Isolating Bacillus subtilis and optimizing its fermentative medium for GABA and nattokinase production

Abstract

The objective of this study was to create an optimized culture medium that would maximize the productivity of both γ-aminobutyric acid (GABA) and nattokinase in bacteria. First, Bacillus subtilis was screened from rice straw. Different media compositions were then optimized for GABA and nattokinase production using the Taguchi experimental design method, and the effects of different nitrogen and carbon sources were investigated. Of the various key ingredients tested in the media, fructose and yeast extract were found to have the most significant effect on GABA and nattokinase production. The optimal pH value and temperature for GABA production were found to be 7.0 and 37°C, respectively, after 72 h. The maximum GABA yield from B. subtilis under flask culture was 15.40 mg/mL. For nattokinase production, the optimal pH and temperature were found to be 8.0 and 30°C, respectively, after 48 h, which yielded approximately 130.96 units/mL of nattokinase. © 2013 Taylor & Francis.