midas_g_112 was particularly abundant in R2 inoculum, with a relative abundance of approximately 43%, though this decreased to about 19% in biofilm samples. Interestingly, while midas_g_112 was not detected in the inocula of R1 and R3, it appeared in the biofilm samples of both reactors, with average relative abundances of 3% in R1 and 9% in R3. This unclassified genus is commonly found in Danish anaerobic digester wastewater treatment plants , explaining its presence in the R2 inoculum. Its detection in biofilm samples of the other reactors suggests it may contribute to CO biomethanation. midas_g_112 is also frequently observed in anaerobic digestion processes and has been detected in TBR systems for syngas and CO methanation .