While cultivating mushrooms, we must think about the problems posed by harmful microorganisms. It is important to know what microorganisms are harmful and to understand their features. In this paper, first the features of major harmful microorganisms are introduced, and then countermeasures against these harmful microorganisms are suggested. Secondly, results of studies on the influence of global warming on mushroom cultivation are introduced. The main results are 1) mycelia of Lentinula edodes, shiitake mushroom, are easily damaged by Trichoderma harzianum in warmer conditions of 33 degrees Celsius, 2) the isolation rates of T. harzianum from bed logs of L. edodes are higher in areas where daily maximum temperatures frequently exceed 30 degrees Celsius than in other areas, 3) Hypocrea lactea is spread by airborne infection, 4) edible vinegar cont

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In a long-term consecutive administration study for 311 days at an aquaculture site, we considered the possibility of application of an oral immunostimulant of maitake (Grifola frondosa) fruiting bodies (maitake powder) to yellowtail (Seriola quinqueradiata). The cumulative fish mortality was significantly reduced by administration of maitake powder (approximately 45 mg/kg body weight/day) compared with the untreated control (P < 0.05). Fish administered maitake powder were also superior in body weight gain to the untreated control though the difference was not significant, and feeding efficiency was similar between the groups. Phagocytic activity was significantly stimulated by maitake powder administration compared with the untreated control (P < 0.05). We also performed a follow-up study on immunostimulation by maitake powder, with consecutive administration of the powder at a dosage of 48.5-mg or 91.6-mg/kg body weight/day for 28 days in an interior water tank test. The phagocytic rate was significantly improved by maitake administration compared with the untreated control at days 7, 14 and 28 (P < 0.01). The above results indicate that maitake powder is useful for improvement of mortality in yellowtail aquaculture through immunostimulation of macrophages.

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Tricholoma matsutake forms a fairy ring, and the area it encloses is called “shiro” in Japanese. The (oxalato)aluminate complex is an antimicrobial substance that was isolated from a shiro front, an active mycorrhizal zone, in symbiosis with Japanese red pine at Sakai (Kyoto). This complex may expel soil microorganisms from the shiro front in conjunction with the outward extension of the shiro. In order to confirm the common occurrence of the (oxalato)aluminate complex in shiros, we investigated whether it was present in shiros at Nishiokoppe (Hokkaido), Iwate (Iwate), and Ooshika and Shiojiri (Nagano) in the fruiting season. The host plants for shiros were Japanese red pine at Iwate and Shiojiri, Sakhalin fir at Nishiokoppe, and southern Japanese hemlock at Ooshika. The complex was detected in all active mycorrhizal zones of the shiros examined, and its concentration strongly correlated with mycelial density, antimicrobial activity, and pH. These results demonstrated that the (oxalato)aluminate complex is common to shiros of T. matsutake with different host plants.

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The protective effect of volatile compounds from spent substrates of shiitake (Lentinula edodes) and bunashimeji (Hypsizygus marmoreus) against Alternaria sooty spot of cabbage was investigated. Cabbage plants exposed to volatile compounds from both spent substrates were protected significantly from formation of necrotic spots on the leaves by Alternaria brassicicola (O-264 isolate). Because spent substrate of shiitake had a protective effect at a lower amount than bunashimeji, volatiles from the spent substrate of shiitake were tested for antifungal activity against O-264 spores. The germ tube elongation of spores was inhibited by spent substrate of shiitake, but the inhibition disappeared when the spent substrate was removed, suggesting the presence of fungistatic volatiles. Then, volatiles from the spent substrate of shiitake were tested for the induction of systemic disease resistances. Cabbage plants treated with the volatiles were protected from necrotic spots caused by O-264 even after removal of the spent substrate, implying that the volatiles from spent substrate of shiitake induced systemic disease resistance.

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Rice bran is used for various applications in Japan, but it is costly to collect and cannot be stored. Although we considered use of defatted rice bran as a substitute for rice bran in P. eryngii cultivation, it reduced the yield. Cultivation using wheat meal and defatted rice bran indicated comparable or greater performance relative to the standard plot in comparison of yield and size of parts of fruiting bodies. Thus, it is effective to combine wheat meal and defatted rice bran in P. eryngii cultivation.

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