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Sorghum malt a-amylase can compete with bacterial a-amylase in industrial applications, if sufficiently stable and produced in a large enough quantity. Conditions for maximal a-amylase production in sorghum malt and the physico-chemical properties of the a-amylase so produced are reported in this study. Sorghum grains were steeped in buffers with varying pH (4.0-8.0) for 24 h, at room temperature, and germinated for another 48 h to obtain the green malt. The buffer that induced the highest quantity of a-amylase was chosen as the optimal pH and served as the medium for further steeping experiments conducted at different temperatures (10, 20, 30, 40, 50 and 60 C). The a-amylase activity in the extract was determined in order to obtain the optimum temperature for a-amylase induction at this particular pH. For the purpose of comparison, the a-amylase produced at the optimum pH and temperature was purified to apparent homogeneity by a combination of ion-exchange and size-exclusion chromatography, and further characterized. Eight-fold higher a-amylase activity was induced in pH 6.5 buffer at 20 C compared with water, the traditional steeping medium. The K m and V max were estimated to be 1.092 AE 0.05 mg mL À1 and 3516 AE 1.981 units min À1, respectively. The activation energy of the purified amylase for starch hydrolysis was 6.2 kcal K À1 mol À1. Chlorides of calcium and manganese served as good activators, whereas CuSO 4 inhibited the enzyme with a 42% loss in activity at 312 mM salt concentration.

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Cellulases have wide applications and biotechnological potentials for various industries. A bacterium producing an extracellular, thermostable cellulase was isolated from plant leaf litters of Lagerstroemia indica Linn, inside a botanical garden. According to morphological, biochemical and physiological characterization, it was tentatively identified as Enterobacter sp. Molecular characterization, using the 16S rRNA gene sequencing was used to confirm the identity of the bacterium as Enterobacter cloacae IP8. Effects of some cultural factors such as carbon and nitrogen sources, pH and temperature, on cellulase production from the bacterium, were investigated. Some physicochemical properties of the crude cellulase from E. cloacae IP8 were determined to evaluate its potentials for industrial applications. The maximum yield of cellulase (10.78 U/mL) was at 28 h of incubation using carboxymethyl cellulose (CMC) (1.5%, w/v), peptone (2.0%, w/v), inoculum size (1.0%, v/v), pH and temperature of 7.0 and 45 oC, respectively, and agitation speed 150 rpm. The crude cellulase exhibited optimum activity at 60 oC, retaining 75.0% of its maximal activity at 70 oC. It had optimum pH of 7.0, retaining 58.0% of its original activity at acidic pH 5.0. Metal ions Na+, Ca2+ and Mg2+ remarkably enhanced activity of the cellulase while K+ and EDTA inhibited activity of the cellulase from E. cloacae IP8. The characteristics of the cellulase from E. cloacae IP8 revealed the enzyme as being thermostable and an acidic to neutral metalloenzyme. Therefore, the enzyme from this strain could be applied in industrial applications such as lignocellulosic biomass conversion into fuel and other value added products.

Objective: Some properties of cellulase purified from the culture supernatant of Bacillus coagulans Co4, isolated from cocoa pod dumpsite were investigated for possible biotechnological applications. Methods: The crude cellulase was purified to apparent homogeneity using a combination of acetone precipitation, CM Sepharose CL-6B ion exchange chromatography and gel filtration on Sephadex G-100. The molecular and thermodynamic properties of the purified enzyme were studied following standard procedures. Results: The specific activity of the purified cellulase rose from 0.10 to 47 units/mg of protein, at the end of purification. The molecular weight was found to be 14.5 kDa; and an apparent K m value of 0.18±0.06 mg/ml of carboxylmethylcellulose. The optimum pH and temperature were 7.5 and 60 o C respectively. The activation energy for carboxylmethylcellulose hydrolysis (E a ) was 16.5 kJ/mol. Na + and K + had no effects on its activity at concentrations up to 200 mM, whereas Ca 2+ and Mg 2+ served as inhibitors at concentrations above 25 and 40 mM respectively. The cellulase retained 40% residual activity when heated at 60 o C for 40 minutes. Conclusison: On the basis of these properties, it is concluded that the purified cellulase is moderately thermostable and may have applications in the bioconversion of agricultural wastes into economically useful products.