RESUMO
Lipase from Rhizomucor miehei (RML) is a promising biocatalyst used in food industry, fine chemicals, and biodiesel production. Yeast surface display allows direct application of lipase in form of whole-cell biocatalyst, avoiding purification and immobilization process, but the protease of the host cell may affect the activity of displayed lipase. Herein, we used the protease-deficient Pichia pastoris, PichiaPink™ as host to display RML efficiently. RML gene, GCW21 gene and α-factor gene were co-cloned into plasmid pPink LC/HC and transformed into protease-deficient P. pastoris. After inducution expression for 96 h, the lipase activity of displayed RML reached 121.72 U/g in proteinase-A-deficient P. pastoris harboring high-copy plasmid, which exhibited 46.7% higher than recombinant P. pastoris without protease defect. Displayed RML occurred the maximum activity at pH 8.0 and 45 °C and the optimal substrate was p-nitrophenyl octanoate. Metal ions Li+, Na+, K+, and Mg2+ of 1-10 mM had activation towards displayed RML. Displayed RML was effectively improved in PichiaPink™ protease-deficient system, which may promote the further research and development for the industrial application of RML.
Assuntos
Técnicas de Visualização da Superfície Celular , Proteínas Fúngicas/biossíntese , Lipase/biossíntese , Rhizomucor/genética , Saccharomycetales , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Lipase/química , Lipase/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Rhizomucor/enzimologia , Saccharomycetales/genética , Saccharomycetales/metabolismoRESUMO
A cell surface displayed system in Pichia pastoris GS115 was developed by using GCW61, a glycosylphosphatidylinositol-modified cell wall protein from P. pastoris, as the anchor protein. Thermomyces lanuginosus lipase (TLL) was successfully displayed on the P. pastoris cell wall by fusing GCW61 gene with TLL2 gene (NCBI Accession: O59952) that was optimized with codon bias and synthesized. Cell surface displayed TLL2 was confirmed by the immunofluorescence microscopy. Flask fermentation was performed for 144 h with lipase activity up to 1964.76 U/g. Enzymatic properties of cell surface displayed TLL2 were also investigated. Displayed TLL2 occurred the maximum activity at pH 9 and 55°C and demonstrated characteristics of wide thermal adaptability and alkaline pH resistance. The optimum substrate was p-nitrophenyl hexanoate. Bivalent metal ions Ca2+, Mn2+, and Zn2+ had the activation effect on displayed TLL2, while Cu2+, Fe2+, Fe3+, K+, Li+, Na+, and Co2+ ions had the inhibitory effect on it. Since cell surface displayed TLL2 required less purification steps compared with free enzyme and showed high enzyme activities, it would be able to be further applied in various potential applications.
