Characterisation of a thermo-alkali-stable lipase from oil-contaminated soil using a metagenomic approach |
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Authors: | Jianhua Zheng Cuina Liu Liguo Liu Qi Jin |
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Institution: | 1. MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China;2. School of Labor & Human Resources, Renmin University of China, Beijing, China |
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Abstract: | Lipases are widely used for a variety of biotechnological applications. Screening these industrial enzymes directly from environmental microorganisms is a more efficient and practical approach than conventional cultivation-dependent methods. Combined with activity-based functional screening, six clones with lipase activity were detected and a gene (termed lipZ01) isolated from a target clone with the highest lipase activity was cloned from an oil-contaminated soil-derived metagenomic library and then sequenced. Gene lipZ01 was expressed in Pichia pastoris GS115 and the molecular weight of the recombinant lipase LipZ01 was estimated by electrophoresis analysis to be approximately 50 kDa. The maximum activity of the purified lipase was 42 U/mL, and the optimum reaction temperature and pH value were 45 °C and 8.0, respectively. The enzyme was highly stable in the temperature range 35–60 °C and under alkaline conditions (pH 7–10). The presence of Ca2+ and Mn2+ ions could significantly enhance the activity of the lipase. The purified lipase preferentially hydrolysed triacylglycerols with acyl chain lengths ≥8 carbon atoms, and the conversion degree of biodiesel production was nearly 92% in a transesterification reaction using olive oil and methanol. Some attractive properties suggested that the recombinant lipase may be valuable in industrial applications. |
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Keywords: | BMGY buffered glycerol-complex medium BMMY buffered methanol-complex medium dNTP deoxynucleoside triphosphate DTT 1 4-dithiothreitol EDTA ethylenediaminetetraacetic acid FAMEs fatty acid methyl esters LAOR LB medium supplemented with ampicillin olive oil substrate and rhodamine B ORF open reading frame PAGE polyacrylamide gel electrophoresis PMSF phenylmethanesulphonyl fluoride SDS sodium dodecyl sulphate YEPD yeast extract peptone and dextrose YNB yeast nitrogen base |
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