Enzyme-mediated synergistic bioremediation of PAH and heavy metal co-contaminated soil using nocardia species and Helianthus annuus.
Ghasemi A, Abtahi SA, Jafarinia M, Azadi D
Summary
PubMedResearchers demonstrated that combining beneficial bacteria (Nocardia species) with sunflower plants can effectively remove toxic pollutants and heavy metals from contaminated soil, achieving 84-92% removal of PAHs and 70-79% removal of heavy metals—significantly better than either approach alone, offering a sustainable solution for agricultural and industrial land restoration.
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Key Findings
A five-species Nocardia consortium combined with sunflower achieved 84.5-92.3% PAH degradation and 69.7-78.9% heavy metal removal, significantly outperforming bioremediation alone (76.8-85.6%, 63.4-72.5%) and phytoremediation alone (55.2-65.4%, 48.6-58.7%)
Three Nocardia species (N. farcinica 85%, N. otitidiscaviarum 82%, N. cyriacigeorgica 80%) showed highest PAH degradation efficiency, with N. wallacei and N. veterana identified for the first time as effective PAH degraders and heavy metal removers
Combined treatment enhanced soil fertility (organic carbon increased 1.8%, total nitrogen 42 mg/kg) and reduced metal bioaccumulation in plants with translocation factors of 0.20-0.60
Original Abstract
Heavy metals and polycyclic aromatic hydrocarbons (PAHs) are persistent soil contaminants posing risks to human health, environmental stability, and agricultural productivity via oxidative stress, neurotoxicity, carcinogenicity, and reduced crop yields. This study evaluated the bioremediation potential of native Iranian Nocardia species combined with sunflower (Helianthus annuus) remediation for restoring PAHs and heavy metal-co-contaminated soils. Thirty-six soil samples from Fars Province, Iran, were analyzed to isolate bioremediating Nocardia using turbidometric, chromatographic, biochemical, molecular, and enzymatic assays. Greenhouse experiments employed spiked soils (PAHs: 100-200 mg/kg; heavy metals: As, Hg, Cd, Pb, Cr; 3-400 mg/kg) across low, medium, and high levels, with five treatments (control, phytoremediation(P), bioremediation(B), combined phytoremediation and bioremediation (MB), sterile control) assessed over 90 days for soil properties, contaminants, plant growth, translocation (TF)/bioaccumulation factors (BAF). Thirteen Nocardia isolates (36.11%) were identified belonging to eight species. N. farcinica (85%), N. otitidiscaviarum (82%), and N. cyriacigeorgica (80%) led in PAH degradation; N. wallacei (75%), N. kruczakiae (70%), and N. cyriacigeorgica (65%) excelled in heavy metal removal. This results showed that the first report of identification of N. wallacei and N. veterana as PAHs degrading and heavy metals removal agents. A consortium of these five species in the MB treatment achieved 84.5-92.3% PAH degradation and 69.7-78.9% heavy metal removal, significantly outperforming B (76.8-85.6%, 63.4-72.5%), P (55.2-65.4%, 48.6-58.7%), and controls (p < 0.001). MB enhanced soil fertility (OC: 1.8%, TN: 42 mg/kg), microbial activity, and reduced metal translocation (TF/BAF: 0.20-0.60). In conclusion integrated Nocardia bioremediation and sunflower phytoremediation offers a promising sustainable strategy for co-contaminated soils, with potential for field-scale application in industrial and agricultural contexts following further validation.
This connects to 9 other discoveries — 1 species, 3 topics, 5 related articles
Species Mentioned
The common sunflower is a species of large annual forb of the daisy family Asteraceae. The common sunflower is harvested for its edible oily seeds, which are often eaten as a snack food. They are also used in the production of cooking oil, as food for livestock, as bird food, and as plantings in ...
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