The first report of bacterial pathogenesis of non-motile (Aeromonas veronii Hickman-Brenner, 1987) in Sterlet juveniles (Acipenser ruthenus Linnaeus, 1758) in Sari

This study was carried out after receiving a report of the mortality of Sterlet sturgeon (Acipenser ruthenus) juveniles from a fish farm in Sari-Mazandaran in April 2021 to isolate and identify the pathogen in the ill Sterlet sturgeon (A. ruthenus)  juveniles. Sampling was performed from 20 ill Sterlet (A. ruthenus) juveniles. Clinical symptoms were recorded, followed by autopsy, kidney, and liver tissue sampling, bacterial culture, biochemical tests, anti-biogram test, DNA isolation, and 16Sr RNA gene sequencing. The tested isolate with 1418 base pairs (bp) was identified as a non-motile strain of A. veronii bacteria. It was registered in the World Gene Bank (NCBI) under the name Aeromonas veronii TMU000126. This strain of bacterium showed sensitivity to the Florfenicol as well as, resistance to Trimethoprim-sulfamethoxazole, Oxytetracycline, Doxycycline, and Fosfomycin antibiotics. The results revealed that the non-motile strain of A. veronii, like its motile strain, was the cause of disease and mortality in Sterlet sturgeon (A. ruthenus). According to the available studies, this study might be considered the first study on the disease of the sturgeon species of Sterlet (A. ruthenus), and the pathogenicity of the non-motile strain of A. veronii species.