Villorita cyprinoides was selected to isolate total heterotrophic bacteria (THB) and arylsulfatase producing becteria (APB). Both THB and APB colonised more in the visceral mass of the shellfish during pre-monsoon season. Physico-chemical parameters do not exert any significant influence over the distribution of THB and APB. Micrococus was the predominant genus among TNB and Moraxella  among APB. Higher percentage of bacteria showed more affinity towards carbohydrates. The microbial participation in the breakdown of conjugated sulfuric esters and their importance in the physiology and nutrition of host organisms were discussed in the light of available literature.