关键词: 放射型根瘤菌, 辅酶Q10, 诱变, 发酵条件优化

Abstract: Rhizobium radiobacte WSH2601 was mutagenized by using UV-radiation and NTG mutation consecutively. An actinomycin-D resistant mutant, R. radiobacte WSH-F06, was isolated after two runs of screening. The CoQ10 yield of mutant WSH-F06 increased by 16% compared to that of the parent strain. The effects of nutritional and environmental conditions on the production of CoQ10 by R. radiobacte WSH-F06 were investigated in shaking flasks. A complex carbon source consisting of glucose (30 g/L) and molasses (60 g/L) was shown to be suitable. In addition, R. radiobacter WSH-F06 could assimilate a variety of nitrogen sources, including organic and inorganic nitrogen compounds. A compound nitrogen source consisting of (NH4)2SO4 (7 g/L), peptone (5 g/L), yeast extract (5 g/L), corn steep liquor (30 g/L) was developed by using orthogonal experiments. The inoculum size had no obvious effect on CoQ10 fermentation. The optimum initial pH for CoQ10 fermentation was 7.2, while the optimum volume of medium (medium volume vs. flask volume ) was 50 mL/500 mL. Under the optimized fermentation conditions, the CoQ10 yield and the intracellular CoQ10 content reached 34 mg/L and 2.4 mg/g, which were 2.6- and 1.1-fold higher than that of the parent strain under the original conditions, respectively.

Key words: Rhizobium radiobacter, coenzyme Q10, mutation, fermentation