ASSESSMENT OF CHILIKA BUFFALO CURD MICROBIAL ISOLATES FOR THEIR PROBIOTIC POTENTIAL

Abstract

India has a huge repertoire of fermented foods and most of it has not been scientifically investigated. In this study probiotic microorganisms were isolated from the curd of Chilika buffalo using diffusion chamber method. The isolated microorganisms were characterized in vitro for their probiotic potential. Their ability to tolerate bile, low pH, ability to Auto-aggregate, co-aggregate with pathogens and their susceptibility to clinically relevant antibiotics were determined. The positive attributes of these probiotic isolates were further explored in C. elegans Three of the isolates were tested for their ability to boost host immunity and defenses in face of pathogen infection. E. coli O157:H7 infected worms previously exposed to probiotic isolates showed more resilience and lived longer compared to those fed upon E. coli OP50. Lactobacillus casei NKN 344 promoted longevity in worms and significantly increased the lifespan of the C. elegans. The molecular mechanism of action behind this effect was investigated using Real time PCR and fluorescence microscopy. The expression of genes known to influence longevity in worms was quantified. L. casei significantly upregulates expression of genes involved in autophagy pathway and in energy homeostasis. The increased expression of aak-2 proved to be the key in probing molecular mode of action, aak-2 subunit of AMPK phosphorylates DAF-16 facilitating its nuclear localization. DAF-16 nuclear localization was probed using transgenic strain of C. elegans expressing GFP fused DAF-16. In an activated form DAF-16 activates the genes necessary in survival and stress resistance. L. casei extends lifespan of worm in an AMPK pathway dependent manner.