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Background  Metagenomics is a useful tool in the search for new lipases that might have characteristics that make them suitable for application in biocatalysis. This paper reports the cloning, co-expression, purification and characterization of a new lipase, denominated LipG9, and its specific foldase, LifG9, from a metagenomic library derived from a fat-contaminated soil.    Results  Within the metagenomic library, the gene  lipg9  was cloned jointly with the gene of the foldase,  lifg9.  LipG9 and LifG9 have 96% and 84% identity, respectively, with the corresponding proteins of  Aeromonas veronii  B565. LipG9 and LifG9 were co-expressed, both in N-truncated form, in  Escherichia coli  BL21(DE3), using the vectors pET28a(+) and pT7-7, respectively, and then purified by affinity chromatography using a Ni 2+  column (HiTrap Chelating HP). The purified enzyme eluted from the column complexed with its foldase. The molecular masses of the N-truncated proteins were 32 kDa for LipG9, including the N-terminal His-tag with 6 residues, and 23 kDa for LifG9, which did not have a His-tag. The biochemical and kinetic characteristics of the purified lipase-foldase preparation were investigated. This preparation was active and stable over a wide range of pH values (6.5-9.5) and temperatures (10-40°C), with the highest specific activity, of 1500 U mg −1 , being obtained at pH 7.5 at 30°C. It also had high specific activities against tributyrin, tricaprylin and triolein, with values of 1852, 1566 and 817 U mg −1 , respectively. A phylogenetic analysis placed LipG9 in the lipase subfamily I.1. A comparison of the sequence of LipG9 with those of other bacterial lipases in the  Protein Data Bank  showed that LipG9 contains not only the classic catalytic triad (Ser 103 , Asp 250 , His 272 ), with the catalytic Ser occurring within a conserved pentapeptide, Gly-His-Ser-His-Gly, but also a conserved disulfide bridge and a conserved calcium binding site. The homology-modeled structure presents a canonical α/β hydrolase folding type I.    Conclusions  This paper is the first to report the successful co-expression of a lipase and its associated foldase from a metagenomic library. The high activity and stability of Lip-LifG9 suggest that it has a good potential for use in biocatalysis.    Electronic supplementary material  The online version of this article (doi:10.1186/s12934-014-0171-7) contains supplementary material, which is available to authorized users.

First co-expression of a lipase and its specific foldase obtained by metagenomics