SUMMARY: Conidia of Pithomyces chartarum (Berk. & Curt.) M. B. Ellis strain c rapidly bound benzimidazole (BIZ), thiabendazole (TBZ), furidazole (FUD), and 2-phenyl benzimidazole (PBIZ) when mixed with aqueous solutions of the compounds at room temperature. Almost complete removal (> 95%) of the compounds from solution could be achieved by raising the spore/compound ratio in the reaction mixtures. The binding process was temperature-independent over the range of o to 65°C and pH-dependent (optimum at pH 4.5). BIZ binding was more sensitive to variation of ionic strength than was binding of TBZ, FUD or PBIZ.
Binding of BIZ conformed to the Langmuir adsorption isotherm; binding of the substituted benzimidazoles conformed to the isotherm over only part of the concentration range tested. Analysis of the binding data indicated that BIZ was bound to a single class of sites on the spore surface while the substituted benzimidazoles were bound to two or more classes differing in their affinity. This adsorption may be the first in a series of events leading to inhibition of spore germination by benzimidazole derivatives.
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