Biodegradation of crude oil by a halotolerant and biosurfactant producing strain of Mucor circinelloides in different microcosm conditions

ABSTRACT

Most petroleum-polluted soils have extreme conditions such as high salinity. The purpose of this study was to evaluate the effect of salinity in various concentrations of NaCl on oil hydrocarbons degradation and biosurfactant production by Mucor circinelloides. Also, the effect of biosurfactant production by the fungal strain on crude oil removal was studied. Finally, the oil biodegradation process by M. circinelloides was investigated in microcosm conditions. The fungi could grow in the presence of up to 200 g L⁻¹ NaCl and was able to remove 87.5% and 49.8% of 10 g L⁻¹ crude oil in MSM at 0 and 50 g L⁻¹ NaCl, respectively. It could also degrade 87% of aliphatic hydrocarbons in 25 g L⁻¹ NaCl. M. circinelloides was able to produce biosurfactant, and reduce the surface tension to 27.6 mN m⁻¹ and 32.9 mN m⁻¹ in NaCl concentrations of 0 and 25 g L⁻¹, respectively. The best performance of M. circinelloides in microcosm was achieved as 56.2% in soil with 10 g kg⁻¹ crude oil, C/N/P ratio of 100:10:1, 25 g kg⁻¹ NaCl and 20 g kg⁻¹ wheat bran over the period of 105 days. In conclusion, here a potent strain was introduced and characterised for the biodegradation of crude oil in non-saline and saline environments. It is able to use crude oil as a sole and supplementary source of carbon and also produce biosurfactant so as to facilitate crude oil degradation.

KEYWORDS:

• Biodegradation
• biosurfactant
• crude oil
• microcosm
• saline environment

Disclosure statement

The authors have declared that no conflicting interests exist.