African Journal of Biotechnology Vol. 6 (6), pp. 699-706, 19 March 2007   

ISSN 1684–5315 © 2007 Academic Journals        

Full Length Research Paper

Determination of kinetic parameters of α-amylase producing thermophile Bacillus sphaericus

Z. Al-Qodah^1*, H. Daghstani², Ph. Geopel³ and W. Lafi⁴

¹Center of Environmental Studies, The Hashemite University Zarqa, 13115, P.O. Box 330127 Jordan.

²College Zarka University, Sciences Department of Medical Allied.

³Technical University of Hamburg, Department of Biotechnology 1, Harburg, Germany.

⁴Department of Chemical Engineering Al-Balqa Applied University.

*Corresponding authors E-mail:  zak@hu.edu.jo

Accepted 27 December, 2006

Studies on the α-amylase-producing thermophilic bacterium isolated and identified from a hot spring in Jordan and designated as Bacillus sphaericus were carried out in a laboratory scale fermenter. The growth and enzyme production optimum conditions were pH 7 and 50^oC. The kinetic study of cellular growth indicates μ_max, K_s, τ_d, Y_x/s and k_d were 0.53 h^-1, 1.1 g/l, 1.98 h, 0.44 g cell/g starch and 0.4 g/l/h, respectively.  The optimum starch concentration for the enzyme production was 32 g/l and higher concentrations show substrate inhibition with inhibition constant K_i 190 mg/l. The kinetic parameters of α-amylase activation V_max, and K_m were 263 μmole mg^-1 enzyme min^-1 and 0.97 mg/ml, respectively. The effect of different carbon and nitrogen sources on the cellular growth was tested.

Key words: Bacillus sphaericus, thermostable α-amylase thermostable enzymes, kinetic parameters, batch fermentation, Jordan hot springs.