Role of potato extract in extracellular laccase production of Pleurotus florida

Pleurotus florida produces extracellular laccase when grown on potato-dextr ose medium but not in the other minimal media containing only dextrose. Whe n potato extract has been fractionated in G-25 column two types of fraction s were obtained with respect to iodine colouration. Fractions of the first peak (P1) gives blue colouration with iodine indicating the presence of sta rch whereas the fractions of the other region (P2) decolourise the iodine c olour indicating presence of one or more reducing compound(s). The P2 fract ions give red colour after reacting with diazonized sulphanilic acid sugges ting phenolic nature of the compound(s). Addition of fractions of either P1 or P2 in the minimal media can not support the laccase production in P. fl orida but combination of the two fractions is sufficient to induce laccase production. Similarly minimal media containing starch from the other two so urces can stimulate the laccase production in P. florida only in presence o f P2 fraction. On the basis of these observation we propose that phenolic c ompound(s) present in potato extract is capable of inducing laccase synthes is in P. florida.