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KMID : 0364820110470030255
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Korean Journal of Microbiology
2011 Volume.47 No. 3 p.255 ~ p.262
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Isolation and Characterization of Acid Protease Produced by Staphylococcus sp. CB2-3 from Digestive Organ of Harmonia axyridis
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Kim Se-Jong
Whang Kyung-Sook
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Abstract
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Six protein-degrading bacteria were isolated from digestive organ of Harmonia axyridis. Theseisolates were categorized as Staphylococcus sciuri subsp. sciuri (3 strains), Bacillus subtilis (1 strain), and Bacillus thuringiensis (2 strains) by 16S rRNA gene sequence analysis. The Staphylococcus sp. CB2-3 was selected as a protease-producing bacterium which showed the highest protease activity of 58.5 U/ml at the pH 5.0 medium. The optimal pH and temperature of protease activity were pH 5.0 and 40°C, respectively. This acid protease had a relatively high stability of 80% between 30-50°C at broad temperature range. The opimal medium compositions of carbon, nitrogen and mineral source for cell growth and protease activity were investigated. When sorbitol (0.5%) was used as carbon source, enzyme activity was increased about 2 times than that of the basal medium. When skim milk (0.5%) was used as nitrogen source, activity was increased about 2.5 times than that of the control. Cell growth and enzyme activity were increased by mineral source such as KCl,
K2HPO4, FeSO4, but was completely inhibited by divalent ions such as Co2+, Zn2+, Mn2+, Cu2+.
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KEYWORD
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Harmonia axyridis, Staphylococcus sp, CB2-3, acid protease, digestive organ
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