Methanogenic biodegradation of C13 and C14n-alkanes activated by addition to fumarate

Abstract

n-Alkanes comprise a substantial proportion of crude oil; however, their degradation mechanism under methanogenic conditions is still unclear. Here, we investigated the initial activation mechanism of biodegradation of n-tridecane and n-tetradecane by methanogenic cultures enriched from a low-temperature oilfield production water. Methane accumulated in alkane-degrading enrichment cultures during the whole incubation period of 364 days, demonstrating that alkanes were actively degraded. Putative metabolites consistent with succinylated n-tridecane and n-tetradecane were detected, together with alkylsuccinate synthase-like genes, suggesting that alkanes were initially activated upon the addition of fumarate. Smithella and Desulfatibacillum in conjunction with hydrogenotrophic and acetoclastic methanogens were proposed to be important alkane degraders under methanogenic conditions. The results of this work added evidence that fumarate addition is a key activation mechanism in methanogenic alkane degradation.