The effects of quorum sensing molecule farnesol on the yield and activity of extracellular polysaccharide from Grifola frondosa in liquid fermentation.

A strategy by exogenous addition of quorum sensing molecule farnesol to improve the production, antioxidant activity and antitumor activity of extracellular polysaccharide (EPS) of Grifola frondosa by liquid fermentation was proposed in the study. The highest yield of EPS induced by farnesol was 1.25 g/L, which was 150% higher than that of the control. Four polysaccharides including EPS-C-0M, EPS-C-0.2M, EPS-F-0M and EPS-F-0.2M were extracted and purified under the conditions of control and farnesol respectively. The physicochemical properties, antioxidant activities and antitumor activities were studied. Their chemical composition differed in sugar, protein and uronic acid contents, and they were composed of six constituent monosaccharides with different ratios, with the average molecular weights of 1.12 × 103, 1.89 × 103, 1.41 × 103 and 2.02 × 103 kDa, respectively. They presented similar FT-IR spectra, but different surface morphology. Antioxidant experiments showed that they had strong scavenging activities on ABTS+, hydroxyl radical, O2- and DPPH radical. Antitumor experiments showed that they had strong inhibitory effects on human cervical cancer (HeLa) cells and human liver cancer cells (HepG2) cells. Among the four polysaccharides, EPS-F-0.2M showed the highest antioxidant and antitumor activities, indicating that farnesol could regulate the biological activity of EPS by affecting structure and properties. These results demonstrated that appropriate adjustment of culture conditions had potential application in the development of polysaccharides with high antioxidant and antitumor activity. It provided a new strategy to enhance the production and bioactivity of edible and medicinal fungal polysaccharides by using quorum sensing molecules.

Optimization of effect factors for mycelial growth and exopolysaccharide production by Schizophyllum commune.

This paper is concerned with the optimization of effect factors for mycelial growth and exopolysaccharide production by Schizophyllum commune by one-factor-at-a-time and orthogonal methods. The one-factor-at-a-time method was adopted to investigate the effects of six different compounds (sodium carboxymethylcellulose, L: -glutamic acid, V(B1), naphthalene acetic acid, oleic acid, and Tween 80) on mycelial growth and exopolysaccharide production. Among these factors, oleic acid, V(B1) and Tween 80 were identified to be the most important factors. Subsequently, the concentration of oleic acid, V(B1) and Tween 80 were optimized using the orthogonal matrix method. The effects of the factors on the mycelial growth of S. commune were in the order of oleic acid > V(B1) > Tween 80, and those on exopolysaccharide production were in the same order. The optimal concentration for mycelia and exopolysaccharide were determined as oleic acid 0.1% (v/v), V(B1) 0.5 mg/L, and Tween 80 6 mg/L. The subsequent verification experiments confirmed the validity of the models. Under this optimized conditions in shake flask culture, the mycelial yield and exo-biopolymer production were 25.93 and 2.79 g/L, respectively, which were considerably higher than those obtained in the preliminary studies. The result was further confirmed in a 7-L fermentor experiments.