Normal alkanes predominate. Heavy gas oils and light lubricating oils. Asphalts - Polycyclic compounds. Aliphatic hydrocarbons are easier to degrade than aromatic compounds. Straight chain aliphatics are easier to degrade than branched chain hydrocarbons.
Saturated hydrocarbons are easier to degrade than unsaturated hydrocarbons.
Long chain aliphatics are more easily degraded than short chain aliphatics. Many C9 and shorter compounds can be biotoxic. Degradation by oxidation of the terminal methyl group and subsequent b oxidation. The presence of branching within an alkane interferes with b oxidation. Evidence for the anaerobic degradation of aliphatics is equivocal.