Bright Singh, I S; Rosamma, Philip; Rejish Kumar, V J; Jayaprakash, N S(Blackwell Publishing Ltd, March 1, 2006)
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Abstract:
Surveys for bacteriological analysis of larval samples
to isolate the associated vibrios were carried out during
1985^1992, 2001 and 2002 in three di¡erent
hatcheries located on the southwest coast of India.
Vibrio isolates were examined for their species diversity,
virulence based on haemolysis in prawn blood
agar, lipolysis, proteolysis and chitinolysis and antibiotic
sensitivity.Vibrio cholerae was the predominant
species in the apparently healthy larval samples,
whereas V. alginolyticus and V. vulni¢cus dominated
during disease and morbidity. No correlation was
found between the hydrolytic properties and haemolytic
activity of the vibrios associated with the larvae.
All isolates were resistant to erythromycin and resistance
to oxytetracycline, ampicillin and streptomycin
sulphate was prevalent among the larger section of
the Vibrio population. This suggested that antibiotic
application may not be of much use to protect the larvae
fromvibriosis. This is the ¢rst report on the diversity
of Vibrio species associated with Macrobrachium
rosenbergii larvae and their virulence characteristics
based on haemolysis in prawn blood agar
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