Methanogen

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

Biogas Production and Microbial Communities of Mesophilic and Thermophilic Anaerobic Co-Digestion of Animal Manures and Food Wastes in Costa Rica

Abstract: Biomass generated from agricultural operations in Costa Rica represents an untapped renewable resource for bioenergy generation. This study investigated the effects of two temperatures and three mixture ratios of manures and food wastes on biogas production and microbial community structure. Increasing the amount of fruit and restaurant wastes in the feed mixture significantly enhanced the productivity of the systems (16% increase in the mesophilic systems and 41% in the thermophilic). The methane content of biogas was also favored at higher temperatures. Beta diversity analysis, based on high-throughput sequencing of 16S rRNA gene, showed that microbial communities of the thermophilic digestions were more similar to each other than the mesophilic digestions. Species richness of the thermophilic digestions was significantly greater than the corresponding mesophilic digestions (F = 40.08, p = 0.003). The mesophilic digesters were dominated by Firmicutes and Bacteroidetes while in thermophilic digesters, the phyla Firmicutes and Chloroflexi accounted for up to 90% of all sequences. Methanosarcina represented the key methanogen and was more abundant in thermophilic digestions. These results demonstrate that increasing digestion temperature and adding food wastes can alleviate the negative impact of low C:N ratios on anaerobic digestion.

Genomic remnants of ancestral methanogenesis and hydrogenotrophy in Archaea drive anaerobic carbon cycling

Abstract: Anaerobic methane metabolism is among the hallmarks of Archaea, originating very early in their evolution. Here, we show that the ancestor of methane metabolizers was an autotrophic CO2-reducing hydrogenotrophic methanogen that possessed the two main complexes, methyl-CoM reductase (Mcr) and tetrahydromethanopterin-CoM methyltransferase (Mtr), the anaplerotic hydrogenases Eha and Ehb, and a set of other genes collectively called “methanogenesis markers” but could not oxidize alkanes. Overturning recent inferences, we demonstrate that methyl-dependent hydrogenotrophic methanogenesis has emerged multiple times independently, either due to a loss of Mtr while Mcr is inherited vertically or from an ancient lateral acquisition of Mcr. Even if Mcr is lost, Mtr, Eha, Ehb, and the markers can persist, resulting in mixotrophic metabolisms centered around the Wood-Ljungdahl pathway. Through their methanogenesis remnants, Thorarchaeia and two newly reconstructed order-level lineages in Archaeoglobi and Bathyarchaeia act as metabolically versatile players in carbon cycling of anoxic environments across the globe.

Influence of Albizia lebbeck Saponin and Its Fractions on In Vitro Gas Production Kinetics, Rumen Methanogenesis, and Rumen Fermentation Characteristics.

Abstract: The present study was undertaken to investigate the effect of crude seed powder (CSP) and gross saponins extract (GSE) of seeds of Albizia lebbeck on antimicrobial activity by taking two Gram-positive (Staphylococcus aureus and Bacillus cereus), two Gram-negative (Escherichia coli and Salmonella Typhi) bacteria, and two fungi species (Aspergillus niger and Candida butyric) were taken at 25, 50, 100, 250, and 500 µg levels using agar well diffusion method. Zone of inhibition was increased with increasing of concentration of CSP and saponins which indicates that Gram-negative bacteria (E. coli), Gram-positive bacteria (B. cereus), and A. niger were significantly susceptible to inhibition. Another experiment was conducted to study the effect of GSE and saponins fraction A and B of A. lebbeck supplementation at 6% on DM basis on methane production and other rumen fermentation parameters using in vitro gas production test, by taking three different type diets, that is, high fiber diet (D1, 60R : 40C), medium fiber diet (D2, 50R : 50C), and low fiber diet (D3, 40R : 60C). Significant () increase was seen in IVDMD, methane production; however ammonia nitrogen concentration decreased as compared to control. The methane production was reduced in a range between 12 and 49% by saponin supplemented diets except in case of GSE in D2. Sap A showed the highest methane reduction per 200 mg of truly digested substrate (TDS) than other treatment groups. Results in relation with quantification of methanogens and protozoa by qPCR indicated the decreasing trend with saponins of A. lebbek in comparison with control except total methanogen quantified using mcr-A based primer.

Bioreactor performance and microbial community dynamics in a production-scale biogas plant in northeastern China

Abstract: In cold regions, heating is necessary to maintain the continuous and steady year-round operation of biogas fermentation. In this study, changes in the liquid composition, biogas production, and microbial diversity in heated- and unheated-phase samples were evaluated in a production-scale biogas plant that was fed continuously with cattle manure as a mono-substrate in Heilongjiang province in northeastern China. The volatile solid (VS) and volatile fatty acid (VFA) contents both gradually decreased in the heated and unheated fermentation processes. The chemical oxygen demand (COD) removal efficiency in the unheated phase sampled on June 15 (s-6-15) and October 15 (a-10-15) and in the heated phase sampled on January 15 (w-1-15) was 63.35%, 44.2% and 44.0%, respectively. The biogas production yields were in agreement with the results obtained for the VS and VFA contents and COD removal efficiency. The performance of the reactor in the heated phase was less efficient than that in the unheated phase, and the biogas production efficiency in June-August was higher than that in the other months. However, the CH4 content in the biogas remained similar all year. Moreover, ARDRA (Amplified Ribosomal DNA Restriction Analysis) was used to study the microbial community composition in the fermentation process. The results showed that the methanogenic archaeal consortium consisted mainly of members of the genera Methanomicrobiales and Methanosarcinales. In the heated phase, hydrogenotrophic methanogens represented the dominant methanogen in w-1-15 feedstock. After fermentation, the strict aceticlastic methanogen Methanosaeta became the dominant methanogen. In the unheated phase, the hydrogenotrophic methanogens and aceticlastic methanogens were equivalent in s-6-15 feedstock and effluent, and aceticlastic methanogens were dominant in both a-10-15 feedstock and effluent. Assessments of the bacteria diversity of the microbial communities revealed that the common strains in the feed and effluent of the three samples included the rumen bacteria, Bacteroides, Clostridium, Ruminococcaceae and Proteobacteria. Keywords: biogas production, production-scale plant, dairy manure, microbial community, northeast of China DOI: 10.3965/j.ijabe.20171001.2025 Citation: Gao Y M, Yang A Y, Bao J, Ma R X, Yan L, Wang Y J, et al. Bioreactor performance and microbial community dynamics in a production-scale biogas plant in northeastern China. Int J Agric & Biol Eng, 2017; 10(1): 191－201.