Wai Prathumpai1*, Pranee Rachtawee1,
Sutamat Khajeeram1 and Pariya Na Nakorn2

1Bioresources Technology Unit, National Center for Genetic Engineering and Biotechnology,
National Science and Technology Development Agency, 113 Thailand Science Park, Klong Nueng, Klong Luang, Pathum Thani, 12120, Thailand.
2Department of Biotechnology, Faculty of Science and Technology, Thammasat University,
Klong Nueng, Klong Luang, Pathum Thani, 12120, Thailand.

Abstract

The optimization of b-glucan production by Ophiocordycepsdipterigena BCC 2073 was carried out. For the three-step optimization performed in 250-mL Erlenmeyer flasks, at the first step, the maximum b-glucan production of 16.48±0.60 g/Lwas obtained using molasses and malt extract. During the second step, we sought to find an alternative carbon source; the highest b-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 b-glucan content (18.16±0.15 g/L) was obtained with yeast extract. To reduce the use of yeast extract for b-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 b-glucan production. At the last step of optimization, the highest b-glucan production of 35.77±3.01g/L was obtained in the medium consisting of 68.8 g/L hydrolyzed cassava starch, 2.62g/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.

Keywords: Ophiocordycepsdipterigena, b-glucan,fractional factorial design, central composite design, biopolymer.