Enhancing Biogenic Methane Production from Coals; How the Microbial Ecology and Diversity Responds

Karen Budwill¹, Tara Penner², and Julia Foght^2
1Alberta Research Council, Edmonton, AB, Canada
²University of Alberta, Edmonton, AB, Canada

Contempory biogenic methane is known to occur in many coal seams. We have been investigating how nutrient additions could enhance methanogenesis to economic levels in coals. However, very little is known about the types and role of microorganisms involved in this methane generation. The purpose of this study was to determine the major Bacterial and methanogenic Archaeal species detectable in coal seams by 16S rRNA gene sequencing, and determine how these microbial populations might change with additions of complex nitrogen sources. Most of the Bacterial sequences amplified from uncultured coal samples were related to the Proteobacteria including Pseudomoas stutzeri, Thauera spp. and Acidovorax spp. and are reported to have various physiological traits, including hydrogen utilization, nitrate reduction and nitrogen fixation. When the coal samples were incubated in the laboratory with added complex nitrogen sources, methane was produced in significant amounts, and the Bacterial populations changed to comprise fermentative organisms within the Clostridia and the Bacteriodetes. Nearly all of the Archaeal sequences detected in methanogenic enrichment cultures inoculated with coal were closely related to Methanosarcina spp., which is capable of using a broad range of carbon sources for methane production, including acetate, H₂/CO₂, formate and methanol. Archaeal 16S rRNA gene sequences could not be amplified from DNA extracted from uncultured coal cores, and methane was not produced in significant amounts from coal incubated in minimal salts medium, indicating that methanogens are not present in very high numbers in the coal itself. This research has provided an insight into microbial diversity and ecology of coal beds which can be used in the development of enhanced methanogenesis as a secondary CBM recovery technology.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas