Abstract-This work was devoted to the construction of recombinant strains Escherichia coli BL21 (DE3) and Pichia pastoris X33, producing a 1,3-specific thermostable lipase from Thermomyces lanuginosus. The sequences of two lipase genes were optimized for expression in bacteria and methylotrophic yeasts, then synthesized and cloned into the corresponding expression vectors. As a result of genetic engineering manipulations, E. coli and P. pastoris strains were constructed that efficiently produced recombinant lipase from T. lanuginosus, which accumulated in the cytoplasm in an amount of 30-40% of the total cellular protein. Recombinant P. pastoris clones secreted lipase into the nutrient medium at a concentration of at least 1 g/L. Lipases produced by the recombinant clones, designated as rE.coli/lip and rPichia/lip, respectively, contained a six-histidine sequence (-His6) in the C-terminal region. The resulting lipases were immobilized on/in solid inorganic supports in order to develop heterogeneous biocatalysts (HB) for the enzymatic conversion of triglycerides and fatty acids. The rPichia/lip enzyme was adsorbed on mesoporous silica and macroporous carbon aerogel. The properties of the prepared HB, their enzymatic activity, substrate specificity and operational stability were studied in the reaction of esterification of fatty acids with aliphatic alcohols in organic solvents at 20 ± 2°C. It was found that immobilized lipases had a relatively wide substrate specificity, as well as high operational stability, and the prepared HB almost completely retained their high esterifying activity for several tens of reaction cycles.
Key words: Escherichia coli, Pichia pastoris, recombinant strains-producers, Thermomyces lanuginosus lipase gene, immobilization, biocatalysts, esterification
The authors are grateful to V. L. Kuznetsov for the provided samples of carbon aerogel and A. V. Ryabchenko for gene-engineering manipulation aimed at obtaining the recombinant rE. coli strain, a producer of the rE.coli/lip enzyme.
The work was carried out under the Project on Fundamental Research within the framework of a state assignment to the Institute for Catalysis "Catalysts and Processes of Renewable Raw Material Conversion" (no. 0239-2021-0005).
Production of Structured Phosphatidylcholine with High Content of Myristic Acid by Lipase-Catalyzed Acidolysis and Interesterification
