ISOLATION AND CHARACTERIZATION OF BACTERIAL PATHOGENIC Bacillus sp. FROM THE Lethrinus lentjanin COASTAL AREA OF INDIA

Abstract

India stands at the sixth-largest position in the sector of marine and freshwater fisheries and the second-largest in the production of aquaculture. In view of the economic benefits, this highlights the importance of controlling infectious fish diseases that pose threat to the production of aquaculture. It was hypothesized lesions found on the dorsal scales in the Lenthrinus lentjan, could be the reason for the massive morbidity and mortality. Live surface floating fish samples with pathological signs were collected from offshore areas of the Pallam fishing village, located in the Kanyakumari District of Tamil Nadu, India in August 2013. Detailed histological studies confirmed the presence of similar bacterial infections in the tissues adjacent to the lesion sites. The pathogen was isolated and it was subjected to a series of biochemical and 16S RNA sequencing and it was identified the causative bacterial pathogen as Bacillus sp. The pathogen possessed sub-terminal endospore-forming nature and also it has strong hemolytic activities. The organism was named as Bacillus sp. MSU1400. Furtherly, the study was complemented with the Pasteur method, performed on white carp fishes, in vitro, for the confirmation of the pathogen. The pathogen was sensitive to ampicillin, cephalexin, and gentamycin but it was resistant to tetracycline.