Oxidative Phosphorylation for Aerobic Survival, But Not for Growth: The Peculiar ‘Make-Accumulate-Consume’ Strategy in Zymomonas mobilis

• DOI: 10.20944/preprints202309.1412.v1
• Publication Date: 2023-09-25T08:20:59Z
• Authors: Inese Strazdina; Mara Bikerniece; Evelina Rezija Pa...; Karlis Shvirksts; Mara Grube; Zane Lasa; Reinis Rutkis; Uldis Kalnenieks
• Keywords: Zymomonas mobilis; Cellular respiration; Bioenergetics; Chemiosmosis

Understanding the energy metabolism and its regulation is one of clues to metabolic engineering stress-resistant lignocellulose-converting microbial strains, including also promising ethanologen Zymomonas mobilis. Z. mobilis an obligately fermentative, facultatively anaerobic bacterium, carrying active respiratory chain with a low energy-coupling efficiency. Its respiration does not supply aerobically growing culture on sugary media, yet oxidative phosphorylation has been demonstrated in non-growing cells ethanol. In present work we show that respiring, cells, receiving regular small amounts ethanol, significantly contributes maintenance their viability. Accordingly, no improvement viability seen NADH dehydrogenase (ndh)-deficient mutant, unable oxidize The ethanol effect hampered by protonophoric uncoupler CCCP, or inhibitor ATP synthase, DCCD. At higher concentrations (6% v/v) causes stress slows down growth. By monitoring activity several gene promoters under green fluorescent protein reporter system, demonstrate downregulation these promoters, particular ndh promoter. We speculate decrease mitigates production reactive oxygen species.