Growth Characteristics ofMethanomassiliicoccus luminyensisand Expression of Methyltransferase Encoding Genes

Abstract

DNA sequence analysis of the human gut revealed the presence a seventh order of methanogens referred to as Methanomassiliicoccales. Methanomassiliicoccus luminyensis is the only member of this order that grows in pure culture. Here, we show that the organism has a doubling time of 1.8 d with methanol + H2 and a growth yield of 2.4 g dry weight/mol CH4. M. luminyensis also uses methylamines + H2 (monomethylamine, dimethylamine, and trimethylamine) with doubling times of 2.1–2.3 d. Similar cell yields were obtained with equimolar concentrations of methanol and methylamines with respect to their methyl group contents. The transcript levels of genes encoding proteins involved in substrate utilization indicated increased amounts of mRNA from the mtaBC2 gene cluster in methanol-grown cells. When methylamines were used as substrates, mRNA of the mtb/mtt operon and of the mtmBC1 cluster were found in high abundance. The transcript level of mtaC2 was almost identical in methanol- and methylamine-grown cells, indicating that genes for methanol utilization were constitutively expressed in high amounts. The same observation was made with resting cells where methanol always yielded the highest CH4 production rate independently from the growth substrate. Hence, M. luminyensis is adapted to habitats that provide methanol + H2 as substrates.

The hydrogen threshold of obligately methyl-reducing methanogens

“…The exact ATP gains achieved by these different modes of energy conservation are not known, but the growth yields on hydrogen and methanol (dry weight; Equation 2 ) reported for Methanosphaera stadtmanae (∼4 g per mol methane; Miller and Wolin 1985 ) and Methanimicrococcus blatticola (3.5–6.0 g per mol methane) are in the same range as that of Methanosarcina barkeri (4.6 g per mol methane in methyl-reducing and 6.5 g per mol methane in methyl-fermenting cultures; Müller, Blaut and Gottschalk 1986 ). Growth yields for Methanomassiliicoccus luminyensis are much lower (2.4 g per mol methane; Kröninger, Gottschling and Deppenmeier 2017 ). This agrees with the metabolic model that was previously proposed for Methanomassiliicoccales , which predicts the translocation of 3–4 protons per two molecules of methane (Lang et al .…”

Viral and metabolic controls on high rates of microbial sulfur and carbon cycling in wetland ecosystems

“…Mirroring the sulfate-reducing populations, the diversity of detected methanogens suggests that a wide range of substrates—including acetate, hydrogen and formate, C1 compounds, and primary and secondary alcohols—could potentially be utilized for methanogenesis. While Arc I group archaea have been hypothesized to produce methane from methylated thiol groups [ 71 ], Methanosarcina species can utilize H 2 /CO 2 , acetate, dimethylsulfide, methanol, monomethylamine, dimethylamine, and trimethylamine [ 72 , 73 ], and Methanomassiliicoccus luminyensis is able to grow on methanol, mono-, di-, or trimethylamine with hydrogen [ 74 ]. Moreover, Methanofollis ethanolicus can utilize ethanol/CO 2 , 1-propanol/CO 2 , 1-butanol/CO 2 , H 2 /CO 2 , and formate for growth and methane production, converting ethanol to methane and acetate [ 75 ], while Methanofollis liminatans can utilize formate, H 2 /CO 2 , 2-propanol/CO 2 , 2-butanol/CO 2 , and cyclopentanol/CO 2 , converting these secondary and cyclic alcohols to their respective ketones [ 76 ].…”

Aquatic and terrestrial cyanobacteria produce methane

“…Estimated global CH4 production rates divided into various cyanobacterial habitats showing the potential contribution of cyanobacteria in global CH4 cycling. References (66)(67)(68)(69)(70)(71) View/request a protocol for this paper from Bio-protocol.…”