Isolation And Characterization Of Diesel Oil-Degrading Yeast From Cameroon Soil And Effects Of Various Factors On Its Biodegradation Potential

Potential diesel oil-degrading yeast strain KML was isolated from Cameroon soil sample with no previous history of diesel oil contamination. The isolate KML was identified as Yarrowia lipolytica based on its morphological, physiological and biochemical characteristics, and the5.8S rRNA-ITS gene sequence analysis. Studies of the biodegradation potential of the isolate was performed with various factors and results showed that, among all the factors tested, the optimal temperature that supported the growth of isolate KML was30℃, the optimal pH-value was9, and the initial diesel oil concentration that increased the biodegradation rate was1%(v/v). Results also showed that the optimum inoculums concentration among all the concentrations tested was7×106cells/ml, and yeast extract at1mg/ml concentration appeared to be the best source of nitrogen as nutrient. Isolate KML degraded up to78.0%of diesel oil in the presence of rhamnolipid as biosurfactants at10mg/ml concentration. Gas chromatography-mass spectrometry (GC-MS) analysis showed significant changes in the peaks of hydrocarbons present in the residual diesel oil extracted after5and9days of incubation compared to the control.