Dataset Information

Biogas-producing microbial composition of an anaerobic digester and associated bovine residues.

ABSTRACT: Influenced by feedstock type and microbial inoculum, different microbial groups must precisely interact for high-quality biogas yields. As a first approach for optimization, this study aimed to identify through time the biogas-producing microbial community in a 10-ton dry anaerobic digester treating cattle manure by denaturing gradient gel electrophoresis (DGGE) and metagenomics. Moreover, the associated bovine residues or feedstocks (leachate, manure, oxidation lagoon water, rumen) were also characterized to determine their contribution. A diverse and dynamic community characterized by Bacteria (82%-88%) and a considerable amount of Archaea (8%-15%) presented profiles particular to each stage of biogas production. Eukaryotes (2.6%-3.6%), mainly fungi, were a minor but stable component. Proteobacteria represented 47% of the community at the start of the run but only 18% at the end, opposite to the Bacteroidetes/Chlorobi group (8% and 20%, respectively), while Firmicutes (12%-18%) and Actinobacteria (12%-32%) remained relatively constant. Methanogens of the order Methanomicrobiales represented by several species of Methanoculleus were abundant at the end of the run (77%) contrary to Methanosarcinales (11%) and Methanobacteriales (0.7%). Therefore, methanogenesis mainly occurred by the hydrogenotrophic pathway. Manure and oxidation lagoon water seemed to contribute key microorganisms, while rumen dominated by Methanobrevibacter (72%) did not proliferate in the digester. Manure particularly possessed Methanoculleus (24%) and uncultured methanogens identified by DGGE, whereas oxidation lagoon was exclusively abundant in Methanolinea (18%) and Methanosaeta (19%). Leachate, as the microbial inoculum from a previous run, adequately preserved the biogas-producing community. These results could lead to higher biogas yields through bioaugmentation strategies by incorporating higher proportions or an enriched inoculum from the relevant feedstocks.

SUBMITTER: Senes-Guerrero C

PROVIDER: S-EPMC6741126 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Biogas-producing microbial composition of an anaerobic digester and associated bovine residues.

Senés-Guerrero Carolina C Colón-Contreras Franco A FA Reynoso-Lobo Javier F JF Tinoco-Pérez Benito B Siller-Cepeda Jorge H JH Pacheco Adriana A

MicrobiologyOpen 20190525 9

Influenced by feedstock type and microbial inoculum, different microbial groups must precisely interact for high-quality biogas yields. As a first approach for optimization, this study aimed to identify through time the biogas-producing microbial community in a 10-ton dry anaerobic digester treating cattle manure by denaturing gradient gel electrophoresis (DGGE) and metagenomics. Moreover, the associated bovine residues or feedstocks (leachate, manure, oxidation lagoon water, rumen) were also ch ...[more]

PMID: 31129926

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Project description:BACKGROUND:High levels of ammonia and the presence of sulphide have major impacts on microbial communities and are known to cause operating problems in anaerobic degradation of protein-rich material. Operating strategies that can improve process performance in such conditions have been reported. The microbiological impacts of these are not fully understood, but their determination could help identify important factors for balanced, efficient operation. This study investigated the correlations between microbial community structure, operating parameters and digester performance in high-ammonia conditions. METHOD:Continuous anaerobic co-digestion of household waste and albumin was carried out in laboratory-scale digesters at high ammonia concentrations (0.5-0.9 g NH3/L). The digesters operated for 320 days at 37 or 42 °C, with or without addition of a trace element mixture including iron (TE). Abundance and composition of syntrophic acetate-oxidising bacteria (SAOB) and of methanogenic and acetogenic communities were investigated throughout the study using 16S rRNA and functional gene-based molecular methods. RESULTS:Syntrophic acetate oxidation dominated methane formation in all digesters, where a substantial enhancement in digester performance and influence on microbial community by addition of TE was shown dependent on temperature. At 37 °C, TE addition supported dominance and strain richness of Methanoculleus bourgensis and altered the acetogenic community, whereas the same supplementation at 42 °C had a low impact on microbial community structure. Both with and without TE addition operation at 42 °C instead of 37 °C had low impact on digester performance, but considerably restricted acetogenic and methanogenic community structure, evenness and richness. The abundance of known SAOB was higher in digesters without TE addition and in digesters operating at 42 °C. No synergistic effect on digester performance or microbial community structure was observed on combining increased temperature with TE addition. CONCLUSIONS:Our identification of prominent populations related to enhanced performance within methanogenic (high dominance and richness of M. bourgensis) and acetogenic communities are valuable for continued research and engineering to improve methane production in high-ammonia conditions. We also show that a temperature increase of only 5 °C within the mesophilic range results in an extreme dominance of one or a few species within these communities, independent of TE addition. Furthermore, functional stable operation was possible despite low microbial temporal dynamics, evenness and richness at the higher temperature.

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Project description:The aim of the study was to evaluate the effect of herbicidal ionic liquids on the population changes of microorganisms used in a batch anaerobic digester. The influence of the following ionic liquids: benzalkonium (2,4-dichlorophenoxy)acetate (BA)(2,4-D), benzalkonium (4-chloro-2-methylphenoxy)acetate (BA)(MCPA), didecyldimethylammonium (2,4-dichlorophenoxy)acetate (DDA)(2,4-D), didecyldimethylammonium (4-chloro-2-methylphenoxy)acetate (DDA)(MCPA), as well as reference herbicides (4-chloro-2-methylphenoxy)acetic acid (MCPA) and (2,4-dichlorophenoxy)acetic acid (2,4-D) in the form of sodium salts on biogas production efficiency was investigated. The effective concentration (EC50) values were determined for all tested compounds. (MCPA)- was the most toxic, with an EC50 value of 38.6⁻41.2 mg/L. The EC50 for 2,4-D was 55.7⁻59.8 mg/L. The addition of the test substances resulted in changes of the population structure of the microbiota which formed the fermentation pulp. The research was based on 16S rDNA analysis with the use of the Next Generation Sequencing method and the MiSeq platform (Illumina, San Diego, CA, USA). There was a significant decrease in bacteria belonging to Firmicutes and Archaea belonging to Euryarchaeota. A significant decrease of the biodiversity of the methane fermentation microbiota was also established, which was expressed by the decrease of the operational taxonomic units (OTUs) and the value of Shannon's entropy. In order to determine the functional potential of bacterial metapopulations based on the 16SrDNAprofile, the PICRUSt(Phylogenetic Investigation of Communities by Reconstruction of Unobserved States)tool was used, which allowed to determine the gene potency of microorganisms and their ability to biodegrade the herbicides. In the framework of the conducted analysis, no key genes related to the biodegradation of MCPA or 2,4-D were found, and the observed decrease of their content in the supernatant liquid was caused by their sorption on bacterial biomass.

Dataset Information

Biogas-producing microbial composition of an anaerobic digester and associated bovine residues.

Publications

Biogas-producing microbial composition of an anaerobic digester and associated bovine residues.

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