Production of biogas: relationship between methanogenic and sulfate-reducing microorganisms

Abstract

The production of high-quality methane depends on many factors, including temperature, pH, substrate, composition and relationship of the microorganisms. The qualitative and quantitative composition of methanogenic and sulfate-reducing microorganisms and their relationship in the experimental bioreactors has never been studied. The aim of this research was to characterize, for the first time, the diversity of the methanogenic microorganisms and sulfate-reducing bacteria, and study their relationship and biogas production in experimental bioreactors. Amplification of 16S rRNA gene fragments was carried out. Purified amplicons were paired-end sequenced on an Illumina Mi-Seq platform. The dominant morphotypes of these microorganisms in the bioreactor were homologous (99%) by the sequences of 16S rRNA gene to the Methanosarcina, Thermogymnomonas, Methanoculleus genera and Archaeon deposited in GenBank. Three dominant genera of sulfate-reducing bacteria, Desulfomicrobium, Desulfobulbus and Desulfovibrio, were detected in the bioreactor. The phylogenetic trees showing their genetic relationship were constructed. The diversity and number of the genera, production of methane, hydrogen sulfide and hydrogen in the bioreactor was investigated. This research is important for understanding the relationship between methanogenic microbial populations and other bacterial physiological groups, their substrate competition and, in turn, can be helpful for controlling methanogenesis in bioreactors.

Molybdate to prevent the formation of sulfide during the process of biogas production

“…Sulfate-reducing bacteria (SRB) reduce sulfate (SO 4 2- ) to sulfide by transferring electrons obtained by the degradation of organic matter such as lactate and acetate. The presence of SRB decreases the final biogas production by competing with methanogen for acetate and by generating toxic H 2 S 5–8 . Values higher than 500 ppmv of sulfide in the biogas, produce a dangerous corrosive effect, significantly reducing the lifetime of pipes and other metallic hardware 9 .…”

Recent Advances in Metabolic Pathways of Sulfate Reduction in Intestinal Bacteria

“…DSR is a process that includes several reactions, providing energy for the creation of adenosine triphosphate (ATP) in bacterial cells of SRB. Sulfate is used as a terminal acceptor and provides energy for growth and is released from the oxidation of organic compounds (lactate, propionate, and butyrate) or hydrogen [39,40]. Reduction of sulfate occurs over many different intermediates that are not released to the environment.…”

Fermentation of plant residues to produce biogas

“…Methanogenic microorganisms are sensitive, and a small change in this parameter can stop their activity [4][5] . Regarding pH, each stage of the AD process works in different ranges: the optimum hydrolysis and acidogenesis is between 4.5 and 7, and the acetogenesis and methanogenesis are between 6.8 and 8.2 [6].…”