Heavy metal tolerance of nematode-trapping fungi in lead-polluted soils

A study was conducted to establish whether the diversity of nematode-trapping fungi in Pb-polluted soils increases or decreases with increasing degree of soil contamination, and whether the fungi from polluted soils exhibit higher tolerance to Pb toxicity than those from unpolluted soils. Five genera containing 28 nematode-trapping fungi were recorded in total from five collection sites highly contaminated by Pb, with the concentration ranging from 306 to 4907 mg kg−1. These fungi fell into seven groups according to their trapping mechanisms. In this area, the most frequent group was the net former of which 16 species were recorded and its occurrence frequency (61.15%) was higher than those of the others. Fungal diversity of NTF was slightly positively correlated with the Pb pollution levels (r = 0.29), which suggested the distribution of nematode-trapping fungi was not restricted by the heavy metal at these sites. The mycelial growth of nematode-trapping fungi which derived from either Pb-polluted soils or from unpolluted soils was completely inhibited by 1.8 mmol of Pb. At the Pb concentration of 1.2 mmol, the inhibition growth rates varied between 18.50 and 22.57% and there was no significant difference in the Pb tolerance of nematode-trapping fungi as to whether the strains derived from Pb pollution soils or unpolluted soils.