Bacteria and archaea involved in anaerobic digestion of distillers grains with solubles

Abstract

Cereal distillers grains, a by-product from bioethanol industry, proved to be a suitable feedstock for biogas production in laboratory scale anaerobic digesters. Five continuously stirred tank reactors were run under constant conditions and monitored for biogas production and composition along with other process parameters. Iron additives for sulfide precipitation significantly improved the process stability and efficiency, whereas aerobic pretreatment of the grains had no effect. The microbial communities in the reactors were investigated for their phylogenetic composition by terminal restriction fragment length polymorphism analysis and sequencing of 16S rRNA genes. The bacterial subcommunities were highly diverse, and their composition did not show any correlation with reactor performance. The dominant phylotypes were affiliated to the Bacteroidetes. The archaeal subcommunities were less diverse and correlated with the reactor performance. The well-performing reactors operated at lower organic loading rates and amended with iron chloride were dominated by aceticlastic methanogens of the genus Methanosaeta. The well-performing reactor operated at a high organic loading rate and supplemented with iron hydroxide was dominated by Methanosarcina ssp. The reactor without iron additives was characterized by propionate and acetate accumulation and high hydrogen sulfide content and was dominated by hydrogenotrophic methanogens of the genus Methanoculleus.

Microbial Community Response to Seasonal Temperature Variation in a Small-Scale Anaerobic Digester

“…These results are consistent with the study by Ziganshin et al [16] who also found a greater number of Bacterial TRFs in samples from a mesophylic digester processing distillers dry grains with solubles. However, these authors found almost twice the number of TRFs in both domains than were detected in this study.…”

Unexpected Stability of Bacteroidetes and Firmicutes Communities in Laboratory Biogas Reactors Fed with Different Defined Substrates

“…Archaeal communities, among others, have been investigated by using anoxic reactors that utilized liquid manure and different agricultural products as substrates (17,23,26). Many studies that analyzed both the archaeal and bacterial communities (10,16,18,19,39,42) or only bacterial communities (7) were accomplished, but the majority of the microbially diverse populations in anaerobic digesters has still not yet been sampled, as revealed by a recent meta-analysis (25). Additionally, the majority of the sequences found could not be assigned to an established genus (25).…”

Changing Feeding Regimes To Demonstrate Flexible Biogas Production: Effects on Process Performance, Microbial Community Structure, and Methanogenesis Pathways

“…The vial was immediately sealed with a butyl rubber stopper and an aluminum crimp. The concentration of VFAs was determined from the headspace by use of a 5890 series II gas chromatograph (Hewlett Packard, Palo Alto, CA, USA) as described earlier (18). For TAN analysis, an aliquot (125 l) of the solution was diluted to 1:2,000 with distilled water and the TAN was determined by a standard Nessler method using a benchtop spectrometer (DR 3900; Hach-Lange, Loveland, CO, USA).…”