Project description: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.
Project description:The present study describes the complete and annotated genome sequence of Methanomassiliicoccus luminyensis strain B10 (DSM 24529(T), CSUR P135), which was isolated from human feces. The 2.6-Mb genome represents the largest genome of a methanogenic euryarchaeon isolated from humans. The genome data of M. luminyensis reveal unique features and horizontal gene transfer events, which might have occurred during its adaptation and/or evolution in the human ecosystem.
Project description:Across the tree of life, DNA in living cells is associated with proteins that coat chromosomes, constrain their structure and influence DNA-templated processes such as transcription and replication. In bacteria and eukaryotes, HU and histones, respectively, are the principal constituents of chromatin, with few exceptions. Archaea, in contrast, have more diverse repertoires of nucleoid-associated proteins (NAPs). The evolutionary and ecological drivers behind this diversity are poorly understood. Here, we combine a systematic phylogenomic survey of known and predicted NAPs with quantitative protein abundance data to shed light on the forces governing the evolution of archaeal chromatin. Our survey identifies the Diaforarchaea as a hotbed of NAP gain and loss and we validate novel candidate NAPs in two members of this clade, Thermoplasma volcanium and Methanomassiliicoccus luminyensis, using sucrose gradient-based nucleoid enrichment coupled to quantitative mass spectrometry. Comparative analysis across a panel of 19 archaea revealed that investment in NAP production varies over two orders of magnitude, from <0.03% to >5% of total protein. Integrating genomic and ecological data, we demonstrate that growth temperature is an excellent predictor of relative NAP investment across archaea. Our results suggest that high levels of chromatinization have evolved as a mechanism toprevent uncontrolled helix opening and runaway denaturation – rather than, for example, to globally orchestrate gene expression – with implications for the origin of chromatin in both archaea and eukaryotes.