Effect of the Composition of Culture Media on the Laccase Production of Lentinus edodes Strains MORAIS 1 , H., RAMOS 1 , A. C., CSERHÁTI 2∗ , T., FORGÁCS 2 , E., DARWISH 2 , Y., ILLÉS 3 , Z. 1 Instituto Nacional de Investigacao Agraria Av. da Republica QUINTA DO MARQUÉS 2784-505 Nova Oeiras, Portugal 2 Hungarian Academy of Sciences ∗ Corresponding author Chemical Research Centre Phone: + 36 1 325 7900 Institute of Chemistry Fax: + 36 1 325 7554 P.O. Box 17 E-mail : forgacs@cric.chemres.hu 1525, Budapest, Hungary 3 Central European University 1051 Nádor u. 9 Budapest, Hungary Summary The effect of charge, ion radii and concentration of cations and fermentation time on the laccase production of four Lentinus edodes strains was determined using 28 different fermentation media and 60 days of fermentation time. Samples were taken every 10 days and the laccase activity was determined by visible spectrophotometry. Principal component analysis (PCA) was used for the assessment of similarities and dissimilarities between the laccase activities of the samples. As PCA is not suitable for the separation of the strength (potency) and selectivity of the effect of various factors (composition of cultures, fermentation time, Lentinus edodes strains) on the laccase production, they were separated by the spectral mapping technique (SPM). The dimensionality of the matrices of PC loadings and variables and the selectivity maps were reduced to two by the non-linear mapping technique. The results of PCA and SPM were compared by calculating linear relationships among the potency values and the corresponding coordinates of PCA and SPM maps. It was established that neither the type of the cations nor their concentration in the fermentation media had a significant effect on the laccase production. It was found that the type of the Lentinus edodes strains and the fermentation time exerts a considerable effect both on the strength and on the selectivity of the laccase production. It was further proven that the results of PCA and SPM were considerably different. Therefore, their simultaneous application in future quantitative structure activity relation- ship (QSAR) studies is highly recommended. © WILEY-VCH Verlag Berlin GmbH, 13086 Berlin, 2001 0138-4988/01/0411-0307 $ 17.50+.50/0 Acta Biotechnol. 21 (2001) 4, 307–320