Purification and characterization of manganese superoxide dismutase from Ganoderma microsporum.

Manganese superoxide dismutase (Mn-SOD) in the mycelium of Ganoderma microsporum was purified to homogeneity by heat treatment at 70 degrees C, ammonium sulfate fractionation, DEAE-52 anion-exchange chromatography, and Sephacryl SH-200 chromatography. The molecular mass of its native form was estimated to be 98 kD by size-exclusion chromatography. This enzyme is tetrameric composed of four subunits of equal size of 25 kD. The pI of this purified Mn-SOD was located at pH 6.34 and 5.06 by isoelectric focusing. Comparisons of 17 amino acids from the N-terminus of Mn-SOD subunit with the derived amino acid sequences from the reported Mn-SOD cDNA clones of other sources indicated a high degree of homology among the Ganoderma genus but the Mn-SOD from G. microsporum showed a high variation when compared with other organisms.

[Identification of Candida albicans by specific primers of polymerase chain reaction and DNA probes].

Candida albicans is a pathogenic yeast. Two sets of universal primers were used for specific identification of Candida albicans with PCR-amplified ribosomal DNA internal transcribed spacers (ITS). Among the species of Candida, the amplified ITSI and ITSII of DNA fragments were similar in size. The PCR product was purified and labeled with digoxigenin and used as DNA probe in the detection with target DNA of Candida albicans by hybridization. Two sets of specific primers (CA1 and CA2 to amplify ITSI, CA3 and CA4 to amplify ITSII) were designed by alignment of ribosomal ITS sequence of pathogenic Candida albicans with other species to detect C. albicans by PCR. The sensitivity of PCR using the specific primers to detect pure culture of C. albicans was 0.1 ng (about 10(3)-10(4) cells). If the yeast cells were mixed with two other strains, there was a 10-fold decrease in sensitivity (1 ng or 10(4)-10(5) cells) under the same PCR conditions.

Differentiation and grouping of isolates of the Ganoderma lucidum complex by random amplified polymorphic DNA-PCR compared with grouping on the basis of internal transcribed spacer sequences.

Laccate polypores of the Ganoderma lucidum species complex are widespread white rot fungi of economic importance, but isolates cannot be identified by traditional taxonomic methods. Parsimony analysis of nucleotide sequences from the internal transcribed spacers (ITS) of the ribosomal gene (rDNA) distinguished six lineages in this species complex. Each ITS lineage may represent one or more putative species. While some isolates have identical ITS sequences, all of them could be clearly differentiated by genetic fingerprinting using random amplified polymorphic DNA (RAPD). To investigate the suitability of RAPD markers for taxonomic identification and grouping of isolates of the G. lucidum complex, RAPD fragments (RAPDs) were used as phenotypic characters in numerical and parsimony analyses. Results show that data from RAPDS do not distinguish the same clades as ITS data do. Groupings based on analysis of RAPD data were very sensitive to the choice of the grouping method used, and no consistent grouping of isolates could be proposed. However, analysis with RAPDs did resolve several robust terminal clades containing putatively conspecific isolates, suggesting that RAPDs might be helpful for systematics at the lower taxonomic levels that are unresolved by ITS sequence data. The limitations of RAPDs for systematics are briefly discussed. The conclusion of this study is that ITS sequences can be used to identify isolates of the G. lucidum complex, whereas RAPDs can be used to differentiate between isolates having identical ITS sequences. The practical implications of these results are briefly illustrated.