Optimization of Growth Medium of Bacillus sp. TTMP20 by Response Surface Methodology

Abstract

High-density culture is able to obtain high concentration and activity of microbes, which is a key technology for fermentation industry. This will greatly shorten fermentation cycle and reduce production cost. Bacillus sp. TTMP20 is a strain with a high yield of 2,3,5,6-tetramethylpyrazine (TTMP). In this study, the growth medium of Bacillus sp. TTMP20 was optimized. Different carbon/nitrogen sources were investigated, and the best carbon source (glucose) and nitrogen source (yeast extract) was determined. With the concentrations of glucose, yeast extract and pH as influence factors, response surface method was used to optimize the above-mentioned influence factors to maximize cell density of the strain. The optimal growth medium is as follows: 4 g/L of yeast extract, 15.754 g/L of glucose, 2 g/L of K2HPO4, 10 g/L of NaCl, and 6.50 of pH. The predicted and actual maxima are 1.388 and 1.3, respectively. This is 61.4% higher than the cell density of the basic medium. This will provide the adequate seed culture for the subsequent fermentation of TTMP, and improve the application level of Bacillus sp. TTMP20.