Carbon Monoxide as an Electron Donor for the Biological Reduction of Sulphate

Several strains of Gram-negative and Gram-positive sulphate-reducing bacteria (SRB) are able to use carbon monoxide (CO) as a carbon source and electron donor for biological sulphate reduction. These strains exhibit variable resistance to CO toxicity. The most resistant SRB can grow and use CO as an electron donor at concentrations up to 100%, whereas others are already severely inhibited at CO concentrations as low as 1-2%. Here, the utilization, inhibition characteristics, and enzymology of CO metabolism as well as the current state of genomics of CO-oxidizing SRB are reviewed. Carboxydotrophic sulphate-reducing bacteria can be applied for biological sulphate reduction with synthesis gas (a mixture of hydrogen and carbon monoxide) as an electron donor

Enrichment of anaerobic syngas-converting communities and isolation of a novel carboxydotrophic Acetobacterium wieringae strain jm

The datasets generated for this study can be found in the 16S rRNA gene sequences submitted to the European Nucleotide Database (ENA) accession numbers LR655884, LR657299 to LR657303, PRJEB33623. The Whole Genome Shotgun project of Acetobacterium wieringae strain JM has been deposited at DDBJ/ENA/GenBank under the accession VSLA00000000.Syngas is a substrate for the anaerobic bioproduction of fuels and valuable chemicals. In this study, anaerobic sludge was used for microbial enrichments with synthetic syngas and acetate as main substrates. The objectives of this study were to identify microbial networks (in enrichment cultures) for the conversion of syngas to added-value products, and to isolate robust, non-fastidious carboxydotrophs. Enrichment cultures produced methane and propionate, this last one an unusual product from syngas fermentation. A bacterium closely related to Acetobacterium wieringae was identified as most prevalent (87% relative abundance) in the enrichments. Methanospirillum sp. and propionate-producing bacteria clustering within the genera Anaerotignum and Pelobacter were also found. Further on, strain JM, was isolated and was found to be 99% identical (16S rRNA gene) to A. wieringae DSM 1911T. Digital DNA-DNA hybridization (dDDH) value between the genomes of strain JM and A. wieringae was 77.1%, indicating that strain JM is a new strain of A. wieringae. Strain JM can grow on carbon monoxide (100% CO, total pressure 170 kPa) without yeast extract or formate, producing mainly acetate. Remarkably, conversion of CO by strain JM showed shorter lag phase than in cultures of A. wieringae DSM 1911T, and about four times higher amount of CO was consumed in 7 days. Genome analysis suggests that strain JM uses the Wood-Ljungdahl pathway for the conversion of one carbon compounds (CO, formate, CO2/H2). Genes encoding bifurcational enzyme complexes with similarity to the bifurcational formate dehydrogenase (Fdh) of Clostridium autoethanogenum are present, and possibly relate to the higher tolerance to CO of strain JM compared to other Acetobacterium species. A. wieringae DSM 1911T grew on CO in medium containing 1 mM formate.The involved research was financially supported by Project NWO-GK-07 from the Netherlands Science Foundation (NWO), a Gravitation Grant (Project 024.002.002) of the Netherlands Ministry of Education, Culture and Science, and by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020–Programa Operacional Regional do Norte. The financial support from FCT and European Social Fund (POPH-QREN) through the grant PD/BD/128030/2016 given to AA, and through the project INNOVsyn – Innovative strategies for syngas fermentation (POCI-01-0145-FEDER-031377), are gratefully acknowledged.info:eu-repo/semantics/publishedVersio

Genome analyses of the carboxydotrophic sulfate-reducers Desulfotomaculum nigrificans and Desulfotomaculum carboxydivorans and reclassification of Desulfotomaculum caboxydivorans as a later synonym of Desulfotomaculum nigrificans

Desulfotomaculum nigrificans and D. carboxydivorans are moderately thermophilic members of the polyphyletic spore-forming genus Desulfotomaculum in the family Peptococcaceae. They are phylogenetically very closely related and belong to 'subgroup a' of the Desulfotomaculum cluster 1. D. nigrificans and D. carboxydivorans have a similar growth substrate spectrum; they can grow with glucose and fructose as electron donors in the presence of sulfate. Additionally, both species are able to ferment fructose, although fermentation of glucose is only reported for D. carboxydivorans. D. nigrificans is able to grow with 20% carbon monoxide (CO) coupled to sulfate reduction, while D. carboxydivorans can grow at 100% CO with and without sulfate. Hydrogen is produced during growth with CO by D. carboxydivorans. Here we present a summary of the features of D. nigrificans and D. carboxydivorans together with the description of the complete genome sequencing and annotation of both strains. Moreover, we compared the genomes of both strains to reveal their differences. This comparison led us to propose a reclassification of D. carboxydivorans as a later heterotypic synonym of D. nigrificans.We would like to gratefully acknowledge the help of Christine Munk and Megan Lu for finishing the genome sequence (both at JGI). The work conducted by the U.S. Department of Energy Joint Genome Institute is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, and was also supported by grants CW-TOP 700.55.343 and ALW 819.02.014 of the Netherlands Science Foundation (NWO) and grant 323009 of the European Research Council

Genome assembly of a novel psychrotolerance bacterium, Trichococcus ART1 .

A psychrotolerant anaerobe, strain ART1T, was isolated from a psychrophilic anaerobic digester treating . 16S rRNA gene sequence of strain ART1T was highly similar to those of other Trichococcus species (> 99%), but digital DNA-DNA hybridization (dDDH) values were lower than 70% indicating that strain ART1 is a new species of the genus Trichococcus. Cells of strain ART1T were immotile cocci and stained Gram-positive. Growth was optimal at pH 7.5 and cells could grow in a temperature range of 0 to 37°C (optimum 30°C). Strain ART1T could degrade several carbohydrates, and the main products from glucose fermentation are lactate, acetate, formate, and ethanol.

Genome assembly of a novel psychrotolerance bacterium, Trichococcus ART1 .

A psychrotolerant anaerobe, strain ART1T, was isolated from a psychrophilic anaerobic digester treating . 16S rRNA gene sequence of strain ART1T was highly similar to those of other Trichococcus species (> 99%), but digital DNA-DNA hybridization (dDDH) values were lower than 70% indicating that strain ART1 is a new species of the genus Trichococcus. Cells of strain ART1T were immotile cocci and stained Gram-positive. Growth was optimal at pH 7.5 and cells could grow in a temperature range of 0 to 37°C (optimum 30°C). Strain ART1T could degrade several carbohydrates, and the main products from glucose fermentation are lactate, acetate, formate, and ethanol.

Genome assembly of a novel psychrotolerance bacterium, Trichococcus ART1 .

A psychrotolerant anaerobe, strain ART1T, was isolated from a psychrophilic anaerobic digester treating . 16S rRNA gene sequence of strain ART1T was highly similar to those of other Trichococcus species (> 99%), but digital DNA-DNA hybridization (dDDH) values were lower than 70% indicating that strain ART1 is a new species of the genus Trichococcus. Cells of strain ART1T were immotile cocci and stained Gram-positive. Growth was optimal at pH 7.5 and cells could grow in a temperature range of 0 to 37°C (optimum 30°C). Strain ART1T could degrade several carbohydrates, and the main products from glucose fermentation are lactate, acetate, formate, and ethanol.

H2 enrichment from synthesis gas by Desulfotomaculum carboxydivorans for potential applications in synthesis gas purification and biodesulfurization

9 páginas, 5 figuras, 1 tabla.Desulfotomaculum carboxydivorans, recently isolated from a full-scale anaerobic wastewater treatment facility, is a sulfate reducer capable of hydrogenogenic growth on carbon monoxide (CO). In the presence of sulfate, the hydrogen formed is used for sulfate reduction. The organism grows rapidly at 200 kPa CO, pH 7.0, and 55°C, with a generation time of 100 min, producing nearly equimolar amounts of H2 and CO2 from CO and H2O. The high specific CO conversion rates, exceeding 0.8 mol CO (g protein)−1 h−1, makes this bacterium an interesting candidate for a biological alternative of the currently employed chemical catalytic water–gas shift reaction to purify synthesis gas (contains mainly H2, CO, and CO2). Furthermore, as D. carboxydivorans is capable of hydrogenotrophic sulfate reduction at partial CO pressures exceeding 100 kPa, it is also a good candidate for biodesulfurization processes using synthesis gas as electron donor at elevated temperatures, e.g., in biological flue gas desulfurization. Although high maximal specific sulfate reduction rates (32 mmol (g protein)−1 h−1) can be obtained, its sulfide tolerance is rather low and pH dependent, i.e., maximally 9 and 5 mM sulfide at pH 7.2 and pH 6.5, respectively.This research was financially supported by a grant from the Technology Foundation STW (grant STW-WBC 5280), applied science division of NWO, the Netherlands, and Shell Global Solutions (Amsterdam, the Netherlands) and Paques B.V. (Balk, the Netherlands).Peer reviewe