Novel thermophilic and thermostable lipolytic enzymes from a Thailand hot spring metagenomic library

Functional screening for lipolytic enzymes from a metagenomic library (origin: Jae Sawn hot spring, patatin-like phospholipase (PLP) and an esterase (Est 1). PLP contained four conserved domains similar to other patatin-like proteins with lipid acyl hydrolase activity. Likewise, sequence alignment analysis revealed that Est 1 can be classified as a family V bacterial lipolytic enzyme. Both PLP and Est 1 were expressed heterologously as soluble proteins in E. coli and exhibited more than 50% of their maximal activities at alkaline pH, of 7-9 and 8-10, respectively. In addition, both enzymes retained more than 50% of maximal activity in the temperature range of 50-75 degrees C, with optimal activity at 70 degrees C and were stable at 70 degrees C for at least 120 min. Both PLP and Est 1 exhibited high V-max toward p-nitrophenyl butyrate. The enzymes had activity toward both short-chain (C-4 and C-5) and long chain (C-14 and C-16) fatty acid esters. The isolated enzymes, are therefore, different from other known patatin-like phospholipases and esterases, which usually show no activity for substrates longer than C-10. We suggest that PLP and EstA enzymes are novel and have a; b potential use in industrial applications. (C) 2007 Elsevier B.V. All rights reserved.