Efficient biosynthesis of d-ribose using a novel co-feeding strategy in Bacillus subtilis without acid formation

Normally, low d-ribose production was identified as responsible for plenty of acid formation by Bacillus subtilis due to its carbon overflow. An approach of co-feeding glucose and sodium citrate is developed here and had been proved to be useful in d-ribose production. This strategy is critical because it affects the cell concentration, the productivity of d-ribose and, especially, the formation of by-products such as acetoin, lactate and acetate. d-ribose production was increased by 596% from 7106 to 11341gl(-1) without acid formation by co-feeding 222gl(-1)h(-1) glucose and 0036gl(-1)h(-1) sodium citrate to a 60gl(-1) glucose reaction system. Actually, the cell density was also enhanced from 1151 to 1384gl(-1). These parameters revealed the importance of optimization and modelling of the d-ribose production process. Not only could zero acid formation was achieved over a wide range of co-feeding rate by reducing glycolytic flux drastically but also the cell density and d-ribose yield were elevated by increasing the hexose monophosphate pathway flux.