The AlkB1 Alkane Monoxygenase of Rhodococcus qingshengii Strain X5 Is not Required for Growth on Alkanes

Investigation of monooxygenase systems responsible for the primary oxidation of alkanes is essential for the understanding of bacterial metabolism of these hydrocarbons. Genome analysis of Rhodococcus qingshengii strain X5 showed a wide variety of genes encoding the relevant enzymes, including 5 homologs of AlkB-type alkane monooxygenases. A strain with knockout of the alkB1 gene was constructed. Comparison of the ability of the wild-type strain and the mutant strain to grow on alkanes of various chain length at two temperatures (6 and 28°C) revealed the preservation of the basic phenotype: although growth of the mutant at low temperatures was weakened, the spectrum of oxidizable substrates did not change. This suggests that other functioning monooxygenase systems are active at different temperatures towards a wide range of alkanes.