Evaluation of nutritional substrate and physical stress (gamma irradiation) in β-glucan productivity by mushroom (Pleurotus ostreatus)

Abstract

β -Glucans present in mushrooms are bioactive polysaccharides that have many pharmacological (immuno-modulatory, antitumoral, hepatoprotector, anti- inflammatory and antioxidant) activities. The β-glucans productivity of the mushroom depends upon the growing conditions, nutritional substrates, biotic and abiotic stress factors that result in an enzymes over-expression. The study shows the potential response of glucan production by fungi grown on newly designed animal plant crude (hydrolyzate) extract broth (APCEB) substrate (animal-, plant-waste crude extract broth fortified with 1g KH₂PO₄ l^-1) and gamma irradiation. On application of physical stress factors (gamma irradiation, 1 to 6 kGy), 1 kGy gamma irradiation doses resulted in an increase in: protein (37.5%), carbohydrates (32.15%), glucans (12.0%) and growth (dry mass, 14.8%); these were due to the enhancement of low doses (1.0 kGy) of gamma irradiation upon growth and metabolism that was synergized by the radioprotective components (cysteine) that prevailed in the animal extract. This substrate supported the growth and glucan production of Pleurotus ostreatus than by Schizophyllum commune and Saccharomyces cerevisae. There are suggested procedures to assure the percentage of glucan purity and entity. The APCEB substrate is a general basic formula in which the animal and plant remains can be replaced by many others. The yield of this media economizes the glucan production.

Key words: β-Glucans, Pleurotus ostreatus, Schizophyllum commune, Saccharomyces cerevisae, gamma irradiation, submerged cultures and nutritional synergism