Impacts of long chain fatty acids injection on biogas reactors performance stability and microbial community structure and function

Biogas plants often face multivarious challenges during the operation, with the accumulation of long chain fatty acids from the influent feedstock being one of the most important. Although the negative effect of lipids excess in anaerobic digestion is known, there is limited knowledge of what happens at transcriptomics level when the microbial community is exposed to such kind of incidents. The present study aimed to shed light on the response of the biogas microbiome under an impact load of long chain fatty acids. The utilization of genome-centric metagenomics has provided novel insights into the microcosm of biogas reactors. Remarkably, this approach led for the first time to discovery of Nigerium sp. and has also illuminated the functionalities of this microorganism within this specific environment. Furthermore, a revelation emerged associated with the ability of Candidatus Hydrogenedentes sp. for & beta;-oxidation. The transcriptional analysis revealed the Cluster of Orthologous Group (COG) category "Lipid metabolism" as the dominant category in up-regulated genes. Furthermore, activation of genes encoding cell motility proteins, including flagellar assembly and bacterial chemotaxis, was evidenced.