Phosphotransferase system ( PTS ) independent glucose 1 utilization in Corynebacterium glutamicum by inositol

15 Phosphoenolypyruvate dependent glucose phosphorylation via the phosphotransferase system 16 (PTS) is the major path of glucose uptake in Corynebacterium glutamicum, but some growth from 17 glucose is retained in the absence of the PTS. The growth defect of a deletion mutant lacking the 18 general PTS component Hpr in glucose medium could be overcome by suppressor mutations 19 leading to high expression of inositol utilization genes or by addition of inositol to the growth 20 medium if a glucokinase is overproduced simultaneously. PTS-independent glucose uptake was 21 shown to require at least one of the inositol transporters IolT1 or IolT2 as a mutant lacking IolT1, 22 IolT2 and the PTS component Hpr could not grow with glucose as sole carbon source. Efficient 23 glucose utilization in the absence of the PTS necessitated overexpression of a glucokinase gene in 24 addition to either iolT1 or iolT2. IolT1 and IolT2 are low affinity glucose permeases with KS-values 25 of 2.8 mM and 1.9 mM, respectively. As glucose uptake and phosphorylation via the PTS differs 26 from glucose uptake via IolT1 or IolT2 and phosphorylation via glucokinase by the requirement for 27 phosphoenolpyruvate, the roles of the two pathways for L-lysine production were tested. The L28 lysine yield by C. glutamicum DM1729, a rationally engineered L-lysine producing strain, was 29 lower than by its PTS-deficient derivate DM1729∆hpr, which, however, showed low production 30 rates. Combined overexpression of iolT1 or iolT2 with ppgK, the gene for PolyP/ATP-dependent 31 glucokinase, in DM1729∆hpr enabled L-lysine production as fast as by the parent strain DM1729, 32 but with 10 to 20 % higher L-lysine yield. 33 on O cber 5, 2017 by gest ht://aem .sm .rg/ D ow nladed fom