The Biogas (rich in methane CH4) production is carried out through the process of anaerobic digestion (AD), in which residues are substrates for a microbial consortium that by their metabolism stabilize organic matter and generate by-products. Through co-digestion of residues from 1G and 2G ethanol production is possible to obtain sufficient CH4 to supply an integrated 1G2G plant ethanol. However, the AD process is highly complex from a microbiological point of view, since these microorganisms can follow different metabolic routes depending on the substrate or experimental conditions. The present work aimed to realize the characterization of the microbial community present in a co-digestion reactor of filter cake (1G), vinasse (1G), and deacetylation liquor (2G), under 55°C, to assess the change in this microbial community when the CH4 production was stable. Genetic sequencing of the 16S ribosomal RNA gene of samples from the microbial consortium was performed before being inserted into the reactor (sample 1), and when the CH4 production was stabilized (sample 2). Figure 1 shows the Family characterization made of the two samples. It is possible to notice that there is a difference between the two characterized samples. Among the main families found in Sample 2, the family stands out (~30%) Petrotogaceae, characteristic in thermophilic processes. Two other families that stand out in Sample 2 are (~3%) Syntrophomonadaceae and (~20%) Ruminococcaceae, which are bacteria from the acetogenic group and characterized by degrading cellulosic materials, which are predominant in the reactor. Methanomicrobiaceae which was present just in sample 2, indicating that the metabolic route of syntrophic oxidation of acetate coupled with hydrogenotrophic methanogenesis, was possibly predominant. With these results, it is possible to better understand the change that the microbial consortium undergoes, and which Bacteria and Archeae are involved in the degradation of residues from ethanol production
