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KMID : 0545119920020030189
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Journal of Microbiology and Biotechnology
1992 Volume.2 No. 3 p.189 ~ p.196
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Biochemical Properties of Starch Granule Non-Digestive Enzyme(SGNA) of Bacillus polymyxa No.26
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Sohn, Cheon Bae
Kim, Myung Hee/Bae, Jung Surl/Kim, Cheorl Ho
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Abstract
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A α-1,4-D-glucan maltohydrolase (β-amylase), secreted by the mesophilic aerobic bacterium Bacillus polymyxa No.26, was purified and characterized. The enzyme production was increased after a logarithmic phase of bacterial growth and paralleled with the onset of bacterial sporulation. By applying anion exchange chromatography and gel filtration the enzyme was purified 16.7-fold and had a specific activity of 285.7 units/㎎. Two enzyme activities were eluted on a column of DEAE-Sephadex chromatography, and they were designated as E-I for a major enzyme peak and E-II for a minor peak. Of them, E-I enzyme peak was further purified by using gel chromatography. The molecular mass of this enzyme was determined to be 64,000 daltons and consisted of a single subunit, showing an isoelectric point of 8.9. The enzyme was able to attack specifically the α-1,4-glycosidic linkages in soluble starch and caused its complete hydrolysis to maltose and β-limited dextrin. This amylolytic enzyme displayed a temperature optimum at 45℃ and a pH optimum at 7.0. The amino acid composition of the purified enzyme was quite similar to the other bacterial β-amylases reported. Surprisingly, the purified enzyme from this aerobe only exhibited hydrolytic activity on soluble starch, not on starch granules. The degradation of raw starch by β-amylase was greatly stimulated by pullulanase addition. These results differentiated from other β-amylases reported. Based on a previous result that showed the enzyme system involves in effective degradation of raw starch granules, this result strongly suggested that the purified enzyme (E-I) can be a synergistic part of starch granule-digestion and E-II plays a crucial role in digestion of starch granules.
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