Emergence of antibiotic resistance among aquaculture pathogens has made it necessary to look into environment friendly, effective and sustainable methods such as probiotic and immunostimulants among others.. In the present study, LAB were isolated from the gut of fish species namely Rastrelliger kanagurta and analyzed for their antibacterial activity against various fish, shrimp and human pathogens. Different LAB species such as Lactobacillus plantarum, L. bulgaricus, L. brevis and L. viridiscens were encountered in the gut of R. kanagurta. Several strains showed good activity against fish, shrimp and human pathogens. LAB from the gut of such marine species may be developed as possible probiont for environment friendly health management of fresh water, estuarine and marine species currently exploited in aquaculture.

Biofilms are microbial communities that cause serious chronic infections in the environment by enhancing antimicrobial resistance. Bacteria in the biofilm can be up to a thousand times more resistant to antibiotics than the same bacteria circulating in a planktonic state. The emergence of antibiotic-resistant microorganism has led to the exploration of different therapeutic agents like ribosomally synthesized microorganism peptides referred to as bacteriocins. In this study, bacteriocin producing bacteria Pseudomonas aeruginosa isolated from a soil sample. It was found to be effective against Methicillin-resistant Staphylococcus aureus (MRSA). Furthermore the bacteriocin was partial purified by ammonium sulfate, the precipitate has highly effective against MRSA (400AU/mL). MRSA cells were treated with precipitated culture supernatant of P. aeruginosa TA6 was analyzed by FT-IR. The treated and untreated MRSA showed band variations at 682.59 and 3442.15cm-1 corresponding to the alkyl and amide group respectively. Bacteriocin showed marked inhibition activity against the biofilm of MRSA. About 0.05% and 0.02% attachment of biofilm was observed in the presence of 1X MIC (10 μg/mL) and 2X MIC (20 g/mL) respectively. Our results recommend that bacteriocins that make stable pores on biofilm cells are extremely potent for the treatment of MRSA biofilm infections.

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