Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA.
ISME J. 2012 Jan;6(1):146-57. doi: 10.1038/ismej.2011.88. Epub 2011 Jul 21.
Insight into the mechanisms for the anaerobic metabolism of aromatic compounds by the hyperthermophilic archaeon Ferroglobus placidus is expected to improve understanding of the degradation of aromatics in hot (>80° C) environments and to identify enzymes that might have biotechnological applications. Analysis of the F. placidus genome revealed genes predicted to encode enzymes homologous to those previously identified as having a role in benzoate and phenol metabolism in mesophilic bacteria. Surprisingly, F. placidus lacks genes for an ATP-independent class II benzoyl-CoA (coenzyme A) reductase (BCR) found in all strictly anaerobic bacteria, but has instead genes coding for a bzd-type ATP-consuming class I BCR, similar to those found in facultative bacteria. The lower portion of the benzoate degradation pathway appears to be more similar to that found in the phototroph Rhodopseudomonas palustris, than the pathway reported for all heterotrophic anaerobic benzoate degraders. Many of the genes predicted to be involved in benzoate metabolism were found in one of two gene clusters. Genes for phenol carboxylation proceeding through a phenylphosphate intermediate were identified in a single gene cluster. Analysis of transcript abundance with a whole-genome microarray and quantitative reverse transcriptase polymerase chain reaction demonstrated that most of the genes predicted to be involved in benzoate or phenol metabolism had higher transcript abundance during growth on those substrates vs growth on acetate. These results suggest that the general strategies for benzoate and phenol metabolism are highly conserved between microorganisms living in moderate and hot environments, and that anaerobic metabolism of aromatic compounds might be analyzed in a wide range of environments with similar molecular targets.
深入了解嗜热古菌 Ferroglobus placidus 的芳香族化合物厌氧代谢机制，有望增进对高温（>80°C）环境中芳香族化合物降解的了解，并鉴定出可能具有生物技术应用的酶。对 F. placidus 基因组的分析揭示了编码与先前在中温菌的苯甲酸和苯酚代谢中具有作用的酶同源的基因。令人惊讶的是，F. placidus 缺乏所有严格厌氧菌中发现的 ATP 非依赖性 II 类苯甲酰辅酶 A（辅酶 A）还原酶（BCR）基因，但却具有编码 bzd 型 ATP 消耗 I 类 BCR 的基因，类似于在兼性菌中发现的基因。苯甲酸盐降解途径的下部似乎与光养菌 Rhodopseudomonas palustris 中的途径更为相似，而不是所有异养厌氧苯甲酸盐降解菌报告的途径。预测参与苯甲酸盐代谢的许多基因存在于两个基因簇之一中。通过苯磷酸中间产物进行苯酚羧化的基因在单个基因簇中被鉴定出来。使用全基因组微阵列和定量逆转录聚合酶链反应分析转录丰度表明，预测参与苯甲酸或苯酚代谢的大多数基因在以这些底物生长时的转录丰度高于以乙酸盐生长时的转录丰度。这些结果表明，生活在温和和高温环境中的微生物之间的苯甲酸和苯酚代谢的一般策略具有高度保守性，并且可以在具有相似分子靶标的广泛环境中分析芳香族化合物的厌氧代谢。
