Methanogen

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

Effects of FACE on Population and Activities of Methanogen and Methanotroph in Paddy Soil

Abstract: A free-air CO2 enrichment (FACE) experiment was conducted during rice-growing season in 2005 in paddy fields at Jiangdu of Jiangsu province with two different N fertilization levels (Usual N - UN and Low N - LN) and two levels of rice-straw-returning-back-to-field (HR, NR) to evaluate population changes of methanogens and methanotrophs by the most-probable-number (MPN) method as well as methane production and oxidizing potential by gas chromatography. Results showed that elevated atmospheric CO2 concentrations increased methanogens population at tillering stage, but restrained methanogens activity at heading and harvest stages under HR condition. Rising atmospheric CO2 concentrations increased methanotrophs activity under LN condition, and methanotrophs population in FACE condition was significantly higher than that of Ambient in heading stage. But methanotrophs activities under UN and HR conditions were restrained except at heading stage. Methane production potential showed that FACE promoted methane release, especially under UN condition. High methane oxidizing activity was found under UN condition with enough exterior-CH4 and rising atmospheric CO2 concentrations.

Methanogen Levels Are Significantly Associated with Fecal Microbiota Composition and Alpha Diversity in Healthy Adults and Irritable Bowel Syndrome Patients

Abstract: Hydrogenotrophic microbes play an essential role in the disposal of hydrogen and the maintenance of the hydrogen balance in gut ecosystems. Their abundances vary between individuals and have been reported to be associated with human gut disorders such as irritable bowel disease. ABSTRACT Hydrogenotrophic microbes, primarily including the three functional groups methanogens, sulfate-reducing bacteria, and reductive acetogens, use hydrogen as an energy source and play an important role in maintaining the hydrogen balance in gut ecosystems. A distorted hydrogen balance has been associated with irritable bowel syndrome (IBS). However, the role of hydrogenotrophic microbes in overall microbiota composition and function remains largely unknown. This study aims to assess the distribution and stability of hydrogenotrophic functional groups in healthy adults (HAs) and IBS patients and their association with overall microbiota composition and IBS symptoms. A two-time-point study with 4 weeks in between was performed with 27 HAs and 55 IBS patients included. Our observations revealed that methanogens showed a bimodal distribution across samples. A high-level methanogen microbiota was consistently associated with higher alpha diversity, and its composition was significantly different from that of individuals with a low-level methanogen microbiota. In general, these associations were more pronounced in IBS patients than in HAs. The differences in the copy numbers of genes indicative of total bacteria and acetogens between HAs and IBS patients and their correlations with IBS symptom severity, anxiety, depression, and quality of life (QoL) were sampling time dependent. Hydrogenotrophic functional groups did not show negative abundance correlations with each other in HAs and IBS patients. These findings suggest that methanogen levels in the gut have a pronounced association with microbiota alpha diversity and composition, and the interactions between hydrogenotrophic functional groups are complex in gut ecosystems. IMPORTANCE Hydrogenotrophic microbes play an essential role in the disposal of hydrogen and the maintenance of the hydrogen balance in gut ecosystems. Their abundances vary between individuals and have been reported to be associated with human gut disorders such as irritable bowel disease. This study confirms that methanogen levels show a bimodal distribution. Moreover, a high-level methanogen microbiota was associated with higher alpha diversity, and its composition was different from that of individuals with a low-level methanogen microbiota. These associations are more pronounced in IBS patients than in healthy subjects. In addition, associations between hydrogenotrophic microbes and IBS symptom scores vary over time, which argues for the use of longitudinal study designs. Last but not least, this study suggests that the different hydrogenotrophic microbes coexist with each other and do not necessarily compete for hydrogen in the gut. The findings in this study highlight the impact of methanogens on overall microbiota composition and function.

Growth of Bacteroides Xylanolyticus in the Presence and Absence of a Methanogen

Abstract: Bacteroides xylanolyticus X5-1 is a Gram-negative motile xylanolytic bacterium, isolated from cattle manure (I.Scholten-Koerselman et al., 1986). It ferments xylan, but not cellulose to ethanol, acetate, hydrogen and carbon dioxide as the main end products. In addition, both C5 and C6 sugars are used for growth.

Co-cultivation of the anaerobic fungus Caecomyces churrovis with Methanobacterium bryantii enhances transcription of carbohydrate binding modules

Abstract: Anaerobic fungi and methanogenic archaea are two classes of microorganisms found in the rumen microbiome that metabolically interact during lignocellulose breakdown. Here, stable synthetic co-cultures of the anaerobic fungus Caecomyces churrovis and the methanogen Methanobacterium bryantii (not native to the rumen) were formed, demonstrating that microbes from different environments can be paired based on metabolic ties. Transcriptional and metabolic changes induced by methanogen co-culture were evaluated in C. churrovis across a variety of substrates to identify mechanisms that impact biomass breakdown and sugar uptake. A high-quality genome of C. churrovis was obtained and annotated, which is the first sequenced genome of a non-rhizoid forming anaerobic fungus. C. churrovis possess an abundance of CAZymes and carbohydrate binding modules and, in agreement with previous studies of early-diverging fungal lineages, N6-methyldeoxyadenine (6mA) was associated with transcriptionally active genes. Co-culture with the methanogen increased overall transcription of CAZymes, carbohydrate binding modules, and dockerin domains in co-cultures grown on both lignocellulose and cellulose and caused upregulation of genes coding associated enzymatic machinery including carbohydrate binding modules in family 18 and dockerin domains across multiple growth substrates relative to C. churrovis monoculture. Two other fungal strains grown on a reed canary grass substrate in co-culture with the same methanogen also exhibited high log2fold change values for upregulation of genes encoding carbohydrate binding modules in families 1 and 18. Transcriptional upregulation indicated that co-culture of the C. churrovis strain with a methanogen may enhance pyruvate formate lyase (PFL) function for growth on xylan and fructose and production of bottleneck enzymes in sugar utilization pathways, further supporting the hypothesis that co-culture with a methanogen may enhance certain fungal metabolic functions. Upregulation of CBM18 may play a role in fungal-methanogen physical associations and fungal cell wall development and remodeling.