Characterisation of a microbial community associated with a deep, coal seam methane reservoir in the Gippsland Basin, Australia David J. Midgley a, ⁎, Philip Hendry a , Kaydy L. Pinetown b , David Fuentes b , Se Gong b , Danielle L. Mitchell b , Mohinudeen Faiz c a CSIRO Molecular and Health Technologies, P.O. Box 184, North Ryde, NSW, 1670, Australia b CSIRO Petroleum, P.O. Box 136, North Ryde, NSW, 1670, Australia c Origin, Exploration New Ventures, P.O. Box 148, Brisbane, Qld, 4001, Australia abstract article info Article history: Received 2 July 2009 Received in revised form 21 January 2010 Accepted 21 January 2010 Available online 28 January 2010 Keywords: Bacteria Archaea Coal seam methane Coal bed methane Microbial community Methanogenesis There is growing interest in optimising biogenic coal seam methane generation; however, relatively little is known about the microbiology of coal. To begin to address this deficiency, the biodiversity of a microbial community within a deep coal gas reservoir was investigated using the Amplified Ribosomal DNA Restriction Analyses (ARDRA) method. Additionally, a cultured subset of organisms from this community was examined for the ability to produce methane. ARDRA revealed that this community included both bacterial and archaeal lineages. The bacterial community was dominated by proteobacterial and Firmicutes taxa, though one actinobacterial taxa was also detected. This study is the first report of methanogenic archaea in an Australian coal seam gas reservoir. Cultures derived from the microbial community in the groundwater were able to produce methane from yeast extract and H 2 /CO 2 , but did not produce methane from coal. The ecological and physiological implications of these data are discussed. © 2010 Published by Elsevier B.V. 1. Introduction 1.1. Importance and background Rising extraction and remediation costs of coal production, along with climate change, have fuelled the global interest in alternative sources of energy. Worldwide, coal seam methane (CSM) reserves are large (1.4 × 10 14 m 3 ) and represent a significant energy resource (Dresselhaus and Thomas, 2001). Moreover, if coupled with CO 2 capture and injection technologies, coal seam methane has the potential to be a comparatively clean source of energy (Damen et al., 2005). Methane associated with coal is known to have two origins. The first is thermogenic methanogenesis where methane is formed as a by-product of thermocatalytic reactions during the coalification process. The second, biogenic methane formation, results from microbial degradation of coal. In some coals, it has been suggested that biogenic methane generation may be a substantial, and importantly contemporary, source of CSM (Faiz and Hendry, 2006; Kotarba, 2001; Thielemann et al., 2004). Coals are made up of decomposed plant remains that initially form peats. After peatification, peat may be metamorphosed into coal of various ranks depending on its depth of burial and temperature. Coalification involves the loss of labile components leaving behind more resistant, typically aromatic compounds that are bonded into a complex, heterogeneous ultrastructure (Faison, 1993). Biogenic methane formation thus requires an array of catabolic enzymes, from numerous organisms, which act syntrophically to degrade coal. The initial stages of anaerobic coal degradation are presumably conducted by fermentative bacteria with methanogenic archaea performing the final conversions of CO 2 ,H 2 , acetate, formate or other simple compounds to methane. 1.2. Microbial communities associated with coal There are relatively few studies of microbial communities associated with CSM reservoirs (Green et al., 2008; Li et al., 2008; Rogoff et al., 1962; Shimizu et al., 2007; Strąpoć et al., 2008). These studies suggest that coals within CSM reservoirs are generally colonised by an array of bacterial taxa that commonly include members of the Proteobacteria, most frequently from the families: Comamondaceae and Geobacter- aceae, though other proteobacterial families are also reported (Li et al., 2008; Penner et al., 2008; Shimizu et al., 2007). In addition to Proteobacteria, numerous Firmicutes, mostly from the order Clostri- diales have also been detected (Green et al., 2008; Shimizu et al., 2007; Strąpoć et al., 2008) along with a group of organisms from the Tenericutes family Acholeplasmataceae (Green et al., 2008). The Bacteroidetes also frequently feature in coal microbial assemblages, and while some taxa can be assigned to families such as the International Journal of Coal Geology 82 (2010) 232–239 ⁎ Corresponding author. Tel.: +61 2 9490 5062. E-mail address: David.Midgley@csiro.au (D.J. Midgley). 0166-5162/$ – see front matter © 2010 Published by Elsevier B.V. doi:10.1016/j.coal.2010.01.009 Contents lists available at ScienceDirect International Journal of Coal Geology journal homepage: www.elsevier.com/locate/ijcoalgeo