Strazdina, I.; Bikerniece, M.; Paegle, E.R.; Shvirksts, K.; Grube, M.; Lasa, Z.; Rutkis, R.; Kalnenieks, U. Oxidative Phosphorylation for Aerobic Survival, but Not for Growth: The Peculiar ‘Make-Accumulate-Consume’ Strategy in Zymomonas mobilis. Fermentation2023, 9, 951.
Strazdina, I.; Bikerniece, M.; Paegle, E.R.; Shvirksts, K.; Grube, M.; Lasa, Z.; Rutkis, R.; Kalnenieks, U. Oxidative Phosphorylation for Aerobic Survival, but Not for Growth: The Peculiar ‘Make-Accumulate-Consume’ Strategy in Zymomonas mobilis. Fermentation 2023, 9, 951.
Strazdina, I.; Bikerniece, M.; Paegle, E.R.; Shvirksts, K.; Grube, M.; Lasa, Z.; Rutkis, R.; Kalnenieks, U. Oxidative Phosphorylation for Aerobic Survival, but Not for Growth: The Peculiar ‘Make-Accumulate-Consume’ Strategy in Zymomonas mobilis. Fermentation2023, 9, 951.
Strazdina, I.; Bikerniece, M.; Paegle, E.R.; Shvirksts, K.; Grube, M.; Lasa, Z.; Rutkis, R.; Kalnenieks, U. Oxidative Phosphorylation for Aerobic Survival, but Not for Growth: The Peculiar ‘Make-Accumulate-Consume’ Strategy in Zymomonas mobilis. Fermentation 2023, 9, 951.
Abstract
Understanding the energy metabolism and its regulation is one of the clues to metabolic engineering of stress-resistant lignocellulose-converting microbial strains, including also the promising ethanologen Zymomonas mobilis. Z. mobilis is an obligately fermentative, facultatively anaerobic bacterium, carrying an active respiratory chain with a low energy-coupling efficiency. Its respiration does not supply energy to aerobically growing culture on sugary media, yet oxidative phosphorylation has been demonstrated in non-growing cells with ethanol. In the present work we show that in respiring, non-growing Z. mobilis cells, receiving regular small amounts of ethanol, oxidative phosphorylation significantly contributes to the maintenance of their viability. Accordingly, no improvement of viability is seen in the NADH dehydrogenase (ndh)-deficient respiratory mutant, unable to oxidize ethanol. The ethanol effect is hampered also by the protonophoric uncoupler CCCP, or the inhibitor of ATP synthase, DCCD. At higher concentrations (6% v/v) ethanol causes stress that slows down culture growth. By monitoring the activity of several respiratory gene promoters in aerobically growing culture under ethanol stress with the green fluorescent protein reporter system, we demonstrate downregulation of these promoters, in particular the ndh promoter. We speculate that the decrease of the respiratory chain activity mitigates the production of reactive oxygen species.
Keywords
Zymomonas mobilis; respiratory chain; Type II NADH dehydrogenase; oxidative phosphorylation; starvation; viability; make-accumulate-consume strategy; ethanol stress
Subject
Biology and Life Sciences, Immunology and Microbiology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
,
,
,
,
*
