Methanol utilizing Desulfotomaculum species utilizes hydrogen in a methanol-fed sulfate-reducing bioreactor

Abstract

A sulfate-reducing bacterium, strain WW1, was isolated from a thermophilic bioreactor operated at 65°C with methanol as sole energy source in the presence of sulfate. Growth of strain WW1 on methanol or acetate was inhibited at a sulfide concentration of 200 mg l −1 , while on H 2 /CO 2 , no apparent inhibition occurred up to a concentration of 500 mg l −1 . When strain WW1 was co-cultured under the same conditions with the methanol-utilizing, non-sulfatereducing bacteria, Thermotoga lettingae and Moorella mulderi, both originating from the same bioreactor, growth and sulfide formation were observed up to 430 mg l −1 . These results indicated that in the co-cultures, a major part of the electron flow was directed from methanol via H 2 /CO 2 to the reduction of sulfate to sulfide. Besides methanol, acetate, and hydrogen, strain WW1 was also able to use formate, malate, fumarate, propionate, succinate, butyrate, ethanol, propanol, butanol, isobutanol, with concomitant reduction of sulfate to sulfide. In the absence of sulfate, strain WW1 grew only on pyruvate and lactate. On the basis of 16S rRNA analysis, strain WW1 was most closely related to Desulfotomaculum thermocisternum and Desulfotomaculum australicum. However, physiological properties of strain WW1 differed in some aspects from those of the two related bacteria.

Syntrophy in anaerobic global carbon cycles

“…The dominant sugar users in a lake sediment were not the typical fermentative anaerobes, but syntrophic metabolizers that could only be grown anaerobically and in co-culture with a hydrogen-using methanogen [13]. Microorganisms that grow by syntrophic formate or methanol oxidation have also been obtained [14,15]. Members of the Desulfotomaculum cluster Ih are present in diverse methanogenic ecosystems including sediments, digestor sludges, and rice paddy soils [16–18].…”

Physiology, Ecology, Phylogeny, and Genomics of Microorganisms Capable of Syntrophic Metabolism

“…Syntrophic methanol‐degrading enrichments were obtained from thermophilic digestors using cobalt‐deficient medium to suppress methanogenesis 99 . Moorella mulderi and a Desulfotomaculum species were isolated from the enrichment 100,101 . Although the sulfate reducer used methanol in pure culture, it appeared to use the hydrogen produced by M. mulderi when grown in coculture.…”

“…99 Moorella mulderi and a Desulfotomaculum species were iso-lated from the enrichment. 100,101 Although the sulfate reducer used methanol in pure culture, it appeared to use the hydrogen produced by M. mulderi when grown in coculture. A syntrophic methanol-degrading coculture of a Moorella species with a H 2 -utilizing Methanothermobacter strain was obtained when sulfate was deleted from the cobalt-deficient medium.…”

The deep-subsurface sulfate reducer Desulfotomaculum kuznetsovii employs two methanol-degrading pathways

“…It is not clear whether SRB use a MT system or a MDH. Several SRB utilize methanol for growth, such as Desulfosporosinus orientis 24 , Desulfobacterium catecholicum 25 , Desulfobacterium anilini 26 , Desulfovibrio carbinolicus 27 , Desulfovibrio alcoholivorans 28 , and nine Desulfotomaculum strains 10 , 29 – 33 including D. kuznetsovii . The latter species is a methylotrophic thermophilic sulfate-reducing bacterium that was isolated from a geothermal water reservoir at a depth of about 3000 m 10 .…”