Modification of E. coli central metabolism to optimize the biotransformation of L-isoleucine into 4-hydroxyisoleucine by enzymatic hydroxylation

The enzymes of the Entner-Doudoroff pathway (EDP) and/or the oxidative branch of the pentose phosphate pathway (OBPPP) have been inactivated in the E. coli 2Δ (ΔsucAB, ΔaceAK, P _L -brnQ) [pEL-IDO] strain, which is used for the biotransformation of L-isoleucine into 4-hydroxyisoleucine (4-HIL) by enzymatic hydroxylation. We established that the inactivation of the EDP in the 2Δ [pEL-IDO] strain does not virtually affect the basic parameters of the process, whereas the blocking of the OBPPP reduces the efficiency of biomass accumulation and L-isoleucine transformation in conversion to glucose. However, the simultaneous inactivation of the enzymes of the EDP and OBPPP in the 2Δ [pEL-IDO] strain allowed us to achieve a considerable improvement of the process, namely, a 20% reduction in glucose consumption and a 35% decrease in biomass yield at a constant L-isoleucine/4-HIL conversion rate at a level of 88%.