Degradation of used Engine Oil Alkanes by its Indigenous Bacteria, Production of PHA and Secretion of an Elastomer-Like Biopolymer

Microbes have been shown to adapt to extreme environments and to develop the ability to use various substrates. Here in collaboration with a local oil recycling company (Qubec, Canada), we assessed the biodiversity of bacteria and studied their ability to metabolize used engine oil (UEO). The bacterial species identified (Paenibacillus, Klebsiella, Micrococcus, Microbacterium, Bacillus, Pseudomonas, Rhodococcus and Stenotrophomonas) were similar to those found elsewhere in the world, including countries with much warmer climate than Canada (like China, India, and Egypt to name a few). This suggests that UEO as main carbon source -and not climate- is determinant for the biodiversity on UEO collection sites. Many bacterial strains identified here resisted to exposure to UEO at higher concentration (20 % v/v) than reported earlier. As observed in earlier reports for many bacteria under various growth conditions, bacteria screened from this UEO source were also able to produce an intracellular biopolymer that was identified as a polyhydroxyalkanoate (PHA). We also identified an interesting consortium (composed of Stenotrophomonas and Rhodococcus) that metabolized UEO alkanes, and appeared suitable for two applications bioremediation and biopolymer production. Under specific conditions, this same bacterial consortium secreted an elastomer-like biopolymer. The biopolymer formed at the surface of broth cultures where it was easily recovered. Based on FTIR analyses, the biopolymer was tentatively identified as ethylene propylene diene monomer (an EPDM rubber). To our knowledge, the conversion of UEO into an extracellular elastomer by bacteria has not been previously reported. Both species were found to be necessary for production of this biopolymer, suggesting a synergy among their respective metabolic machinery.