Biodegradation of crude oil present in wastewaters: evaluation of biosurfactant production and catechol 2,3 dioxygenase activity

Water demand is increasing because of demographic and urban development in the last decades. Crude oil is an essential energy resource for many anthropogenic activities. However, it is associated with the generation of environmental pollution. The degradation of crude oil by microorganisms involves a biochemical process of various enzymes such as dehydrogenases, hydroxylases, and oxygenase’s for the degradation of aromatic and aliphatic hydrocarbons. A crucial enzyme involved in the degradation of aromatic hydrocarbons is catechol 2,3-dioxygenase. In addition, in adverse environmental conditions, various microorganisms produce biosurfactants, such as an adaptation and survival mechanism. In the present work, a native microbial consortium was used to study the hydrocarbon biodegradation of crude oil and its potential use to remove organic pollutants in wastewater. The kinetic degradation of crude oil was analyzed to determine the production of biosurfactants and the enzyme activity of catechol 2,3 dioxygenase. The degradation of the hydrocarbon was determined by aromatic-hydrocarbons (96.11%) and total-hydrocarbons (74.23%). The maximum values of the biosurfactant production were evaluated by oil displacement (206.95 mg/L) and emulsification capacity (DO600 0.2895). The kinetic analysis showed that the complex mixture of hydrocarbons was responsible for generating the stress to synthesize biosurfactants through a native microbial consortium. However, the decrease in catechol 2,3 dioxygenase activity and biosurfactant production was related to the degradation of aromatic hydrocarbons. The microbial consortium could produce biosurfactants during crude oil degradation, and it has a great potential to remove aromatic hydrocarbons present in wastewater.

Keywords: Bioremediation, Enzyme activity, hydrocarbons, Bioemulsifiers, Wastewater.