The effect of the source of microorganisms on adaptation of hydrolytic consortia dedicated to anaerobic digestion of maize silage

Abstract

The main aim of this study was to evaluate the effect of the source of microorganisms on the selection of hydrolytic consortia dedicated to anaerobic digestion of maize silage. The selection process was investigated based on the analysis of changes in the hydrolytic activity and the diversity of microbial communities derived from (i) a hydrolyzer of a commercial agricultural biogas plant, (ii) cattle slurry and (iii) raw sewage sludge, during a series of 10 passages. Following the selection process, the adapted consortia were thoroughly analyzed for their ability to utilize maize silage and augmentation of anaerobic digestion communities. The results of selection of the consortia showed that every subsequent passage of each consortium leads to their adaptation to degradation of maize silage, which was manifested by the increased hydrolytic activity of the adapted consortia. Biodiversity analysis (based on the 16S rDNA amplicon sequencing) confirmed the changes microbial community of each consortium, and showed that after the last (10th) passage all microbial communities were dominated by the representatives of Lactobacillaceae, Prevotellaceae, Veillonellaceae. The results of the functional analyses showed that the adapted consortia improved the efficiency of maize silage degradation, as indicated by the increase in the concentration of glucose and volatile fatty acids (VFAs), as well as the soluble chemical oxygen demand (sCOD). Moreover, bioaugmentation of anaerobic digestion communities by the adapted hydrolytic consortia increased biogas yield by 10-29%, depending on the origin of the community. The obtained results also indicate that substrate input (not community origin) was the driving force responsible for the changes in the community structure of hydrolytic consortia dedicated to anaerobic digestion.