Biosurfactant-producing Aspergillus, Penicillium, and Candida Performed Higher Biodegradation of Diesel Oil than a Non-producing Fungal Strain

Abstract

The biosurfactant production can enhance the hydrocarbon biodegradation, as the hydrophobicity of these compounds reduces the degradation rates. Much of the attention was given to microbial hydrocarbon biodegradation, while limited work is present regarding the capacity of fungal biosurfactants for enhancing the remediation process. This research work identified the potential of biosurfactant production and hydrocarbon degradation of selected fungal strains belonging to Aspergillus, Penicillium, and Candida genera in contrast to a hydrocarbon-degrading and biosurfactant non-producing fungal strain. The highest biodegradation was noted for Aspergillus niger FA5 (90.7%), followed by Penicillium chrysogenum FP4 and Aspergillus terreus FP6 (87.4 and 85.0%, respectively), and lastly, Candida sp. FG2 (80.1%). Biosurfactant-producing hydrocarbon degrading fungal strains A. niger FA5, P. chrysogenum FP4, A. terreus FP6, and Candida sp. FG2 degraded hydrocarbons 1.32-, 1.27-, 1.24-, and 1.18-fold higher than non-producing A. flavus FP10 (68.6%). When the data were analyzed for correlation, hydrocarbon degradation was found negatively corelated to surface tension (r = –0.747, p = 0.005), while positively correlated with emulsification index (r = 0.964, p < 0.001), and cell hydrophobicity (r = 0.835, p < 0.001). The results indicate that fungi capable of attaching hydrocarbons at high concentration to the cell surface and effectively reducing surface tension were able to exhibit significant improvements in the rate of hydrocarbon degradation. Hence, it is concluded that if a fungus can produce biosurfactant that can improve hydrocarbon emulsification and reduce surface tension, the hydrocarbon breakdown can be accelerated from 12 to 22% compared to non-producers