A thermostable bacterial lipase from Geobacillus zalihae was expressed in a novel yeast Pichia sp. strain SO. The preliminary expression was too low and discourages industrial production. This study sought to investigate the optimum conditions for T1 lipase production in Pichia sp. strain SO. Seven medium conditions were investigated and optimized using Response Surface Methodology (RSM). Five responding conditions namely; temperature, inoculum size, incubation time, culture volume and agitation speed observed through Plackett-Burman Design (PBD) method had a significant effect on T1 lipase production. The medium conditions were optimized using Box-Behnken Design (BBD). Investigations reveal that the optimum conditions for T1 lipase production and Biomass concentration (OD600) were; Temperature 31.76 °C, incubation time 39.33 h, culture volume 132.19 mL, inoculum size 3.64%, and agitation speed of 288.2 rpm with a 95% PI low as; 12.41 U/mL and 95% PI high of 13.65 U/mL with an OD600 of; 95% PI low as; 19.62 and 95% PI high as; 22.62 as generated by the software was also validated. These predicted parameters were investigated experimentally and the experimental result for lipase activity observed was 13.72 U/mL with an OD600 of 24.5. At these optimum conditions, there was a 3-fold increase on T1 lipase activity. This study is the first to develop a statistical model for T1 lipase production and biomass concentration in Pichia sp. Strain SO. The optimized production of T1 lipase presents a choice for its industrial application.
Keywords: Geobacillus zalihae; Pichia sp.; optimization; response surface methodology; thermostable lipase.