Abstract:
Thermostable alpha amylase is used in the production of glucose syrup, desizing fabric in
textile industry, fermentation industries, paper sizing, detergent and brewing industries. An
-amylase from Caldimonas manganoxidans NMS 1, isolated from Nelum-wewa hot water
springs, situated in Sewanapitiya in the Polonnaruwa District of Sri Lanka, has been purified
to homogeneity as determined by polyacrylamide gel electrophoresis. Kinetic studies of this
-amylase
production from Caldimonas manganoxidans NMS 1 and the effect of inhibitors on enzyme
activity were studied along with the effect of immobilization on the enzyme. The optimum
extracellular α-amylase activity, 56 U/ml at 50 ˚C over a 20 hour incubation period, was
observed in a media comprising of 10 % soya powder in a basal media containing 5 g/l
NaCl, 0.5 g/l KCl, 0.5 g/l MgSO4.7H2O, 0.04 g/l MnSO4, 0.3 g/l FeSO4, 0.87 g/l K2HPO4,
0.022 g/l CaCl2 and 1 % soluble starch solution while ammonium sulphate (10 % and 20
%), soya powder (20 %) and urea (10 % and 20 %) showed enzyme activities of 1 U/ml,
15 U/ml, 37 U/ml, 1 U/ml and 1 U/ml respectively. Salts of calcium ions (1 mM), manganese
ions (1 mM), copper ions (1 mM), and ferrous ions (1 mM) showed 31 %, 31 %, 18 % and
10 % enhancement of α-amylase activity respectively. Sodium ions (1 mM), magnesium
ions (1 mM), and zinc ions (1 mM) showed a 33 %, 37 % and 37 % inhibition of α-amylase
activity respectively. The surfactant sodium dodecyl sulphate (1 mM) and urea (1 mM)
inhibited enzyme activity by 35 % and 10 % respectively. The heavy metal mercuric ions (1
mM) and the chelating agent ethylene diamine tetraacetic acid (1 mM) strongly inhibited α-
amylase activity by 49 % and 57 % respectively. Immobilization of enzyme using low
melting agarose and agarose showed a retained activity of 43 % and 48 % respectively
with respect to purified, un-immobilized α-amylase at 50 ˚C. Immobilization using KCarrageenan
at 37 ˚C showed 48 % retained activity. The α-amylase isolated from
Caldimonas manganoxidans NMS 1 thus has potential applications in industry.
