THE ROLE OF BACTERIAL AND ARCHAEA IN DETERMINING THE METABOLIC PATHWAY OF BIOGAS FERMENTATION AT LOW TEMPERATURES

Abstract

The challenge in achieving large-scale biogas production still lies in the biogas fermentation process at low temperatures. Our goal was to delve into the metabolic pathway behind the formation of biogas at these lower temperatures, focusing on the dominant bacterial and archaeal communities. Employing a batch system with activated sludge inoculum at 10°C, we fermented cow manure at 12°C for 150 days. Through genetic sequencing and taxonomic analysis using OTUs from the 16S rDNA gene, we investigated bacterial and archaeal species. Correlation analysis between their abundance was conducted using Pearson correlation and t-tests via IBM SPSS Statistics. Our findings revealed a biogas production of around 0.74 L/day, with CH4 levels surpassing 0.45 L/g VS. Peak efficiency occurred between day 60 and 110, reaching its apex on day 90. Clostridium cellulovorans dominated, ranging from 13.9% to 27%, followed by Terrisporobacter petrolarius, around 16.2% to 23%. Specifically, the formation of biogas (CH4) predominantly occurred through the H2 pathway, led by significant hydrogenotrophic Archaea OTUs like Methanocorpusculum sinense (ranging from 4.95% to 37.10%) and Methanobrevibacter millerae (with relative abundances between 2.00% and 11.20%)