Enzymes involved in oxidation of long-chain n-alkanes are still not well known, especially those in Grampositivebacteria. This work describes the alkane degradation system of the n-alkane degrader actinobacteriumGordonia sp. strain SoCg, which is able to grow on n-alkanes from dodecane (C12) to hexatriacontane (C36) asthe sole C source. SoCg harbors in its chromosome a single alk locus carrying six open reading frames (ORFs),which shows 78 to 79% identity with the alkane hydroxylase (AH)-encoding systems of other alkane-degradingactinobacteria. Quantitative reverse transcription-PCR showed that the genes encoding AlkB (alkane 1-monooxygenase),RubA3 (rubredoxin), RubA4 (rubredoxin), and RubB (rubredoxin reductase) were induced by bothn-hexadecane and n-triacontane, which were chosen as representative long-chain liquid and solid n-alkanemolecules, respectively. Biotransformation of n-hexadecane into the corresponding 1-hexadecanol was detectedby solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME/GC-MS) analysis.The Gordonia SoCg alkB was heterologously expressed in Escherichia coli BL21 and in Streptomyces coelicolorM145, and both hosts acquired the ability to transform n-hexadecane into 1-hexadecanol, but the correspondinglong-chain alcohol was never detected on n-triacontane. However, the recombinant S. coelicolor M145-AH,expressing the Gordonia alkB gene, was able to grow on n-triacontane as the sole C source. A SoCg alkBdisruption mutant that is completely unable to grow on n-triacontane was obtained, demonstrating the role ofan AlkB-type AH system in degradation of solid n-alkanes.
|Numero di pagine||10|
|Rivista||Applied and Environmental Microbiology|
|Stato di pubblicazione||Published - 2011|
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