title: Kinetic study of the toxicity of zinc and lead ions to the heavy metals accumulating fungus Paecilomyces marquandii.
abstract: Studies have been carried out to determine the toxicity of zinc and lead ions to germinating spores and hyphal growth of heavy metal accumulating fungus Paecilomyces marquandii (former Verticillium marquandii). Inhibitive concentration (IC50) of zinc and lead ions was assayed by three different methods: image analysis, nephelometric on-line measurement and microcalorimetry. A kinetic model of spore germination and germ tube elongation was formulated and used as an auxiliary tool to determine IC50 values upon image analysis data. The inhibitive effect of Zn2+ and Pb2+ to P. marquandii spores was mathematically described by the Edwards equation. Comparing the obtained IC50 values, lead ions occurred to be more toxic to the germinating spores of P. marquandii than zinc ions (2.80 and 5.20 mM, respectively), although zinc ions induced a more significant delay in the development of the hyphae (13.84 h for 5 mM of Zn2+ and 9.30 h for 5 mM of Pb2+), which was demonstrated by the lengthened lag-phase (spore-swelling phase).
authors.affiliation: Department of Industrial Microbiology and Biotechnology, University of Łódź, Banacha 12/16, 90-237 Lodz, Poland.
authors.forename: Mirosława
authors.initials: M
authors.lastname: Słaba
authors.forename: Marcin
authors.initials: M
authors.lastname: Bizukojć
authors.forename: Bartłomiej
authors.initials: B
authors.lastname: Pałecz
authors.forename: Jerzy
authors.initials: J
authors.lastname: Długoński
mesh_terms: D007854:Lead / Q000378:metabolism*; D008954:Models, Biological; D010143:Paecilomyces / Q000254:growth & development*; D013172:Spores, Fungal / Q000254:growth & development*; D015032:Zinc / Q000378:metabolism*
chemical_list: D007854:Lead; D015032:Zinc