Department for Agrobiotechnology, Institute for Environmental Biotechnology, University of Natural Resources and Life Sciences Vienna, Konrad Lorenz Strasse 20, 3430 Tulln, Austria.
J Biotechnol. 2012 Feb 20;157(4):490-8. doi: 10.1016/j.jbiotec.2011.09.027. Epub 2011 Oct 2.
Crude oil consists of a large number of hydrocarbons with different susceptibility to microbial degradation. The influence of hydrocarbon structure and molecular weight on hydrocarbon biodegradation under anaerobic conditions is not fully explored. In this study oxygen, nitrate and sulphate served as terminal electron acceptors (TEAs) for the microbial degradation of a paraffin-rich crude oil in a freshly contaminated soil. During 185 days of incubation, alkanes from n-C11 to n-C39, three n- to iso-alkane ratios commonly used as weathering indicators and the unresolved complex mixture (UCM) were quantified and statistically analyzed. The use of different TEAs for hydrocarbon degradation resulted in dissimilar degradative patterns for n- and iso-alkanes. While n-alkane biodegradation followed well-established patterns under aerobic conditions, lower molecular weight alkanes were found to be more recalcitrant than mid- to high-molecular weight alkanes under nitrate-reducing conditions. Biodegradation with sulphate as the TEA was most pronounced for long-chain (n-C32 to n-C39) alkanes. The observation of increasing ratios of n-C17 to pristane and of n-C18 to phytane provides first evidence of the preferential degradation of branched over normal alkanes under sulphate reducing conditions. The formation of distinctly different n- and iso-alkane biodegradation fingerprints under different electron accepting conditions may be used to assess the occurrence of specific degradation processes at a contaminated site. The use of n- to iso-alkane ratios for this purpose may require adjustment if applied for anaerobic sites.
原油由大量对微生物降解具有不同敏感性的碳氢化合物组成。烃结构和分子量对厌氧条件下烃生物降解的影响尚未得到充分探索。本研究以氧气、硝酸盐和硫酸盐作为末端电子受体（TEA），研究了富含石蜡的原油在新污染土壤中的微生物降解。在 185 天的培养过程中，定量并统计分析了从正构烷烃 n-C11 到 n-C39、三种常用作风化指标的正构烷烃与异构烷烃比值和未解析复杂混合物（UCM）。不同 TEA 用于烃降解导致 n-和异构烷烃的降解模式不同。尽管在好氧条件下 n-烷烃的生物降解遵循既定模式，但在硝酸盐还原条件下，发现低分子量烷烃比中至高分子量烷烃更具抗降解性。硫酸盐作为 TEA 的生物降解作用最明显的是长链（n-C32 至 n-C39）烷烃。正十七烷与姥鲛烷比值和正十八烷与植烷比值的增加，首次提供了在硫酸盐还原条件下支链烷烃优先降解的证据。在不同电子接受条件下形成的明显不同的 n-和异构烷烃生物降解指纹图谱可用于评估特定降解过程在污染地点的发生情况。如果应用于厌氧地点，为达到此目的而使用的正构烷烃与异构烷烃比值可能需要进行调整。
