Abstract
The optimization of beta-glucan production by Ophiocordyceps dipterigena BCC 2073 was carried out. For the three-step optimization performed in 250-mL Erlenmeyer flasks, at the first step, the maximum beta-glucan production of 16.48 +/- 0.60 g/L was obtained using molasses and malt extract. During the second step, we sought to find an alternative carbon source; the highest beta-glucan production of 16.96 +/- 1.33 g/L was obtained using yeast extract and hydrolyzed cassava starch. The third step involved the optimization of nitrogen sources, and the highest beta-glucan content (18.16 +/- 0.15 g/L) was obtained with yeast extract. To reduce the use of yeast extract for beta-glucan production, a fractional factorial design at 2 levels was applied after the three-step optimization to reduce the concentration of yeast extract by combination with other suitable inorganic nitrogen sources. The medium consisting of 2.5 g/L yeast extract as a sole nitrogen source yielded 24.65 +/- 2.21 g/L beta-glucan production. At the last step of optimization, the highest beta-glucan production of 35.77 +/- 3.01 g/L was obtained in the medium consisting of 68.8 g/L hydrolyzed cassava starch, 2.62 g/L molasses and 2.5 g/L yeast extract using central composite design. The evaluation of b-glucan production was carried out in a 5-L bioreactor, and 76.87 +/- 0.96 g/L of material was obtained.
