Investigation of some virulence determents in aeromonas hydrophila strains obtained from different polluted aquatic environments

This study aimed to investigate some virulence characteristics of aeromonas hydrophila (a. hydrophila ) strains obtained from different egyptian aquatic environments in terms of enzymatic activities,presence of virulence genes and their pathogenicity in oreochromis niloticus. a total of 35 a. hydrophila isolates obtained from apparently healthy fish and water samples were examined. isolates were collected from three different water sources of the river nile; 15 isolates from el-sharkawia stream that receives lofty loads of industrial effluents. 11 isolates from el-rayah el-towfeky stream at an area known to receive loads of sewage and agricultural discharges and 9 isolates from bahr yousuf canal at el-fayoum governorate. water and fish samples obtained from the studied areas were also analysed for existence of heavy metals. isolates obtained from el-sharkawia stream,exhibited the uppermost enzymatic activities and virulence genes compared to isolates retrieved from other sources. all a. hydrophila isolates were pathogenic to oreochromis niloticus. presence of heavy metal pollutants (cr,pb and mn) in the aquatic environment affected the virulence of a. hydrophila isolates with variations in their enzymatic activities and presence of virulence genes. © 2017 jordan journal of biological sciences.