Biogenic formation of methane from coal is of great interest as an underexploited source of clean energy. The
goal of some coal bed producers is to extend coal bed methane productivity and to utilize hydrocarbon wastes
such as coal slurry to generate new methane. However, the process and factors controlling the process, and thus
ways to stimulate it, are poorly understood. Subbituminous coal from a nonproductive well in south Texas was
stimulated to produce methane in microcosms when the native population was supplemented with nutrients
(biostimulation) or when nutrients and a consortium of bacteria and methanogens enriched from wetland
sediment were added (bioaugmentation). The native population enriched by nutrient addition included Pseudomonas
spp., Veillonellaceae, and Methanosarcina barkeri. The bioaugmented microcosm generated methane more
rapidly and to a higher concentration than the biostimulated microcosm. Dissolved organics, including
long-chain fatty acids, single-ring aromatics, and long-chain alkanes accumulated in the first 39 days of the
bioaugmented microcosm and were then degraded, accompanied by generation of methane. The bioaugmented
microcosm was dominated by Geobacter sp., and most of the methane generation was associated with growth
of Methanosaeta concilii. The ability of the bioaugmentation culture to produce methane from coal intermediates
was confirmed in incubations of culture with representative organic compounds. This study indicates that
methane production could be stimulated at the nonproductive field site and that low microbial biomass may
be limiting in situ methane generation. In addition, the microcosm study suggests that the pathway for
generating methane from coal involves complex microbial partnerships.