The identification and partial characterisation of a novel inducible extracellular thermostable esterase from the archaeon Sulfolobus shibatae.

Abstract Extracellular esterases have so far only been reported in eubacteria, here we report the first identification and partial characterisation of a novel inducible extracellular esterase from the thermoacidophilic archaeon Sulfolobus shibatae . This esterase exhibits remarkable stability to both acid and heat. Esterase activity is induced by growth on a range of polyoxyethylenesorbitan (Tween) compounds as sole carbon source. Activity occurs over a wide temperature (25-99°C) and pH (pH4.0-9.0) range and is optimal at 90°C and pH6.0. It exhibits high thermal stability, with a half-life of 20 min at 120°C, and shows a transient thermal activation of 60% at 90°C. The thermal inactivation of function occurs by first order kinetics, and after 120 min incubation at 120°C 50% of activity still remains, It is able to hydrolyse mono- and diglycerides, but is unable to hydrolyse the triglycerides olive oil and triolein, which is indicative of an esterase and not a lipase.