Phenotypic Assessment of Probiotic and Bacteriocinogenic Efficacy of Indigenous LAB Strains from Human Breast Milk.

Breast milk is the combination of bioactive compounds and microflora that promote newborn's proper growth, gut flora, and immunity. Thus, it is always considered the perfect food for newborns. Amongst their bioactives, probiotic communities-especially lactic acid bacteria (LAB)-are characterized from breast milk over the first month of parturition. In this study, seven LAB were characterized phenotypically and genotypically as Levilactobacillus brevis BDUMBT08 (MT673657), L. gastricus BDUMBT09 (MT774596), L. paracasei BDUMBT10 (MT775430), L. brevis BDUMBT11 (MW785062), L. casei BDUMBT12 (MW785063), L. casei BDUMBT13 (MW785178), and Brevibacillus brevis M2403 (MK371781) from human breast milk. Their tolerance to lysozyme, acid, bile, gastric juice, pancreatic juice, and NaCl and potential for mucoadhesion, auto-aggregation, and co-aggregation with pathogens are of great prominence in forecasting their gut colonizing ability. They proved their safety aspects as they were negative for virulence determinants such as hemolysis and biofilm production. Antibiogram of LAB showed their sensitivity to more than 90% of the antibiotics tested. Amongst seven LAB, three isolates (L. brevis BDUMBT08 and BDUMBT11, and L. gatricus BDUMBT09) proved their bacteriocin producing propensity. Although the seven LAB isolates differed in their behavior, their substantial probiotic properties with safety could be taken as promising probiotics for further studies to prove their in vivo effects, such as health benefits, in humans.

Phenotypic assessment of safety and probiotic potential of native isolates from marine fish Moolgarda seheli towards sustainable aquaculture.

Aquaculture is a highly productive and fast-growing agricultural sector. The occurrence of epidemic or sporadic disease outbreak is a major limiting factor in this sector, thus better alternatives are the need of the hour. Use of indigenous probiotics is a promising strategy to control infectious diseases. Thus, the present study was aimed to screen and characterize potent indigenous probiotics from marine fish, Moolgarda seheli, towards enhancing sustainable aquaculture production. Totally 347 bacterial isolates were obtained from M. seheli gastrointestinal tract, out of these, four isolates (KAF121, 124, 135, 136) were confirmed as potent probiotics in terms of biosafety, highly resistant to acidic pH, gastric juice, bile salt, high hydrophobicity to solvents, auto and co-aggregation potential. These four isolates also exhibited virtuous antioxidant activity. Further the isolates, KAF124 and 135 proved their efficiency in growth and survival of fish after challenged againt Aeromonas hydrophila. The isolates were identified based on their 16S rRNA gene sequence and the data were submitted to Genbank as Pseudomonas aeruginosa KAF121 (MH393516), Bacillus cereus KAF124 (MH393226), Bacillus thuringiensis KAF135 (MH393230), and Pseudomonas otitidis KAF136 (MH393230). The results conclude that two isolates, KAF124 and KAF135 are highly safe and potent probiotics which are first time isolated from the marine fish M. seheli. The two Bacillus strains could be used as better alternatives to antibiotics and other chemical-based drugs to prevent/control infectious diseases in aquaculture.

Bacteriocin-a potential antimicrobial peptide towards disrupting and preventing biofilm formation in the clinical and environmental locales.

Biofilm, a consortium of microbial cells, protected by extracellular polymeric matrix, is considered a global challenge due to the inherent antibiotic resistance conferred by its lifestyle. Besides, it poses environmental threats causing huge damage in food industries, fisheries, refineries, water systems, pharmaceutical industries, medical industries, etc. Living in a community of microbial populations is most critical in the clinical field, making it responsible for about 80% of severe and chronic microbial diseases. The necessity to find an alternative approach is the need of the hour to solve these crises. So far, many approaches have been attempted to disrupt the initial stage of biofilm formation, including adherence and maturation. Bacteriocins are a group of antimicrobial peptides, produced by bacteria having the potential to disrupt biofilm either by itself or in combination with other drugs than antibiotic counterparts. A clear understanding on mechanisms of bacterial biofilm formation, progression, and resistance will surely lead to the development of innovative, effective biofilm control strategies in pharmaceutical, health care industries and environmental locales.

Effect of Bacillus cereus peptide conjugated with nanoporous silica on inactivation of Listeria monocytogenes in apple juice, as an ecofriendly preservative.

Bacteriocins are ribosomally synthesized antimicrobial proteins/peptides. They are of great interest in the food processing industries as potential natural preservative agent to control food-borne pathogens. Bacillus spp. are one among the potential probiotics receiving more attention since they produce a broad spectrum of antimicrobial bioactive peptides. In this study, a small-scale medium composition and bioprocessing parameters were statistically optimized to increase the yield of bacteriocin namely cerein from Bacillus cereus NS02 showing antagonism against a wide range of food-borne pathogens. The cerein was partially purified, characterized, and evaluated for their optimal reaction condition. It was subjected to surface adsorption onto food-grade silica to evaluate its maximal adsorption, reached at 4 h, 40 °C, pH 6-7, and at the initial concentration of 200 AU mL-1. The effectiveness of silica-adsorbed and silica-free cerein was checked in Listeria monocytogenes inoculated fresh apple juice and demonstrated biopreservative activity. In juice treated with silica-cerein, the colony forming unit (CFU) was found to be less in count on the 15th day of storage at 4 °C whereas, free-cerein was found to contain 3.8 log CFU mL-1. While, on the same day of storage, the control juice contained the strength of 14.6 log CFU mL-1. Based on the above, this study concludes that the identified heat stable low molecular weight peptide cerein from B. cereus NS02 could serve as a potential biopreservative with effective antilisterial activity in the food system. However, a more detailed study is required to determine if their quality change especially the effect of cerein in organoleptic and nutritional properties of food beyond their addition is necessary, before it is to be exploited as an ecofriendly biopreservative.