A thermophilic, lipolyticBacillussp., and continuous assay of itsp-nitrophenyl-palmitate esterase activity

The newly-isolated extremely thermophilic Bacillus sp.strain Wai28A5, able to grow at 70°C on tripalmitin and other triglycerides, possessed a p-nitrophenyl-palmitate esterase activity with a half-life of 60 min at 70°C and 12 min at 85°C.This activity was produced during exponential growth on tripalmitin, and the level of activity decreased once growth stopped.Transfer to tripalmitin-containing medium resulted in induction of the esterase activity.The activity was largely cell-associated (60 to 87% of the total activity).The p-nitrophenyl-palmitate esterase activity was proportional to the amount of culture added to enzyme assays and was destroyed by autoclaving, showing it to be enzymatic.A continuous assay for esterase activity was developed, and proved to be sensitive enough to detect 0.02 mU ml-1 esterase activity.Maximal esterase activity was at 400 p~M p-nitrophenyl-palmitate and the optimum pH (at 70°C) was 8.7.