A bi-enzymatic cascade to yield pyruvate as co-substrate for L-tyrosine production.

A bi-enzymatic cascade to yield pyruvate as co-substrate for L-tyrosine production. Appl Microbiol Biotechnol. 2020 Oct 31;: Authors: Guo X, Wu W, Zhang M, Wu L, Huang J Abstract L-Tyrosine is a versatile compound used in the fine chemical, pharmaceutical, and functional food industries. Here, we report a bi-enzymatic cascade involving alanine racemase (ALR) and D-amino acid oxidase (DAAO) to produce pyruvate, as co-substrate for L-tyrosine production, from the cheap substrate L-alanine. The BpALR (ALR from Bacillus pseudofirmus) was used as a whole-cell biocatalyst, converting L-alanine to D, L-alanine. The FsDAAO (DAAO from Fusarium solani) was immobilized to oxidize the D-alanine generated in the first step to pyruvate. Both systems were combined as a continuous-flow reactor for maximized L-alanine-to-pyruvate conversion rates. The optimal parameters and appropriate conditions for FsDAAO immobilization were investigated. The pyruvate concentration of 86.6 g/L was achieved within 17 h. Subsequently, a whole-cell biocatalyst system for L-tyrosine production, catalyzed by the tyrosine phenol-lyase (TPL) from Erwinia herbicola (EhTPL), was developed, and a fed-batch approach was applied with phenol and the pyruvate produced with the ALR/DAAO system mentioned above. The concentration of phenol and pyruvate in the reactor should not exceed 7.5 g/L and 10 g/L, respectively. Significantly, the L-tyrosine concentration of 152.5 g/L wa...
Source: Applied Microbiology and Biotechnology - Category: Microbiology Authors: Tags: Appl Microbiol Biotechnol Source Type: research