In vitro evaluation of probiotic potential of Pediococcus pentosaceus L1 isolated from paocai—a Chinese fermented vegetable

Harnessing Enterococcus faecium WFD-128 from yogurt fermentation: Unveiling probiotic attributes and targeted inhibition of Shigella sonnei diarrheal pathogenesis

Diarrhea is a leading cause of mortality among children under five, with few effective interventions beyond oral rehydration, antibiotics, and zinc supplementation. This study aimed to identify and evaluate the probiotic and anti-diarrheal potential of Enterococcus faecium WFD-128, isolated from fermented yogurt, through in vitro, in silico, and in vivo approaches. The bacterium showed notable antibacterial activity, with inhibition zones measuring 21 mm and 19 mm against Shigella flexneri and Shigella sonnei, respectively. Additionally, it exhibited anti-biofilm effectiveness of 82 % and 80 % against these pathogens. It exhibited resistance to Amoxicillin, intermediate sensitivity to Ampicillin and Chloramphenicol, and tolerance to bile salts over 3-48h, and to acidic pH levels ranging from 2 to 8. Gas Chromatography-Mass Spectrometry (GC-MS) identified 68 volatile compounds, of which [1,1'-Bicyclohexyl]-4-carboxylic acid, 4'-propyl-, 4-fluorophenyl ester (-8.5) and Cholest-4-en-26-oic acid, 3-oxo-, methyl ester (-7.9) showed strong binding affinities to the diarrheal protein T3SS of Shigella sonnei (PDB: 6WRY) in molecular docking studies. These compounds exhibited favorable pharmaceutical properties in ADMET analysis, further supported by molecular dynamics simulations. In vivo experiments with albino mice validated the bacterium's therapeutic potential. Histopathological analysis revealed significant recovery of diarrhea-affected organs, including the kidney, liver, intestine, and spleen, following treatment with E. faecium. This aligns with in vitro and in silico findings, demonstrating the bacterium's therapeutic effectiveness. This study highlights the promise of E. faecium as a probiotic-based treatment against bacteria-induced diarrhea, offering a strong foundation for the development of innovative anti-diarrheal therapeutics.

Safety, Antagonistic Activity, and Probiotic Properties of Lactic Acid Bacteria Isolated from Jeotgal, Korean Fermented Seafoods

Probiotics are in high demand in the health functional food market as they effectively inhibit pathogens and improve host health. Therefore, in order to develop novel probiotic strains, new strains were isolated from various type of jeotgal, traditional Korean fermented seafood products, and their safety and probiotic properties have been evaluated. Based on 16S rRNA gene sequence analysis, six strains (JRD1, Pediococcus pentosaceus; JRD2, Lactiplantibacillus plantarum; JRD6, Pediococcus acidilactici; CLJ21, Lactiplantibacillus plantarum; CLJ24, Pediococcus pentosaceus; CLJ28, Leuconostoc mesenteroides subsp. dextranicum) were selected and subjected to further analysis. As a result, all six strains did not show hemolytic activity, antibiotics resistance, and cell cytotoxicity, confirming that they are safe for human use. Among them, JRD1, JRD6, and CLJ24 exhibited high survival rates under simulated gastrointestinal conditions. Additionally, these three strains demonstrated strong adhesion abilities on HT-29 cells, with values of 6.02, 5.77, and 5.86 log CFU/mL, respectively. Furthermore, JRD1, JRD6, and CLJ24 showed relatively high antagonistic activity against both Salmonella Typhimurium and Staphylococcus aureus through competition, exclusion, and displacement of their adhesion. Interestingly, cell-free supernatants (CFS) from three strains effectively inhibited the growth of both S. Typhimurium and S. aureus. Furthermore, CFS of CLJ24, JRD1, and JRD6 demonstrated anti-inflammatory effects in intestinal epithelial cells. The results suggest that CLJ24, JRD1, and JRD6 have potential to be development as functional probiotic strains with both antibacterial and anti-inflammatory activities.

Probiotic and immunostimulating effects of live and heat-killed Pediococcus pentosaceus TAP041

The selected strain, TAP041, showing an excellent ability to reduce the glyoxal and methylglyoxal levels, was identified by 16S rRNA gene-based phylogenetic analysis as Pediococcus pentosaceus. It demonstrated probiotic properties, including acid, bile salt, pancreatin, lysozyme tolerance, gut adhesion, and auto/coaggregation. In RAW264.7 macrophages, both live and heat-killed strains induced nitric oxide production and activated inducible nitric oxide synthase. RAW264.7 treated with P. pentosaceus TAP041 increased the expression level of tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and cyclooxygenase-2, and regulated the expression of c-Jun amino-terminal kinase, p38, and extracellular signal-regulated kinase. These findings suggest that both live and heat-killed P. pentosaceus TAP041 can be used as potential immunostimulatory agents in functional food additives.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01530-2.

Exploiting Potential Probiotic Lactic Acid Bacteria Isolated from Chlorella vulgaris Photobioreactors as Promising Vitamin B12 Producers

Lactic acid bacteria (LAB) have been documented as potential vitamin B12 producers and may constitute an exogenous source of cobalamin for the microalga Chlorella vulgaris, which has been described as being able to perform vitamin uptake. Hence, there is an interest in discovering novel B12-producing probiotic LAB. Therefore, the purpose of the current work was to perform a phenotype-genotype analysis of the vitamin B12 biosynthesis capacity of LAB isolated from C. vulgaris bioreactors, and investigate their probiotic potential. Among the selected strains, Lactococcus lactis E32, Levilactobacillus brevis G31, and Pediococcus pentosaceus L51 demonstrated vitamin B12 biosynthesis capacity, with the latter producing the highest (28.19 ± 2.27 pg mL-1). The genomic analysis confirmed the presence of pivotal genes involved in different steps of the biosynthetic pathway (hemL, cbiT, cobC, and cobD). Notably, P. pentosaceus L51 was the only strain harboring cobA, pduU, and pduV genes, which may provide evidence for the presence of the cobalamin operon. All strains demonstrated the capability to withstand harsh gastrointestinal conditions, although P. pentosaceus L51 was more resilient. The potential for de novo cobalamin biosynthesis and remarkable probiotic features highlighted that P. pentosaceus L51 may be considered the most promising candidate strain for developing high-content vitamin B12 formulations.

Diversity of the bacteriocins, their classification and potential applications in combat of antibiotic resistant and clinically relevant pathogens

There is almost a century since discovery of penicillin by Alexander Fleming, a century of enthusiasm, abuse, facing development of antibiotic-resistance and clear conclusion that the modern medicine needs a new type of antimicrobials. Bacteriocins produced by Gram-positive and Gram-negative bacteria, Archaea and Eukaryotes were widely explored as potential antimicrobials with several applications in food industry. In last two decades bacteriocins showed their potential as promising alternative therapeutic for the treatment of antibiotic-resistant pathogens. Bacteriocins can be characterised as highly selective antimicrobials and therapeutics with low cytotoxicity. Most probably in order to solve the problems associated with the increasing number of antibiotic-resistant bacteria, the application of natural or bioengineered bacteriocins in addition to synergistically acting preparations of bacteriocins and conventional antibiotics, can be the next step in combat versus drug-resistant pathogens. In this overview we focussed on diversity of specific lactic acid bacteria and their bacteriocins. Moreover, some additional examples of bacteriocins from non-lactic acid, Gram-positive and Gram-negative bacteria, Archaea and eukaryotic organisms are presented and discussed. Therapeutic properties of bacteriocins, their bioengineering and combined applications, together with conventional antibiotics, were evaluated with the scope of application in human and veterinary medicine for combating (multi-)drug-resistant pathogens.

Effect of two insect meals on the gut commensal microbiome of healthy sea trout (Salmo trutta vr. trutta)

BACKGROUND

The balance of the intestinal commensal microbiome of fish and other animals plays an important role in the physiological processes of healthy animals, contributes to the defense against pathogens, stimulates the immune system and facilitates nutrient metabolism. In the last decade, the interest in the application of the insects in fish nutrition increased, although little is known regarding the effects of insect meals on the gastrointenstinal tract microbiome of the sea trout fingerlings. The aim of this study was to evaluate the effect of two diets containing mealworm (MW) and superworm (SW) on the microbiome of the digesta of sea trout fingerlings and the relative abundances of different taxa among communities under controlled conditions.

RESULTS

The insect meals produced a similar weight gain and survival rate to sea trout fed fishmeal. The most abundant bacterial phylum in all the treatment groups was Firmicutes followed by Proteobacteria and Actinobacteria, and significant differences in the amount of Cyanobacteria were observed in the SW group.

CONCLUSIONS

The insect meals did not produce differences in the three most abundant phyla in the sea trout digesta. However, the effect of each type of meal on the lower taxonomic levels was evident, particularly in the case of the superworm meal. These microbiome differences indicated that mealworm meal was more related to fishmeal than superworm meal. Our results highlight the potential effects of insect meals, such as mealworm and superworm meals, on the microbiota of sea trout.

In-vitro evaluation of the probiotic potential and the fermentation profile of Pediococcus and Enterococcus strains isolated from Moroccan camel milk

The promotion of human health through natural approaches like functional foods and probiotics is in high demand. The medicinal plants are the major feed of Moroccan dromedary, which improves the functional properties of their milk. A few studies have reported the probiotic and functional aptitudes of lactic acid bacteria (LAB) of this milk. In this context, our study aimed to identify LAB isolated from Moroccan raw camel milk and investigate their probiotic features and their fermentation profile. The molecular identification of twelve isolates indicated that they belong to Pediococcus pentosaceus, Enterococcus faecium, and Enterococcus durans. All LAB strains displayed high tolerance to gastrointestinal conditions (survival rate of 31.85-96.52% in pH 2.5, 35.23-99.05% in 0.3 bile salts, and 26.9-90.96% in pepsin), strong attachment abilities (auto-aggregation and hydrophobicity ranged from 28.75 to 95.9% and from 80.47 to 96.37%, respectively), and high co-aggregation ability with pathogenic bacteria. Importantly, they did not present antibiotic resistance or hemolytic activity. Our LAB strains demonstrated antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis, and Salmonella enterica. Moreover, they could acidify cow milk (ΔpH of 2.55 after 24 h) and improve its antioxidant ability (inhibition of 36.77% of DPPH). Based on the multivariate analysis, Pediococcus pentosaceus Pd24, Pd29, Pd38, Enterococcus faecium Ef18, and Enterococcus durans Ed22 were selected as the most promising probiotics. Therefore, we propose that Pediococcus pentosaceus isolated from camel milk could be used as potential probiotic strains and/or starter cultures in functional milk fermentation.

Dynamic Analysis of the Bacterial Community and Determination of Antioxidant Capacity during the Fermentation of Sour Tea

The imbalance of the redox state caused by extra reactive oxygen species is closely related to many diseases. Therefore, it is necessary for people to ingest antioxidants through food. The safety of some synthetic antioxidants has been questioned. In this context, it is worth exploring natural and safe antioxidants from biological sources. Tea has good antioxidant activity, and the antioxidant activity of fermented sour tea is better than that of other types. It is necessary to clarify the antioxidant capacity of sour tea during fermentation, as well as the microbial community and its sources. Nonculture and culture-dependent methods were adopted to track the changes in the microbial population and community structure during the fermentation of sour tea. Sequence analysis of 16S rRNA gene amplification revealed significant differences in community complexity and structure at different fermentation times. The highest proportion of operational taxonomic units (OTU s) in all samples was Latilactobacillus, which was determined to be Lactiplantibacillus plantarum by further analysis. The second highest proportion of OTUs was Enterobacter. With the fermentation of sour tea, the antioxidant capacity increased, and all isolated Lb. plantarum had good DPPH clearance rates. Our findings suggest that Lb. plantarum plays a crucial role in the fermentation process of sour tea. The possibility of discovering new antioxidants was provided by the determination of the antioxidant capacity and bacterial community during the fermentation of sour tea.

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

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.

Pediococcus pentosaceus: Screening and Application as Probiotics in Food Processing

Lactic acid bacteria (LAB) are vital probiotics in the food processing industry, which are widely spread in food additives and products, such as meat, milk, and vegetables. Pediococcus pentosaceus (P. pentosaceus), as a kind of LAB, has numerous probiotic effects, mainly including antioxidant, cholesterol-lowering, and immune effects. Recently, the applications in the probiotic- fermentation products have attracted progressively more attentions. However, it is necessary to screen P. pentosaceus with abundant functions from diverse sources due to the limitation about the source and species of P. pentosaceus. This review summarized the screening methods of P. pentosaceus and the exploration methods of probiotic functions in combination with the case study. The screening methods included primary screening and rescreening including gastric acidity resistance, bile resistance, adhesion, antibacterial effects, etc. The application and development prospects of P. pentosaceus were described in detail, and the shortcomings in the practical application of P. pentosaceus were evaluated to make better application of P. pentosaceus in the future.

Characterization of Probiotic Properties of Antifungal Lactobacillus Strains Isolated from Traditional Fermenting Green Olives

The aim of this work is to characterize the potential probiotic properties of 14 antifungal Lactobacillus strains isolated from traditional fermenting Moroccan green olives. The molecular identification of strains indicated that they are composed of five Lactobacillus brevis, two Lactobacillus pentosus, and seven Lactobacillus plantarum. In combination with bile (0.3%), all the strains showed survival rates (SRs) of 83.19-56.51% at pH 3, while 10 strains showed SRs of 31.67-64.44% at pH 2.5. All the strains demonstrated high tolerance to phenol (0.6%) and produced exopolysaccharides. The autoaggregation, hydrophobicity, antioxidant activities, and surface tension value ranges of the strains were 10.29-41.34%, 15.07-34.67%, 43.11-52.99%, and 36.23-40.27 mN/m, respectively. Bacterial cultures exhibited high antifungal activity against Penicillium sp. The cell-free supernatant (CFS) of the cultures showed important inhibition zones against Candida pelliculosa (18.2-24.85 mm), as well as an antibacterial effect against some gram-positive and gram-negative bacteria (10.1-14.1 mm). The neutralized cell-free supernatant of the cultures displayed considerable inhibitory activity against C. pelliculosa (11.2-16.4 mm). None of the strains showed acquired or horizontally transferable antibiotic resistance or mucin degradation or DNase, hemolytic, or gelatinase activities. Lactobacillus brevis S82, Lactobacillus pentosus S75, and Lactobacillus plantarum S62 showed aminopeptidase, β-galactosidase, and β-glucosidase activities, while the other enzymes of API-ZYM were not detected. The results obtained revealed that the selected antifungal Lactobacillus strains are considered suitable candidates for use both as probiotic cultures for human consumption and for starters and as biopreservative cultures in agriculture, food, and pharmaceutical industries.

In vitro evaluation of lactic acid bacteria with probiotic activity isolated from local pickled leaf mustard from Wuwei in Anhui as substitutes for chemical synthetic additives

The extensive abuse of chemical synthetic additives has raised increased attention to food safety. As substitutes, probiotics play an important role in human health as they balance the intestinal microbes in host. This study was aimed to isolate and evaluate the potential probiotic activities of lactic acid bacteria (LAB) from a local pickled leaf mustard (PLM) from Wuwei city in Anhui province through in vitro experiments. A total of 17 LAB strains were obtained as probiotics. All the isolates were sensitive to chloramphenicol, tetracycline, erythromycin, and doxycycline but exhibited resistance to antibiotics (e.g., streptomycin, kanamycin, gentamicin, and vancomycin). Out of the 17 strains, 9 were sensitive to most of the antibiotics and had no cytotoxic activity on human colorectal adenocarcinoma cell line (HT-29) cells. The isolated AWP4 exhibited antibacterial activity against four indicator pathogen strains (ATCC8099: Escherichia coli, ATCC6538: Staphylococcus aureus, ATCC9120: Salmonella enteric, and BNCC192105: Shigella sonnei). Based on the phylogenetic analysis of the 16S rRNA gene, AWP4 belonged to Lactiplantibacillus plantarum. This study indicated that the Wuwei local PLM could be a potential resource to isolate beneficial LAB as probiotics. The data provide theoretical guidance for further animal experiments to estimate the probiotic effect and safety of Lpb. plantarum AWP4 in vivo.

Evaluation of Probiotic Properties of Pediococcus acidilactici M76 Producing Functional Exopolysaccharides and Its Lactic Acid Fermentation of Black Raspberry Extract

This study aimed to determine the probiotic potential of Pediococcus acidilactici M76 (PA-M76) for lactic acid fermentation of black raspberry extract (BRE). PA-M76 showed outstanding probiotic properties with high tolerance in acidic GIT environments, broad antimicrobial activity, and high adhesion capability in the intestinal tract of Caenorhabditis elegans. PA-M76 treatment resulted in significant increases of pro-inflammatory cytokine mRNA expression in macrophages, indicating that PA-M76 elicits an effective immune response. When PA-M76 was used for lactic acid fermentation of BRE, an EPS yield of 1.62 g/L was obtained under optimal conditions. Lactic acid fermentation of BRE by PA-M76 did not significantly affect the total anthocyanin and flavonoid content, except for a significant increase in total polyphenol content compared to non-fermented BRE (NfBRE). However, fBRE exhibited increased DPPH radical scavenging activity, linoleic acid peroxidation inhibition rate, and ABTS scavenging activity of fBRE compared to NfBRE. Among the 28 compounds identified in the GC-MS analysis, esters were present as the major groups. The total concentration of volatile compounds was higher in fBRE than that in NfBRE. However, the undesirable flavor of terpenes decreased. PA-M76 might be useful for preparing functionally enhanced fermented beverages with a higher antioxidant activity of EPS and enhanced flavors.

Growth and adhesion inhibition of pathogenic bacteria by live and heat-killed food-origin Lactobacillus strains or their supernatants

The study aimed to evaluate qualitatively and quantitatively the antimicrobial capacity of 10 potential probiotic Lactobacillus strains against model enteropathogens and spoilage microorganisms. The probiotic strains (live and heat-killed forms) were also assessed for their ability to inhibit adhesion of selected pathogens to Caco-2 cells. The largest inhibition zones (the diffusion method) were connected with the usage of whole bacteria cultures (WBC), also high and moderate with cell-free supernatant (CFS) and the lowest with cell-free neutralized supernatant (CNS). The highest antagonistic activity of Lactobacillus strains was observed against L. monocytogenes strains, moderate activity against Salmonella, Shigella, Escherichia coli, Pseudomonas and, the lowest against S.aureus, Bacillus and Enterococcus. The inhibition of adhesion to Caco-2 cells was very high in the case of E. coli, Salmonella and L. monocytogenes, and moderate in the case of S.aureus. On average, the inhibition effect was higher when pathogenic bacteria were treated by WBC, than heat-killed Lactobacillus. Although, in most samples, the effect was not significantly different (P> 0.05). The strains Lb. brevis O24 and Lb. rhamnosus K3 showed the biggest overall antimicrobial properties, and were most effective in adherence inhibition of investigated indicator strains. These bacteria or their metabolites can be used for the production of various foods or pharmaceutical products.

The Biotechnological Potential of Pediococcus spp. Isolated from Kombucha Microbial Consortium

In the past decade, the probiotic market has grown rapidly, both for foods and supplements intended to enhance wellness in healthy individuals. Different lactic acid bacteria (LAB), especially Lactobacillus spp., of different origins have already been used to develop commercial probiotic products. Nowadays, LAB new alternative sources, such as non-dairy fermented food products, are being exploited. One such source is Kombucha, a fermented low-alcohol beverage made of tea leaves. In this regard, we tested seven Pediococcus spp. strains isolated from a local industrial Kombucha for their biotechnological potential. Two, out of the seven isolates, identified as Pediococcus pentosaceus (L3) and Pediococcus acidiliactici (L5), were selected as successful candidates for the food industry, due to their probiotic and technological properties. In regard to their resistance in the gastro-intestinal tract, both selected strains were tolerant to a pH of 3.5, presence of 0.3% pepsin, and 0.5% bile salt concentration. On the antagonistic side, the fresh suspension of selected isolates had high inhibitory activity against pathogenic bacteria, such as Salmonella enterica Typhimurium, Listeria monocytogenes, Listeria ivanovii, Bacillus cereus, Proteus hauseri, and methicillin resistant Staphylococcus aureus. In addition, moderate to high inhibitory activity was noticed against foodborne molds (e.g., Penicillium expansum and Penicillium digitatum). These safety issues were supported by their negative hemolytic activity and good antioxidant potential (56-58%). Selected isolates were sensitive to ampicillin, penicillin, erythromycin, and lincomycin, while a broad range of other antibiotics were not effective inhibitors. On the technological side, both strains tolerated 5% NaCl and, during the freeze-drying process, had a good survival rate (86-92%). The selected Pediococcus strains have proven properties to be used for further development of functional products.

In vitro probiotic properties of Pediococcus pentosaceus L1 and its effects on enterotoxigenic Escherichia coli-induced inflammatory responses in porcine intestinal epithelial cells

This study aimed to evaluate in vitro probiotic characteristics of Pediococcus pentosaceus strain L1 from pickled radish and investigate its impacts on inflammatory responses in porcine intestinal epithelial cells (IEC) to enterotoxigenic Escherichia coli (ETEC) F4⁺. The abilities of P. pentosaceus L1 to tolerate gastrointestinal conditions and to antagonize ETEC F4⁺ growth were determined. Adhesion of P. pentosaceus L1 and its effect on ETEC F4⁺ adhesion to porcine IPEC-J2 IEC were evaluated. Furthermore, the effects of this strain on proinflammatory gene expression and cytokines/chemokine production in porcine IPEC-J2 IEC induced by ETEC F4⁺ were determined. P. pentosaceus L1 showed good tolerance to the medium adjusted at pH 2.5 and consequently supplemented with 0.3% oxgall. Reduction of ETEC F4⁺ growth in co-culture with L1 was found. Effective adhesion of L1 to porcine. IPEC-J2 IEC was observed under these conditions. P. pentosaceus L1 decreased the adhesion of ETEC F4⁺ to IPEC-J2 IEC and the extent of inhibition of ETEC F4⁺ adhesion depended on the timing of L1 addition. Further analysis revealed down-regulation of expression of ETEC F4⁺-induced proinflammatory genes encoding interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-8 (IL-8) in IPEC-J2 IEC. Expression of the genes involved in NF-κB pathway, including RELA and NFKB1, were also repressed, as was production of IL-6, TNF-α, and IL-8. These results indicate that P. pentosaceus L1 may have potential as a probiotic for control of ETEC infection in pigs.

In Vitro Evaluation of Probiotic Potential of Lactic Acid Bacteria Isolated from Yunnan De'ang Pickled Tea

This study aimed to investigate the probiotic potential of lactic acid bacteria (LAB) strains isolated from De'ang pickled tea, a traditional food consumed by the De'ang nationality of Yunnan, China. Twenty-six LAB strains isolated from De'ang pickled tea were subjected to identification based on 16S rRNA gene sequence analysis. Twenty-four belonged to Lactobacillus plantarum, one belonged to Enterococcus casseliflavus, and one belonged to Lactobacillus acidophilus. Eighteen out of 26 LAB strains which showed a higher capability to tolerate simulated gastrointestinal juices were chosen to further evaluate their probiotic properties. Varied adhesive abilities and auto-aggregative capacities of selected LAB strains were dependent on species and even strains. All tested LAB strains were resistant to kanamycin, streptomycin, gentamycin, and vancomycin and sensitive to tetracycline and chloramphenicol. Ten out of the 18 strains are resistant to ampicillin, and the remaining strains are sensitive to ampicillin; 4 out of the 18 strains showed resistance to erythromycin. Compared to reference strain Lactobacillus rhamnosus strain GG, these LAB strains had a greater or comparative antimicrobial activity against Salmonella typhimurium or Escherichia coli. In contrast, eight out of the 18 strains suppressed growth of Shigella flexneri. Two L. plantarum strains, ST and STDA10, not only exhibited good probiotic properties but also showed a good ability of scavenging DPPH and ABTS⁺. This study suggests that L. plantarum ST and STDA10 could be used as potential probiotics applied in functional foods.

Antibiotic susceptibility profile of Pediococcus spp. from diverse sources

The aim of the present study was to assess the antibiotic susceptibility profile of Pediococcus strains from diverse sources. From a total of 115 dairy and non-dairy samples, 40 Pediococcus strains were isolated. Their biochemical and molecular characterization confirmed them as P. pentosaceus and P. acidilactici. All the 40 identified isolates were evaluated for antibiotic susceptibility using disc diffusion assay against a total of 20 antibiotics. The isolates exhibited varied range of responses towards the antibiotics depending on the strain type, source and location of isolation. All the isolates were either sensitive or intermediate resistant to amoxycillin, erythromycin, ceftriaxone, cloxacillin, cefoperazone, penicillin, netillin, gentamycin and chloramphenicol. Resistance towards vancomycin and nalidixic acid was exhibited by most of the isolates. A total of 16 strains belonging to dosa batter (n = 4; n = number of isolates), fermented vegetables (n = 4), fermented grape juice (n = 4), idly batter (n = 3) and the only isolate from butter milk exhibited sensitivity/intermediate towards 80-90% of the studied antibiotics. No considerable difference in susceptibility pattern was observed between the two Pediococcus species, i.e., P. pentosaceus and P. acidilactici. Overall, the maximum resistance was exhibited by isolates belonging to silage (Sil-2; 50%) followed by cow milk (PD-41), dosa batter (8-PD) and human isolate (PD-45) which showed resistance towards 40% of studied antibiotics. The susceptibility profiling of Pediococcus strains will be helpful in their safer selection for future food and feed applications.

Food-Origin Lactic Acid Bacteria May Exhibit Probiotic Properties: Review

One of the most promising areas of development in the human nutritional field over the last two decades has been the use of probiotics and recognition of their role in human health and disease. Lactic acid-producing bacteria are the most commonly used probiotics in foods. It is well known that probiotics have a number of beneficial health effects in humans and animals. They play an important role in the protection of the host against harmful microorganisms and also strengthen the immune system. Some probiotics have also been found to improve feed digestibility and reduce metabolic disorders. They must be safe, acid and bile tolerant, and able to adhere and colonize the intestinal tract. The means by which probiotic bacteria elicit their health effects are not understood fully, but may include competitive exclusion of enteric pathogens, neutralization of dietary carcinogens, production of antimicrobial metabolites, and modulation of mucosal and systemic immune function. So far, lactic acid bacteria isolated only from the human gastrointestinal tract are recommended by the Food and Agriculture Organization (FAO) and World Health Organization (WHO) for use as probiotics by humans. However, more and more studies suggest that strains considered to be probiotics could be isolated from fermented products of animal origin, as well as from non-dairy fermented products. Traditional fermented products are a rich source of microorganisms, some of which may exhibit probiotic properties. They conform to the FAO/WHO recommendation, with one exception; they have not been isolated from human gastrointestinal tract. In light of extensive new scientific evidence, should the possibility of changing the current FAO/WHO requirements for the definition of probiotic bacteria be considered?