Optimization of Culture Process Conditions for Chitinase Production by a Soil Isolate Streptomyces shandonggensis CTI105 Using Response Surface Methodology

Abstract

Response surface methodology was used to optimize culture process conditions for chitinase production by Streptomyces shandonggensis CTI105. Firstly, a chitinase producing microorganism was screened and isolated from soft shell crab molted shell-enriched top soil from a nearby soft shell crab farming area in Chanthaburi province, Thailand. The most potent isolate, with the CZ/CS ratio of 2.08±0.14 at 7 days of incubation time at 35^oC, was identified as Streptomyces shandonggensis based on 16S rRNA gene sequence analysis. Secondly, the three important culture process parameters including colloidal chitin concentration (0.5-2.5%), culture pH (4-8), and culture temperature (25–45°C) were optimized to obtain the maximum response of chitinase activity using the statistical Box-Behnken design. The quadratic polynomial equation model developed incorporates three linear, three quadratic, and one interaction term (colloidal chitin concentration and pH). The predicted chitinase production obtained from the quadratic polynomial model using the optimum conditions of colloidal chitin concentration, pH and temperature (1.53% w/v, 6.06 and 34.89^oC respectively) was 36.39 Unit ml^-1. The result demonstrated that Box-Behnken design response surface methodology was an effective way to obtain optimal conditions for chitinase production by Streptomyces shandonggensis.