ISOENZYMES OF MANGANESE-DEPENDENT PEROXIDASE AND LACTASE PRODUCED BY THE LIGNIN-DEGRADING BASIDIOMYCETE CERIPORIOPSIS-SUBVERMISPORA

The white-rot basidiomycete Ceriporiopsis subvermispora produces two f amilies of ligninolytic enzymes, namely manganese-dependent peroxidase s (MnPs) and laccases, when growing in liquid cultures of defined comp osition. In medium containing 11 p.p.m. of Mn(II), up to seven isoenzy mes of MnP and four isoenzymes of laccase were resolved by isoelectrof ocusing (IEF), with pi values in the range 4.10-4.60 and 3.45-3.65. re spectively. Occasionally, a fifth laccase isoform of pI 4.70 was also detected. In cultures with 25 and 40 p.p.m. of Mn(II), mainly the MnPs with higher pi values are produced. The isoenzyme pattern of MnP is n ot altered throughout the growth period of the fungus. MnP and laccase are also produced by C. subvermispora when growing on wood chips of P inus radiata. Highest levels of both enzymes were obtained during the first week of incubation. A second peak of MnP activity was observed d uring the fourth week, whereas very low revels of laccase were extract ed from the chips after the second week of growth. IEF analysis showed that the pi values of these laccases are similar to those of laccases produced in liquid cultures, being in the range 3.45-3.65. In contras t, four isoforms of MnP were resolved during the first week of incubat ion on wood chips, with pi values of 4.40, 4.17, 4.04 and 3.53. This p rofile underwent a transition during the second week of growth, at the end of which isoforms of MnP with pi Values of 3.53, 3.40, 3.30 and 3 .20 were resolved by IEF. Immunoblotting studies showed that the molec ular mass of MnP isoenzymes from liquid cultures was about 52.5 kDa, w hereas the molecular masses of MnPs extracted from wood varied from 52 .5 kDa to 62.5 kDa upon ageing of the cultures. The amino terminal seq uences of seven MnP isoenzymes were determined. The consensus sequence s of MnPs from liquid and solid cultures were clearly distinct, althou gh both showed homology to MnPs from related white-rot fungi.