Multiple forms of carboxylesterase activity in Acinetobacter calcoaceticus

A carboxylesterase activity (E.C.3.1.1.) was found in all four strains of Acinetobacter calcoaceticus tested. The activity was present in both 2 × 104gav h−1 supernatant and bacterial wall‐membrane fractions. The activity in the supernatant was in two molecular weight forms, the predominant form with a Mr of about 103 K and a minor form Mr approximately 600 K. The activity was inhibited by phenylmethylsulfonyl fluoride. SDS‐PAGE showed that in A. calcoaceticus NCIB 8250 the activity was composed of three components of Mr 43, 40 and 38 K. The individual components showed different activities with 1‐ or 2‐naphthyl esters. Of the other strain used, one showed a nearly identical pattern of component activities, while the other two showed only two component activities.