Fumarate reduction in Proteus mirabilis.

E G Van der Beek; L F Oltmann; A H Stouthamer

doi:10.1007/bf00690228

Home/Archive/PubMed

PubMed · 189721

Fumarate reduction in Proteus mirabilis.

E G Van der Beek·L F Oltmann·A H Stouthamer

View original source ↗Export metadata ↓

Abstract

1. Proteus mirabilis formed fumarate reductase under anaerobic growth conditions. The formation of this reductase was repressed under conditions of growth during which electron transport to oxygen or to nitrate is possible. In two of three tested chlorate-resistant mutant strains of the wild type, fumarate reductase appeared to be affected. 2. Cytoplasmic membrane suspensions isolated from anaerobically grown P. mirabilis oxidized formate and NADH with oxygen and with fumarate, too. 3. Spectral investigation of the cytoplasmic membrane preparation revealed the presence of (probably at least two types of) cytochrome b, cytochrome a1 and cytochrome d. Cytochrome b was reduced by NADH as well as by formate to approximately 80%. 4. 2-n-Heptyl-4-hydroxyquinilone-N-oxide and antimycin A inhibited oxidation of both formate and NADH by oxygen and fumarate. Both inhibitors increased the level of the formate/oxygen steady state and the formate/fumarate steady state. 5. The site of inhibition of the respiratory activity by both HQNO and antimycin A was located at the oxidation side of cytochrome b. 6. The effect of ultraviolet-irradiation of cytoplasmic membrane suspensions on oxidation/reduction phenomena suggested that the role of menaquinone is more exclusive in the formate/fumarate pathway than in the electron transport route to oxygen. 7. Finally, the conclusion has been drawn that the preferential route for electron transport from formate and from NADH to fumarate (and to oxygen) includes cytochrome b as a directly involved carrier. A hypothetical scheme for the electron transport in anaerobically grown P. mirabilis is presented.

Explore related subjects

Anaerobiosis Antimycin A Cyclic N-Oxides Cytochromes Electron Transport Formates Fumarates Hydroxyquinolines NAD Oxidoreductases Proteus mirabilis Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

E G Van der Beek, L F Oltmann, A H Stouthamer. 1976-11-02. Fumarate reduction in Proteus mirabilis.. https://doi.org/10.1007/bf00690228

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2026

Host-virus dynamics in anaerobic digesters facing abiotic inhibition.

Viruses play a major role in controlling the structure and dynamics of microbial communities in anaerobic digesters, ecosystems sensitive to disturbances that inhibit methane production. Here, we studied the interplay between abiotic disturbances, microbiome and virome composition, and process performance, to assess whether provirus induction can be triggered by abiotic stresses known to inhibit anaerobic digestion (ammonium, phenol and sodium chloride). We monitored viral dynamics in batch mesophilic anaerobic digesters fed with biowaste through shotgun metavirome sequencing. The diversity of both prokaryotes and viruses was high, with Clostridiales dominating the prokaryotic community and Caudoviricetes dominating the viromes. We identified 132 viral contigs and 19 host genera that were differentially abundant under disturbed conditions. No significant impact of the tested abiotic stresses on provirus induction was observed under the current experimental and analytical framework. The results were consistent with viruses exerting steady, background-level predation through a putative combination of kill-the-winner dynamics at the sub-genus level and piggyback-the-winner dynamics, rather than stress-triggered, synchronous lytic bursts. A few auxiliary metabolic genes were detected, potentially targeting carbon, sulfur and cofactor metabolism in anaerobic digestion. Temperate viruses were dominant, representing up to 71% of the viral genomes confirmed as complete across all conditions. Electron microscopy analysis revealed diverse virus-like particles, including head-tailed particles typical of Caudoviricetes, but also spherical, rod-shaped and spindle-shaped particles typical of archaeal viruses. Notably, we present a new virus family, Eurekaviridae, of spindle-shaped viruses associated with methanogenic archaea.

Anaerobiosis↗

PubMed2026

Strict Aerobic Lifestyle and Anaerobic Survival of Bacteria: Inseparable Twins?

For many decades the existence of strict aerobic bacteria was part of every textbook. However, considering habitats like soils or surfaces, many of these microorganisms are exposed to drastic changes in oxygen tension. A simple rain shower can change oxygen diffusion rates by a factor of 10.000. Thus, for many of the so-called strict aerobic bacteria, anaerobic growth and survival strategies were discovered, mainly relying on the use of alternative electron acceptors to oxygen, redox-active metabolites, or fermentation processes generating ATP at the substrate level. Survival without growth was recognized as an important lifestyle of bacteria. With the increasing availability of genome data, many highly diverse growth and survival strategies have become apparent in bacteria. But the overall picture is far from complete. Only recently, a novel puzzle piece of the anaerobic survival strategy of the opportunistic pathogen and model bacterium Pseudomonas aeruginosa in the absence of alternative electron acceptors was elucidated. It relies on the re-wiring of carbon flux away from the Entner-Doudoroff pathway towards the pentose-phosphate pathway and use of a phosphoketolase to allow for metabolic flux while preventing nonproductive NADH formation under these fermentation conditions and for ATP generation via acetate kinase.

Anaerobiosis↗

PubMed2025

Anaerobic breviate protist survival in microcosms depends on microbiome metabolic function.

Anoxic and hypoxic environments serve as habitats for diverse microorganisms, including unicellular eukaryotes (protists) and prokaryotes. To thrive in low-oxygen environments, protists and prokaryotes often establish specialized metabolic cross-feeding associations, such as syntrophy, with other microorganisms. Previous studies show that the breviate protist Lenisia limosa engages in a mutualistic association with a denitrifying Arcobacter bacterium based on hydrogen exchange. Here, we investigate if the ability to form metabolic interactions is conserved in other breviates by studying five diverse breviate microcosms and their associated bacteria. We show that five laboratory microcosms of marine breviates live with multiple hydrogen-consuming prokaryotes that are predicted to have different preferences for terminal electron acceptors using genome-resolved metagenomics. Protist growth rates vary in response to electron acceptors depending on the make-up of the prokaryotic community. We find that the metabolic capabilities of the bacteria and not their taxonomic affiliations determine protist growth and survival and present new potential protist-interacting bacteria from the Arcobacteraceae, Desulfovibrionaceae, and Terasakiella lineages. This investigation uncovers potential nitrogen and sulfur cycling pathways within these bacterial populations, hinting at their roles in syntrophic interactions with the protists via hydrogen exchange.

Anaerobiosis↗