The respiratory chain of the ethanol-producing bacterium Zymomonas mobilis is able to oxidize both species nicotinamide cofactors, NADH and NADPH. A mutant strain with a chloramphenicol-resistance determinant inserted in ndh (encoding an : CoQ oxidoreductase type II) lacked membrane NADPH oxidase activities, while its D-lactate activity was increased. Cells showed very low respiration rate glucose no ethanol. aerobic growth elevated; exponential persisted longer, resulting higher biomass...

Zymomonas mobilis, an ethanol-producing bacterium, possesses the Entner-Doudoroff (E-D) pathway, pyruvate decarboxylase and two alcohol dehydrogenase isoenzymes for fermentative production of ethanol carbon dioxide from glucose. Using available kinetic parameters, we have developed a model that incorporates enzymic reactions E-D both dehydrogenases, transport related to ATP metabolism. After optimizing reaction parameters within likely physiological limits, resulting was capable simulating...

Performing oxidative phosphorylation is the primary role of respiratory chain both in bacteria and eukaryotes. Yet, branched chains prokaryotes contain alternative, low energy-coupling electron pathways, which serve for functions other than ATP generation (like those protection, adaptation to low-oxygen media, redox balancing, etc.), some are still poorly understood. We here demonstrate that withdrawal reducing equivalents by energetically uncoupled bacterium Zymomonas mobilis accelerates...

Mathematical modeling of metabolism is essential for rational metabolic engineering. The present work focuses on several types approach to quantitative understanding central network and energetics in the bioethanol-producing bacterium Zymomonas mobilis. Combined use Flux Balance, Elementary Mode thermodynamic analysis its metabolism, together with dynamic core catabolic pathways, can help design novel substrate product pathways by systematically analysing solution space engineering, yields...

Acetaldehyde is a valuable product of microbial biosynthesis, which can be used by the chemical industry as entry point for production various commodity chemicals. In ethanologenic microorganisms, like yeast or bacterium Zymomonas mobilis, this compound immediate metabolic precursor ethanol. aerobic cultures Z. it accumulates volatile, inhibitory byproduct, due to withdrawal reducing equivalents from alcohol dehydrogenase reaction respiration. The active respiratory chain mobilis with its...

Expression of the genes engineered green fluorescent protein and Zymomonas mobilis native malic enzyme from plasmid vectors under Z. respiratory NADH dehydrogenase promoter (Pndh) was strongly enhanced by aeration, both in wild type Zm6 its respiratory-deficient mutant derivative Zm6-ndh backgrounds. Pndh aerobically growing cultures activated about an order magnitude relative to non-aerated control. Its induction approached maximum level already at moderate aeration (1-5% oxygen saturation...

The genome of the ethanol-producing bacterium Zymomonas mobilis encodes a bd-type terminal oxidase, cytochrome bc1 complex and several c-type cytochromes, yet lacks sequences homologous to any known bacterial c oxidase genes. Recently, it was suggested that putative respiratory peroxidase, receiving electrons from via c552, might function as peroxidase and/or an alternative oxidase. present study designed test this hypothesis, by construction mutant (Zm6-perC), comparison its properties with...

Ability to ferment in the presence of oxygen increases robustness bioprocesses and opens opportunity for novel industrial setups. The ethanologenic bacterium Zymomonas mobilis performs rapid efficient anaerobic ethanol fermentation, yet its respiratory NADH dehydrogenase (Ndh)-deficient strain (ndh-) is known produce with high yield also under oxic conditions. Compared wild type, it has a lower rate consumption, an increased expression lactate (Ldh). Here we present quantitative study...

To investigate the mechanisms of Zymomonas mobilis uncoupled aerobic metabolism, growth properties wild‐type strain Zm6 were compared to those its respiratory mutants cytB and cydB , effects ATPase inhibitor DCCD on intracellular ATP concentration studied. The strongly indicated that apparent lack oxidative phosphorylation in aerobically growing Z. culture might be caused by hydrolyzing activity H + ‐dependent all analyzed strains. Aerobic yields mutants, their capacity synthesis with...

Perturbation of the aerobic steady‐state in a chemostat culture ethanol‐producing bacterium Zymomonas mobilis with small pulse ethanol causes burst oxidation, although reactant ratio alcohol dehydrogenase (ADH) reaction ([NADH][acetaldehyde][H + ])/([ethanol][NAD ]) remains above K eq value. Simultaneous catalysis synthesis and oxidation by two ADH isoenzymes, residing different redox microenvironments, has been proposed previously. In present study, this hypothesis is verified construction...

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Zymomonas mobilis is the most efficient bacterial ethanol producer and its physiology potentially applicable to industrial-scale bioethanol production. However, compared other industrially important microorganisms, Z. metabolome adaptation various nutritional genetic perturbations have been poorly characterized. For rational metabolic engineering, it essential understand how central metabolism intracellular redox balance are maintained in under conditions. In this study, we applied...

Abstract Acetaldehyde, a valuable commodity chemical, is volatile inhibitory byproduct of aerobic fermentation in Zymomonas mobilis and several other microorganisms. Attempting to improve acetaldehyde production by minimizing its contact with the cell interior facilitating removal from culture, we engineered Z. strain synthesis reaction localized periplasm. For that, pyruvate decarboxylase (PDC) was transferred periplasmic compartment. This achieved construction Zm6 PDC‐deficient mutant,...

Understanding the energy metabolism and its regulation is one of clues to metabolic engineering stress-resistant lignocellulose-converting microbial strains, also including promising ethanologen Zymomonas mobilis. Z. mobilis an obligately fermentative, facultatively anaerobic bacterium, carrying active respiratory chain with low energy-coupling efficiency. Its respiration does not supply aerobically growing cultures on sugary media, yet oxidative phosphorylation has been demonstrated in...

Mutant strain of the facultatively anaerobic, ethanol-producing bacterium Zymomonas mobilis, deficient in Fe-containing alcohol dehydrogenase isoenzyme (ADH II), showed impaired homeostasis intracellular NAD(P)H during transition from anaerobic to aerobic conditions, and also steady-state continuous cultures at various oxygen supplies. At same time, ADH II deficiency aerobically grown cells was accompanied by a threefold increase catalase activity about 50% hydrogen peroxide excretion. It is...

Zymomonas mobilis is an ethanologenic, facultatively anaerobic alpha-proteobacterium, known for its inhibitory effect on the growth of a wide variety microorganisms. This property might be interesting design novel antimicrobials, yet it has negative implications biotechnology, as hinders use Z. producer microorganism in cocultivation. So far, chemical nature compound(s) not been established. In present study, we demonstrate that putative inhibitor low-molecular-weight (below 3 kDa),...

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...

Relative to several model bacteria, the ethanologenic bacterium Zymomonas mobilis is shown here have an elevated resistance exogenous antimicrobial peptides (AMPs) – both, with regard peptide bulk concentration in medium, and numbers of molecules per cell. By monitoring integration AMPs bacterial cell membrane observing resulting effect on energy-coupling, it concluded that membranotropic effects tested Z. Escherichia coli are comparable. The advantage over E. apparently results from its...

Relative to several model bacteria, the ethanologenic bacterium Zymomonas mobilis is shown here have elevated resistance exogenous antimicrobial peptides (AMPs)— with regard both peptide bulk concentration in medium and numbers of molecules per cell. By monitoring integration AMPs bacterial cell membrane observing resulting effect on energy coupling, it concluded that membranotropic effects tested Z. Escherichia coli are comparable. The advantage over E. apparently results from its uncoupled...

Z. mobilis ATCC 29191 and its respiratory knockout mutants, kat-, ndh-, cytB-, cydB- , were grown under anaerobic aerobic conditions. FT‐IR spectroscopy was used to study the variations of cell macromolecular composition. Quantitative analysis showed that concentration ratios—nucleic acids lipids, for parent strain, strains, clearly distinguished strain from mutant derivatives corresponded fairly well expected degree biochemical similarity between strains. Two different FT‐IR‐spectra...