Comparison of Bacterial And Archaeal Microbiome In Two Bioreactors Fed With Cattle Sewage And Corn Biomass

The bacterial and archaeal communities of two biogas producing plants (P1 and P2), associated with a 999 kW cogeneration unit, both located in North Italy, were analyzed at start up and fully operating phases, by means of various molecular approaches: i) Automated Ribosomal Intergenic Spacer Analysis; ii) cloning and sequencing of PCR amplicons of archaeal genes 16Srrna and mcrA; iii) 16S rDNA high throughput next generation sequencing. P1 and P2 use the same technology and both were fed with cattle manure and corn silage. During the study of P1 also the post digestor (fed with pig manure) was analyzed. The aim of this research was to characterize the bacterial and archaeal community in two very similar plants to profile the core microbiome. The results of this analysis highlighted that the two plants (producing comparable quantities of volatile fatty acids, biogas, and energy) differed in anerobic microbiota (Bacteria and Archaea). Notably the methanogenic community of P1 was dominated by the strict acetoclastic Methanosaeta (Methanothrix) (up to 23.05%) and the unculturable Candidatus Methanofastidiosum (up to 32.70%), while P2 was dominated by the acetoclastic, but more substrate-versatile, Methanosarcina archaeal genus (49.19%). The data demonstrated that the performances of plants with identical design, in similar operating conditions, yielding comparable amount of biogas (average of 8662 m3 /day and 7916 m3/day respectively for P1 and P2), VFA (1643 mg/L and 1634 mg/L) and energy recovery (23.90-24 MWh/d) depends on the stabilization of an effective and functionally optimized methanogenic community rather than on the species composition

Beyond the usual suspects: methanogenic communities in eastern North American peatlands are also influenced by nickel and copper concentrations

Peatlands both accumulate carbon and release methane, but their broad range in environmental conditions means that the diversity of microorganisms responsible for carbon cycling is still uncertain. Here we describe a community analysis of methanogenic archaea responsible for methane production in 17 peatlands from 36 to 53 N latitude across the eastern half of North America, including three metal-contaminated sites. Methanogenic community structure was analyzed through Illumina amplicon sequencing of the mcrA gene. Whether metal-contaminated sites were included or not, metal concentrations in peat were a primary driver of methanogenic community composition, particularly nickel, a trace element required in the F430 cofactor in methyl-coenzyme M reductase that is also toxic at high concentrations. Copper was also a strong predictor, likely due to inhibition at toxic levels and/or to cooccurrence with nickel, since copper enzymes are not known to be present in anaerobic archaea. The methanogenic groups Methanocellales and Methanosarcinales were prevalent in peatlands with low nickel concentrations, while Methanomicrobiales and Methanomassiliicoccales were abundant in peatlands with higher nickel concentrations. Results suggest that peat-associated trace metals are predictors of methanogenic communities in peatlands.

Characteristics and Metabolic Patterns of Soil Methanogenic Archaea Communities in the High Latitude Natural Wetlands of China

Background: Soil methanogenic microorganisms are one of the primary methane-producing microbes in wetlands. However, we still poorly understand the community characteristic and metabolic patterns of these microorganisms according to vegetation type and seasonal changes. Therefore, to better elucidate the effects of the vegetation type and seasonal factors on the methanogenic community structure and metabolic patterns, we detected the characteristics of the soil methanogenic mcrA gene from three types of natural wetlands in different seasons in the Xiaoxing'an Mountain region, China. Result: The results indicated that the distribution of Methanobacteriaceae (hydrogenotrophic methanogens) was higher in winter, while Methanosarcinaceae and Methanosaetaceae accounted for a higher proportion in summer. Hydrogenotrophic methanogenesis was the dominant trophic pattern in each wetland. The results of principal coordinate analysis and cluster analysis showed that the vegetation type considerably influenced the methanogenic community composition. The methanogenic community structure in the Betula platyphylla – Larix gmelinii wetland was relatively different from the structure of the other two wetland types. Indicator species analysis further demonstrated that the corresponding species of indicator operational taxonomic units from the Alnus sibirica wetland and the Betula ovalifolia wetland were closer. Network analysis showed that cooperative and competitive relationships exist both within and between the same or different trophic methanogens. The core methanogens with higher abundance in each wetland were conducive to adaptation to environmental disturbances. Conclusions: This information is crucial for the assessment of metabolic patterns of soil methanogenic archaea and future fluxes in the wetlands of the Xiaoxing'an Mountain region given their vulnerability.