Temporal changes in microbial community composition during culture enrichment experiments with Indonesian coals

Enrichment cultures produced similar communities when grown on coals from the same seam (Mangus sub bituminous and Mangus anthracite), rather than from different seams of similar type (Burung sub bituminous and Mangus sub bituminous). Methanosaeta was the dominant methanogen species in the sub bituminous Burung coal culture, but was a lesser proportion in cultures of both Mangus sub bituminous and anthracite coals where Methanosarcina species were a greater proportion. Interestingly, obligate hydrogenotrophic methanogens from the genera of Methanobacterium, which were present at low levels in culture enrichment of all coal substrates, increased in proportion only in the absence of coal in the no-coal control enrichment cultures. These results suggest that the low rank Burung sub bituminous coal favours methane production by the obligate acetoclastic Methanosaeta members while both Mangus coals also favour metabolically versatile Methanosarcina members, and the absence of coal favours hydrogenotrophic methanogens. Despite the similarity of communities grown on coals from the same seam, greater quantities of methane were generated from the lower rank coals when compared to higher rank coals.