Association of laccase activity with conidiation in an aflatoxigenic strain ofAspergillus parasiticus

The relationship between laccase activity and asexual development in Aspergillus parasiticus was established. A. parasiticus produced a laccase activity similar to that reported for Aspergillus nidulans. Laccase activity appeared only in conidiating cultures and was absent from vegetative cultures. Shaking of the cultures inhibited conidiation and suppressed laccase activity. The composition of the media affected the degree of conidiation and the specific activity of laccase. Ammonium sulphate as sole nitrogen source was suppressive, whereas glutamate was highly stimulatory to both conidiation and laccase production. The addition of citrate was also stimulatory to conidia production and, to a lesser degree, laccase activity. There appears to be no quantitative correlation between laccase activity and the number of conidia produced.