title: Conversion of Corynebacterium glutamicum from an aerobic respiring to an aerobic fermenting bacterium by inactivation of the respiratory chain.
abstract: In this study a comparative analysis of three Corynebacterium glutamicum ATCC 13032 respiratory chain mutants lacking either the cytochrome bd branch (ΔcydAB), or the cytochrome bc1-aa3 branch (Δqcr), or both branches was performed. The lack of cytochrome bd oxidase was inhibitory only under conditions of oxygen limitation, whereas the absence of a functional cytochrome bc1-aa3 supercomplex led to decreases in growth rate, biomass yield, respiration and proton-motive force (pmf) and a strongly increased maintenance coefficient under oxygen excess. These results show that the bc1-aa3 supercomplex is of major importance for aerobic respiration. For the first time, a C. glutamicum strain with a completely inactivated aerobic respiratory chain was obtained (ΔcydABΔqcr), named DOOR (devoid of oxygen respiration), which was able to grow aerobically in BHI (brain-heart infusion) glucose complex medium with a 70% reduced biomass yield compared to the wild type. Surprisingly, reasonable aerobic growth was also possible in glucose minimal medium after supplementation with peptone. Under these conditions, the DOOR strain displayed a fermentative type of catabolism with l-lactate as major and acetate and succinate as minor products. The DOOR strain had about 2% of the oxygen consumption rate of the wild type, showing the absence of additional terminal oxidases. The pmf of the DOOR mutant was reduced by about 30% compared to the wild type. Candidates for pmf generation in the DOOR strain are succinate:menaquinone oxidoreductase, which probably can generate pmf in the direction of fumarate reduction, and F1FO-ATP synthase, which can couple ATP hydrolysis to the export of protons.
authors: Institut für Bio- und Geowissenschaften, Biotechnologie, Jülich, Germany.
authors: Abigail
authors: A
authors: Koch-Koerfges
authors: Nina
authors: N
authors: Pfelzer
authors: Laura
authors: L
authors: Platzen
authors: Marco
authors: M
authors: Oldiges
authors: Michael
authors: M
authors: Bott
mesh_terms: D000332:Aerobiosis; D048230:Corynebacterium glutamicum / Q000254:growth & development / Q000378:metabolism*; D004579:Electron Transport; D014450:Electron Transport Complex III / Q000502:physiology; D003576:Electron Transport Complex IV / Q000502:physiology; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D010101:Oxygen Consumption; D018892:Proton-Motive Force
chemical_list: D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III; D005947:Glucose