Exploring the petrochemical bioremediation capacities of aerobic thermophilic bacteria

Yenketsamy, Thalia Thanushree
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Crude oil is a common environmental contaminant that has detrimental effects on marine, freshwater and soil environments and the biota that inhabit these ecological niches. Numerous oil remediation strategies have been developed, with different efficacies and downstream effectiveness. One approach that has garnered a lot of attention is the use of bacteria for hydrocarbon bioremediation. This study explored the hydrocarbon bioremediation capabilities of aerobic, thermophilic bacteria on alkane hydrocarbons. A substantial collection of aerobic thermophilic bacteria was screened through liquid and plate-based assays for their capacity to degrade oil hydrocarbons and the potential to produce biosurfactants. Three strains of Bacillus licheniformis, namely But5A1A, But5A1B and Wam9A3, showed promise in terms of their oil degradation and biosurfactant production capabilities. Complete genome sequencing of these strains was undertaken with the purpose of identifying the molecular basis underlying the observed hydrocarbon degradation. Although no clear pathway was established, a number of enzymes with known roles in hydrocarbon degradation, for example alkane monooxygenases, were identified. Moreover, genes that encode the biosurfactant lichenysin, which may be responsible for the oil displacement activities observed during the screening assays, were also identified. This biosurfactant is likely responsible for the enhanced degradation capacity observed in B. licheniformis But5A1A. Finally, GC-MS analysis was used to analyse the degradation capacities of these strains. These results support the observations made during the liquid assays and further suggests the production of alkanes by these bacterial strains of an unconfirmed function. Overall, these strains demonstrate great potential for future bioremediation ventures
A dissertation submitted in fulfilment of the requirements for the degree Master of Science in Molecular and Cell Biology in the Faculty of Science, University of the Witwatersrand, Johannesburg, 2020
Yenketsamy, Thalia Thanushree. (2020). Exploring the petrochemical bioremediation capacities of aerobic thermophilic bacteria. University of the Witwatersrand, https://hdl.handle.net/10539/30204