A thermophilic, lipolytic Bacillus sp., and continuous assay of its p-nitrophenyl-palmitate esterase activity

Abstract

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 μM p-nitrophenyl-palmitate and the optimum pH (at 70°C) was 8.7.

Bacillus sp., Lipase, p-Nitrophenyl-palmitate esterase, Thermostable enzyme