Abstract

This study was conducted to assess the ability of sunflower (Tithonia diversifolia) inoculated with Pseudomonas species to remediate soils contaminated with heavy metals (lead and zinc). The contaminants were added to 20 kg soil in pots as lead nitrate (Pb (NO₃)₂) and zinc nitrate (Zn (NO₃)₂); 400 mg/l metal concentrations were added to 20 kg soil in pots. The experimental design was a randomized complete block design (RCBD) with the two metal types (lead, zinc) and three species of Pseudomonas replicated thrice.  The results reveal that all the Pseudomonas sp. (P. putida ATCC 29352, P. cepacia ATCC 29351 and P. fluorescens F113) used showed the potential for remediating zinc and lead. However, P. fluorescens inoculated sunflower remediate zinc (Zn) the best, followed by sunflower inoculated with P. putida ATCC 29352, and sunflower inoculated with P. cepacia ATCC 29351 at 8 Weeks After Planting (WAP). The order of remediation ability of sunflower inoculated with Pseudomonas spp. in soil polluted with lead (Pb) is in the order of sunflower inoculated with P. cepacia ATCC 29351 ˃ sunflower inoculated with P. putida ATCC 29352 > sunflower inoculated with P. fluorescens F113. The shoot and root of the plant were analysed for Zn and Pb uptake after 8 weeks.  The bio-concentration factor (BCF) and translocation factor (TF) assessed at 8WAP showed that translocation of Zn from root to shoot by sunflower with Pseudomonas spp., was higher than Pb. In conclusion this research suggests that sunflower inoculated with Pseudomonas spp., has phytoextraction ability and could be used to remediate soil contaminated with Zn and Pb.

Key words: Bioremediation, phytoremediation, Pseudomonas spp., heavy metals.