Cloning, Expression, and Purification of a GDSL-like Lipase/Acylhydrolase from a Native Lipase-Producing Bacterium, Lactobacillus fermentum

Lipase enzymes are of great importance in various industries. Currently, extensive efforts have been focused on exploring new lipase producer microorganism as well as genetic and protein engineering of available lipases to improve their functional features.

For screening lipase-producing lactobacilli, isolated strains were inoculated onto tributyrin agar plates. Molecular identification of lipase-producing Lactobacilli was performed by sequencing the 16Sr DNA gene, and a phylogenetic tree was constructed. The LAF_RS05195 gene, encoding lipase protein in L. fermentum isolates, was identified using specific primers, amplified by PCR (918 bp) and cloned into the pET28a (+) vector. The recombinant proteins were expressed 2, 4, 6, and 12 hours after induction with IPTG and assessed using the SDS polyacrylamide gel electrophoresis (SDS-PAGE). Enzymatic activity of the purified recombinant protein was measured at 410 nm in the presence of ρ-NPA and ρ-NPP.  

Among five identified native lipase-producing isolates, one isolate showed 98% similarity with Enterococcus species. The other four isolates indicated 98% similarity to L. fermentum. After purification steps with Ni-NTA column, a single protein band of about 34 kDa was detected on SDS-PAGE gel. The enzymatic activity of purified recombinant protein alongside ρ-NPA and ρ-NPP was measured to be 0.6 U/ml and 0.2 U/ml, respectively.

In the present research, a novel lipase/esterase from L. fermentum was cloned and expressed. The novel lipase/esterase has the merit to be further studied due to its substrate specificity.