Department of Microbiology, Max Planck Institute for Marine Microbiology, Bremen, 28359, Germany.
Environ Microbiol. 2014 Jan;16(1):130-40. doi: 10.1111/1462-2920.12251. Epub 2013 Sep 12.
The anaerobic degradation of propane and butane is typically initiated by activation via addition to fumarate. Here we investigated the mechanism of activation under sulfate-reducing conditions by one pure culture (strain BuS5) and three enrichment cultures employing stable isotope analysis. Stable isotope fractionation was compared for cultures incubated with or without substrate diffusion limitation. Bulk enrichment factors were significantly higher in mixed vs. static incubations. Two dimensional factors, given by the correlation of stable isotope fractionation of both carbon and hydrogen at their reactive positions (Lambda reactive position, Λrp), were compared to analyse the activation mechanisms. A characteristic reactive position isotope fractionation pattern was observed, distinct from aerobic degradation. Λrp values ranged from 10.5 to 11.8 for propane and from 7.8 to 9.4 for butane. Incubations of strain BuS5 with deuterium-labelled n-alkanes indicated that butane was activated solely at the subterminal C atom. In contrast, propane was activated mainly at the subterminal C atom but also significantly at the terminal C atoms. A conservative estimate suggests that about 70% of the propane activation events occurred at the subterminal C atom and about 30% at the terminal C atoms.
丙烷和丁烷的厌氧降解通常通过与富马酸盐的加成来激活。在这里，我们通过一个纯培养物（BuS5 菌株）和三个采用稳定同位素分析的富集培养物来研究硫酸盐还原条件下的激活机制。比较了有或没有基质扩散限制的培养物的稳定同位素分馏。与静态孵育相比，混合孵育的整体富集因子显著更高。通过比较两个维度的因素，即反应位置的碳和氢的稳定同位素分馏之间的相关性（反应位置同位素分馏，Λrp），来分析激活机制。观察到了一种特征性的反应位置同位素分馏模式，与好氧降解不同。丙烷的 Λrp 值范围为 10.5 到 11.8，丁烷的 Λrp 值范围为 7.8 到 9.4。用氘标记的正烷烃对 BuS5 菌株进行孵育表明，丁烷仅在亚末端 C 原子处被激活。相比之下，丙烷主要在亚末端 C 原子处被激活，但在末端 C 原子处也有显著的激活。保守估计表明，大约 70%的丙烷激活事件发生在亚末端 C 原子上，大约 30%发生在末端 C 原子上。
