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Biotechnology and Applied Biochemistry (2002) 36, (127–131) (Printed in Great Britain)

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Application of statistically based experimental designs for the optimization of exo-polysaccharide production by Cordyceps militaris NG3

Chun-Ping Xu, Sang-Woo Kim, Hye-Jin Hwang and Jong-Won Yun¹

Department of Biotechnology, Taegu University, Kyungsan, Kyungbuk 712-714, South Korea

Key words: central composite design, mycelial growth, Plackett–Burman design, response-surface analysis, submerged culture.

¹To whom correspondence should be addressed (e-mail jwyun@taegu.ac.kr).

Statistically based experimental designs were applied to the optimization of medium composition for exo-polysaccharide production by Cordyceps militaris NG3 in shake-flask cultures. First, the Plackett–Burman design was used to search for the main factors on mycelia and exo-polysaccharide production. Among these variables, sucrose and corn steep powder were found to be two significant factors and had positive effects on mycelial yield (with confidence level > 80%) and exo-polysaccharide production (with confidence level > 90%). Subsequently, to study the mutual interactions between variables, the effects of the two main factors on exo-polysaccharide production were further investigated using a central composite design. The optimal composition was found to be 1.03 g/l corn steep powder, 2.95 g/l sucrose, 0.1 g/l K₂HPO₄, 0.5 g/l MgSO₄ · 5H₂O and 0.1 g/l KNO₃ for the enhanced production of the exo-polysaccharide, which was 2.604 g/l in shake-flask cultures. Under optimal culture conditions, the maximum exo-polysaccharide concentration in a 5 l stirred-tank bioreactor was 3.8 g/l.

Received 15 April 2002/7 June 2002; accepted 27 June 2002

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