title: Culture pH affects exopolysaccharide production in submerged mycelial culture of Ganoderma lucidum.
abstract: In submerged culture of Ganoderma lucidum, the pH optimum for cell growth has been shown to be lower than that for exopolysaccharides (EPS) formation. Therefore, in the present study, a two-stage pH-control strategy was employed to maximize the productions of mycelial biomass and EPS. When compared, a batch culture without pH control had a maximum concentration of EPS and endopolysaccharides, which was much lower than those with pH control. Maximum mycelial growth (12.5 g/L) and EPS production (4.7 g/L) were achieved by shifting the controlled pH from 3.0 to 6.0 after day 4. The contrast between the controlled-pH process and uncontrolled pH was marked. By using various two-stage culture processes, it was also observed that culture pH has a significant affect on the yield of product, mycelial morphology, chemical composition, and molecular weight of EPS. A detailed observation of mycelial morphology revealed that the productive morphological form for EPS production was a dispersed pellet (controlled pH shifting from 3.0 to 6.0) rather than a compact pellet with a dense core area (controlled pH 4.5) or a feather-like pellet (controlled pH shifting from 6.0 to 3.0). Three different polysaccharides were obtained from each pH conditions, and their molecular weights and chemical compositions were significantly different.
authors.affiliation: Department of Biotechnology, Daegu University, Kyungsan, Kyungbuk 712-714, Korea.
authors.forename: Hyun Mi
authors.initials: HM
authors.lastname: Kim
authors.forename: Moon Ki
authors.initials: MK
authors.lastname: Park
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Yun
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation; D003470:Culture Media / Q000737:chemistry* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D011134:Polysaccharides / Q000378:metabolism*; D020940:Reishi / Q000166:cytology / Q000502:physiology*
chemical_list: D003470:Culture Media; D011134:Polysaccharides