AN OVERVIEW OF THE RECENT ADVANCES ON THE PHYSIOLOGY AND MOLECULAR-BIOLOGY OF LIGNIN PEROXIDASES OF PHANEROCHAETE-CHRYSOSPORIUM

The lignin-degrading white-rot fungus Phanerochaete chrysosporium prod uces two families of extracellular peroxidases designated lignin perox idases (LIPs) and manganese-dependent peroxidases (MNPs) which are com ponents of the lignin degradation system of this organism. The number and types of LIP and MNP isozymes produced vary dramatically in respon se to changes in culture conditions. Protease-mediated degradation of LIPs was shown to be the major cause for the decay of LIP activity in idiophasic cultures of P. chrysosporium. Use of biochemical mutants ha s not only yielded information on the relative importance of LIPs and MNPs in lignin degradation but has given us insights into the regulati on of production of LIPs and MNPs. The genes encoding the major LIPs h ave been cloned and sequenced and were shown to have a high degree of homology to each other. Karyotyping studies indicated that heterokaryo tic strains contain ten chromosomes and that the LIP genes are distrib uted on at least two chromosomes.