Diversity and heavy metal tolerance of fungi associated with different coal overburden strata of Tikak colliery, Assam

Heavy metal tolerance assay to the fungal isolates grown in agar plates supplemented with and without heavy metals. Experiments were set in triplicates for each concentration of a heavy metal. Colony diameter was measured after 15 days of incubation in a BOD incubator. Colony diameter in agar plates without adding heavy metal was considered as a positive control for normal growth of each isolate. Increase in one unit or more in colony diameter than the initial inoculum size (about 1-2 mm in diameter) was considered tolerant at that particular concentration of the heavy metal.