STUDY ON PRODUCTION OF PLANT GROWTH PROMOTER OLIGO-β-GLUCAN BY IRRADIATION IN COMBINATION WITH HYDROGEN PEROXIDE TREATMENT

Abstract

             The degradation of β-glucan extracted from brewer yeast Saccharomyces by gamma Co-60 irradiation in combination with chemical treatment is an effective method for producing water-soluble and low molecular weight products. At the dose of 250 kGy, the combined treatment of 0.5, 1 and 2% H₂O₂ has increased the content of water- soluble products to 1.2, 14.5 and 47.1%, respectively. The molecular weight (Mw) of b-glucan and treated with 2% H₂O₂ has decreased from 33.1 to 10.2 kDa by the increasing of the irradiation dose from 50 to 250 kGy. The water-soluble β-glucan preparations with Mw in range of 10.2-33.1 kDa have been applied for investigating the growth promotion effect on lettuce; and the results have shown that, oligo-β-glucan with molecular weight of about 18.9 kDa prepared by irradiation of 15% β-glucan in the 2% H₂O₂ solution at 100 kGy has displayed an optimum promotion. In a comparison with the untreated control sample, the treatment by oligo-β-glucan with Mw ~ 18.9 kDa and at the concentration of 100 ppm has made an increase of fresh biomass, plant height, root length and dried matter content of lettuce about 36.2, 18.2, 41.7 and 6.2%, respectively. The preparation oligo-β-glucan may potentially be applied for production of clean and high quality agro-products.