Dynamics of a Perturbed Microbial Community during Thermophilic Anaerobic Digestion of Chemically Defined Soluble Organic Compounds.

Knowledge of microbial community dynamics in relation to process perturbations is fundamental to understand and deal with the instability of anaerobic digestion (AD) processes. This study aims to investigate the microbial community structure and function of a thermophilic AD process, fed with a chemically defined substrate, and its association with process performance stability. Next generation amplicon sequencing of 16S ribosomal RNA (rRNA) genes revealed that variations in relative abundances of the predominant bacterial species, and were not linked to the process performance stability, while dynamics of bacterial genera of low abundance, and (other than ), were associated with microbial community function and process stability. A decrease in the diversity of the archaeal community was observed in conjunction with process recovery and stable performance, implying that the high abundance of specific archaeal group(s) contributed to the stable AD. Dominance of hydrogenotrophic particularly corresponded to an enhanced microbial acetate and propionate turnover capacity, whereas the prevalence of hydrogenotrophic and acetoclastic was associated with instable AD. Acetate oxidation via syntrophic interactions between and was potentially the main methane-formation pathway during the stable process. We observed that supplementation of Se and W to the medium improved the propionate turnover by the thermophilic consortium. The outcomes of our study provided insights into the community dynamics and trace element requirements in relation to the process performance stability of thermophilic AD.