Co-expression， purification and characterization of the lipase and foldase of Burkholderia contaminans LTEB11.

Genes encoding lipase LipBC (lipA) and foldase LifBC (lipB) were identified in the genome of Burkholderia contaminans LTEB11. Analysis of the predicted amino acid sequence of lipA showed its high identity with lipases from Pseudomonas luteola (91%)， Burkholderia cepacia (96%) and Burkholderia lata (97%)， and classified LipBC lipase in the lipase subfamily I.2. The genes lipA and lipB were amplified and cloned into expression vectors pET28a(+) and pT7-7， respectively. His-tagged LipBC and native LifBC were co-expressed in Escherichia coli and purified. LipBC and LifBC have molecular weights of 35.9 kDa and 37 kDa， respectively， and remain complexed after purification. The Lip-LifBC complex was active and stable over a wide range of pH values (6.5-10) and temperatures (25-45 °C)， with the highest specific activity (1426 U mg) being against tributyrin. The Lip-LifBC complex immobilized on Sepabeads was able to catalyze the synthesis of ethyl-oleate in n‑hexane with an activity of 4 U g， maintaining high conversion (>80%) over 5 reaction cycles of 6 h at 45 °C. The results obtained in this work provide a basis for the development of applications of recombinant LipBC in biocatalysis.