청국장 유래 Bacillus licheniformis의 β-Galactosidase 특성 (Properties of β-Galactosidase from Bacillus licheniformis Isolated from Cheongkookjang.)

서지정보

· 발행기관 : 한국미생물·생명공학회
· 수록지 정보 : 한국미생물·생명공학회지 / 40권 / 1호 / 17 ~ 22페이지
· 저자명 : 윤기홍

초록

가정에서 제조된 청국장으로부터 lactose를 glucose와galactose로 가수분해하는 β-galactosidase의 생산균을 분리하였다. 분리균 YB-1105는 형태적 특성, 생화학적 성질 및16S rRNA 유전자 염기서열에 근거하여 Bacillus licheniformis로확인되었다. B. licheniformis YB-1105의 배양상등액과 균체파쇄액에서 모두 β-galactosidase 활성이 관찰되었으며 이들은 모두 pH 6.5와 50oC의 반응조건에서 paranitrophenyl-β-D-galactopyranoside의 가수분해 활성이 최대로 나타났다. 그러나 균체파쇄상등액에 비해 배양상등액의β-galactosidase 활성은 산성 pH와 고온에서 크게 영향을 받았다. 한편 두 분획의 가수분해 활성은 낮은 농도의 galactose에의해도 급격하게 저해되었으나, glucose와 mannose는고농도에 의해서는 약하게 저해를 받는 것으로 확인되었다.

영어초록

A bacterial strain was isolated from homemade Cheongkookjang as a producer of the β-galactosidase, capable of hydrolyzing lactose to liberate galactose and glucose residues. The isolate YB-1105 has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. β-Galactosidase activity was detected in both the culture supernatant and the cell extract of B. licheniformis YB-1105. The enzymes of both fractions demonstrated maximum activity for hydrolysis of para-nitrophenyl-β-Dgalactopyranoside (pNP-βGal) under identical reaction conditions of pH 6.5 and 50oC. However, β-galactosidase activity from the culture filtrate was affected more than that from the cell free extract at acidic pHs and high temperatures. The hydrolyzing activity of both β-galactosidases for pNP-βGal was dramatically decreased by the addition of low concentrations of galactose, but was only marginally decreased by high concentrations of glucose or mannose.

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