454 pyrosequencing analyses of bacterial and archaeal richness in 21 full-scale biogas digesters

Abstract

The microbial community of 21 full-scale biogas reactors was examined using 454 pyrosequencing of 16S rRNA gene sequences. These reactors included seven (six mesophilic and one thermophilic) digesting sewage sludge (SS) and 14 (ten mesophilic and four thermophilic) codigesting (CD) various combinations of wastes from slaughterhouses, restaurants, households, etc. The pyrosequencing generated more than 160,000 sequences representing 11 phyla, 23 classes, and 95 genera of Bacteria and Archaea. The bacterial community was always both more abundant and more diverse than the archaeal community. At the phylum level, the foremost populations in the SS reactors included Actinobacteria, Proteobacteria, Chloroflexi, Spirochetes, and Euryarchaeota, while Firmicutes was the most prevalent in the CD reactors. The main bacterial class in all reactors was Clostridia. Acetoclastic methanogens were detected in the SS, but not in the CD reactors. Their absence suggests that methane formation from acetate takes place mainly via syntrophic acetate oxidation in the CD reactors. A principal component analysis of the communities at genus level revealed three clusters: SS reactors, mesophilic CD reactors (including one thermophilic CD and one SS), and thermophilic CD reactors. Thus, the microbial composition was mainly governed by the substrate differences and the process temperature.

Effect of Seasonal Temperature on the Performance and on the Microbial Community of a Novel AWFR for Decentralized Domestic Wastewater Pretreatment

“…This result was consistent with the previous studies [45][46][47]. This high diversity might suggest that a variety of bacterial communities participated in multiple metabolic pathways of organic matter degradation under seasonal temperature variation.…”

“…The predominant bacteria in the AWFR system during the whole operation period were grouped into four phyla affiliated with Firmicutes, Proteobacteria, Bacteroidetes, and Chloroflexi, which occupied 89.3 ± 4.08% of the total phyla ( Figure 9). These dominant phyla were also detected in the full-scale biogas digesters [47,48]. During the start-up period, the predominant microorganisms in the AWFR system belonged to the phylum Proteobacteria, Firmicutes, Bacteroidetes and Chloroflexi, with a relative abundance of 33.01%, 22.19%, 19.94% and 11.29%, respectively.…”

“…During the start-up period, the dominant class was Gammaproteobacteria affiliated with the phylum Proteobacteria, with a relative abundance of 13.67%, followed by Bacteroidia, Clostridia, Anaerolineae and Bacilli, with a relative abundance of 12.87%, 11.88%, 10.96% and 9.89%, respectively. Among these predominant classes, Bacteroidia and Clostridia played significant roles in hydrolysis metabolism [47][48][49]. Gammaproteobacteria was the most representative class during the start-up period, which was also the main contributor to the phylum Proteobacteria.…”

“…Bacteroidales affiliated with the class Bacteroidia had been identified as hydrolyser and fermenter that participated in the conversation of cellulose and polysaccharide into VFAs [49]. Clostridiales affiliated with the class Clostridia was correlated with methane production, due to their diverse metabolism that utilized polysaccharide fermentation to produce VFAs for methanogenesis [47,48]. It was interesting to note that the class Bacteroidales was much more abundant in winter (12.45%) than in summer (6.61%), corresponding to an increase of VFAs in the winter.…”

Straw- and slurry-associated prokaryotic communities differ during co-fermentation of straw and swine manure

“…Previous studies showed that archaea accounted for up to 20 % in anaerobic digesters Sundberg et al 2013). In this study, though the primer set should cover most methanogens, the highest relative abundance of Euryarchaeota only accounted for 4.85 % of total reads.…”