Bright Singh, I S; Rosamma, Philip; Sreedharan, K(SBM, January 16, 2012)
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Abstract:
Aeromonas spp. are ubiquitous aquatic organisms, associated with multitude of diseases in several species of
animals, including fishes and humans. In the present study, water samples from two ornamental fish culture
systems were analyzed for the presence of Aeromonas. Nutrient agar was used for Aeromonas isolation, and
colonies (60 No) were identified through biochemical characterization. Seven clusters could be generated
based on phenotypic characters, analyzed by the programme NTSYSpc, Version 2.02i, and identified as:
Aeromonas caviae (33.3%), A. jandaei (38.3%) and A. veronii biovar sobria (28.3%). The strains isolated
produced highly active hydrolytic enzymes, haemolytic activity and slime formation in varying proportions.
The isolates were also tested for the enterotoxin genes (act, alt and ast), haemolytic toxins (hlyA and aerA),
involved in type 3 secretion system (TTSS: ascV, aexT, aopP, aopO, ascF–ascG, and aopH), and
glycerophospholipid-cholesterol acyltransferase (gcat). All isolates were found to be associated with at least
one virulent gene. Moreover, they were resistant to frequently used antibiotics for human infections. The
study demonstrates the pathogenic potential of Aeromonas, associated with ornamental fish culture systems
suggesting the emerging threat to public health