Tetramethylpyrazine (TTMP) is an important aroma compound in traditional fermented foods, and has physiological activities such as regulating cardiac contraction, repairing damaged liver and kidney.To improve the quality of fermented Douchi, this study optimized the TTMP metabolism capacity of Bacillus subtilis.Based on the reported TTMP synthesis pathway, phosphoenolpyruvate carboxykinase gene (pckA) was deleted in B.subtilis BJ3-2 via homologous recombination technology to study the effect of BJ3-2ΔpckA on the flavor of fermented Douchi.The results showed that knocking out pckA did not affect the growth of B.subtilis.Compared to B.subtilis BJ3-2, the content of TTMP was increased 23.71% at 45 ℃ for 72 h by BJ3-2ΔpckA, and the fermented Douchi was characterized by fragrant soy sauce flavor, little off ammonia flavor, and high-quality flavor.It is the first time found that pckA has a significantly regulating effect on TTMP synthesis, which will provide a theoretical basis for the improvement of the fermentation quality of Douchi.
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