Changes in the microbial community during the acclimation process of anaerobic digestion for treatment of synthetic lipid-rich wastewater

Changes in the microbial community were investigated during the acclimation process of anaerobic digestion while treating synthetic lipid-rich wastewater, which comprised of glucose, acetic acid, lactic acid, and soybean oil. The oil content in the synthetic wastewater was increased successively from 0% to 25% and finally to 50% of the total carbon content, to clarify the effect of substrate type change from easily degradable organic materials to lipid. The oil decomposition-associated methane production rate increased as the microorganisms acclimated to the oil and eventually levelled off around 0.76 L/d. Analysis of the microbial community using next generation 16S rRNA gene sequencing (NGS) revealed the characteristic changes of dominant microorganisms Synergistales, Anaerolineales, Actinomycetales, and Nitrospirales from the domain bacteria, and Methanobacteriales and Methanosarcinales from the domain archaea. The increase in the relative abundance of Synergistales was found to be highly correlated with the increased rate of methane production from oil.