FIG. 5.

Proposed pathway for the oxidation of alkane to fatty acid by strain Hxd3. An alkane (A) is subterminally carboxylated at C-3 (step I) to form an intermediate (B). Two adjacent terminal carbon atoms are then eliminated (step II) to form a fatty acid one carbon shorter than the original alkane (C). This fatty acid can be beta oxidized (step III) and subsequently mineralized to CO₂ or undergo transformation, such as chain elongation and C-10 methylation (step IV). Compound B (in brackets) is only a hypothetical intermediate and has not been observed. Atoms originating from the alkane are shown in bold type.