Degradation of the Isoprenoid 2,6,10,14-Tetramethylpentadecane by a Denitrifying Microcosm

Dawson, Katherine S.¹, Jennifer Macalady¹ (1) Pennsylvania State University, State College, PA

Despite enhanced preservation due to low reactivity, both aerobic and anaerobic mechanisms are active in the biodegradation of normal, branched and aromatic hydrocarbons in the marine environment. Bregnard et al. (1997) demonstrated the degradation of the saturated, branched chain hydrocarbon pristane (2,6,10,14-tetramethylpentadecane) by denitrifying microcosms and enrichment cultures obtained from an aquifer. Following a similar protocol, we recently demonstrated the loss of nitrate from enrichments using an activated sludge inoculum where pristane was the sole carbon source. At room temperature, the nearly complete disappearance of 1.5 mM nitrate was observed within 26 days. After the addition of concentrated nitrate to the cultures, an additional ~1 mM of added nitrate was consumed in 14 days. This loss of nitrate accounts for a 1.29 mg loss of pristane, 8.57% of the initial substrate, in 40 days. Additional experiments are in progress, to enrich cultures of sulfate reducing bacteria which utilize pristane and archaeal tetraether lipid cores as a sole carbon source. The results of these experiments will contribute new understanding of anaerobic degradation of hydrocarbons in oil reservoirs and pollutant plumes.