Open AccessAnalysis of the key enzymes of butyric and acetic acid fermentation in biogas reactors
Author(s) -
Gabris Christina,
Bengelsdorf Frank R.,
Dürre Peter
Publication year - 2015
Publication title -
microbial biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.287
H-Index - 74
ISSN - 1751-7915
DOI - 10.1111/1751-7915.12299
Subject(s) - acidogenesis , biogas , anaerobic digestion , acetate kinase , fermentation , biochemistry , food science , chemistry , bacteria , biology , microbiology and biotechnology , methane , gene , organic chemistry , escherichia coli , ecology , genetics
Summary This study aimed at the investigation of the mechanisms of acidogenesis, which is a key process during anaerobic digestion. To expose possible bottlenecks, specific activities of the key enzymes of acidification, such as acetate kinase ( A ck, 0.23–0.99 U mg −1 protein), butyrate kinase ( B uk, < 0.03 U mg −1 protein) and butyryl‐ CoA :acetate‐ CoA transferase ( B ut, 3.24–7.64 U mg −1 protein), were determined in cell free extracts of biogas reactor content from three different biogas reactors. Furthermore, the detection of A ck was successful via W estern blot analysis. Quantification of corresponding functional genes encoding B uk ( buk ) and B ut ( but ) was not feasible, although an amplification was possible. Thus, phylogenetic trees were constructed based on respective gene fragments. Four new clades of possible butyrate‐producing bacteria were postulated, as well as bacteria of the genera R oseburia or C lostridium identified. The low B uk activity was in contrast to the high specific B ut activity in the analysed samples. Butyrate formation via B uk activity does barely occur in the investigated biogas reactor. Specific enzyme activities ( A ck, B uk and B ut) in samples drawn from three different biogas reactors correlated with ammonia and ammonium concentrations ( NH 3 and NH 4 + ‐ N ), and a negative dependency can be postulated. Thus, high concentrations of NH 3 and NH 4 + ‐ N may lead to a bottleneck in acidogenesis due to decreased specific acidogenic enzyme activities.