Use of Stimulatory Agents To Enhance the Production of Bioactive Exopolysaccharide from Pleurotus tuber-regium by Submerged Fermentation

Abstract

Fatty acids, organic solvents and surfactants were investigated for their stimulatory effects on the growth of fungal mycelium and production of exopolysaccharide (EPS) by submerged fermentation of an edible mushroom Pleurotus tuber-regium. Addition of 3.0 g/L Tween 80 at the late stage of exponential growth phase provided the best stimulatory effect on mycelial biomass and fungal EPS production with a 51.3 and 41.8% increase, respectively. The chemical structure of the EPS produced with addition of Tween 80 was found to be a glucomannan with similar monosaccharide composition and glycosidic linkages but a significantly lower molecular weight (3.18 ± 0.09 × 10(6) Da), compared to the control (4.30 ± 0.12 × 10(6) Da). These two EPS could significantly inhibit the growth of chronic myelogenous leukemia K562 cells in a dose dependent manner, with an estimated IC(50) value of 43.7 and 47.6 μg/mL, respectively. The use of stimulatory agents to enhance production of bioactive fungal EPS can be applied in other fungal fermentation processes for enhancing production of useful metabolites.

Effect of chemicals on production, composition and antioxidant activity of polysaccharides of Inonotus obliquus

“…All the organic solvents had no detrimental effect on cell growth. It is not consistent with the previous results, in which all the organic solvents, particularly chloroform and toluene, inhibited P. tuberregium mycelial growth [21].…”

“…2). This is not in agreement with the results in which EPS production by G. Lucidum [17], C. militaris [20], and P. tuber-regium [21] was inhibited with fatty acid of linoleic acid or was remarkably increased by palmitic acid. This could be partially attributed to the different lipid compositions of the mycelium among these mushrooms.…”

“…The new discovery in the experiment is that chloroform and ethanol significantly increased IPS1 content although they drastically suppressed the concentration of EPS during submerged culture of I. obliquus. Based on the present results and previously reports [21,29], it may be thought that the increased production of I. obliquus IPS is a secretory function of organic solvents. Fig.…”

“…When chloroform and acetone were added into the medium, the EPS production was only 76.7% and 75.3%, respectively, compared to that of the control. However, the detrimental effect of all the organic solvents on I. obliquus EPS production was not consistent with the previous studies in which methanol and hexane significantly (p < 0.05) increased the P. tuber-regium EPS production by 17.7% and 15.5%, respectively [21]. Chloroform and toluene increased Collybia maculate TG-1 EPS production and 0.3% (v/v) toluene increased the EPS production by 86% [29].…”

“…The research of the influence of plant oils on EPS yield by Grifola frondosa showed that the increased concentration of olive oil and soybean oil led to a higher EPS production [15]. Tween 80 was found to be the most effective in enhancing the production of bioactive EPS of Pleurotus tuber-regium [21,22] and the highest Antrodin C production of Antrodia camphorata was obtained with addition of Tween 80 [23]. These stimulatory agents were presumed to increase cell permeability by reorganizing the cell membrane and/or directly affecting synthesis of enzymes involved in the formation of target products [23,24].…”