Methanogen

About: Methanogen is a research topic. Over the lifetime, 1146 publications have been published within this topic receiving 48254 citations.

Influence of dietary organic trace minerals on enteric methane emissions and rumen microbiota of heat-stressed dairy steers

Abstract: Abstract Ruminants are the main contributors to methane (CH4), a greenhouse gas emitted by livestock, which leads to global warming. In addition, animals experience heat stress (HS) when exposed to high ambient temperatures. Organic trace minerals are commonly used to prevent the adverse effects of HS in ruminants; however, little is known about the role of these minerals in reducing enteric methane emissions. Hence, this study aimed to investigate the influence of dietary organic trace minerals on rumen fermentation characteristics, enteric methane emissions, and the composition of rumen bacteria and methanogens in heat-stressed dairy steers. Holstein (n=3) and Jersey (n=3) steers were kept separately within a 3×3 Latin square design, and the animals were exposed to HS conditions (Temperature-Humidity Index [THI], 82.79 ± 1.10). For each experiment, the treatments included a Control (Con) consisting of only basal total mixed rations (TMR), National Research Council (NRC) recommended mineral supplementation group (NM; TMR + [Se 0.1 ppm + Zn 30 ppm + Cu 10 ppm]/kg dry matter), and higher concentration of mineral supplementation group (HM; basal TMR + [Se 3.5 ppm + Zn 350 ppm + Cu 28 ppm]/kg dry matter). Higher concentrations of trace mineral supplementation had no influence on methane emissions and rumen bacterial and methanogen communities regardless of breed (p > 0.05). Holstein steers had higher ruminal pH and lower total volatile fatty acid (VFA) concentrations than Jersey steers (p < 0.05). Methane production (g/d) and yield (g/kg dry matter intake) were higher in Jersey steers than in Holstein steers (p < 0.05). The relative abundances of Methanosarcina and Methanobrevibacter olleyae were significantly higher in Holstein steers than in Jersey steers (p < 0.05). Overall, dietary organic trace minerals have no influence on enteric methane emissions in heat-stressed dairy steers; however, breed can influence it through selective alteration of the rumen methanogen community.

Isolation of a methyl-reducing methanogen outside the Euryarchaeota

Abstract: Abstract Methanogenic archaea are main contributors to methane emissions, and thus play a crucial role in carbon cycling and global warming. Until recently, methanogens were confined to the phylum Euryarchaeota, but metagenomic studies revealed the presence of genes encoding the methyl coenzyme M reductase complex in other archaeal clades, thereby opening up the premise that methanogenesis is taxonomically more widespread. Nevertheless, laboratory cultivation of these non-Euryarchaeal methanogens was missing to allow the study of their physiology and to corroborate their potential methanogenic capability. Here we describe a thermophilic co-culture from an oil field, containing a single archaeon (strain LWZ-6) belonging to the proposed order Candidatus Verstraetearchaeia, together with a H2-producing Acetomicrobium sp. CY-2. Strain LWZ-6, for which we propose the name Verstraetearchaeum methanopetracarbonis, is a H2-dependent methylotrophic methanogen. Although previous metagenomic studies speculated on the fermentative potential of Verstraetearchaeial methanogens, strain LWZ-6 does not ferment sugars, peptides, and amino acids. Its energy metabolism is linked to methanogenesis, with methanol and monomethylamine as electron acceptors and H2 as electron donor. Comparative (meta)genome analysis revealed that H2-dependent methylotrophic methanogenesis is a shared trait among Verstraetearchaeia. Our findings corroborate that the diversity of methanogens expands beyond the classical Euryarchaeota and change our current conception of the global carbon cycle.

Methanogenic Diversity in an Anaerobic Digester with Chicken Feces

Abstract: Methanogenic diversity was characterized in an anaerobic digester with chicken feces by using a culture-independent approach 50 clones of a 16S rDNA gene library were randomly selected and their sequences were phylogenetically analyzed 46 of them (92%) was determined belonging to Methanogenium with similarities to Methanogenium marinum strain AK-1 between 99% to 100%; 3 clones (6%), KD525, KD526, and KD567, belonging to Methanoculleus with similarities 99% to Methanoculleus sp dm2; one clone (2%), KD519, belonging to Methanocorpusculum with a similarity 99% to Methanocorpusculum bavaricum Further more, the phylogenetic analyse of alpha subunit A of methyl-coenzyme M reductase (mcrA) clones were also performed Gas chromatography assay showed that the content of formic acid was 2885 g/L, 817% of the total volatile fatty acid of the fresh fermentation slurry; and the produced biogas from the digester was also determined, mainly composing of methane (555%), carbon dioxide (411%), and hydrogen (32%)