2.9. Determination of Median Lethal Dose (LD50) of A. hydrophila.
An overnight culture of A. hydrophila TISTR 1321
in TSB was centrifuged at 5,000 rpmfor 10minutes. Bacterial
cells were washed twice with physiological saline (0.85%
NaCl) and then resuspended in the same solution to obtain a
bacterial suspension with the concentration of 108 CFU/mL.
The bacterial suspension was subjected to tenfold serial
dilutions using the physical saline as a diluent and then used
to challenge groups of 20 hybrid catfish. One hundred