Background: Renewable energy production is currently a major issue worldwide. Biogas is a promising renewable energy carrier as the technology of its production combines the elimination of organic waste with the formation of a versatile energy carrier, methane. In consequence of the complexity of the microbial communities and metabolic pathways involved the biotechnology of the microbiological process leading to biogas production is poorly understood. Metagenomic approaches are suitable means of addressing related questions. In the present work a novel high-throughput technique was tested for its benefits in resolving the functional and taxonomical complexity of such microbial consortia. Results: It was demonstrated that the extremely parallel SOLiD™ short-read DNA sequencing platform is capable of providing sufficient useful information to decipher the systematic and functional contexts within a biogasproducing community. Although this technology has not been employed to address such problems previously, the data obtained compare well with those from similar high-throughput approaches such as 454-pyrosequencing GS FLX or Titanium. The predominant microbes contributing to the decomposition of organic matter include members of the Eubacteria, class Clostridia, order Clostridiales, family Clostridiaceae. Bacteria belonging in other systematic groups contribute to the diversity of the microbial consortium. Archaea comprise a remarkably small minority in this community, given their crucial role in biogas production. Among the Archaea, the predominant order is the Methanomicrobiales and the most abundant species is Methanoculleus marisnigri. The Methanomicrobiales are hydrogenotrophic methanogens. Besides corroborating earlier findings on the significance of the contribution of the Clostridia to organic substrate decomposition, the results demonstrate the importance of the metabolism of hydrogen within the biogas producing microbial community. Conclusions: Both microbiological diversity and the regulatory role of the hydrogen metabolism appear to be the driving forces optimizing biogas-producing microbial communities. The findings may allow a rational design of these communities to promote greater efficacy in large-scale practical systems. The composition of an optimal biogas-producing consortium can be determined through the use of this approach, and this systematic methodology allows the design of the optimal microbial community structure for any biogas plant. In this way, metagenomic studies can contribute to significant progress in the efficacy and economic improvement of biogas production.

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Characterization of a biogas-producing microbial community by short-read next generation DNA sequencing

The metagenome of a biogas-producing microbial community of a production-scale biogas plant fermenter analysed by the 454-pyrosequencing technology

https://link.springer.com/content/pdf/10.1016%2Fj.jasms.2009.05.014.pdf

Top-Down Proteomics Reveals Novel Protein Forms Expressed in Methanosarcina acetivorans

The current practice of using stanchion breeding cow houses results in a semi-dry manure that ideally should be used as the substrate for the anaerobic fermentation. The conventional liquid-slurry biogas fermentation is disadvantageous with high running costs due to requirement such as water addition and running efficiency, among others. This study aimed to establish a high-speed semi-dry methane fermentation system for cow manure, by comparing productivity in wet and semi-dry conditions (> 90 and 83-85% water content, respectively), and mesophilic and thermophilic conditions (38 and 55°C, respectively). The highest methane productivity was obtained for 30 days in semi-dry or wet, thermophilic conditions (0.4-16.2 Lâ€§Kg-1VSâ€§day-1). The highest accumulated production was 60 days (192.1 Lâ€§Kg-1VS) in semi-dry thermophilic conditions. The pronounced difference in methane production at different temperatures in semi-dry digesters was studied by characterizing the microbial community changes in mesophilic and thermophilic digesters. For bacteria, the class Clostridia (including family Clostridiaceae and the genus Clostridium) was dominant in the thermophilic digester. In the thermophilic digester, a succession of taxa from the genus Methanobrevibacter and family Methanobacteriaceae to genus Methanoculleus in archaea was observed. The convergence of archaeal microbiota in thermophilic conditions was more pronounced than in mesophilic conditions. These results indicate that the proposed procedure is capable of improving methane productivity per scale and lowering the running costs concomitant and downsizing the fermentation scale.

	 

	Key words: Semi-dry fermentation, methane yield, anaerobic digestion, cow manure, biogas.

/pdf/comparison-between-wet-and-semi-dry-anaerobic-biogas-diester-2z2ynrhgfl.pdf

Comparison between wet and semi-dry anaerobic biogas diester under thermophilic and mesophilic conditions: Methane productivity and analysis of microbiota

/pdf/improving-bio-technology-processes-using-computational-3jcfiyau71.pdf

Improving Bio-technology Processes Using Computational Techniques

Methane produced microbiologically is currently used as an energy source, especially by cities and industries, albeit at a level far below its potential; the incentive is currently to save money on disposal costs for waste problems. Anaerobic digestion can be helpful in degrading several halogenated hydrocarbon wastes, and methanogens are partly responsible. Ethane instead of methane may be a future product of interest. Some pure cultures of methanogens may be suitable for production of B-12, or perhaps the speciality biochemical F420, a 5-deazaflavin of interest to both methanogen and streptomyces researchers. Methanogens can cause a variety of problems, including biocorrosion, increased atmospheric methane, and ruminant nutrition loss. Studies of tropical wetlands, including rice paddies and swamps, and the study of a variety of ruminants in the tropics are particularly interesting and appropriate at this time, with respect to methane produced in these ecosystems. In some cases, it may be possible to control methane production by the use of inhibitors or ecological control mechanisms.

L Daniels

Papers

Biotechnological potential of methanogens.