Desulfotomaculum carboxydivorans sp.nov., a novel sulfate-reducing bacterium capable of growth at 100% CO

A moderately thermophilic, anaerobic, chemolithoheterotrophic, sulfate-reducing bacterium, strain CO-1-SRBT, was isolated from sludge from an anaerobic bioreactor treating paper mill wastewater. Cells were Gram-positive, motile, spore-forming rods. The temperature range for growth was 30¿68 °C, with an optimum at 55 °C. The NaCl concentration range for growth was 0¿17 g l¿1; there was no change in growth rate until the NaCl concentration reached 8 g l¿1. The pH range for growth was 6·0¿8·0, with an optimum of 6·8¿7·2. The bacterium could grow with 100 % CO in the gas phase. With sulfate, CO was converted to H2 and CO2 and part of the H2 was used for sulfate reduction; without sulfate, CO was completely converted to H2 and CO2. With sulfate, strain CO-1-SRBT utilized H2/CO2, pyruvate, glucose, fructose, maltose, lactate, serine, alanine, ethanol and glycerol. The strain fermented pyruvate, lactate, glucose and fructose. Yeast extract was necessary for growth. Sulfate, thiosulfate and sulfite were used as electron acceptors, whereas elemental sulfur and nitrate were not. A phylogenetic analysis of 16S rRNA gene sequences placed strain CO-1-SRBT in the genus Desulfotomaculum, closely resembling Desulfotomaculum nigrificans DSM 574T and Desulfotomaculum sp. RHT-3 (99 and 100 % similarity, respectively). However, the latter strains were completely inhibited above 20 and 50 % CO in the gas phase, respectively, and were unable to ferment CO, lactate or glucose in the absence of sulfate. DNA¿DNA hybridization of strain CO-1-SRBT with D. nigrificans and Desulfotomaculum sp. RHT-3 showed 53 and 60 % relatedness, respectively. On the basis of phylogenetic and physiological features, it is suggested that strain CO-1-SRBT represents a novel species within the genus Desulfotomaculum, for which the name Desulfotomaculum carboxydivorans is proposed. This is the first description of a sulfate-reducing micro-organism that is capable of growth under an atmosphere of pure CO with and without sulfate. The type strain is CO-1-SRBT (=DSM 14880T=VKM B-2319T)

Bibliographic Details

Main Authors:	Parshina, S.N., Sipma, J., Nakashimada, Y., Henstra, A.M., Smidt, H., Lysenko, A.M., Lens, P.N.L., Lettinga, G., Stams, A.J.M.
Format:	Article/Letter to editor biblioteca
Language:	English
Subjects:	acetoxidans, acid, anaerobic bioreactor sludges, carbon-monoxide conversion, carboxydothermus-hydrogenoformans, dna, gen. nov., metabolism, performance liquid-chromatography,
Online Access:	https://research.wur.nl/en/publications/desulfotomaculum-carboxydivorans-spnov-a-novel-sulfate-reducing-b
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