• Korean Journal of Microbiology
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• v.31 no.1
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• pp.27-36
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• 1993

Rhizobium fredii USDA191 은 대기 중의 질소를 환원하여 식물체의 생육에 필요한 질소원을 공급해주는 세균으로 다량의 체외 다당류를 합성한다. 전위요소 Tn5의 삽입에 의한 돌연변이 유도로 다당류결핍 변이주 R. fredii YKL293 가 분리되었으며 이 변이주로부터 Tn5 에 인접한 DNA 단편이 pUC19 에 클로닝되었고(plyk5293),이 DNA 단편을 탐침으로 하여 .lambda.NM1149 에 구성되 USDA191 genomic library 로부터 야생형체외다당류 합성관련 유전자(exo) 를 함유한 클론 .lambda. NM1149 22E 를 plaque 혼성화에 의하여 분리하였다. 클론 NM1149.22E 에 들어있는 exo 유전자를 pBR322 에 옮겨서 pJW33을 만들고, 재조합체 pJW33 을 Escherichia coli POII734 에 도입시켜 lacZ 구조유전자를 함유한 MudI 1734 가 exo 유전자의 프러모토와 융합되어 lacZ 구조유전자의 전사가 이루어지도록 하였다. 위와 같이 만들어진 재조합체 플라스미드 pUM21을 함유한 E. coli JM83 은 .betha.-galactosidase 를 합성하였으며, 야생형 tacZ 유전자를 갖고 있는 E. coli LE392 에 비해서 14-25배 정도 낮은 역가를 보였다.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.44-51
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• 2007

Marine bacterial strains were isolated trom coastal regions of Goa and screened for the strains that produce the highest amount of mucous expolysaccharide (EPS). Our screening resulted in the identification of the strain Vibrio furnissii VB0S3 (hereafter called VB0S3), as it produced the highest EPS in batch cultures during the late logarithmic growth phase. The isolate was identified as VB0S3 based on morphological and biochemical properties. Growth and EPS production were studied in mineral salts medium supplemented with NaCl (1.5%) and glucose (0.2%). The exopolymer was recovered from the culture supernatant by using three volumes of cold ethanol precipitation and dialysis procedure. Chemical analyses of EPS revealed that it is primarily composed of neutral sugars, uronic acids, and proteins. Fourier-transform infrared (FT-IR) spectroscopy revealed the presence of carboxyl, hydroxyl, and amide groups, which correspond to a typical heteropolymeric polysaccharide, and the EPS also possessed good emulsification activity. The gas chromatographic analysis of an alditol-acetate derivatized sample of EPS revealed that it was mainly composed of galactose and glucose. Minor components found were mannose, rhamnose, fucose, ribose, arabinose, and xylose. EPS was readily isolated from culture supernatants, which suggests that the EPS was a slime-like exopolysaccharide. This is the first report of exopolysaccharide characterization that describes the isolation and characterization of an EPS expressed by Vibrio surnissii strain VB0S3. The results of the study contribute significantly and go a long way towards an understanding of the correlation between growth and EPS production, chemical composition, and industrial applications of the exopolysaccharide in environmental biotechnology and bioremediation.