Understanding the Effect of Redox Potential On Microbial Metabolism Through Comparative Proteomic Profiling: Using Microbial Production of 1,3-Propandiol As An Example

Anaerobic and micro-aerobic fermentation processes are widely applied for the microbial production of fuels and chemicals. Redox potential (oxidoreduction potential, ORP) level was shown to be a critical factor affecting the growth and metabolism of (facultative) anaerobes, but the molecular mechanism remains largely unknown. We investigated the effect of ORP control on the fermentative production of 1,3-propanediol, a bulk chemical that is produced under micro-aerobic or anaerobic conditions. We developed a novel redox potential-based screening strategy and isolated Klebsiella oxytoca mutants with enhanced 1,3-propanediol-producing capability. Moreover, we used comparative proteomic profiling method to understand the metabolic shift of K. oxytoca when the extracellular ORP was altered. Comparative analysis of the cytoplasmic proteome of K. oxytoca under two different ORP levels revealed ~40 differentially expressed proteins, one third of which are involved in the central glycerol metabolism, amino acid and nucleotide biosynthesis pathways, thus providing new targets for further metabolic engineering of 1,3-propandiol producers.