New strategy to enhance catalytic performance of Escherichia coli whole cell biocatalysts harboring P450cam mutants

Cytochrome P450cam mutants (Y96F and F87W-Y96F) can catalyze the oxidation of dichlorobenzene and other aromatic compound that wild type P450cam cannot catalyze. The expression of the single mutant Y96F in an Escherichia coli host resulted in indigo formation (approximately 23 mg/l), of which productivity was comparable to the highest reported so far using other P450cam mutant cultures. On the other hand, recombinant E. coli that harbored F87W-Y96F exhibited little activity for indigo production. However, co-expression of E. coli glycerol dehydrogenase (GLD) with F87W-Y96F triggered a marked increase in the productivity of indigo (approximately 20 mg/l) without external glycerol addition. These results indicate the potential of introducing GLD-mediated NADH regeneration that utilizes endogenous NAD+ and glycerol in E. coli to enhance markedly the catalytic performance of a low-activity recombinant P450cam system. The present E. coli whole-cell biocatalysts might be applicable to practical microbial indigo production.