Histopathological tissue alterations of targeted organs of ornamental goldfish, Carassius auratus in India caused by a new pathogenic bacterial strain, Bacillus licheniformis PKBMS 16 identified on the basis of morpho- biochemical and 16S rDNA characterization

A highly pathogenic ampicillin-resistant bacteria Bacillus licheniformis have been identified from liver and kidney of symptomatic Goldfish Carassius auratus L. of India which may lead to a huge loss in the production of goldfish. Molecular characterization of the bacteria confirms its morphological and biochemical evidence. Phylogenetic analysis of the 16S rRNA gene sequence indicates Bacillus licheniformis PKBMS 16 (KX235179) was most similar to those of Bacillus licheniformis , strain B3 (HM030741.1, 99%) and was placed highest bootstrap value. The pathogenic effect of the bacteria, Bacillus licheniformis PKBMS 16 with a dose of 1.0 x 10 5 CFU/ml after 10 and 20 days of post-infection has been found to induce significant changes in histological, hematological, and serum biochemical parameters in the experimental group. Histologically, the internal organs, mainly the liver and kidney are severely damaged which may be the target organ for this isolated bacteria. The results on Bacillus licheniformis causing Bacilliosis in ornamental are worthy and significant because no reports on the in vivo pathogenicity of Bacillus species are available yet. However, this is the first reported episode from India, and it is reasonable to believe that in the experimental challenge, this bacterium produced a systemic pathology in terms of histological and hemato-biochemical alteration in Carassius auratus similar to many other known fish pathogens.