Diversity and variability of methanogens during the shift from mesophilic to thermohilic conditions while biogas production

Abstract

Anaerobic digestion (AD) is the most popular path of organic waste disposal. It is often used in wastewater treatment plants for excessive sludge removal. Methanogenic fermentation had usually been performed under mesophilic conditions, but in the past few years the thermophilic processes have become more popular due to economics and sludge sanitation. Methanogens, the group of microorganisms responsible for methane production, are thought to be sensitive to temperature change and it has already been proven that the communities performing methanogenesis under mesophilic and thermophilic conditions differ. But in most cases the research performed on methanogen diversity and changeability was undertaken in two separate anaerobic chambers for meso- and thermophilic conditions. It is also known that there is a group of microorganisms performing AD which are insensitive to temperature. Also the linkage between digester performance and its microbial content and community changeability is still not fully understood. That is why in this experiment we analyzed the bacterial community performing methanogenesis in a pilot scale anaerobic chamber during the shift from mesophilic to thermophilic conditions to point at the group of temperature tolerant microorganisms and their performance. The research was performed with PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis). It occurred that the community biodiversity decreased together with a temperature increase. The changes were coherent for both the total bacteria community and methanogens. These bacterial shifts were also convergent with biogas production-it decreased in the beginning of the thermophilic phase with the bacterial biodiversity decrease and increased when the community seemed to be restored. DGGE results suggest that among a wide variety of microorganisms involved in AD there is a GC-rich group relatively insensitive towards temperature change, able to adapt quickly to shifts in temperature and perform AD effectively. The studies of this microbial group could be a step forward in developing more efficient anaerobic digestion technology.

Biphasic Study to Characterize Agricultural Biogas Plants by High-Throughput 16S rRNA Gene Amplicon Sequencing and Microscopic Analysis

“…Among the bacterial members found in these anaerobic digester systems, those belonging to the classes Clostridia and Bacteroidetes dominated the biogas communities, followed by Proteobacteria, Bacilli, Flavobacteria, Spirochetes, and Erysipelotrichi. Depending on the process conditions, such as temperature and fed substrates, differences in the community profiles were identified [39][40][41]. For example, the bacterial phyla Actinobacteria, Deltaproteobacteria, and Spirochaetes were frequently found in mesophilic bioreactors [42], whereas members of the phylum Thermotogae (42%) were observed to be a predominant taxon under thermophilic conditions [1,43,44].…”

Comparative proteomic analysis of Methanothermobacter thermautotrophicus reveals methane formation from H2 and CO2 under different temperature conditions

“…Methanogens are common in petroleum reservoirs with temperatures in the range from 20 to 80°C (Enoki, Shinzato, Sato, Nakamura, & Kamagata, ; Hendrickson et al., ; Kato, Kosaka, & Watanabe, ; Luo, Zhang, Suzuki, Hattori, & Kamagata, ; Nazina et al., ). Anaerobic digestion systems are operated at temperatures ranging from 20 to 60°C (Ahring, ; Ahring, Ibrahim, & Mladenovska, ; Ziembinska‐Buczynska, Banach, Bacza, & Pieczykolan, ; Zinder et al., ). However, quantitative characterization of the cellular details of the response of methanogens to temperature is rare.…”

Identification and genome reconstruction of abundant distinct taxa in microbiomes from one thermophilic and three mesophilic production-scale biogas plants

“…In comparison, thermophilic plants show higher methane content of the biogas, faster process turnover rates and a sanitising effect [ 10 ]. Depending on the process conditions, such as temperature and fed substrates, differences in the biogas microbiome have been observed [ 13 , 14 ].…”