Functional Characterization of a 28-Kilobase Catabolic Island from Pseudomonas sp. Strain M1 Involved in Biotransformation of -Myrcene and Related Plant-Derived Volatiles

• Pedro Soares-Castro ^[1] ; Pedro Montenegro-Silva ^[1] ; Hermann J. Heipiepe ^[2] ; Pedro M. Santos ^[1]
  1. [1] Universidade do Minho

     Universidade do Minho

     Braga (São José de São Lázaro), Portugal

     
  2. [2] Centre for Environmental Research-UFZ, Leipzig
• Localización: Applied and Environmental Microbiology, ISSN 0099-2240, Vol. 83, Nº 9, 2017
• Idioma: inglés
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• Resumen

  • Pseudomonas sp. strain M1 is able to mineralize highly hydrophobic and recalcitrant compounds, such as benzene, phenol, and their methylated/halogenated derivatives, as well as the backbone of several monoterpenes. The ability to use such a spectrum of compounds as the sole carbon source is, most probably, associated with a genetic background evolved under different environmental constraints.

    The outstanding performance of strain M1 regarding -myrcene catabolism was elucidated in this work, with a focus on the biocatalytical potential of the -myrceneassociated core code, comprised in a 28-kb genomic island (GI), predicted to be organized in 8 transcriptional units. Functional characterization of this locus with promoter probes and analytical approaches validated the genetic organization predicted in silico and associated the -myrcene-induced promoter activity to the production of -myrcene derivatives. Notably, by using a whole-genome mutagenesis strategy, different genotypes of the 28-kb GI were generated, resulting in the identi- fication of a novel putative -myrcene hydroxylase, responsible for the initial oxidation of -myrcene into myrcen-8-ol, and a sensor-like regulatory protein, whose inactivation abolished the myr trait of M1 cells. Moreover, it was demonstrated that the range of monoterpene substrates of the M1 enzymatic repertoire, besides -myrcene, also includes other acyclic (e.g., -linalool) and cyclic [e.g., R-()-limonene and ()- -pinene] molecules. Our findings are the cornerstone for following metabolic engineering approaches and hint at a major role of the 28-kb GI in the biotransformation of a broad monoterpene backbone spectrum for its future biotechnological applications.

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