Enforcing ATP hydrolysis enhanced glycolysis and promoted solvent production under anaerobic conditions

Abstract

Background The intracellular ATP level, an indicator of cellular energy state, plays a critical role in regulating the intracellular metabolic activities. The classical ATP paradox that the glycolytic rate negatively correlates with the intracellular ATP level was well studied. Reducing intracellular ATP level could stimulate the glycolytic rate, thereby enhancing products accumulation in aerobic conditions. However, there are limited studies about the effect of reducing cellular ATP level on anaerobic glycolysis and products formation.Results Taking anaerobic ABE (acetone-butanol-ethanol) fermentation by Clostridium acetobutylicum as a model, we reduced the intracellular ATP level by introducing an independent ATP hydrolysis module of F 1 -ATPase. We found that the low intracellular ATP level in C. acetobutylicum compared to that in aerobic microbes, was further reduced and the glucose uptake was remarkably enhanced, achieving a 78.8% increase of volumetric glucose utilization rate. The total solvent production was improved with increase in productivity (46.5%), titer (9.9%) and yield (14.5%) compared to control, with an early onset of solventogenesis and a shortened fermentation period. Consistently, genome-scale metabolic modeling revealed the elevated metabolic fluxes through glycolysis, TCA cycle, and pyruvate metabolism in F 1 -ATPase overexpression strain.Conclusions Decreasing the cellular energy level could further enhance the glycolytic rate at anaerobic condition and lead to significantly improvement on solvents synthesis. Our findings provide a novel strategy for improving ABE fermentation performance, which is beneficial for industrial Weizmann process. Engineering intracellular ATP level can thus be considered as a promising tool to enhance the efficiency of other anaerobic fermentation processes.

Clostridium acetobutylicum atpG-Knockdown Mutants Increase Extracellular pH in Batch Cultures

“…The effects of atpG knockdown in C. acetobutylicum were also assessed by examining glucose consumption, which is known to be affected by ATP levels ( Koebmann et al, 2002b ; Dai et al, 2020 ). Glucose concentration decreased steadily during exponential and stationary phases in both ATCC 824 and 824-2866KD ( Figure 3 ; Supplementary Figure S3 ).…”