Suleeporn Kitcha, Benjamas Cheirsilp and Supasilp Maneerat

pp. 723 - 728

Abstract

A cyclodextrin glycosyltransferase (CGTase) producing bacterium was isolated from a farm soil sample and identified as Bacillus sp. C26. The highest CGTase production by Bacillus sp. C26 was achieved using 1% (w/v) sago starch and 1% (w/v) yeast extract as carbon source and nitrogen source, respectively with an initial pH of 10 and a temperature of 37°C.
Other carbon sources such as soluble starch and rice starch were almost as good as sago starch but tapioca and corn were poor substrates for CGTase production. There was very little difference between the various N-sources tested i.e. peptone, tryptone and yeast extract. Under the optimal conditions, the specific growth rate and CGTase production rate of Bacillus sp. C26 were 0.193 h^-1 and 5.94 U mg^-1 h^-1, respectively. The partially purified CGTase from Bacillus sp. C26 exhibited 2 peaks
of optimum pH at 6.0 and 8.5 and had an optimum temperature of 65°C. The enzyme was stable from pH 7.0 to 9.0 and retained its high activity up to 50°C.

Keywords

• alkalophilic bacterium
• Bacillus sp.
• cyclodextrin
• CGTase
• sago starch