Optimization and characterization of solvent-tolerant lipases from Geobacillus stearothermophilus CHI1

Lipases are enzymes attractive for their use in enzymatic biotechnology, mainly those produced by extremophiles. Recently, the isolation of thermophilic bacteria Geobacillus spp. from the geothermal waters of the crater lake of the “El Chichón” volcano in Mexico was reported. In this work, the lipolytic activity of the G. stearothermophilus CHI1 strain was characterized and optimized. This strain was able to produce enzymes with maximum lipolytic activity at 60 °C and 80°C, with pH values of 5, 9, and 11; showed tolerance of solvents; was able to perform catalysis independently of metal ions; and showed greater affinity towards medium-chain substrates. Results of biochemical characterization and optimization suggest the presence of more than one type of lipolytic activity in Geobacillus stearothermophilus CHI1. All these characteristics make these enzymes attractive in biotechnological processes at high temperatures and alkaline pH (e.g., detergent additives), as well as in the understanding of their biological utility in Geobacillus.