A multitrophic population established in wool-scour effluent produced esterase activity with specificity to steryl, wax and triacylglyceryl esters. The wax esterase activity peaked just prior to the esterase activity toward cholesteryl oleate andp-nitrophenol palmitate. The activity was present in both the extracellular and cell membrane fractions. Partial characterization revealed the presence of multiple esterase bands on native polyacrylamide gels. The bacterial esterase activity could be enhanced by the addition of mineral salts.