2018年6月22日
Identification and characterization of the S-layer formed on the sheath of Thiothrix nivea
Archives of Microbiology
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- 巻
- 200
- 号
- 8
- 開始ページ
- 1
- 終了ページ
- 9
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1007/s00203-018-1543-x
- 出版者・発行元
- Springer Verlag
Thiothrix nivea is a filamentous sulfur-oxidizing bacterium common in activated sludge and its filament is covered with a polysaccharide layer called sheath. In this study, we found that T. nivea aggregates under acidic conditions. A hexagonal lattice pattern, a typical morphological feature of proteinaceous S-layers, was newly observed on the surface of the sheath by transmission electron microscopy. The pattern and the acid-dependent aggregation were not observed in T. fructosivorans, a relative sheath-forming bacterium of T. nivea. The putative S-layer of T. nivea was detached by washing with unbuffered tris(hydroxymethyl)aminomethane base (Tris) solution and a protein of 160 kDa was detected by electrophoresis. Based on partial amino acid sequences of the protein, its structural gene was identified. The gene encodes an acidic protein which has a putative secretion signal and a Ca2+-binding domain. The protein was solubilized with urea followed by dialysis in the presence of calcium. A hexagonal lattice pattern was observed in the aggregates formed during dialysis, revealing that the protein is responsible for S-layer formation. Biosorption ability of copper, zinc, and cadmium onto the T. nivea filament decreased upon pretreatment with Tris, demonstrating that the S-layer was involved in metal adsorption. Moreover, aggregation of Escherichia coli was promoted by acidification in the presence of the S-layer protein, suggesting that the protein is potentially applicable as an acid-driven flocculant for other bacteria.
- リンク情報
- ID情報
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- DOI : 10.1007/s00203-018-1543-x
- ISSN : 1432-072X
- ISSN : 0302-8933
- PubMed ID : 29934786
- SCOPUS ID : 85048882898