Karyotype analysis of interspecific fusants of basidiomycetes by pulsed-field gel electrophoresis

The purpose of this research was to analyze the karyotype of the interspecific fusants of twoPleurotus species. Auxotrophic mutants derived from the cultivated strain ofP. ostreatus andP. cornucopiae were used. Protoplasts were fused electrically, and the fusants were selected under auxotrophic complementation. Esterase isozyme analysis showed that several fusants had isozyme bands originating from both parental strains, and others had unilateral isozyme bands. The fusant that had expressed isozyme bands of both parental strains showed chromosomal DNA bands of both of the parental strains in pulsedfield gel electrophoresis analysis. Despite the above results, the chromosomal composition of the fusants obtained by the pulsed-field gel electrophoresis did not exhibit all of the bands of both fusion parents.     

Effects of cultural conditions on high temperature tolerance of Lentinula edodes mycelia

The effects of several cultural conditions on high temperature tolerance of vegetative mycelia of five Lentinula edodes strains were investigated. Mycelium of longer culture age (70 days) was significantly shown high temperature tolerance compared to mycelium of shorter culture ages (14 and 30 days) for four strains, whereas SA142 that showed reverse. When the culture plates were pretreated at 30 and 33 degrees C for 48 h incubation before heat treatment (40 degrees C, 8 h), mycelia of L. edodes strains were shown high temperature tolerance. Effects of nutritional factors in BM (basic medium) for the high temperature tolerance of L. edodes strains were also investigated. While yeast extract (as nitrogen source) and starch (as carbon source) were added to BM media, as a result cultured vegetative mycelia of L. edodes strains were significantly shown high temperature tolerance against heat treatment (40 degrees C, 6 and 8 h). Further more, addition of bases (adenine + cytosine), vitamin (biotin) and organic acid (tartaric acid) to BM media, consequently vegetative mycelia of some L. edodes strains were also effective to increase high temperature tolerance.