Isolation, phenotypic and molecular characterization of motile Aeromonas species, the cause of bacterial hemorrhagic septicemia in affected farmed carp in Iran

Abstract

<strong>Background:</strong> Motile <em>Aeromonas</em> species cause heavy<br />mortalities in carp farms during spring and summer in Iran. <strong>Objectives:</strong> The aim of this study was to detect phenotypic<br />and genotypic characterization of motile <em>Aeromonas</em> species isolated from<br />diseased carps in some northern and southern provinces of Iran. <strong>Methods:</strong> A number of 40 samples from 22 fish farms were<br />collected. The identified motile <em>Aeromonas</em> species were sequenced and<br />phylogenetic tree was drawn by MEGA6 using UPGMA analysis. <strong>Results:</strong> A number of 19 bacterial isolates were<br />identified as motile <em>Aeromonas</em> sp. by biochemical tests, and the DNA<br />segments of 16S rRNA gene of all these strains gave 1200 bp after running on 1%<br />agarose electrophorus gel. Also, the sequencing results showed that the<br />bacterial samples were determined as <em>A. hydrophila</em> and <em>A. veronii</em><br />biovar veronii. <strong>Conclusions:</strong> Phylogenetic analysis revealed that motile <em>Aeromonas</em><br />strains in this study were separated in two clusters and four genogroups with high similarities