Copper effect in petroleum hydrocarbons biodegradation by microorganisms associated to Juncus maritimus: role of autochthonous bioaugmentation

Abstract

The bioremediation potential of microorganisms from a saltmarsh plant rhizosphere and application of bioaugmentation in estuarine sediment co-contaminated were investigated. Rhizosediment (sediment in contact with plant roots) of Juncus maritimus was contaminated with copper and/or petroleum, inoculated with different autochthonous microbial consortia (resistant to copper and/or with petroleum degraders) and put in vessels to which plants were transplanted. Vessels were irrigated through a system that simulated estuarine tides. After 5 months, vessels were dismantled and copper and petroleum content in rhizosediments were determined. Copper’s presence reduced the potential of the microorganisms associated to J. maritimus rhizosphere for bioremediation of petroleum hydrocarbons in co-contaminated sediment. Indeed, hydrocarbons removal decreased from 39 to 25% when copper was present. In addition, bioaugmentation was not effective to overcome metal negative effects on petroleum hydrocarbons degradation, and the same removal rate was being observed (ca. 25%). Different methodologies for the formulation of consortia must be tested in this situation of co-contamination. Obtained results should be taken in consideration when planning the recovery of moderately impacted estuaries, aiming an effective protection and management of these areas, in the case of co-contamination.