Mycodegradation of Crude Petroleum Oil by Locally Marine Candida tropicalis

Aims: A great demand for crude oil as a source of energy has resulted in an increase in its production, which in turn a gross pollution of the environment. In this study, isolation of local marine yeast with a high potency in petroleum oil biodegradation was the target.

Place and Duration of Study: Samples were collected from oil-spilled seawater in Shalateen, Red Sea, Egypt.

Methodology: Redox indicator 2, 6-dichlorophenolindophenol (DCPIP) and oil extract dichloromethane were used for biodegradable crude oil verification. GC-MS analysis of the residual degraded oil was carried out during the biodegradation process. Biotoxicity of residual oil extracts was performed at interval time (0, 6th and 12th day). Bioaugmentation process was accomplished to imitate application on polluted site and determine biodegradable oil activities for both amended and non- amended polluted water samples (either under sterile or non-sterile conditions).

Results: Local marine Candida tropicalis strain was isolated and identified using partial sequence of 18sRNA gene. C. tropicalis was significantly (p < 0.05) capable to remove 98.63±0.73% crude oil (50% v/v) after 12 days of incubation at 25°C. Using GC-MS analysis, marine yeast isolate was capable of degrading the aliphatic fractions in crude oil, where almost hydrocarbons peaks were consumed during the degradation process. Using Artemia salina as a biomarker to test the toxic effect of residual oil extracts at interval time (0, 6th and 12th day), compared with the blank and control test, revealed that no-toxic intermediates or end products were detected. Non-sterile non-amended culture significantly (p < 0.05) showed 94.23±0.93% oil removal followed by non-sterile amended culture 65.5±7.7%.

Conclusion: These data demonstrated that the prospect in protecting the environment from oil pollution achieves after the application of marine C. tropicalis isolate.