title: Effects of Tween 80 and pH on mycelial pellets and exopolysaccharide production in liquid culture of a medicinal fungus.
abstract: This study investigated the effects of surfactant additives and medium pH on mycelial morphology and exopolysaccharide (EPS) production in liquid culture of a valuable medicinal fungus Cordyceps sinensis Cs-HK1. In the medium containing 20 g l⁻¹ glucose and 6 g l⁻¹ peptone as the sole nitrogen source, the Cs-HK1 fungal mycelia formed smooth and spherical pellets about 1.8-mm mean diameter. The mycelial pellets became less uniform at pH (4.0-5.0) lower than the optimum (pH 6.0) or turned to filamentous form at higher pH (8-9). Surfactants added to the medium inhibited pellet formation, resulting in smaller and looser pellets. Tween 80 exhibited a remarkable promoting effect on EPS production, increasing the EPS yield more than twofold at 1.5% (w/v), which was most probably attributed to the stimulation of EPS biosynthesis and release from the fungal cells by Tween 80.
authors.affiliation: Department of Applied Biology and Chemical Technology, State Key Laboratory of Chinese Medicine and Molecular Pharmacology in Shenzhen, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Yuan-Shuai
authors.initials: YS
authors.lastname: Liu
authors.forename: Jian-Yong
authors.initials: JY
authors.lastname: Wu
mesh_terms: D032661:Cordyceps / Q000187:drug effects / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D025282:Mycelium / Q000378:metabolism; D011134:Polysaccharides / Q000096:biosynthesis; D011136:Polysorbates / Q000494:pharmacology
chemical_list: D003470:Culture Media; D011134:Polysaccharides; D011136:Polysorbates