Monday, July 25, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
The bacterium isolated from cassava flour mill in Brazil was identified as a new strain of alkalophilic Bacillus. The cyclodextrin glycosyltransferase production under ideal conditions (1) has been achieved by medium monitoring containing cassava starch, which is one of the Brazil’s largest agricultural crops. The enzymatic activity was measured, based on the discoloration of phenolphthalein solutions at 550 nm, which occurs after complexation with CD, following the method of Makela(2). In this work the cyclodextrin glycosyltransferase enzyme was purified by ammonium sulphate precipitation and affinity chromatography on β-Cyclodextrin – Sepharose 6B column. The specific activity of the cyclodextrin glycosyltransferase was increased 310-fold, from 9.99 U.mg-1 to 3,199.36 U.mg-1. The molecular weight of the purified enzyme was about 81 KDa. Enzymatic characterization exhibited optimum pH and temperature of 8 and 55°C, respectively. The enzyme was stable at 55°C for 75 min. and in pH 6.0, 7.0, 8.0 and 9.0 during 48 h. The cyclodextrin glycosyltransferase was inhibited by ZnSO4, CuSO4, EDTA, SDS and stimulated by Ca2+. The enzyme produced α-, β- and γ-cyclodextrins in the ratio (g.L-1) of 0.32:6.33:1.02 from cassava starch after 35 h reaction at 55°C.
1 BLANCO, K. C.; LIMA, C. J. B.; OLIVEIRA, P. A. P. L. V.; PIAO, A. C. S.; CONTIERO, J. cyclodextrin glicosiltransferase production by Bacillus sp. subgroup alcalophilus using a central composite design. Res. J. Microbiol, 4, 2009. 450-459.
2 MAKELA, M.; KORPELA, T. K. Determination of the catalytic activity of cyclomaltodextrin glucanotransferase by maltotriose-methylorange assay. J. Biochem. Bioph. 15, 1988. 307-318.