Isolation, characterization and complete genome sequencing of fish pathogenic Aeromonas veronii from diseased Labeo rohita

A pathogenic strain of Aeromonas veronii, named as A8-AHP, was isolated from the kidney tissue of diseased Labeo rohita. Intraperitoneal injection of A. veronii A8-AHP into L. rohita fingerlings resulted in development of clinical signs similar to the natural infection. During disk diffusion assay, A. veronii A8-AHP showed resistance against ampicillin and imipenem. The complete de novo assembled genome of A. veronii A8-AHP consisted of a 4,744,657 bp circular chromosome and three circular plasmids of 10,228, 7706, and 5625 bp. The bacterial genome showed nucleotide sequence identities of 90.5–96.6% with other A. veronii genomes in NCBI database. Genes encoding for several virulence factors viz. polar and lateral flagella, pili, fimbriae, type II secretion system (T2SS), type III secretion system (T3SS), aerolysin, hemolysin, proteases and lipases etc. were detected. Besides, genetic factors related to antibiotic inactivation, target site alteration and efflux pump were also present. A total of 73 metabolic pathways were also detected. The arsenate reductase encoding gene in A. veronii A8-AHP could also of biotechnological significance for bioremediation purposes. Present study reports the first complete genome sequence of fish pathogenic A. veronii from India.