Enhanced L-tyrosine production in Bacillus amyloliquefaciens through alleviation of feedback Inhibition and coordinated pathway expression

L-tyrosine is a commercially significant compound with broad applications in the food and pharmaceutical industries. The development of efficient microbial cell factories for its production is of great interest. This study describes the engineering of the food-safe Bacillus amyloliquefaciens as a host chassis for enhanced L-tyrosine biosynthesis. To overcome the key regulatory constraint of L-tyrosine feedback inhibition, a mutant prephenate dehydrogenase (Eco-TyrAM53I/A354V) from Escherichia coli was introduced. This intervention increased the L-tyrosine titer to 446.32 mg/L, representing a 53% improvement over the control strain. The underlying mechanism was also investigated. Subsequent optimization of expression elements (promoter, 5′-UTR, and terminator) generated strain A8, which produced 560.57 mg/L of L-tyrosine. Additionally, the co-expression of key genes Eco-tyrAM53I/A354V and Bao-aroA significantly enhanced metabolic flux, boosting the titer to 1104.02 mg/L, a 257% increase relative to the control. This work significantly improves L-tyrosine production in a food-grade B. amyloliquefaciens chassis and provides a suite of efficient genetic tools for strain development. The findings and engineered systems established here offer a robust platform for advancing high-level microbial production of L-tyrosine, with strong potential for industrial application.