Research Progress on Propionic Acid Accumulation and Regulation by Syntrophic Propionate-oxidizing Bacteria Community in Anaerobic Digestion Process

FAN Hui;MA Shi-chun;HUANG Yan;DENG Yu;Biogas Institute of Ministry of Agriculture;Key Laboratory of Development and Application of Rural Renewable Energy of Ministry of Agriculture;

syntrophic propionate-oxidizing bacteria;;propionic acid;;anaerobic digestion system;;regulation

Volatile organic acid is important intermediate metabolite during anaerobic digestion process,especially propionic acid. Propionic acid often accumulates under an excessively high organic loading rate,which may cause a rapid acidification and inhibiting the growth of microbes in anaerobic digesters. Thus,the degradation of propionic acid is regarded as the rate-limiting step in anaerobic digestion. However,the anaerobic conversion of propionic acid to acetate,CO2 and H2is highly endergonic and does not occur naturally. Studies showed that propionic acid could be degraded by the syntrophic cooperation of propionate-oxidizing microbes and hydrogenotrophic methanogens. Therefore,based on propionic acid accumulation and its regulation during anaerobic process,the major influential factors of propionic acid accumulation were analyzed in this paper,The regulation methods on propionic acid accumulation suggested in recent years,and the research progress of syntrophic propionate-oxidizing bacteria community were reviewed and summarized,expecting to provide basis for applications of anaerobic digestion technique.