Characterization of Heavy Metal Resistant Fungi for Bioremediation of Agricultural Soils

Abstract

An increase in environmental toxins has led to a need for environmentally acceptable remediation methods. The most common and efficient class of microorganisms that can leach metals are fungi. Characterization of fungi that could have gained metal tolerance were isolated using soil samples from five different orchard farms that had been subjected to metal pollution. Four of the five locations (site I to site IV) had orchard fields near brick kilns, whereas site V, the control site, was located distant from any industrial activity. The potential of a chosen isolate (Aspergillus niger) for the production of metal nano particles as a green technological technique for usage in various applications is a highlight of the work. Heavy metal analysis was done using AAS. Metal accumulation was found to be higher at brick- kiln contaminated agricultural soil as compared to control soil and the following trend was observed at all sites zinc gt copper gt nickel gt lead gt cobalt gt chromium gt cadmium. As evident by the increase in concentrations of various metals during the study period, it is clear that the sites became increasingly contaminated over the period of time, with few exceptions. With regard to different locations, the average metal concentration revealed a wide range of fluctuation. The highest concentration of Cd, Cu and Pb was found at site IV, whereas, the Ni concentration was highest at site I. The highest concentration of Cr and Zn was observed at site III and site II respectively. However, the cobalt concentration was almost similar at the five sites. After that the soil samples were studied for the isolation of fungi. The fungi were further characterized morphologically and on the basis of molecular approach using ITS sequencing. Twenty-six (26) different fungal species were isolated from the soil samples, belonging to diverse groups with Ascomycota as the dominant phylum followed by Zygomycota. The fungal species were molecularly characterized using primers ITS1 and ITS4. The fungal isolates were checked ...