Harnessing hyperthermostable lactonase from Sulfolobus solfataricus for biotechnological applications

Extremozymes have gained considerable interest as they could meet industrial requirements. Among these, SsoPox is a hyperthermostable enzyme isolated from the archaeon Sulfolobus solfataricus. This enzyme is a lactonase catalyzing the hydrolysis of acyl-homoserine lactones; these molecules are involved in Gram-negative bacterial communication referred to as quorum sensing. SsoPox exhibits promiscuous phosphotriesterase activity for the degradation of organophosphorous chemicals including insecticides and chemical warfare agents. Owing to its bi-functional catalytic abilities as well as its intrinsic stability, SsoPox is appealing for many applications, having potential uses in the agriculture, defense, food and health industries. Here we investigate the biotechnological properties of the mutant SsoPox-W263I, a variant with increased lactonase and phosphotriesterase activities. We tested enzyme resistance against diverse process-like and operating conditions such as heat resistance, contact with organic solvents, sterilization, storage and immobilization. Bacterial secreted materials from both Gram-negative and positive bacteria were harmless on SsoPox-W263I activity and could reactivate heat-inactivated enzyme. SsoPox showed resistance to harsh conditions demonstrating that it is an extremely attractive enzyme for many applications. Finally, the potential of SsoPox-W263I to be active at subzero temperature is highlighted and discussed in regards to the common idea that hyperthermophile enzymes are nearly inactive at low temperatures.