Applied Microbiology and Biotechnology 2012-01-01

Identification of phenylalkane derivatives when Mycobacterium neoaurum and Rhodococcus erythropolis were cultured in the presence of various phenylalkanes.

Susanne Herter, Annett Mikolasch, Frieder Schauer

文献索引：Appl. Microbiol. Biotechnol. 93(1) , 343-55, (2012)

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摘要

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.