Radiation degradation of (1→3)-β-d-glucan from yeast with a potential application as a plant growth promoter.

The (1→3)-β-d-glucan extracted from the yeast cell wall was irradiated by γ-rays from a Co-60 source at dose range of 100-300kGy in a swelling condition of 10, 15 and 20% for degradation. The water-soluble contents of irradiated samples obtained by 10% (1→3)-β-d-glucan mixture increased from 25.89 to 66.71% by the increasing of irradiation doses from 100 to 300kGy. While the molecular weight of the water-soluble (1→3)-β-d-glucan was found to be decreased from 48.13 to 10.77kDa. In the UV-spectra of irradiated water-soluble (1→3)-β-d-glucan, a new peak appeared at 265nm with the intensity increased by the increase of the dose. The IR spectra of irradiated (1→3)-β-d-glucan were recognized by a decrease of the peak intensity at 1156cm(-1) indicated to COC glycosidic linkages with the increasing of irradiation dose. In addition, radiation degraded (1→3)-β-d-glucan with Mw about 18kDa prepared at the dose of 250kGy displayed a strongly promotion effect on the growth of mustard green and the optimum concentration of the degraded (1→3)-β-d-glucan was found to be about 75mgl(-1). Thus, the degraded (1→3)-β-d-glucan prepared by radiation technique displayed as a promising, safety and high effective plant growth promoter for agriculture application.