Microbial Biotechnology

Biotechnology Industry

Electronic Journal of Biotechnology ISSN: 0717-3458 Vol. 10 No. 1, Issue of January 15, 2007
© 2007 by Pontificia Universidad Católica de Valparaíso -- Chile Received May 8, 2006 / Accepted October 5, 2006
DOI: 10.2225/vol10-issue1-fulltext-14  

Application of statistical experimental methods to optimize medium for exopolymer production by newly isolated Halobacterium sp. SM5

Patcharee Lungmann
Department of Industrial Biotechnology
Faculty of Agro-Industry
Prince of Songkla University
Hat Yai, Songkhla 90112 Thailand
Tel: 66 44 611221
Fax: 66 44 612 858
E-mail: plungmann@yahoo.com

Wanna Choorit*
Biotechnology Program
School of Agricultural Technology
Walailak University
Nakhonsithammarat 80160, Thailand
Tel: 66 075 672 355
Fax: 66 075 672 302
E-mail: cwanna@wu.ac.th

Poonsuk Prasertsan
Department of Industrial Biotechnology
Faculty of Agro-Industry
Prince of Songkla University
Hat Yai, Songkhla 90112 Thailand
Tel: 66 74 286 361
Fax: 66 74 446727
E-mail: poonsuk918@yahoo.com

*Corresponding author

Financial support: This research was supported by a research grant of Prince of Songkla University.

Keywords: exopolymer, halophilic bacteria, medium optimization, mixture design, response surface method.


CI: confidence interval
KS medium: Kamekura and Seno medium
PHB: Poly-β-hydroxybutyrate
RSM: response surface methodology

Full Text

The study investigated on medium optimization for production of exopolymer by a newly isolated bacterium, Halobacterium sp. SM5, using the mixture design and response surface method. The mixture experiment was designed by setting five parameters at the lowest and highest of concentrations: pseudo components design containing 0.15-0.25 glucose, 0.15-0.25 yeast extract, 0.35-0.45 MgSO4·7H2O, 0.1-0.2 vitamin casamino acid and 0.02-0.06 KCl. The results of the mixture design revealed that the effect of nutrients or elements on the exopolymer produced by the strain SM5 were in the order of MgSO4·7H2O > yeast extract > vitamin casamino acid > KCl > glucose, respectively. The suitable medium recipe for enhancement the exopolymer production was 7.43 g/l glucose, 12.38 g/l yeast extract, 17.33 g/l MgSO4·7H2O, 9.9 g/l vitamin casamino acid and 2.48 g/l KCl. The exopolymer to be produced by the strain SM5 was 2.25 g/l, which was higher than that obtained in the original medium (1.3 times). The yield of exopolymer was 2.13 g/l to be obtained in medium containing 7.43 g/l glucose, 11.37 g/l yeast extract, 22.28 g/l MgSO4·7H2O, 7.44 g/l vitamin casamino acid and 0.99 g/l KCl which was predicted by response surface methodology. However, under an experiment, the yield of exopolymer was 2.08 ± 0.0020 g/l.

Supported by UNESCO / MIRCEN network