Soft-hydrothermal processing

### 7. 英文概要

Subject: Use of Soft-Hydrothermal Processing to improve and Recycle Waste Mushroom Substrate for Sawdust and/or Corn-Cob Substrate Cultivation Media. (Project No. 3J123002)

Representing Research Fellow: Toru Miyamoto, Ph.D, belonging to Maeda Seisakusho Co. Ltd.

Abstract: Recently a lifestyle of fitness is becoming more important in Japan, consequently mushroom production has increased substantially. Therefore, district in which large quantities of mushroom are produced and consumed, such as Nakano city and north region of Nagano prefecture, substantial amount of used and waste culture medium of edible mushroom are recognized as social problem. Hypsizygus marmoreus (peck) bigelow (Tricholomataceae) is a mushroom that is cultivated and commercially available in throughout Japan as well as Lentinula edodes and Flammulina velutipes. Commercial strains and various culture techniques for high productivity have been developed, for example the contents of the medium, temperature of cultivation, and selection of strains, but there no effective methods and useful techniques have been developed for recycling and utilizing the used (spent) culture medium of edible mushroom. As a result, the used (spent) culture medium is disposed as an organic waste without any effective use and application (e.g. utilization, reuse, recycle, etc).

We have developed a groundbreaking method to effectively regenerate used waste culture medium of edible mushroom by means of the soft-hydrothermal processing, which can control the steam saturation ratio. The steam saturation ratio was calculated as follows:

Steam saturation ratio (\%) = $ \{ $ Steam density (kg/m $ ^{3} $ ) / Saturated steam density (kg/m $ ^{3} $ ) \}(\times 100) $

The success of this process lies in the high steam saturation ratio area of the liquid phase of water and is characterized by a higher ionic product (kw) than that of ordinary water. The ionic product is a key parameter to promote ionic reactions and can be related to hydrolysis. The ionic product of water is $ 1.0 \times 10^{-14} $ (mol/l) $ ^{2} $ at room temperature and increases with increasing temperature and pressure. A high ionic product favors the solubility of highly polar and ionic compounds, which creates the possibility of accelerating the hydrolysis reactions of organic compounds.

We have demonstrated that the culture process of hypsizygus marmoreus has been to be adequately mycelial growth and maturation, and a high yield of fruit-bodies and appreciate quality of fruit-bodies have been achieved.

And we have suggested the mechanism of regeneration of the waste culture medium. The waste culture media of the edible mushroom are the plausible candidates as raw materials containing partially degraded lignin. Recently, we succeeded the microbial production of the aromatic monomer of phenyl-propane structure from the waste culture media of the edible mushroom, Hypsizygus marmoreus. The yield was elevated after the pretreatment by the soft-hydrothermal processing of the starting raw materials. In this study, we traced the water/acetonitrile-soluble low-molecular weight compounds during the pretreatment using the LCMS analysis. Multivariate statistical analysis revealed the behavior of aromatic monomers which were consumed along with the growth of H. marmoreus and regenerated by the soft-hydrothermal processing. The LCMS analysis coupled with the chemometrics procedures was a robust tool to summarize and visualize the complex components of the bio-resources. We believe the hydro-thermal processing contributes "the sustainable sound material-cycle Society".

Key words; Corn-cob based Cultivation, Improving and Recycling, Soft-hydrothermal Processing, Sawdust Substrate Cultivation, Waste Culture Medium of Edible Mushroom.