Hypoxylon truncatum grows in the bed logs used for shiitake (Lentinula edodes) cultivation and forms perithecial stromata on them. The surface of these bed logs was divided into 160 quadrats by 8 vertical and 20 transverse equal interval grid lines, and the presence of stromata of H. truncatum in each quadrat was examined to estimate the injurious effects of H. truncatum on the bed logs. The ratio of quadrat to stroma was defined as the ratio of the sum of quadrats with stromata to the total number of quadrats. Each bed log was cut transversely at equal intervals into twenty disks and the area occupied by H. truncatum on the section was identified based on dark areas surrounded by a dark line. A positive correlation was apparent between the ratio of quadrat to stroma and the ratio of the total area occupied by H. truncatum to the total cross-sectional area of the bed log. The ratio of quadrat to stroma was divided into two or three grades, and the bed logs having each grade were used for further tests of shiitake cultivation. The fruiting body yield of shiitake was negatively correlated with the ratio of quadrat to stroma.

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Pleurotus cornucopiae var. citrinopileatus protoplasts derived from a wild-type dikaryotic strain were irradiated with UV light to obtain mutants displaying sporulation-deficient (sporeless) phenotypes. From a total of 5,566 regenerated dikaryotic mycelia obtained after UV treatment, six were shown to be mutants with sporulation-deficient traits. Based on the survival rate, the suitable irradiation dose was estimated to be 19.0-24.7 mJ/cm^2. It was confirmed that five mutants maintained a sporulation-deficient phenotype after subculturing three times at intervals of approximately one week. Furthermore, it was presumed that three of the mutants had a sporeless trait that arose as a dominant mutation from one nucleus of the original dikaryotic strain. In contrast, one mutant had a dominant mutation in the other nucleus, but the defect in the one remaining mutant could not be determined. The mutants obtained at a high irradiation dose (24.7 mJ/cm^2) had a much lower spore germination rate than the other mutants. The sporeless mutants obtained from this study formed fewer than 0.1% of the number of spores formed by the wild strains.

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We analyzed the components of nineteen kinds of soy sauce produced using (instead of Aspergillus oryzae) mushroom strains that produce salt tolerant proteases. Mushroom soy sauces produced by Paecilomyces cicadae NBRC33259 and Mucidula mucida var. asiatica SKB022 showed high total nitrogen contents, with less sodium soy sauces of these strains respectively containing total nitrogen of 1.59% and 1.42%. These mushroom soy sauces also showed a high formol nitrogen content of 1.15% and 0.84%, respectively. These values were approximately that of the tested commercial soy sauce, which contained 1.50% total nitrogen and 1.17% formol nitrogen. Reducing sugar content of the less sodium soy sauce produced by Muc. mucida var. asiatica SKB 021 was 102.5 g/L, and that of the normal soy sauce produced by Muc. mucida var. asiatica SKB 022 was 89.46 g/L. These values were markedly higher than that of the commercial soy sauce (24.5 g/L). High reducing sugar content appears to be an important feature of mushroom soy sauces, although there were no marked differences between other components of some mushroom soy sauces and commercial soy sauce.

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In this study, we examined the effect of earthworm extract on the vegetative mycelial growth of Tricholoma matsutake. Mycelial dry weights were much higher when the vegetative mycelium of the fungus was cultured in Hamada matsutake liquid medium supplemented with earthworm extract instead of the conventionally used dried beer yeast extract. The effect of earthworm powder extract [1.0, 3.0, and 5.0 g/L (w/v)] on the vegetative mycelial growth of the fungus was investigated. Medium containing an extract from 5.0 g/L (w/v) earthworm powder showed better mycelial growth than media containing extracts from 1.0 and 3.0 g/L (w/v) earthworm powder. The vegetative mycelium was cultured in modified Hamada matsutake earthworm extract liquid medium supplemented with trehalose instead of glucose. Mycelial growth was the highest in medium containing 8% trehalose.

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