In Vitro Characterization of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> Strains with Inhibitory Activity on Enteropathogens for Use as Potential Animal Probiotics

The present study evaluates the probiotic properties of three Lactobacillus plantarum strains MJM60319, MJM60298, and MJM60399 possessing antimicrobial activity against animal enteric pathogens. The three strains did not show bioamine production, mucinolytic and hemolytic activity and were susceptible to common antibiotics. The L. plantarum strains survived well in the simulated orogastrointestinal transit condition and showed adherence to Caco-2 cells in vitro. The L. plantarum strains showed strong antimicrobial activity against enterotoxigenic Escherichia coli, Shiga toxin-producing E. coli, Salmonella enterica subsp. enterica serovar Typhimurium, Choleraesuis and Gallinarum compared to the commercial probiotic strain Lactobacillus rhamnosus GG. The mechanism of antimicrobial activity of the L. plantarum strains appeared to be by the production of lactic acid. Furthermore, the L. plantarum strains tolerated freeze-drying and maintained higher viability in the presence of cryoprotectants than without cryoprotectants. Finally, the three L. plantarum strains tolerated NaCl up to 8% and maintained >60% growth. These characteristics of the three L. plantarum strains indicate that they could be applied as animal probiotic after appropriate in vivo studies.     

<Emphasis Type="Italic">Streptomyces</Emphasis> sp. strain SK68, isolated from peanut rhizosphere,promotes growth and alleviates salt stress in tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis> cv. Micro-Tom)

A novel actinobacterium, strain SK68, was isolated from the rhizosphere of peanut plant and its salinity stress alleviation ability was studied using tomato (Solanum lycopersicum cv. Micro-Tom) plants. Based on 16S rDNA based phylogenetic analysis, strain SK68 has been identified as a Streptomyces sp. Strain SK68 had branched substrate mycelium bearing smooth surfaced spores and the spore colour is brownish grey on ISP4 medium. It exhibited enzyme activities such as xylanase, cellulase, amylase, and pectinase and degraded hypoxanthine, casein, and L-tyrosine. The strain SK68 differed in its banding pattern in BOX-PCR and RAPD fingerprinting compared to the closely matching type strains Streptomyces erythrochromogenes NBRC 3304^T (AB184746), S. flavotricini NBRC 12770^T (AB184132), S. racemochromogenes NBRC 12906^T (AB184235), and S. polychromogenes NBRC 13072^T (NR041109). Strain SK68 was evaluated for its salinity stress-alleviating activity in tomato plants with 180 mmol/L NaCl under gnotobiotic condition. A significant increase in plant biomass was observed in strain SK68-inoculated tomato plants under salt stress compared to control and salt-stressed non-inoculated plants.     

Co-encapsulation of lactic acid bacteria and prebiotic with alginate-fenugreek gum-locust bean gum matrix: Viability of encapsulated bacteria under simulated gastrointestinal condition and during storage time

The aim of this study was to enhance the viability of probiotic strains Pediococcus pentosaceus KID7, Lactobacillus plantarum KII2, Lactobacillus fermentum KLAB6 and Lactobacillus helveticus KII13 in gastrointestinal transit, freeze-drying condition and during storage time by microencapsulation using a combination of alginate, fenugreek gum and locust bean gum. The microcapsules were prepared using various ratio of alginate to fenugreek gum to locust bean gum and tested for its dissolution in colonic fluid. The combination that efficiently dissolved in colonic fluid was selected for co-encapsulation of the probiotic strains and prebiotics to produce synbiotic microcapsules. Further, we observed that the bacteria encapsulated with alginate-fenugreek gum-locust bean gum (AFL) matrix tolerated gastrointestinal condition efficiently compared to non-encapsulated bacteria. The encapsulated bacterial cells retained higher viability than non-encapsulated cells during freeze-drying condition and subsequent storage for 3 months at 4°C. These results show the utility of AFL matrix in microencapsulation of probiotics for use in food industry.     

Probiotic Characterization of Lactobacillus paracasei subsp. paracasei KNI9 Inhibiting Adherence of Yersinia enterocolitica on Caco-2 Cells In Vitro

The study was aimed to characterize the probiotic properties of Lactobacillus paracasei subsp. paracasei strain KNI9 and its antagonistic activity against Yersinia enterocolitica subsp. enterocolitica. The strain KNI9 was susceptible to antibiotics such as chloramphenicol, tetracycline, erythromycin, and streptomycin recommended by European food safety authority (EFSA). Strain KNI9 exhibited tolerance to simulated oro-gastrointestinal (OGT) condition, adherence to Caco-2 cells, and antimicrobial activity against intestinal enteric pathogens such as Yersinia enterocolitica subsp. enterocolitica, Shigella boydii, and Listeria monocytogenes. Furthermore, the strain KNI9 inhibited the adherence and invasiveness of Y. enterocolitica subsp. enterocolitica to Caco-2 cell line. These results indicate that the L. paracasei subsp. paracasei KNI9 could be further developed into a potential probiotic strain after appropriate in vivo studies.