Use of hydrolysatedfrom Tuna viscera (Thunnustonggol) as base of culture media for some fish pathogen bacteria

Tuna viscera (Thunnus tonggol) were hydrolyzed by alcalase enzyme at two ranges of temperature (50.0, 57.5 and 65.0 °C) and pH (8.00 and 8.25). Hydrolysated proteins were used, as a commercial peptone, in the culture medium of Tryptic Soy Broth (TSB) to evaluate the growth rate of Vibrio anguillarum, Aeromonas salmonicida and Streptococcus iniae. The highest and lowest amounts of protein were observed at temperatures of 57.5 and 50.0°C, and pH=8.00, respectively. The level of bacterial growth was higher in culture media containing hydrolysated protein compared to TSB medium. Generally, the highest growth rate for three species of bacteria was related to culture medium prepared from hydrolysated protein at 57.5 °C and pH = 8.25. The overall conclusion of this study is that Tuna viscera, as a source of protein, can be substituted for commercial peptone in the formulation of bacterial culture media.