BIOCATALYTIC SYNTHESES OF AROMATICS FROM D-GLUCOSE - RENEWABLE MICROBIAL SOURCES OF AROMATIC-COMPOUNDS

Chemistry is moving into a new era in which renewable resources and st arting materials such as D-glucose will likely be prominent features o f industrial chemical manufacture. The keys to this progress are the d esign, development, and use of microbial biocatalysts. Aromatic biosyn thesis serves as a paradigm for how biocatalysts can be manipulated to achieve the yield, rate, and purity criteria central to chemical manu facture. A disproportionate amount of the metabolic carbon flow of the biocatalyst must first be directed into the common pathway of aromati c amino acid biosynthesis. This review describes ways of achieving thi s goal through the traditional strategy of manipulating the catalytic activity of the first enzyme in the common pathway, as well as the ame lioration of limitations in the in vivo availability of common-pathway enzyme substrates. The inability of individual enzymes to convert the ir substrate to product fast enough to avoid substrate accumulation fu rther impedes carbon flow through the common pathway. This review also discusses identification and removal of these rate-limiting enzymes. Finally, we examine the creation of heterologous biocatalysts and how biocatalysis could be integrated with traditional chemical transformat ions to expand the number of organic chemicals that can be synthesized from glucose.