Alkane hydroxylase from Acinetobacter sp. strain ADP1 is encoded by alkM and belongs to a new family of bacterial integral-membrane hydrocarbon hydroxylases

In Acinetobacter sp. strain ADP1, alkane degradation depends on at least five essential genes. rubAB and xcpR are constitutively transcribed. Here we describe inducible transcription of alkM, which strictly depends on the presence of the transcriptional activator AlkR. alkR itself is expressed at a low level, while a chromosomally located alkM::lacZ fusion is inducible by middle-chain-length alkanes from heptane to undecane, which do not support growth of ADP1, and by long-chain-length alkanes from dodecane to octadecane, which are used as sources of carbon and energy. The putative AlkM substrate 1-dodecene is also an effective inducer. Products of alkane hydroxylase activity like 1-dodecanol prevent induction of alkM expression. alkM is expressed only in stationary phase, suggesting its dependence on at least one other regulatory mechanism. Degradation of n-alkanes is a widespread trait among bac-teria, but little is known about the regulation of genes encoding alkane utilization. Acinetobacter sp. strain ADP1 is able to use long-chain-length alkanes with at least 12 carbon atoms as the sole source of carbon and energy. This requires at least five essential genes: rubAB, encoding rubredoxin and rubredoxin reductase (6); alkM, encoding the alkane hydroxylase; alkR