INTERNATIONAL JOURNAL OF AGRICULTURAL TECHNOLOGY

Volume 16, No. 03, Month MAY, Year 2020, Pages 749 - 760

Species diversity and existence of virulence genes in clinical aeromonas spp. causing motile aeromonas septicemia (mas) isolated from cultured nile tilapia (oreochromis niloticus)

U-taynapun, K., Nganwisuthiphan, T. and Chirapongsatonkul, N.

Abstract Download PDF

Motile Aeromonas septicemia (MAS) is an emerging major disease in Nile tilapia (Oreochromis niloticus) caused by virulent clonal isolates of Aeromonas spp. including A. hydrophila, A. veronii, A. veronii biovar sobria and A. jandaei, aquaculture in Thailand. In this study, we investigated the species diversity and existence of virulence genes of Aeromonas spp. by analyzing 5 MAS incidences which occurred in the different areas (10 Aeromonas isolates from each case). According to the partial 16S rRNA sequence and phylogenetic analysis, 50 tested isolates were assigned to 4 different species with A. veronii or A. veronii biovar veronii as a dominant species (39 isolates, 78%), followed by A. hydrophila (6 isolates, 12%), A. veronii biovar sobria (3 isolates, 6%) and A. jandaei (2 isolates, 4%) respectively. Among the 39 confirmed that A. veronii isolates were the most prevalently virulence genes that were elastase and enolase (100%), and followed by alt (32 isolates, 82.05%), hly/aerA (24 isolates, 61.54%) and lipase (18 isolates, 46.15%). This study demonstrated the currently 4 major pathogenic species of Aeromonas in Nile tilapia reared in Thailand. Moreover, it suggested that A. veronii is the major pathogen that causes MAS and is widely distributed in this area.

Keywords

Aeromonas veronii, Motile Aeromonas septicemia, Nile tilapia, Species diversity, Virulence genes

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