<i>In situ</i> bioaugmented phytoremediation of cadmium and crude oil co-contaminated soil by <i>Ocimum gratissimum</i> in association with PGPR <i>Micrococcus luteus</i> WN01

Heavy metals and petroleum oil are the two most important contaminants in the environment. Currently, phytoremediation is regarded as an effective and affordable solution that allows the attenuation of toxic pollutants through the use of plants. Not many studies are carried out regarding the use of aromatic plants capable of remediating soil that is co-contaminated by heavy metal and petroleum hydrocarbons. A pot experiment was conducted to investigate the influence of cadmium-resistant PGPR <i>Micrococcus luteus</i> on the phytoremediation efficiency of <i>Ocimum gratissimum</i> in Cd and petroleum co-contaminated soil. The plants were harvested after 60 days of treatment and their growth and biomass were determined. The accumulation of Cd in plant shoots and roots was determined. The residual petroleum hydrocarbon concentration during the 60 days of the phytoremediation experiment was determined using GC-FID. <i>O. gratissimum</i> with <i>M. luteus</i> showed the highest Cd accumulation (14.05 mg kg^-1) and the highest reduction of TPH (46.64%). <i>M. luteus</i> ameliorated contaminant toxicity and promoted biomass production of <i>O. gratissimum</i>. These results demonstrated that <i>O. gratissimum</i> in combination with <i>M. luteus</i> can be efficiently used to remediate Cd and petroleum-co-contaminated soils.