METABOLITES OF NATIVE LAB: AN ALTERNATIVE TO FISH SAFETY
SUTAPA SANYAL *
Department of Zoology, Krishnagar Govt. College, Krishnagar, Nadia, West Bengal, PIN-741101, India.
*Author to whom correspondence should be addressed.
Abstract
The present paper delineated diverse perceptivity of Listeria monocytogenes (ATCC 657) and Aeromonas hydrophila (ATCC 646) to anti-listeria and anti-aeromonas compounds produced by different LAB (Lactic acid bacteria) like bacteria of fish. Fish intestine was searched for LAB in respect of their potential exploitation in fish biopreservation. Combative actions of ten LABs were assessed against the pathogenic and spoilage flora by agar well diffusion assay. LAB isolates were effectual in annihilation of indicator strains either with live cells and CFS (cell-free supernatant) or purely in the form of live cells. Antimicrobials were commenced to be functional against the both Gram positive and negative bacteria. Although varied modes of antagonism were reported. The antimicrobial action of neutralised and catalase treated cell free supernatant fluid was secured against Listeria even after heating at 90°C for 10 min. Inhibition against Listeria was mostly exerted by thermostable products. No anti-aeromonas thermostable products were appeared to be linked with antagonism. Few thermolabile products were efficient against Aeromonas. Majority of LAB like isolates with thermostable anti-listeria products found to be worthwhile against Aeromonas with cells only. Proteinaceous antimicrobials competent against Aeromonas as well as Listeria retrieved from two isolates may be more efficacious in fish preservation than the usage of those bacteriocins that perform predominantly against Gram positive bacteria. The study appeals in situ application of indigenous natural bacteriocins of Oreochromis niloticus [Linnaeus, 1758] for shelf life lengthening of fish.
Keywords: Antimicrobials, biopreservation, fish, LAB, proteinaceous, thermolabile, thermostable