EFFECTS OF SOME SUBSTITUTED ANTHRAQUINONES AND ANTHRONES ON LACCASE PRODUCTION IN PZ''UÀ OTUS SAJOR CAJU

Some substituted anthraquinones and anthrones were tested as regards their action on laccase excretion by Pleurotus sajor caju. Electrophoretic anaiysis showed that different isozymes were produced by the fungus in the presence of different compounds. Also other modifications into the culture media were studied, such as tlte degradation of anthraquinones and anthrones as a function of the time. Hydroxy-substituted anthraquinones and anthrones are widespread in nature, often as the corresponding glycosides (1,2). Moreover, some anthraquinone and anthrone derivatives are important as dyestuff intermediates and can be found as water-soluble pollutants in certain industrial wastewaters. Although the biogenesis of natural anthraquinones and/or anthrones is known (1'2)' the knowledge about their enzymatic degradation by micro-organisms is quite poor. For this reason, we have selected a strain of Pleurotus sajor'caju $ries) Singe., "apati" of growing fast on several phenolics, to check its ability to grow on ana to degiade the above mentioned compounds. It is well known that Pleurotu., spf. often respond to the presence of phenolics in the culture media with the excretion of a soluble laccas" (p-diphenol : oxygen oxidoreductase, EC | .r0.3 .2) (3,4). For this reason, the fungus was cultured in the presence of some hydroxy-substituted anthraquinones and anthrones, thai behave as true phenolics, and also in the presence ofanthraquinone sulfonic acids, that are cunently used as dyestuffintermediates. Also other substances, not belonging to the two classes under study, were tested to get a comparison with true or putative laccase inducers. The laccase production versus time ii the presence of these substances was monitored, as well as the degradation of the same compounds. In certain cases, other enzymes, possibly involved in anthraquinone and/or anthrone metabolism were searched. The ability ofthe fungus to grow fast and to fruit was also evaluated.