Study on the bacterial quality of edible oyster, Crassostrea madrasensis and its purification

Edible oysters (Crassostrea madrasensis) collected periodically during the years 1984-1986 from Central Marine Fisheries Research Institute farm at Tuticorin and from the natural beds were studied for their bacterial quality. Seawater samples from the surrounding environs were also simultaneously collected end analysed for physical. chemical and bacteriological parameters. The oyster samples were subjected to purification by employing different methods. The total bacterial count of cultured oysters and natural bed edible oysters ranged between 103 to 104 organisms per ml of oyster fluid. The T.B.C. of the sea water around cultured oysters and natural bed oysters ranged between 102 to 103 organisms per ml of seawater. Faecal coliforms were found to be very low end within permissible limits. The pathogenic bacteria Salmonlla, Streprococci and Staphylococci were absent. The variations in pH, temperature, salinity and dissolved oxygen of the seawater samples were insignificant. The edible oysters were subjected for purification by employing different purification methods among which chlorination was found to be better