Metagenomics survey unravels diversities of biogas? microbiomes with potential to enhance its? productivity in Kenya.
bioRxiv
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Abstract: The obstacle to optimal utilization of biogas technology is poor understanding of biogas? microbiome diversities over a wide geographical coverage. We performed random shotgun sequencing on twelve environmental samples. A randomized complete block design was utilized to assign the twelve biogas reactor treatments to four blocks, within eastern and central regions of Kenya. We obtained 42 million paired-end reads that were annotated against sixteen reference databases using two ENVO ontologies, prior to ?-diversities studies. We identified 37 phyla, 65 classes and 132 orders of micro-organisms. Bacteria dominated the microbiome and comprised of 28 phyla, 42 classes and 92 orders, conveying substrate?s versatility in the treatments. Though, fungi and Archaea comprised of only 5 phyla, the fungi were richer; suggesting the importance of hydrolysis and fermentation in biogas production systems. High ?-diversity within the taxa was largely linked to communities? metabolic capabilities. Clostridiales and Bacteroidales, the most prevalent guilds, metabolize organic macromolecules. The identified affiliates of Cytophagales, Alteromonadales, Flavobacteriales, Fusobacteriales, Deferribacterales, Elusimicrobiales, Chlamydiales, Synergistales to mention but few, also catabolize macromolecules into smaller substrates to conserve energy. Furthermore, ?-Proteobacteria, Gloeobacteria and Clostridia affiliates syntrophically regulate PH2 and reduce metal to provide reducing equivalents. Methanomicrobiales and other Methanomicrobia species were the most prevalence Archaea, converting formate, CO2(g), acetate and methylated substrates into CH4(g). Thermococci, Thermoplasmata and Thermoprotei were among the sulfur and other metal reducing Archaea that contributed to redox balancing and other metabolism within treatments. Eukaryotes, mainly fungi were the least abundant guild, comprised largely Ascomycota and Basidiomycota species. Chytridiomycetes, Blastocladiomycetes and Mortierellomycetes were among the rare species, suggesting their metabolic and substrates limitations. Generally, we observed that environmental and treatment perturbations influenced communities? abundance, ?-diversity and reactor performance largely through stochastic effect. The study of the diversity of the biogas? microbiomes over wide environmental variables and the productivity of biogas reactor systems has provided insights into better management strategies that may ameliorate biochemical limitations to effective biogas production.