Mycoremediation and fungi-assisted phytoremediation of heavy metal contaminated landfills soil / Auwalu Hassan

Auwalu , Hassan (2021) Mycoremediation and fungi-assisted phytoremediation of heavy metal contaminated landfills soil / Auwalu Hassan. PhD thesis, Universiti Malaya.

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Abstract

The research is aimed to study the bioremediation of heavy metal landfill leachate contaminated soil using consortia of indigenous filamentous fungi and indigenous plants. Thirteen identified fungal isolates were used to formulate the consortia for mycoremediation. The mycoremediation was carried out in three phases, namely laboratory trial 1 using five consortia, laboratory trial 2 with varied concentrations of inoculum, and field application. The fungi-assisted phytoremediation was carried out in two phases: laboratory trials using Alocasia calidora, Prosopis juliflora, and Jatropha sp. and field trial using A. calidora. The analyses conducted included soil physicochemical and biological parameters, Fourier-transform infrared spectroscopy (FTIR) and High-performance liquid chromatography (HPLC) for soil, Field emission scanning electron microscopy (FESEM) for fungi, photosynthetic pigments in plants, Liquid chromatography mass spectrometry (LCMS) for plants, and enzymes assay in soil, fungi, and plants. The biosorption of metals in liquid medium showed that the highest removal was 90% at 50 mg/L. The biosorption increased with an increase in pH. In the laboratory trial 1, the soil amended with a consortium of all isolated fungi had best metal removal as 77% (for As) and 71% (for Mn). In laboratory trial 2, soil amended with 30% inoculum showed better removal of 80% As. In the field application, the range of metals removal was 36% - 67% in the treated soil. The FTIR showed the presence of methylene, amine, alkyl, phenol, and peroxide functional groups in the bioremediated soil. The treated A. calidora had maximum accumulation of Ni (201.77 mg/kg) and Pb (220.32 mg/kg) in the shoots and Pb (347.51 mg/kg) and Zn (523.02 mg/kg) in the roots. Fungi inoculated P. juliflora accumulated more Fe (1208.67 mg/kg) and Zn (452.71 mg/kg) in the shoots and Pb (142.66 mg/kg) and Zn (125.51 mg/kg) in the roots. Fe (953.20 mg/kg) was highest in the shoots of treated Jatropha sp. and Ni (153.50 mg/kg) in the root. In the field phytoremediation, Pb (320.32 mg/kg) and Fe (306.04 mg/kg) were maximally accumulated in the shoots and roots, respectively. An upregulated activity of POD, CAT, and APX was observed in the inoculated plants. Various metabolites that aided the metal tolerance, growth, and accumulation were found in the plants (Tryptophan, Indole-acrylic acid, 5,7,2’,3’-Tetahydroflavone, 5,2-Dihydroxy flavone, Scutellarein-6-glucoside, tripeptides, S-(4-Nitrobenzyl) glutathione). The prediction models fitted well with the bioremediation data. It is concluded that fungi bioaugmented soil allowed better metal removal than the untreated soil. The inoculation of A. calidora, P. juliflora, and Jatropha sp. with fungal organisms can be utilized as an effective strategy for enhancing tolerance, growth, and metal removal from polluted soil.

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