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.

Evaluation of polysaccharides content in fruit bodies and their antimicrobial activity of four Ganoderma lucidum (W Curt.: Fr.) P. Karst. strains cultivated on different wood type substrates

“…Baabitskaia et al [28] maintain that polysaccharide production by G. lucidum depends on such conditions as the initial pH of the substrate, C:N ratio and incubation temperature. The influence of substrate pH on polysaccharide production by G. lucidum was also reported by Kim et al [29] and Lee et al [30]. According to Prosiński [31], wood of various tree species differs with regard to the content of cellulose, lignin, hemicellulose, sugars, protein as well as other substances and shows differences in pH.…”

Experimental analysis of the oil addition effect on mycelia and polysaccharide productions in Ganoderma lucidum submerged culture

“…The pH value is always considered one of the critical indicators for mycelia growth and polysaccharide production of G. lucidum [14,15]. From the medium with or without corn oil additions, the pH profiles in cultures were observed and are shown in Fig.…”

“…To accelerate BIO and EPS productions, many studies have been conducted to examine the influence of operation conditions on G. lucidum culture, including medium composition [7][8][9][10][11][12], inoculation density [13], pH [14,15], temperature [7,16], oxygen supply [17], and even cultivation process variation [18]. Furthermore, some reports have emphasized the stimulating effects on BIO and EPS productions by the addition of plant oils.…”

Effects of Tween 80 and pH on mycelial pellets and exopolysaccharide production in liquid culture of a medicinal fungus

“…The morphological characteristics of fungal mycelia usually have a close relationship to the Xow properties of culture broth, the mycelial growth, and product formation. A few recent studies have demonstrated the close association between EPS productivity and mycelial morphology and the inXuence by various culture factors such as nutrients, and medium pH [6,12]. Fungal mycelia in a submerged culture present two major morphological forms-Wlamentous, freely dispersed Wlaments and pellets of aggregated mycelia-and the speciWc growth form in a fungal culture depends on numerous physiochemical factors [13].…”