Isolation of a novel lipase from a metagenomic library derived from mangrove sediment from the south Brazilian coast

Abstract

A novel gene coding for a LipA-like lipase with 283 amino acids and a molecular mass of 32 kDa was isolated and characterized from a metagenomic library prepared from mangrove sediment from the south Brazilian coast. LipA was 52% identical to a lipolytic enzyme from an uncultured bacterium and shared only low identities (< or =31%) with lipases/esterases from cultivable microorganisms. Phylogenetic analysis showed that LipA, together with an orthologous protein from an uncultured bacterium, forms a unique branch within family I of true lipases, thereby constituting a new lipase subfamily. Activity determination using crude extracts of Escherichia coli bearing the lipA gene revealed that this new enzyme has a preference for esters with short-chain fatty acids (C < or = 10) and has maximum activity against p-nitrophenyl-caprate (chain length C10, 0.87 U/mg protein). The optimum pH of LipA was 8.0, and the enzyme was active over a temperature range of 20 to 35 degrees C, with optimum activity against p-nitrophenyl-butyrate at 35 degrees C and pH 8.0.