Potential in heavy oil biodegradation via enrichment of spore forming bacterial consortia

It is quite challenging to recover heavy crude oil due to its high viscosity and long chain hydrocarbon contents. In this study the isolation of thermophilic bacterial consortia from crude oil contaminated soil samples and their ability to degrade heavy crude oil were investigated. Thermophilic spore forming bacteria were inoculated with heavy oil in minimal salt media. Maximum growth was observed on 21st day of incubation at 40 °C. Samples were analyzed for biosurfactant production, where a substantial decrease in surface tension and interfacial tension was not observed. A well-assay was used to check the potential of bacterial consortia for oil-clearing zones on oil agar plate with bacterial cultures and their cell-free filtrates. 16S rRNA sequencing of 27 isolates from oil contaminated soil showed that isolates belonged to three classes: Alpha-proteobacteria, gamma-proteobacteria and Bacilli. Scanning electron microscopy showed that the oil utilizing bacteria were rod-shaped with rough surface and fimbria. Gas chromatography analysis of treated oil after 21 days showed that bacterial consortia efficiently degraded heavy crude oil to light hydrocarbons ranging from C11–C27, from initial C37+ carbon chain of untreated controls. These bacterial consortia showed potential in heavy crude oil biodegradation by breaking it down to smaller hydrocarbon composition.