title: Elongation pattern and fine structure of the sheaths formed by Thiothrix nivea and Thiothrix fructosivorans.
abstract: Thiothrix strains are filamentous sulfur-oxidizing bacteria common in activated sludge. Some of the members, including Thiothrix nivea and T. fructosivorans, are known to form a microtubular sheath that covers a line of cells. The sheaths are assemblages of [→4)-β-d-GlcN-(1→4)-β-d-Glc-(1→]nmodified with unusual deoxy sugars. In an attempt to elucidate the sheath-forming mechanism, the patterns of sheath formation and cell proliferation were determined in this study. Prior to analysis, both sheaths were confirmed to be highly de-N-acetylated. Sheaths in viable filaments were N-biotinylated followed by cultivation and then fluorescently immunostained. Epifluorescence microscopy of the filaments revealed ubiquitous elongation of the sheaths. For visualization of the cell proliferation pattern, the cell membrane was fluorescently stained. The epifluorescence images demonstrated that cell proliferation also proceeds ubiquitously, suggesting that sheath elongation proceeds surrounding an elongating cell. In addition, the fine structure of the Thiothrix filaments was analyzed by transmission electron microscopy employing a freeze-substitution technique. The micrographs of freeze-substituted filaments showed that the sheaths were thin and single layered. In contrast, the sheaths in chemically fixed filaments appeared thick and multilayered. Treatment with glutaraldehyde probably caused deformation of the sheaths. Supporting this possibility, the sheaths were found to be deformed or solubilized by N-acetylation.
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Kawasaki
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Endo
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan.
authors.forename: Atsuo
authors.initials: A
authors.lastname: Fujiwara
authors.affiliation: Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kondo
authors.affiliation: Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Katahira
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nittami
authors.affiliation: School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama, Kawasaki 214-8571, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Sato
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan. Electronic address: mtake@ynu.ac.jp.
authors.forename: Minoru
authors.initials: M
authors.lastname: Takeda
mesh_terms: D000107:Acetylation; D018441:Biofilms / Q000254:growth & development*; D002240:Carbohydrate Sequence; D003432:Cross-Linking Reagents / Q000737:chemistry; D003837:Deoxy Sugars / Q000737:chemistry / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry; D005976:Glutaral / Q000737:chemistry; D006801:Humans; D006868:Hydrolysis; D012722:Sewage / Q000382:microbiology*; D013194:Staining and Labeling / Q000379:methods; D013499:Surface Properties; D053525:Thiothrix / Q000737:chemistry* / Q000254:growth & development / Q000648:ultrastructure; D014865:Waste Disposal, Fluid
chemical_list: D003432:Cross-Linking Reagents; D003837:Deoxy Sugars; D005456:Fluorescent Dyes; D012722:Sewage; D005976:Glutaral
keywords: Elongation; Fine structure; Sheath; Thiothrix fructosivorans; Thiothrix nivea