Redirection electron flow to high coupling efficiency of terminal oxidase to enhance riboflavin biosynthesis.

The metabolic impact of redirection electron flow to high coupling efficiency of terminal oxidases on riboflavin biosynthetic ability was quantitatively assessed during batch culture in this paper. While disruption of the low coupling bd oxidase of the riboflavin overproducing B. subtilis PK, the apparent phenotype with more rapid specific growth rate and higher biomass yield was achieved. Compared to by-products formation, a discernible shift to less acetate and more acetoin in cyd mutant was observed. As the overflow metabolism was decreased in B. subtilis PK cyd, more carbon source was directed to biomass and riboflavin biosynthetic pathway, which resulted in higher biomass and about 30% improvement of riboflavin biosynthetic ability. The higher product-corrected biomass yield in mutant showed that the efficient energy generation is an important factor for exponential growth of riboflavin overproducing B. subtilis strain in batch culture.