The underlying idea has been described in our previous reports (Sakai et al., 2007; Imachi et al., 2008).
The method has been proven to be successful to eliminate non-target fast-growing methanogenic populations. Isolation
of strain RMAST was achieved via three steps: (i) enrichment by the co-culture method with Thermacetogenium phaeum
PBT (Hattori et al., 2000) as the H2-supplying partner organism and acetate as the sole energy source on WS
medium; (ii) isolation of a co-colony with T. phaeum PBT by plate cultivation based on WS medium (Nakamura et al.,
2011); and (iii) isolation of a pure colony of strain RMAST in a solidified medium ofW medium. Separating strain RMAST
from the cells of T. phaeum PBT was very difficult as the methanogen always formed co-colonies from which the
partner bacterium was difficult to eliminate.