Abstract:In order to obtain a high-yield fermentation strain of 2,3,5,6-tetramethylpyrazine (TTMP), Bacillus velezensis CS1.11 screened from moromi was mutated by ultraviolet radiation. The diameter of casein plate hydrolysis ring and the intensity of acetoin color reaction were used as indicators for preliminary screening. The solid-state fermentation of TTMP from steamed soybean meal and roasted wheat was rescreened, and three mutant strains were obtained. Study on protease, amylase activity as well as acetoin synthesis ability showed that two mutant strains CS1.11-32 and CS1.11-33 were better than another, and their TTMP accumulation increased by 47.64% and 78.89%, respectively, compared with the original strain, which were suitable for soy sauce fermentation. The effects of roasted wheat addition amount, water addition amount, inoculation amount, fermentation temperature, and stirring times on the accumulation of TTMP were studied and CS1.11-33 showed better TTMP accumulation ability compared with CS1.11-32. The optimal fermentation conditions for solid-state fermentation of CS1.11-33 to accumulate TTMP were obtained by response surface methodology as follows: Roasted wheat addition of 44%, water addition of 29%, fermentation temperature of 37 ℃, inoculation amount of 8%, and no stirring during fermentation. Under these conditions, the maximum accumulation of TTMP reached 1 895.08 mg/kg dry basis, 2.6 times that before optimization. Breeding and fermentation research of Bacillus velezensis TTMP high-yield strain in moromi will lay the foundation for increasing TTMP concentration in soy sauce, rapidly enhancing Jiang-flavor, and promoting the functional application of TTMP.