Identification of Heavy Metals Tolerant Fungi from Mining Sites at Anka Local Government Area of Zamfara State, Nigeria

Abstract

Study’s Novelty/Excerpt • This study investigates the tolerance levels of soil fungi, particularly Aspergillus niger, Fusarium sp., and Aspergillus fumigatus, against heavy metals such as iron, arsenic, and chromium in contaminated soils from mining sites in Zamfara State, Nigeria. • The research uniquely identifies Aspergillus fumigatus as the most tolerant species, suggesting its potential for bioremediation applications. • By providing detailed tolerance indices across varying concentrations, this study contributes significant insights into fungal resilience and its implications for environmental health management in heavy metal-contaminated regions. Full Abstract The indiscriminate release of heavy metals into the soil is a major health concern worldwide, as most of these heavy metals cannot be broken down into non-toxic forms. Soil samples were collected from mining and non-mining sites (as control) at Anka Local Government Area of Zamfara State, Nigeria. Soil samples analyzed had a pH ranging from 6.17 to 6.65, and the moisture content ranged from 1.8939 to 9.995, Carbon, Potassium, Phosphorus, Nitrogen, Vanadium Chromium, Manganese, Iron, Cobalt, Nickel, Copper Zinc, Stannum were detected in the soil samples contaminated with heavy metals. Iron (Fe), arsenic (Ar), and chromium (Cr) tolerance levels of the fungi isolated from mine site soil were investigated in this study. The highest fungal occurrence was Aspergillus niger with 38%; it was followed by Rhizophus sp and Penicillium sp with 24% and 11%, respectively; and lastly followed by Aspergillus fumigatus, Aspergillus flavus, and Fusarium sp all with 9% frequency of occurrence. The tolerance index (TI) of A. niger, Fusarium sp, and A. fumigatus were tested against Cr, Ar, and Fe at 50,100 and 200 parts per million (ppm). It was discovered that A. niger has TI at 50, 100, and 200 ppm, of 0.95 (high tolerance/HT), 0.87 (HT), and 0.82 (HT) respectively against Fe; against Ar was 0.85 (HT), 0.69 (medium tolerance/MT), and 0.54 (low tolerance/LT), respectively; and against Cr was 0.47 (LT), 0.39 (very low tolerance/VTL), and 0.34 (VLT). The findings demonstrated that A. fumigatus had TIs of 0.77 (MT), 0.71 (MT), and 0.66 (MT) against Fe at 50, 100, and 200 ppm, respectively; 0.93 (HT), 0.88 (HT), and 0.83 (HT) against Ar at 50, 100, and 200 ppm, respectively; and 0.95 (HT), 0.87 (HT), and 0.82 (HT) at 50, 100, and 200 ppm, respectively, against Cr. Specifically, the TI values for Fusarium sp against Fe, Ar, and Cr were determined to be 0.96 (HT), 0.85 (HT), and 0.48 (LT), respectively; likewise, the TI values for Fusarium sp against Ar and Cr were found to be 0.93 (HT), 0.91 (HT), and 0.84 (HT), at 50, 100, and 200 ppm, and 0.94 (HT), 0.90 (HT), and 0.86 (HT) at 50, 100, and 200 ppm, respectively. The findings of the study indicated that the isolates were found to be tolerant against Fe, Ar, and Cr (with A. fumigatus displaying the highest tolerance) and, therefore, could be potential candidates for the bioremediation of heavy metal-contaminated soil.

Keywords

• bioremediation
• fungi
• tolerance
• heavy metals
• contamination
• tolerance index (ti)