Impact of iron reduction on the metabolism of <i>Clostridium acetobutylicum</i>

List, Cornelia; Hosseini, Zhaleh; Meibom, Karin L.; Hatzimanikatis, Vassily; Bernier‐Latmani, Rizlan

doi:10.1111/1462-2920.14640

Cited by 42 publications

(27 citation statements)

References 38 publications

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“…Several vitamins and ions are essential for solventogenesis and sporulation in Clostridium ( Jamroskovic et al, 2016 ; Nimbalkar et al, 2018 ; Li et al, 2018 ; List et al, 2019 ). These findings contributed to the modification of growth media to improve either the sporulation or the solvent formation.…”

Section: Resultsmentioning

confidence: 99%

Transcriptomic and Phenotypic Analysis of a spoIIE Mutant in Clostridium beijerinckii

et al. 2020

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SpoIIE is a phosphatase involved in the activation of the first sigma factor of the forespore, σ F , during sporulation. A spoIIE mutant of Clostridium beijerinckii NCIMB 8052, previously generated by CRISPR-Cas9, did not sporulate but still produced granulose and solvents. Microscopy analysis also showed that the cells of the spoIIE mutant are elongated with the presence of multiple septa. This observation suggests that in C. beijerinckii, SpoIIE is necessary for the completion of the sporulation process, as seen in Bacillus and Clostridium acetobutylicum. Moreover, when grown in reactors, the spoIIE mutant produced higher levels of solvents than the wild type strain. The impact of the spoIIE inactivation on gene transcription was assessed by comparative transcriptome analysis at three time points (4 h, 11 h and 23 h). Approximately 5% of the genes were differentially expressed in the mutant compared to the wild type strain at all time points. Out of those only 12% were known sporulation genes. As expected, the genes belonging to the regulon of the sporulation specific transcription factors (σ F , σ E , σ G , σ K) were strongly down-regulated in the mutant. Inactivation of spoIIE also caused differential expression of genes involved in various cell processes at each time point. Moreover, at 23 h, genes involved in butanol formation and tolerance, as well as in cell motility, were up-regulated in the mutant. In contrast, several genes involved in cell wall composition, oxidative stress and amino acid transport were down-regulated. These results indicate an intricate interdependence of sporulation and stationary phase cellular events in C. beijerinckii.

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Section: Resultsmentioning

confidence: 99%

Transcriptomic and Phenotypic Analysis of a spoIIE Mutant in Clostridium beijerinckii

et al. 2020

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“…FIGURE 3 | Example of reduction of resazurin (alamarBlue) into resorufin. (List et al, 2019), maybe through other processes. Furthermore, we can safely assume that resazurin is not likely to be reduced by anaerobes (or during anaerobic respiration, such as sulfate or nitrate reduction), as it is used in media as an oxygen redox indicator.…”

Section: Resazurin (Alamarblue Tm )mentioning

confidence: 99%

A Review of Methods to Determine Viability, Vitality, and Metabolic Rates in Microbiology

et al. 2020

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Viability and metabolic assays are commonly used as proxies to assess the overall metabolism of microorganisms. The variety of these assays combined with little information provided by some assay kits or online protocols often leads to mistakes or poor interpretation of the results. In addition, the use of some of these assays is restricted to simple systems (mostly pure cultures), and care must be taken in their application to environmental samples. In this review, the necessary data are compiled to understand the reactions or measurements performed in many of the assays commonly used in various aspects of microbiology. Also, their relationships to each other, as metabolism links many of these assays, resulting in correlations between measured values and parameters, are discussed. Finally, the limitations of these assays are discussed.

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“…Previous studies indicated that fermentative bacteria perform Fe(III) reduction by discarding excess reducing equivalents as a form of enhanced fermentation ( Lovley et al, 2004 ; Dalla Vecchia et al, 2014 ). In addition, List et al (2019) suggested that Fe(III) reduction can function as buffer reaction against pH changes in the growth environment, resulting in acidogenesis by fermentation to persist for longer. However, our results showed that the presence of Fe(III) does not critically affect acetogenesis and growth, indicating that the Fe(III) reduction observed in this study is a side reaction for electron transfer not directly linked to energy conservation, as reported in previous studies ( Shah, 2013 ; Dalla Vecchia et al, 2014 ).…”

Section: Discussionmentioning

confidence: 99%

Reductive Transformation of Fe(III) (oxyhydr)Oxides by Mesophilic Homoacetogens in the Genus Sporomusa

Igarashi

Kato

2021

Front. Microbiol.

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Microbial reduction of iron contributes to the dissolution and transformation of iron-containing minerals in nature. Diverse groups of homoacetogenic bacteria (homoacetogens) have been reported to reduce insoluble Fe(III) oxides, such as hydrous ferric oxide (HFO), an Fe(III) mineral commonly found in soils and sediments. Several members of genus Sporomusa reportedly oxidize Fe(0), indicating the presence of an extracellular electron-uptake mechanism. However, the ability of the genus to reduce insoluble Fe(III) oxides is limited, and the underlying reduction mechanism remains to be elucidated. In this study, the HFO reduction ability of three Sporomusa spp. (Sporomusa sp. strain GT1, Sporomusa sphaeroides, and Sporomusa ovata) and a homoacetogen of a different genus (Acetobacterium woodii) were assayed under organotrophic (ethanol) and lithotrophic (H2 + CO2) conditions without a chelator or reducing reagent. All tested homoacetogens showed acetogenic growth and concomitant reduction of HFO under both organotrophic and lithotrophic conditions. Analysis of the growth stoichiometry showed that Fe(III) reduction does not support direct energy conservation, thereby indicating that Fe(III) reduction is a side reaction of acetogenesis to dissipate the excess reducing power. HFO was reduced to a soluble Fe(II) form by microbial activity. In addition, we observed that strain GT1, S. sphaeroides, and S. ovata reduced crystalline Fe(III) oxides, and HFO was reductively transformed into magnetite (Fe3O4) under phosphate-limiting conditions. Separation of HFO by a dialysis membrane still permitted Fe(II) production, although the reduction rate was decreased, suggesting that Fe(III) reduction is at least partially mediated by soluble redox compound(s) secreted from the cells. Finally, culture experiments and comparative genomic analysis suggested that electron transfer by flavins and multiheme c-type cytochrome were not directly correlated with Fe(III) reduction activity. This study reveals the capability of Sporomusa spp. in the reductive transformation of iron mineral and indicates the potential involvement of these organisms in iron and other mineral cycles in nature.

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Impact of iron reduction on the metabolism of Clostridium acetobutylicum

Cited by 42 publications

References 38 publications

Transcriptomic and Phenotypic Analysis of a spoIIE Mutant in Clostridium beijerinckii

Transcriptomic and Phenotypic Analysis of a spoIIE Mutant in Clostridium beijerinckii

A Review of Methods to Determine Viability, Vitality, and Metabolic Rates in Microbiology

Reductive Transformation of Fe(III) (oxyhydr)Oxides by Mesophilic Homoacetogens in the Genus Sporomusa

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