Effects of several metals on spore, biomass, and geosmin production byStreptomyces tendae andPenicillium expansum

Cultures ofStreptomyces tendae andPenicillium expansum grown on Actinomyces and Czapek's media, respectively, were exposed to 5 mg L−1 of manganese, magnesium, iron, cobalt, nickel, copper and zinc, supplied as sulfate salts. Only copper markedly increased geosmin (1α, 10β-dimethyl-9α-decalol), biomass, and spore production. inductively coupled plasma-atomic emission spectrometric analysis ofS. tendae andP. expansum cells did not indicate an accumulation of copper. Both 1 and 5 mg L−1 copper, as copper sulfate, increased total geosmin production in cultures ofS. tendae on several media, but decreased production on others, suggesting that substrate composition affects responses to copper.