When anaerobes encounter oxygen: mechanisms of oxygen toxicity, tolerance and defence

Lu, Zheng; Imlay, James A.

doi:10.1038/s41579-021-00583-y

Cited by 112 publications

(77 citation statements)

References 138 publications

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“…Even though fermentation and growth of C. acetobutylicum is immediately halted by the presence of oxygen (32), literature shows that C. acetobutylicum (50) and other strict anaerobes adapt to oxygen exposure by using defense mechanisms to minimize oxygen stress (2, 51). Our experiments (Table S1) for instance revealed that ca.…”

Section: Discussionmentioning

confidence: 99%

“…Anoxic and hypoxic microsites foster the presence and activity of even obligate anaerobes in oxic environments (1)(2)(3)(4) such as upland soils. As oxygen limitations typically arise if microbial oxygen consumption exceeds diffusive oxygen supply (1,5), hypoxic microsites often coincide with hotspots of microbial activity such as the rhizosphere (6), the detritusphere (7), or biocrusts (8).…”

Section: Introductionmentioning

confidence: 99%

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Impact of fungal hyphae on growth and dispersal of obligate anaerobic bacteria in aerated habitats

Xiong

Kleinsteuber

Sträuber

et al. 2022

Preprint

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Anoxic microsites arising in fungal biofilms may foster the presence of obligate anaerobes even in well-areated environments. Here, we analyzed whether and to which degree fractal hyphae of Coprinopsis cinerea thriving in oxic habitats enable the germination, growth, and dispersal of obligate anaerobic soil bacterium Clostridium acetobutylicum. Time-resolved optical oxygen mapping, microscopy and metabolite analysis revealed the formation and persistence of anoxic circum hyphal niches allowing for spore germination, growth and fermentative activity of the obligate anaerobe in an otherwise oxic environment. Hypoxic liquid films containing 80 ± 10% of atmospheric oxygen saturation around single air-exposed hyphae thereby allowed for efficient clostridial dispersal amid spatially separated (>0.5 cm) anoxic sites. Our results suggest that fungal biomass typical in soil (<550 μg g-1soil) may create anoxic microniches and enable activity as well as dispersal of obligate anaerobes near hyphae in an otherwise inhabitable environment.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of fungal hyphae on growth and dispersal of obligate anaerobic bacteria in aerated habitats

Xiong

Kleinsteuber

Sträuber

et al. 2022

Preprint

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“…The human colon contains a versatile and complex microbial flora, and the majority of these organisms proliferate only under anaerobic conditions (Sender et al 2016;Lu and Imlay 2021). Species of the genera Bacteroides and Phocaeicola are ubiquitous commensals, comprising about thirty percent of the human gut microbiota (Salyers 1984).…”

Section: Introductionmentioning

confidence: 99%

Genetic tools for the redirection of the central carbon flow towards the production of lactate in the human gut bacterium Phocaeicola (Bacteroides) vulgatus

Lück

Deppenmeier

2022

Appl Microbiol Biotechnol

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Species of the genera Bacteroides and Phocaeicola play an important role in the human colon. The organisms contribute to the degradation of complex heteropolysaccharides to small chain fatty acids, which are in part utilized by the human body. Furthermore, these organisms are involved in the synthesis of vitamins and other bioactive compounds. Of special interest is Phocaeicola vulgatus, originally classified as a Bacteroides species, due to its abundance in the human intestinal tract and its ability to degrade many plant-derived heteropolysaccharides. We analyzed different tools for the genetic modification of this microorganism, with respect to homologous gene expression of the ldh gene encoding a D-lactate dehydrogenase (LDH). Therefore, the ldh gene was cloned into the integration vector pMM656 and the shuttle vector pG106 for homologous gene expression in P. vulgatus. We determined the ldh copy number, transcript abundance, and the enzyme activity of the wild type and the mutants. The strain containing the shuttle vector showed an approx. 1500-fold increase in the ldh transcript concentration and an enhanced LDH activity that was about 200-fold higher compared to the parental strain. Overall, the proportion of lactate in the general catabolic carbon flow increased from 2.9% (wild type) to 28.5% in the LDH-overproducing mutant. This approach is a proof of concept, verifying the genetic accessibility of P. vulgatus and could form the basis for targeted genetic optimization. Key points • A lactate dehydrogenase was overexpressed in Phocaeicola (Bacteroides) vulgatus. • The ldh transcript abundance and the LDH activity increased sharply in the mutant. • The proportion of lactate in the catabolic carbon flow increased to about 30%.

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“…The terminal oxidase cytochrome bd (EC 7.1.1.7) is so far found only in the electron transport chains (also known as the respiratory chains) of bacteria and archaea [ 1 ]. Notably, even some microorganisms considered to be strict anaerobes possess the active bd oxidase to respire, which enhances their growth [ 2 , 3 ]. Cytochrome bd reduces molecular oxygen to water at the expense of the concomitant oxidation of species-specific quinols such as ubiquinol, menaquinol, and possibly plastoquinol [ 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Structural Studies of Cytochrome bd and Its Potential Application as a Drug Target

Friedrich

Wohlwend

Borisov

2022

IJMS

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Cytochrome bd is a triheme copper-free terminal oxidase in membrane respiratory chains of prokaryotes. This unique molecular machine couples electron transfer from quinol to O2 with the generation of a proton motive force without proton pumping. Apart from energy conservation, the bd enzyme plays an additional key role in the microbial cell, being involved in the response to different environmental stressors. Cytochrome bd promotes virulence in a number of pathogenic species that makes it a suitable molecular drug target candidate. This review focuses on recent advances in understanding the structure of cytochrome bd and the development of its selective inhibitors.

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When anaerobes encounter oxygen: mechanisms of oxygen toxicity, tolerance and defence

Cited by 112 publications

References 138 publications

Impact of fungal hyphae on growth and dispersal of obligate anaerobic bacteria in aerated habitats

Impact of fungal hyphae on growth and dispersal of obligate anaerobic bacteria in aerated habitats

Genetic tools for the redirection of the central carbon flow towards the production of lactate in the human gut bacterium Phocaeicola (Bacteroides) vulgatus

Recent Advances in Structural Studies of Cytochrome bd and Its Potential Application as a Drug Target

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