Heavy metals have different effects on mycelial morphology of Achlya bisexualis as determined by fractal geometry

The morphological response, as measured by changes to mycelial area, radial extension and border fractal dimension, of the oomycete Achlya bisexualis to Cu, Co, Hg, Zn and Cd at concentrations of between 0.05 and 3 mM is desc ribed. All of the metals decreased mycelial area and radial extension. Bord er fractal dimension increased in the presence of Cu, Co and Hg with indivi dual hyphae extending out beyond the mycelial margin. In the presence of 3 mM Hg these hyphae displayed spiral growth. Zn and Cd had no effect on bord er fractal dimension. We suggest that all of the metals slow growth and tha t Cu, Co and Hg may also disrupt the relationship between tip growth and br anching at the edge of the mycelium. (C) 2001 Federation of European Microb iological Societies. Published by Elsevier Science BN. All rights reserved.