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Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 14, No. 5, 2011
Bioline Code: ej11053
Full paper language: English
Document type: Research Article
Document available free of charge

Electronic Journal of Biotechnology, Vol. 14, No. 5, 2011

 en Effects of substrates and reaction conditions on production of cyclodextrins using cyclodextrin glucanotransferase from newly isolated Bacillus agaradhaerens check for this species in other resources KSU-A11
Ibrahim, Abdelnasser S.S.; El-Tayeb, Mohamed A.; Elbadawi, Yahya B. & Al-Salamah, Ali A.

Abstract

The effects of reaction conditions on cyclodextrins (CDs) production by CGTase from newly isolated Bacillus agaradhaerens check for this species in other resources KSU-A11 is reported. Among six types of starch tested, potato starch gave highest starch conversion into CDs. In addition, CDs yield was about three fold higher when using gelatinized potato starch in comparison to raw starch. The total CDs production was increased with increasing pH, showing maximum starch conversion at pH 10. Furthermore, the proportion of γ-CD was relatively higher under slightly acidic-neutral conditions than at alkaline pH with a maximum proportion of 35.6% at pH 7 compared to 7.6% at pH 10. Maximum starch conversion into CDs was seen at reaction temperature of 55°C. Lower reaction temperature led to higher proportion of γ-CD with maximum percentage at 35°C. Cyclization reaction was significantly promoted in the presence CaCl2 (10 mM), while in the presence of ethyl alcohol there was significant decrease in CD production particularly at high concentration. ß-CD was the major product up to 1 hr reaction period with traces of α-CD and no detectable γ-CD. However, as the reaction proceed, γ-CD started to be synthesised and α-CD concentration increased up to 4 hrs, where the CDs ratios were 0.27:0.65:0.07 for α-CD:ß-CD:γ-CD, respectively. In addition, optimum CGTase/starch ratio was obtained at 80 U/g starch, showing highest starch conversion into CDs. All the parameters involved have been shown to affect the products yield and/or specificity of B. agaradhaerens KSU-A11 CGTase.

Keywords
Bacillus agaradhaerens, cyclodextrin glucanotransferase, cyclodextrinc, enzymatic reaction, starch

 
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