The use of response surface methodology for enhanced production of a thermostable bacterial lipase in a novel yeast system

Abstract

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
• optimization
• Pichia sp.
• response surface methodology
• thermostable lipase

Authors’ contributions

ABS and SNO conceived and monitored the project, SNO, RM and AML designed the experiment, AML executed the project while, ABS, SNO and AML prepared the manuscript.

Disclosure statement

The authors declare that there is no conflict of interests regarding the publication of this paper.

Additional information

Funding

We would like to thank the Ministry of Higher Education Malaysia, for awarding the third author with “The Fundamental Research Grant Scheme Project” [Code: 02-02-14-1499FR] to complete this work. Also, the first author would like to express her gratitude to “Tertiary Education Trust Fund (Tetfund)” Nigeria for providing an academic scholarship for her Master degree.