Bioremediation Potential of Soil Lead (Pb) Tolerant Fungi isolated from Owino Uhuru, a Suburb of Mombasa County, Kenya

Abstract

A lead (Pb) smelter plant located in Owino Uhuru, a suburb of Mombasa County, caused lead poisoning and lifelong health effects. The Government of Kenya closed down the plant after reports of contamination. This study collected 24 soil samples from Owino Uhuru and analyzed them for lead levels using Microplasma Atomic Emission Spectrometry. The study also isolated and identified seven strains of fungi from the lead-contaminated soil and screened them for their ability to absorb lead. The genomic DNA of the fungal isolates was identified using ITS sequences of the rDNA. Blastn analysis indicated that the ITS gene sequences of the isolates had similarities of > 100% with known sequences in the nucleotide sequence database. These fungi were identified as Aspergillus welwitschiae, Aspergillus oryzae, Aspergillus piperis, Aspergillus austwickii, Aspergillus aflatoxiformans and Aspergillus tubingensis. The fungal isolates were tested for their ability to absorb lead at concentrations of 1.0 ppm, 0.8 ppm, 0.6 ppm, 0.4 ppm, and 0.2 ppm. The soil sample closest to the battery recycling plant contained more lead than those collected further away. Soil sample AU06, taken from the area bordering the wall of the lead smelter plant, had the highest lead concentration compared to all the samples. Aspergillus welwitschiae (GRY1) showed a higher potential for lead biosorption of 0.35 ± 0.1 ppm at 0.6 ppm lead concentration compared to other Aspergillus species. The study suggests using these fungal isolates for the removal and bio-treatment of lead-contaminated and polluted environments.