Department of Applied Microbiology, Institute of Microbiology, University of Greifswald, Greifswald, Germany.
Appl Microbiol Biotechnol. 2012 Jan;93(1):343-55. doi: 10.1007/s00253-011-3415-z. Epub 2011 Jun 24.
Phenylalkanes are ubiquitously found in nature as pollutants originating from oil, gas oil and petrol. Rising commercial demand for mineral oil fractions has led to the increased prevalence of environmental contamination, whereby these particular hydrocarbons are encountered by bacteria which have subsequently developed sophisticated metabolic routes for purposes of degradation. Herein a detailed analysis of these metabolic pathways in the degradation of phenylalkanes by Mycobacterium neoaurum and Rhodococcus erythropolis highlighted preponderance for the formation of certain metabolites of which 17 were identified and whereby striking differences were noticed depending specifically upon the length of the substrate's alkyl chain. Although the degradation of even-numbered phenylalkane substrates was assumed to result in the generation of phenylacetic acid formed due to substrate terminal oxidation and subsequent β-oxidation, cultures of M. neoaurum and R. erythropolis were determined in an extracellular accumulation of odd-numbered acidic metabolites, suggesting a simultaneous presence of sub-terminal degradation mechanisms. However, results obtained from biotransformation assays containing even-chained phenylalkanoic acid intermediates as substrates revealed exclusive β-oxidative mechanisms and no generation of odd-numbered degradation products. R. erythropolis in contrast to M. neoaurum also proved viable for hydroxylation of the aromatic ring of metabolites. Interestingly, the generation of phenylacetic acid and subsequently 2-hydroxyphenyl acetic acid was monitored and entailed the presence of the lactone intermediate 2-coumaranone. These results enhance our understanding of the degradation of phenylalkanes and illustrate the potential application of such species in the bioremediation of these common environmental pollutants and in the strains' diverse abilities to transform mineral oil compounds to new valuable products.
苯烷烃作为源自石油、瓦斯油和汽油的污染物，在自然界中普遍存在。对矿物油馏分的商业需求不断增加，导致环境污染日益严重，这些特定的碳氢化合物被细菌遇到，细菌随后为降解目的开发了复杂的代谢途径。本文详细分析了分枝杆菌和红球菌降解苯烷烃的这些代谢途径，突出了某些代谢物的形成优势，其中鉴定出 17 种代谢物，并且根据底物烷基链的长度，注意到了明显的差异。尽管假设偶数个苯烷烃底物的降解会导致由于底物末端氧化和随后的β-氧化而形成的苯乙酸的生成，但分枝杆菌和红球菌的培养物在外源性积累奇数个酸性代谢物中被确定，这表明存在同时存在亚末端降解机制。然而，从含有偶数链苯烷酸中间作为底物的生物转化测定中获得的结果表明，仅存在β-氧化机制，而没有奇数个降解产物的生成。与分枝杆菌相比，红球菌还被证明可用于代谢物芳香环的羟化。有趣的是，监测到苯乙酸的生成，随后是 2-羟基苯乙酸的生成，并需要内酯中间体 2-香豆烷酮的存在。这些结果增强了我们对苯烷烃降解的理解，并说明了这些物种在这些常见环境污染物的生物修复以及在菌株转化矿物油化合物为新有价值产品的多样化能力中的潜在应用。
