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Vibrio parahaemolyticus is a natural microflora of marine and coastal water bodies and associated with mortality of larval shrimp in penaeid shrimp in ponds. Bacteriophages occur virtually in all places where their hosts exist. In this study, total distribution of V. parahaemolyticus and its phages were examined in shrimp ponds, seawater, estuary, animal surface, and tissues. Total vibrio count in sediments of two ponds was found to be 2.6 × 10(3) and 5.6 × 10(3) cfu/g. Incidence of V. parahaemolyticus in the ponds was close, while it was markedly higher in the animal surface and tissue samples. Biochemically identified eight strains of V. parahaemolyticus (V1, V3-V6, V9, V11, and V12) were taken for further infection studies with bacteriophage. Totally five bacteriophages capable of infecting V. parahaemolyticus MTCC-451 strain were isolated from all the samples. One of the isolated bacteriophage Vp1 from estuary was able to lyse all the isolated V. parahaemolyticus strains we used. Therefore, the morphology of Vp1 was estimated in TEM. Vp1 phage head measuring approximately about 50-60 nm diameter with icosahedral outline and a contractile tails of diameter 7 nm and length 100 nm and it was identified as Myoviridae. Therefore, the phages have the potential application in destroying bacterial pathogens.

Marine pollution is a significant issue in recent decades, with the increase in industries and their waste harming the environment and ecosystems. Notably, the rise in shellfish industries contributes to tons of shellfish waste composed of up to 58% chitin. Chitin, the second most ample polymer next to cellulose, is insoluble and resistant to degradation. It requires chemical-based treatment or enzymatic hydrolysis to cleave the chitin polymers. the chemical-based treatment can lead to environmental pollution, so to solve this problem, enzymatic hydrolysis is the best option. Moreover, the resulting biopolymer by-products can be used to boost the fish immune system and also as drug delivery agents. Many marine microbial strains have chitinase producing ability. Nevertheless, we still lack an economical and highly stable chitinase enzyme for use in the industrial sector. So we isolate a novel marine bacterial strain Achromobacter xylosoxidans from the shrimp waste disposal site using chitin minimal medium. Placket-Burman and central composite design statistical models for culture condition optimisation predicted a 464.2 U/ml of chitinase production. The culture conditions were optimised for maximum chitinase production recording up to 467 U/ml. This chitinase from the A. xylosoxidans was 100% active at an optimum temperature of 45 °C (withstand up to 55 °C) and pH 8 with 80% stability. The HPLC analysis of chitinase degraded shellfish waste reveals a major amino acid profile composition-arginine, lysine, aspartic acid, alanine, threonine and low levels of isoleucine and

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The present study concluded that phylogenetic analysis of endosymbiotic bacteria Enterobacter sp from sponge D. granulosa of Lakshadweep islands showed significant antibacterial activity against clinical bacterial pathogens.

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Bacteria were isolated from Asian Sea bass, Lates calcarifer kept in a farm, on the South-east coast of India. During an outbreak of fin rot, the affected fish had hemorrhages at the base of fins, mouth and skin muscles and faded pigments. Pure colonies were isolated on NA and ZMA from internal organs of the fish and the bacterial morphology was identified as gram-negative rod-shaped bacteria. Based on different biochemical tests and sequence of 16S rDNA, the causative bacteria were identified as Pseudomonas sp. KUMS3. Bacterial cells were isolated from liver and kidney of all artificially infected moribund fish and confirmed as Pseudomonas sp. KUMS3 by morphological and biochemical characteristics. During the experimental infection, the first incidence of dead fish was observed on 2nd day after exposure to Pseudomonas sp. KUMS3 and no fish died after 12 days post exposure and the cumulative percent of mortality was 70. Histological lesions were observed in the spleen, liver and kidney of the infected fish. Pseudomonas sp. KUMS3 could be considered as an opportunistic pathogen, which can survive on the fish surface or in water or in the gut and may cause disease when unfavorable conditions develop.