Manganese peroxidase isoenzymes produced by Pleurotus ostreatus grown on wood sawdust

The white rot basidiomycete Pleurotus ostreatus produces two manganese pero xidase (MnP) isoenzymes when grown in solid stationary conditions on poplar sawdust, whereas a lower production of these same enzymes is observed on f ir sawdust. Addition of Mn2+ to poplar culture resulted in a threefold incr ease of MnP activity; the same addition to fir culture was able to increase tenfold the MnP production. The two MnP isoenzymes (MnP2 and MnP3) were pu rified from P. ostreatus poplar culture. The isoenzymes differ in their pi values, molecular masses, and N-terminal sequences. MnP3 has the same N-ter minal sequence as that of a P. ostreatus MnP previously reported. Both isoe nzymes exhibit Mn2+-dependent and Mn2+-independent peroxidase activities wh en tested on phenolic substrates. The gene coding for the new isoenzyme MnP 2 was cloned and sequenced and the promoter region analyzed. Furthermore, t he chromosomal localization of all known P. ostreatus genes was determined. (C) 2000 Academic Press.