Growth and production of laccases by the ligninolytic fungi, Pleurotus ostreatus and Botryosphaeria rhodina , cultured on basal medium containing the herbicide, Scepter® (imazaquin)

The herbicide, Scepter®, whose active principle is imazaquin, is commonly used in soybean farming to combat wide‐leaf weeds. The basidiomycete, Pleurotus ostreatus , and the ascomycete, Botryosphaeria rhodina , were evaluated for their growth and laccase production when cultured on basal media containing Scepter®. Both fungi could grow on the herbicide when cultivated in solid and submerged liquid culture in the presence of Scepter® at concentrations of 0–6% (v/v) for P. ostreatus , and up to 0–50% (v/v) for B. rhodina , and in each case produced laccases when assayed against ABTS [2,2 1 ‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulfonic acid)] and 2,6‐dimethoxyphenol. P . ostreatus could tolerate up to 6% of Scepter® before it became toxic to the fungus, while in the case of B. rhodina , 50% (v/v) Scepter® was the highest amount that supported grow, and laccase activity was detectable up to 25% (v/v). An inverse relationship existed between the level of Scepter® in the culture medium that supported fungal growth and laccase production. Analysis of the results showed that the fungi studied presented different behaviour towards Scepter® in the culture environment. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)