Distribution and diversity of olefins and olefin-biosynthesis genes in Gram-positive bacteria

The natural production of olefins (unsaturated aliphatic hydrocarbons) by certain bacterial genera represents an alternative and sustainable source of biofuels and lubricant components. The biochemical steps of olefin biosynthesis via the ole pathway encoded by oleABCD have been unraveled recently, and the occurrence of olefins has been reported for several Gram-negative and Gram-positive bacteria. However, the distribution and diversity of olefins among the Gram-positive bacteria has not been studied in detail.

We report the distribution of olefin synthesis gene clusters in the bacterial domain and focus on the olefin composition and the determinants of olefin production within the phylum of Actinobacteria. The olefin profiles of numerous genera of the Micrococcales order were analyzed by GC/MS. We describe for the first time olefin synthesis in representatives of the genera Pseudarthrobacter, Paenarthrobacter, Glutamicibacter, Clavibacter, Rothia, Dermacoccus, Kytococcus, Curtobacterium, and Microbacterium. By exchange of the native ole genes of Micrococcus luteus with the corresponding genes of actinobacteria producing different olefins, we demonstrate that the olefin composition can be manipulated with respect to chain length and isomer composition.

This study provides a catalogue of the diversity of olefin structures found in the Actinobacteria. Our ole gene swapping data indicate that the olefin structures are fundamentally determined by the substrate specificity of OleA, and at the same time by the availability of a sufficient supply of suitable fatty acyl-CoA substrates from cellular fatty acid metabolism. This makes OleA of Gram-positive bacteria a promising target for structural analysis and protein engineering aiming to generate olefin chain lengths and isomer profiles which are designed to match the requirements of various industrial applications.