover, fermented soymilk could enhance the fecal excretion of TC, TG and bile acids. These findings demonstrated that soymilk fermented with L. plantarum P-8 was effective in improving the lipid metabolism in hyperlipidemic rats. The hypolipidemic effect of fermented soymilk was partly due to the inhibition of dietary fats absorption and regulation of fecal fats excretion mediated by gut bacteria.     

Phytase-Producing Potential and Other Functional Attributes of Lactic Acid Bacteria Isolates for Prospective Probiotic Applications

Wide variations among multifaceted-health benefitting attributes of probiotics fueled investigations on targeting efficacious probiotics. In the current study, lactic acid bacteria (LAB) isolated from poultry gut, feces of rat, chicken, human infants, and fermented foods were characterized for desired probiotic functional properties including the phytase-producing ability which is one of the wanted characteristics for probiotics for potential applications for upgrading animal nutrition, enhancing feed conversion, and minimizing anti-nutritional properties. Among 62 LAB isolates Weissella kimchii R-3 an isolate from poultry gut exhibited substantial phytase-producing ability (1.77 U/ml) in addition to other functional probiotic characteristics viz. hydrophobicity, autoaggregation, coaggregation with bacterial pathogens, and antimicrobial activity against pathogens. Survival of W. kimchii R-3 cells (in free and calcium alginate encapsulated state) was examined sequentially in simulated gastric and intestinal juices. Encapsulated cells exhibited better survival under simulated gut conditions indicating that encapsulation conferred considerable protection against adverse gut conditions. Furthermore, simulated gastric and intestinal juices with pepsin and pancreatin showed higher survival of cells than the juices without pepsin and pancreatin. W. kimchii R-3 due to its significant functional probiotic attributes may have prospective for commercial applications in human/animal nutrition.     

Ileal mucosal response to the same probiotic Lactobacillus strains is markedly different between suckling and adult mice

While evidence shows that probiotic supplementation exerts beneficial effects on developing children and animals, it is unclear whether it would exert equal or similar effects on adult human and animals. In this study, response to probiotic lactobacilli in ileal mucosa of suckling and adult mice was compared by evaluating gene expression profiles using DNA microarray. Two probiotic strains, Lactobacillus gasseri CP2305s and Lactobacillus plantarum CPA305C were used. Supplementation of probiotics for 7 days affected completely different genes in suckling and adult mice, regardless of the probiotic strain. The results suggested that ileal mucosal responses to probiotics are age stage specific.     

Tannic Acid-Dependent Modulation of Selected Lactobacillus plantarum Traits Linked to Gastrointestinal Survival

Background

Owing to its antimicrobial properties dietary tannins may alter the functional efficacy of probiotic lactobacilli in the gastrointestinal (GI)-tract influencing their growth, viability and molecular adaptation to the intestinal environment.

Methods and Findings

The effects of tannic acid on Lactobacillus plantarum WCFS1 were studied by in vitro growth monitoring and visualizing the morphological alteration on the cell wall using transmission electron microscopy. Growth upon tannic acid was characterized by dose-dependent reductions of initial viable counts and extended lag phases. Lag phase-cells growing upon 0.5 mM tannic acid were abnormally shaped and experienced disturbance on the cell wall such as roughness, occasional leakage and release of cell debris, but resumed growth later at tannic acid concentrations high as 2.5 mM. To gain insight on how the response to tannic acid influenced the molecular adaptation of L. plantarum to the GI-tract conditions, gene expression of selected biomarkers for GI-survival was assessed by RT-qPCR on cDNA templates synthetized from mRNA samples obtained from cells treated with 0.5 or 2 mM tannic acid. Tannic acid-dependent gene induction was confirmed for selected genes highly expressed in the gut or with confirmed roles in GI-survival. No differential expression was observed for the pbp2A gene, a biomarker negatively related with GI-survival. However PBP2A was not labeled by Bocillin FL, a fluorescent dye-labeled penicillin V derivative, in the presence of tannic acid which suggests for enhanced GI-survival reportedly associated with the inactivation of this function.

Conclusions

Probiotic L. plantarum WCFS1 is able to overcome the toxic effects of tannic acid. This dietary constituent modulates molecular traits linked to the adaptation to intestinal environment in ways previously shown to enhance GI-survival.     

Functional and Probiotic Attributes of an Indigenous Isolate of Lactobacillus plantarum

Background

Probiotic microorganisms favorably alter the intestinal microflora balance, promote intestinal integrity and mobility, inhibit the growth of harmful bacteria and increase resistance to infection. Probiotics are increasingly used in nutraceuticals, functional foods or in microbial interference treatment. However, the effectiveness of probiotic organism is considered to be population-specific due to variation in gut microflora, food habits and specific host-microbial interactions. Most of the probiotic strains available in the market are of western or European origin, and a strong need for exploring new indigenous probiotic organisms is felt.

Methods and Findings

An indigenous isolate Lp9 identified as Lactobacillus plantarum by molecular-typing methods was studied extensively for its functional and probiotic attributes, viz., acid and bile salt tolerance, cell surface hydrophobicity, autoaggregation and Caco-2 cell-binding as well as antibacterial and antioxidative activities. Lp9 isolate could survive 2 h incubation at pH 1.5–2.0 and toxicity of 1.5–2.0% oxgall bile. Lp9 could deconjugate major bile salts like glycocholate and deoxytaurocholate, indicating its potential to cause hypocholesterolemia. The isolate exhibited cell-surface hydrophobicity of ∼37% and autoaggregation of ∼31%. Presence of putative probiotic marker genes like mucus-binding protein (mub), fibronectin-binding protein (fbp) and bile salt hydrolase (bsh) were confirmed by PCR. Presence of these genes suggested the possibility of specific interaction and colonization potential of Lp9 isolate in the gut, which was also suggested by a good adhesion ratio of 7.4±1.3% with Caco-2 cell line. The isolate demonstrated higher free radical scavenging activity than standard probiotics L. johnsonii LA1 and L. acidophilus LA7. Lp9 also exhibited antibacterial activity against E. coli, L. monocytogenes, S. typhi, S. aureus and B. cereus.

Conclusion

The indigenous Lactobacillus plantarum Lp9 exhibited high resistance against low pH and bile and possessed antibacterial, antioxidative and cholesterol lowering properties with a potential for exploitation in the development of indigenous functional food or nutraceuticals.     

Comparative genomic analysis of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> GB-LP4 and identification of evolutionarily divergent genes in high-osmolarity environment

Lactobacillus plantarum is one of the widely-used probiotics and there have been a large number of advanced researches on the effectiveness of this species. However, the difference between previously reported plantarum strains, and the source of genomic variation among the strains were not clearly specified. In order to understand further on the molecular basis of L. plantarum on Korean traditional fermentation, we isolated the L. plantarum GB-LP4 from Korean fermented vegetable and conducted whole genome assembly. With comparative genomics approach, we identified the candidate genes that are expected to have undergone evolutionary acceleration. These genes have been reported to associate with the maintaining homeostasis, which are generally known to overcome instability in external environment including low pH or high osmotic pressure. Here, our results provide an evolutionary relationship between L. plantarum species and elucidate the candidate genes that play a pivotal role in evolutionary acceleration of GB-LP4 in high osmolarity environment. This study may provide guidance for further studies on L. plantarum.     

Application of Microencapsulated Synbiotics in Fruit-Based Beverages

In the last years, demand for functional products containing both prebiotics and probiotics (known as synbiotic) has increased, which stimulated their incorporation into other food matrices than milk-based ones. Synbiotics improve gut functionality as well as respond to the increasing demand of consumers who have become aware of the health benefits of a proper diet. The most important criterion for preserving consumer acceptance in such products is maintaining the minimum viability and activity of probiotics from the beginning of production to the end of shelf-life. For their viability, fixation and multiplying within the host, several solutions have been proposed including the fortification with prebiotics and microencapsulation of prebiotics along with probiotics. The challenge of microencapsulation is to protect the probiotic cells in foods that are not usually considered their vehicle, such as fruit matrices. It is generally known that different prebiotics may exert different degrees of protection on the entrapped bacteria cells. For food products, such as fruit beverages, few works exist that investigate the functionality of synbiotic microcapsules in protecting the survivability of probiotic cells during processing and storage. This article provides an overview of this novel trend based on a review of relevant literature. The article summarizes the synbiotic concept, challenges for synbiotic formulation in fruit beverages, and future perspectives.

     

Robustness of Gut Microbiota of Healthy Adults in Response to Probiotic Intervention Revealed by High-Throughput Pyrosequencing

Probiotics are live microorganisms that potentially confer beneficial outcomes to host by modulating gut microbiota in the intestine. The aim of this study was to comprehensively investigate effects of probiotics on human intestinal microbiota using 454 pyrosequencing of bacterial 16S ribosomal RNA genes with an improved quantitative accuracy for evaluation of the bacterial composition. We obtained 158 faecal samples from 18 healthy adult Japanese who were subjected to intervention with 6 commercially available probiotics containing either Bifidobacterium or Lactobacillus strains. We then analysed and compared bacterial composition of the faecal samples collected before, during, and after probiotic intervention by Operational taxonomic units (OTUs) and UniFrac distances. The results showed no significant changes in the overall structure of gut microbiota in the samples with and without probiotic administration regardless of groups and types of the probiotics used. We noticed that 32 OTUs (2.7% of all analysed OTUs) assigned to the indigenous species showed a significant increase or decrease of ≥10-fold or a quantity difference in >150 reads on probiotic administration. Such OTUs were found to be individual specific and tend to be unevenly distributed in the subjects. These data, thus, suggest robustness of the gut microbiota composition in healthy adults on probiotic administration.     

In vitro investigation of <Emphasis Type="Italic">Debaryomyces hansenii</Emphasis> strains for potential probiotic properties

In this study, 23 Debaryomyces hansenii strains, isolated from cheese and fish gut, were investigated in vitro for potential probiotic properties i.e. (1) survival under in vitro GI (gastrointestinal) conditions with different oxygen levels, (2) adhesion to Caco-2 intestinal epithelial cells and mucin, and (3) modulation of pro- and anti-inflammatory cytokine secretion by human monocyte-derived dendritic cells. As references two commercially available probiotic Saccharomyces cerevisiae var. boulardii (S. boulardii) strains were included in the study. Our results demonstrate that the different D. hansenii yeast strains had very diverse properties which could potentially lead to different probiotic effects. One strain of D. hansenii (DI 09) was capable of surviving GI stress conditions, although not to the same degree as the S. boulardii strains. This DI 09 strain, however, adhered more strongly to Caco-2 cells and mucin than the S. boulardii strains. Additionally, two D. hansenii strains (DI 10 and DI 15) elicited a higher IL-10/IL-12 ratio than the S. boulardii strains, indicating a higher anti-inflammatory effects on human dendritic cells. Finally, one strain of D. hansenii (DI 02) was evaluated as the best probiotic candidate because of its outstanding ability to survive the GI stresses, to adhere to Caco-2 cells and mucin and to induce a high IL-10/IL-12 ratio. In conclusion, this study shows that strains of D. hansenii may offer promising probiotic traits relevant for further study.     

Survival of Lactobacillus reuteri DSM 17938 and Lactobacillus rhamnosus GG in the Human Gastrointestinal Tract with Daily Consumption of a Low-Fat Probiotic Spread

Probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. Therefore, probiotic strains should be able to survive passage through the human gastrointestinal tract. Human gastrointestinal tract survival of probiotics in a low-fat spread matrix has, however, never been tested. The objective of this randomized, double-blind, placebo-controlled human intervention study was to test the human gastrointestinal tract survival of Lactobacillus reuteri DSM 17938 and Lactobacillus rhamnosus GG after daily consumption of a low-fat probiotic spread by using traditional culturing, as well as molecular methods. Forty-two healthy human volunteers were randomly assigned to one of three treatment groups provided with 20 g of placebo spread (n = 13), 20 g of spread with a target dose of 1 × 10⁹ CFU of L. reuteri DSM 17938 (n = 13), or 20 g of spread with a target dose of 5 × 10⁹ CFU of L. rhamnosus GG (n = 16) daily for 3 weeks. Fecal samples were obtained before and after the intervention period. A significant increase, compared to the baseline, in the recovery of viable probiotic lactobacilli in fecal samples was demonstrated after 3 weeks of daily consumption of the spread containing either L. reuteri DSM 17938 or L. rhamnosus GG by selective enumeration. In the placebo group, no increase was detected. The results of selective enumeration were supported by quantitative PCR, detecting a significant increase in DNA resulting from the probiotics after intervention. Overall, our results indicate for the first time that low-fat spread is a suitable carrier for these probiotic strains.The human intestinal microflora or microbiota constitutes a metabolically active microbial environment. This community is relatively stable in the guts of healthy individuals (20). Some of the microbial groups harbor species that are potentially harmful, whereas others, such as the bifidobacteria and lactobacilli, are regarded as beneficial (8). Specific members of the genera Lactobacillus and Bifidobacterium are being applied in functional foods as probiotics (25). Probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit on the host (9). The current scientific consensus is that probiotics should be alive to exert their beneficial effect in the human gastrointestinal (GI) tract (6). Consequently, probiotics should remain alive in the product, such that the daily effective dose per serving is still present at the end of the shelf life (14). Food matrices, production processes, or product usages that involve heating can affect the viability of probiotics (24).Typically, those members selected for probiotic application are chosen for their resistance to passage through the upper GI tract and thus are able to transiently colonize the gut (25). Human GI tract survival of probiotics should lead to shedding of live cells in fecal samples. GI tract survival is, however, dependent on both the strain and the food matrix involved (27). Fecal recovery of several probiotic strains has been demonstrated in different food matrices, including fermented milk and yoghurt (10, 26, 29), fruit drinks (21), a cereal bar (22), supplements (13, 17, 27), and infant formula (29).For this study, we have selected two well-established probiotic strains to test the suitability of a low-fat spread as a probiotic carrier, namely, Lactobacillus reuteri DSM 17938 (BioGaia, Sweden) and Lactobacillus rhamnosus GG (ATCC 53103; Valio, Finland). L. reuteri DSM 17938 was derived from L. reuteri ATCC 55730 by curing of two plasmids harboring antibiotic resistance genes (23). A series of in vitro experiments confirmed the retention of the functional properties of the daughter strain, as no differences in colony morphology, fermentation patterns, production of reuterin, generation time, mucus-binding ability, or tolerance to bovine bile were found between L. reuteri ATCC 55730 and DSM 17938. The daughter strain is somewhat more resistant to low pH and grows to a higher density in vitro (23). Several studies have been published which provide data on the survival of L. reuteri ATCC 55730 in the human GI tract at doses of 4 × 10⁸ to 1 × 10¹⁰ CFU/day in freeze-dried matrices and chewable tablets (32-34). Furthermore, L. reuteri DSM 17938 was demonstrated to survive human GI tract passage in the same way as L. reuteri ATCC 55730 (23).L. rhamnosus GG has been isolated from a healthy human intestinal flora by Goldin et al. (10). L. rhamnosus GG is relatively resistant to acid and bile, adheres in vitro to epithelial cells, and can produce an antimicrobial substance (10, 15). A wide range of studies have been published which provide data on the survival of L. rhamnosus GG in the human GI tract (3, 4, 10, 18, 19, 27-30), as well as transient colonization of the intestinal microbiota in healthy adults in various formats, including freeze-dried powder, capsules, and tablets or via fermented milk drinks, yoghurt, or fruit juice. Saxelin et al. (28) evaluated the dose-response effect of orally administered L. rhamnosus GG in powder form on fecal colonization in healthy adults, which indicated that consumption of approximately 10¹⁰ to 10¹¹ CFU/day was required to reach detectable levels in fecal samples from volunteers. This was also the case when L. rhamnosus GG was administered in gelatin capsules (29). Additionally, Saxelin et al. (27) observed that milk, but possibly also other protective compounds in food, can improve the survival of L. rhamnosus GG. Fecal recovery of L. rhamnosus GG in milk-based products was shown at dose levels of around 2 × 10⁹ CFU/day.It is, however, not known whether probiotics can survive passage through the human GI tract after the consumption of a low-fat spread. The objective of this randomized, double-blind, placebo-controlled human intervention study was therefore to test the human GI tract survival of L. reuteri DSM 17938 and L. rhamnosus GG after daily consumption of a low-fat probiotic spread by using traditional culturing, as well as molecular methods. The primary outcome parameter of this study was a significant change from the baseline in the number of probiotic bacteria of the respective strains in fecal samples.     

Characteristics of Bacterial Isolates from the Gut of Freshwater Fish, Labeo rohita that May be Useful as Potential Probiotic Bacteria

In this study, we aimed to evaluate the in vitro probiotic characteristics of three bacteria, Lactobacillus plantarum VSG3, Pseudomonas aeruginosa VSG2, and Bacillus subtilis VSG1, isolated from the gut of Labeo rohita. The bacterial isolates tolerated low pH and high bile concentrations in the fish well. The bacterial adhesion capacity to fish intestinal mucosa revealed that the three potential probiotic isolates had a significantly higher adhesion capacity compared to the pathogenic strains tested. L. plantarum VSG3 exhibited the best adhesion capacity (19.1?%) to the intestinal mucosa. Among the isolates, L. plantarum VSG3 and P. aeruginosa VSG2 showed strong antibacterial activities against fish pathogens as measured in spent culture liquids. Moreover, all the isolates were susceptible to each tested antibiotic, which ensured their inability to exhibit antibiotic-resistance properties. Considering these promising results, selected strains should be further studied to determine their probiotic effects in vivo in fish.     

Screening for potential probiotic from spontaneously fermented non-dairy foods based on in vitro probiotic and safety properties

The aim of this study was to screen potential probiotic lactic acid bacteria from Chinese spontaneously fermented non-dairy foods by evaluating their probiotic and safety properties. All lactic acid bacteria (LAB) strains were identified by 16S rRNA gene sequencing. The in vitro probiotic tests included survival under low pH and bile salts, cell surface hydrophobicity, auto-aggregation, co-aggregation, antibacterial activity, and adherence ability to cells. The safety properties were evaluated based on hemolytic activity and antibiotic resistance profile. The salt tolerance, growth in litmus milk, and acidification ability were examined on selected potential probiotic LAB strains to investigate their potential use in food fermentation. A total of 122 strains were isolated and identified at the species level by 16S rRNA gene sequencing and included 62 Lactobacillus plantarum, 40 Weissella cibaria, 12 Lactobacillus brevis, 6 Weissella confusa, and 2 Lactobacillus sakei strains. One W. cibaria and nine L. plantarum isolates were selected based on their tolerance to low pH and bile salts. The hydrophobicity, auto-aggregation, co-aggregation, and antagonistic activities of these isolates varied greatly. All of the 10 selected strains showed multiple antibiotic resistance phenotypes and no hemolytic activity. The highest adhesion capacity to SW480 cells was observed with L. plantarum SK1. The isolates L. plantarum SK1, CB9, and CB10 were the most similar strains to Lactobacillus rhamnosus GG and selected for their high salt tolerance and acidifying activity. The results revealed strain-specific probiotic properties were and potential probiotics that can be used in the food industry.     

In vitro importance of probiotic Lactobacillus plantarum related to medical field

Lactobacillus plantarum is a Gram positive lactic acid bacterium commonly found in fermented food and in the gastro intestinal tract and is commonly used in the food industry as a potential starter probiotic. Recently, the consumption of food together with probiotics has tremendously increased. Among the lactic acid bacteria, L. plantarum attracted many researchers because of its wide applications in the medical field with antioxidant, anticancer, anti-inflammatory, antiproliferative, anti-obesity and antidiabetic properties. The present study aimed to investigate the in vitro importance of L. plantarum toward medical applications. Moreover, this report short listed various reports related to the applications of this promising strain. In conclusion, this study would attract the researchers in commercializing this strain toward the welfare of humans related to medical needs.