Individually and Synergistic Degradation of Hydrocarbons by Biosurfactant Producing Bacteria

Background: Increasing worldwide contamination with hydrocarbons has urged environmental remediation using biological agents such as bacteria. Our goal here was to study the phylogenetic relationship of two crude oil degrader bacteria and investigation of their ability to degrade hydrocarbons. Materials and Methods: Phylogenetic relationship of isolates was determined using morphological and biochemical characteristics and ۱۶S rDNA gene sequencing. Optimum conditions of each isolate for crude oil degradation were investigated using one factor in time method. The rate of crude oil degradation by individual and consortium bacteria was assayed via Gas chromatography–mass spectrometry (GC-MS) analysis. Biosurfactant production was measured by Du Noüy ring method using Krüss-K۶ tensiometer. Results: The isolates were identified as Dietzia cinnamea KA۱ and Dietzia cinnamea AP and clustered separately, while both are closely related to each other and with other isolates of Dietzia cinnamea. The optimal conditions for D. cinnamea KA۱ were ۳۵°C, pH۹.۰, ۵۱۰ mM NaCl, and minimal requirement of ۴۶.۵ mM NH۴Cl and ۲.۱۰ mM NaH۲PO۴. In the case of D. cinnamea AP, the values were ۳۰°C, pH۸.۰, ۱۷۰ mM NaCl, and minimal requirement of ۵۵.۸ mM NH۴Cl and ۲.۱۰ mM NaH۲PO۴, respectively. Gas chromatography – Mass Spectroscopy (GC-MS) analysis showed that both isolates were able to utilize various crude oil compounds, but D. cinnamea KA۱ was more efficient individually and consortium of isolates was the most. The isolates were able to grow and produce biosurfactant when cultured in MSM supplemented with crude oil and optimization of MSM conditions lead to increase in biosurfactant production. Conclusion: To the best of our knowledge this is the first report of synergistic relationship between two strains of D. cinnamea in biodegradation of crude oil components, including poisonous and carcinogenic compound in a short time.