Bacterial and archeal dynamics of a labscale HYBRID gas fermentation bioreactor fed with CO₂ and H₂

Abstract

16s rDNA-based methods were used in order to identify the dynamics of microbial profiles in a HYBRID gas fermentation bio-methanization reactor. The effects of various H₂ and CO₂ ratios on microbial community were investigated. The HYBRID gas fermentation reactor was composed of granular anaerobic seed and the system fed with only H₂ and CO₂ gases. No additional organic material and trace element was fed during the throughout the experiments; thus, the microbial diversity was directly related to production of methane. The dynamics of the microbial communities were investigated with DGGE and real-time PCR analysis. The results showed that Methanobacteriales members were more dominated than Methanosarcinales and Methanomicrobiales members in the system. DGGE results indicated that Methanosaeta concilii, Methanoculleus sp., Methanosphaerula palustris, Methanofollis formosanus, Methanolinea sp., and Methanobacterium palustre were the most prominent methanogens depending on different H₂/CO₂ ratios. DGGE profiles suggested that hydrogenotrophic and acetoclastic species were responsible for the production of methane. The survival of syntrophic bacteria and acetoclastic methanogens was attributed to their utilization of organic materials provided by lysis. To the best of our knowledge, this is the first microbial profile detection study in a hybrid bioreactor system operated with only pure hydrogen and carbon dioxide.

Keywords:

• Biomethane
• CO₂
• DGGE (denaturing gradient gel electrophoresis)
• hydrogenotrophic methanogen
• quantitative PCR

Acknowledgments

The data presented in this article was produced within the project above, however it is only the authors of this article who are responsible for the results and discussions made herein.

Additional information

Funding

The authors thank Scientific and Technological Research Council of Turkey (TUBITAK) under the grant no. 115Y455 for the financial support of this study. The authors also thank Ege University Scientific Research Fund under the grant no. 16/EBILTEM/003 for the financial support of this study.