Protease, hemolysin and cytotoxin were found in all diseased snakehead fish (Ophicephalus striatus). Aeromonas hydrophila was the predominant bacterium of all fish homogenates from both wounded areas and viscera. Total bacterial count of the fish homogenates was sufficiently high to cause disease and mortality to the fish. A. hydrophila F588, isolated from diseased snakehead fish,produced protease, hemolysin and cytotoxin. No detectable proteolytic, hemolytic or cytotxic activity was found in the fish homogenates or A. hydrophila F588 cell suspension after heating at 100°C for 10 min or autoclaving at 121°C for 15 min at 15 lb/in2. There was a 50% and 55% decrease in proteolytic and hemolytic activities, respectively, as compared to the controls when incubated A. hydrophila F588 in 30% NaCl for 1 1⁄2 mo at 30°C. Cytotoxic activity remained positive in all concentrations (0-30%) of NaCl. No cytotoxic activity could be demonstrated when pH of the samples was 2.0. However, there was only a 60% and 50% decrease in proteolytic and hemolytic activities, respectively, when pH of the samples was 2.0.
Faculty of Veterinary Science, Chulalongkorn University
"Effect of Temperature Salt and pH on Activities of Protease Hemolysin and Cytotoxin of Aeromonas hydrophila,"
The Thai Journal of Veterinary Medicine: Vol. 13:
4, Article 1.
Available at: https://digital.car.chula.ac.th/tjvm/vol13/iss4/1