Shoji Ohga

Yield, mushroom size and time to production of Pleurotus cornucopiae (oyster mushroom) grown on switch grass substrate spawned and supplemented at various rates

To find a cost effective alternative substrate, Pleurotus cornucopiae 608 (yellow basidiomata) was grown on: (1) chopped, pasteurized switch grass (Panicum virgatum, 99%) with 1% ground limestone and (2) a mixture of pasteurized cottonseed hulls (75% dry wt.), 24% chopped wheat straw, and 1% ground limestone (all ingredients wt./wt.). The substrates were spawned at various levels (2.5%, 3.75% or 5% wet wt., crop I) and non-supplemented or supplemented with commercial delayed release nutrient (Campbells S-41) at various levels (0%, 1.5%, 3%, 4.5%, 6%, 7.5% and 9% dry wt., crop II). Maximum yield (weight of fresh mushrooms harvested at maturity) was obtained on cottonseed hull/wheat straw substrate at a 3.75-5% spawn level and 6% S-41 supplement. On switch grass substrate, increasing spawn levels and supplement levels stimulated yields in a linear fashion. However, maximum yields were only 46% or less for those of similar treatments on cottonseed hull/wheat straw substrate. Yields were three times higher on switch grass that was harvested after the grass had senesced (winter; beige color) compared to material that was harvested when the grass was green (summer; time of flowering). Additional physical processing of the material, such as milling, may improve yield potential of this material.

Transcriptional regulation of laccase and cellulase genes in the mycelium of Agaricus bisporus during fruit body development on a solid substrate

The cultivated mushroom Agaricus bisporus was grown and fruited in wheat straw compost. RNA was extracted from samples of mycelium growing in compost during colonization and fruit body development. Laccase gene (combined lcc1 and lcc2) expression and cel3 gene (cellobiohydrolase) expression were determined by Northern blot analysis and by competitive RT-PCR. The level of laccase transcripts was highest in colonized compost (prior to the onset of fruiting), declined during the period of fruit body enlargement and increased again after harvesting and during the second flush of fruit body production. No transcripts of the cel3 gene were detectable in colonized or pre-fruiting cultures, but the level became detectable and rose to a maximum at the veil-break stage of fruiting, declined after harvesting and rose again during the second flush. Gene expression for laccase and cellobiohydrolase correlated with the known changes of laccase and cellulase enzyme activities during the fruiting life cycle.

Cultivation of Pleurotus eryngii on umbrella plant (Cyperus alternifolius) substrate

Mycelial growth and mushroom yields of three strains of Pleurotus eryngii produced on wheat bran-supplemented umbrella plant (Cyperus alternifolius) substrate were assessed using surface brightness, bromophenol blue color reactions, ergosterol and glucosamine contents, and water potential as indicators of strain performance. Mycelial growth was 31%–46% greater, depending on strain, on the umbrella plant substrate compared with the mushroom industry standard sugi (Cryptomeria japonica) substrate. Mushroom yields on the first flush were 20%–23% higher, depending on strain, on the plastic bottle-contained umbrella plant substrate. However, yields on the second break were lower from the umbrella plant substrate. Because many growers in Japan only harvest one flush, production of P. eryngii on umbrella plant substrate may offer commercial producers an alternative basal ingredient to diminishing supplies of sugi sawdust.

Transcriptional regulation of laccase and cellulase in relation to fruit body formation in the mycelium of Lentinula edodes on a sawdust-based substrate.

Extracellular enzyme activities of laccase and cellulase and their transcriptional regulation were investigated at various growth stages in a sawdust-based substrate forLentinula edodes. Changes of laccase and cellulase activities revealed a clear relationship with fruit body development stages. Laccase and cellulase activities were regulated at the level of gene transcription. The level of laccase mRNA was maximal at the fully colonized stage and declined during fruit body development. Cellulase mRNA began to accumulate at the pin (miniature fruit bodies) formation stage. Cellulase mRNA transcripts were maximally expressed at the veil-break stage of fruit body development. This tendency was clearer in the fruiting cultures with the wide-range-weather strains than in non-fruiting cold-weather strains. Transcription of laccase and cellulase genes was also affected by the water conditions of the sawdust-based substrate. Primordia initiation occurred when the water potential of the medium was high for rapid mRNA transcription by the mycelium.

Influence of wood species on the sawdust-based cultivation of Pleurotus abalonus and Pleurotus eryngii.

Mycelial growth and fruit body formation ofPleurotus abalonus andP. eryngii cultured on various sawdust-based substrates from different wood species were investigated. Growth onCryptomeria japonica substrate resulted in good mycelial growth and a high yield of fruit bodies.Larix kaempferi substrate was unsuitable for the cultivation of these mushrooms. The fruit body formation rate correlated with mycelial growth from all the wood species tested. Although differences were found for mycelial growth and fruit body formation on various wood species, there were no wood species that were completely unsuitable exceptL. kaempferi. These results show that a wide range of wood species can be used for the cultivation ofP. abalonus andP. eryngii.

Evaluation of biological activities of extracts from the fruiting body of Pleurotus citrinopileatus for skin cosmetics

Pleurotus citrinopileatus Singer has recently become a popular delicacy in East Asian countries. We prepared a methanol extract, soluble fractions from the methanol extract, and a hot water extract of the fruiting bodies of P. citrinopileatus. The biological activities such as melanin biosynthesis inhibition, tyrosinase inhibition, antioxidant activities [1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, oxygen radical absorbance capacity (ORAC), and superoxide dismutase (SOD)-like activity], antibacterial activities, and antihyaluronidase activities of these extracts were evaluated. We found that the n-hexanesoluble, diethyl ether-soluble, and ethyl acetate-soluble fractions exhibited melanin biosynthesis inhibition in B16 melanoma cells, as well as antioxidant (ORAC) and antibacterial activities. However, the n-butanol-soluble and water-soluble fractions and the methanol and hot water extracts exhibited antioxidant (DPPH radical scavenging, SOD-like activity) and antihyaluronidase activities. These results indicate that the fruiting bodies of P. citrinopileatus have the potential to be used as an ingredient in skin cosmetics.

Effect of water potential on fruit body formation of Lentinula edodes in sawdust-based substrate

The influence of substrate water potential (ψ) on the growth and fruiting of three genotypes of shiitake (Lentinula edodes) was investigated. A slight reduction ofψ (−0.5MPa) stimulated mycelial and colony growth on liquid, agar, and sawdust-based substrates.L. edodes has been found to grow well at aψ around −0.5 MPa, which corresponds to a moisture content around 55%. A small decrease inψ at the final vegetative growth phase had positive effects on flush quantity. The substrateψ was significantly affected by the interaction between genotypes and spawn run time. Theψ of well-colonized mature substrate was −0.7MPa before and −4.OMPa after the fruiting. Theψ rose again to −0.7MPa during rapid absorbance of water by soaking, and this rise was repeated during the second and third flushes. It is suggested that the water-holding capacity of a substrate is related to culture maturity. Excellent water-providing capacity (higherψ) is expected in the substrate of well-matured cultures with a high density of mycelial colonization.

Effect of Electric Impulse on Sporocarp Formation of Ectomycorrhizal Fungus Laccaria laccata in Japanese Red Pine Plantation

We examined the effect of electric impulses on sporocarp formations of ectomycorrhizal fungus in a Japanese red pine (Pinus densiflora) plantation.Laccaria laccata was the dominant species in this study plantation. Spatial distribution concentrated in the electric impulse treatment zone, and recorded a markedly larger number of sporocarps compared with untreated control plots. The effect of electric impulses was also recognized onL. laccata fruiting with a mycorrhizal sapling in a pot. Sporocarp production ofL. laccata was strongly promoted by the electric impulse in experiments bothin vivo natural plantation stands andin vitro pot saplings. Our work indicates the possibility of enhancement of sporocarp production of the mycorrhizal fungi with electric impulses in the nursery and plantation.

Development of an Automatic Electrical Stimulator for Mushroom Sawdust Bottle

In is well known among mushroom farmers that many mushrooms extraordinarily grow within several tens of meters around the spot where lightning strikes. It is supposed that the electrical stimulus of thunderbolts into myceliated logs accelerates the generation or development of mushrooms. Unfortunately, we cannot control natural thunderbolts but we can create artificial thunderbolts such as the pulsed high voltages of pulsed power technology. We started this study in 2002 and reported at PPC 2003 about the effect of an increase in production of shiitake mushrooms. The results showed that the yield from logs to which pulsed high voltage was applied was twice as great as those that received no electrical stimulus. [1]. Although mushrooms have been cultured in the forest using oak logs since old times, automated indoor production is todays standard. The room temperature and humidity in mushroom factories can be suitably controlled. Bottles nested in trays are filled with sawdust and other materials, inoculated with mushroom mycelium, incubated, and finally grown and harvested. In this paper some experiments to increase production of mushrooms from sawdust bottles are described. After the experiments, an electrical stimulator was finally designed and installed at a mushroom factory in February 2005. Pulsed high voltages up to 140 kV were applied to sawdust bottles as an electrical stimulus. Application of pulsed high voltages increased the yield of mushrooms by 13 to 15 percent compared with mushrooms to which it was not applied.

Changes in phenol oxidases and superoxide dismutase during fruit-body formation of Pleurotus on sawdust culture

Abstract Peroxidase and laccase activities increased rapidly up to the formation of primordia and then declined throughout the entire stage of fruiting. In the case of Pleurotus ostreatus, the level of Mn-dependent peroxidase was very low in primordia and fruiting stages but gradually increased with the growth of the fruit-body, whereas no activity was detected in Pleurotus sajor-caju during all growth stages. Superoxide dismutase activity was observed mainly at the fruiting stages. These results show that changes in concentration of lignin-related enzymes are associated with the fruiting process.