Chemostat-grown cells of a newly isolated strain of Methylomonas were flocculated by the addition of small amounts of positively charged flocculants. The flocculation ability of the cells was almost completely lost after extracting the cells with 1–5 mm-EDTA, or by reducing pH to below 4·5. Reconstitution of the flocculation ability of EDTA-extracted cells was obtained either by the addition of an excess amount of calcium ions, or by mixing dialysed EDTA extracts with EDTA-extracted cells. The EDTA extract contained mainly proteins. The major protein was purified to homogeneity by gel filtration, and had a molecular size of 65000 Dal and an isoelectric point of 9·0. Immunological techniques indicated that this protein was located on the surface of the bacteria. We, therefore, propose that the surface protein of the Methylomonas sp. is involved in flocculation by positively charged flocculants.
AtkinsonB.,
DaoudI. S.1976; Microbial floes of protein utilizing the principle of protein-dye and flocculation in fermentation process engineer- binding. Analytical Biochemistry 72:248–254
BradfordM. M.1976; A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye bindin. Advances in Biochemical Engineering 4:41–124
BuckmireF.L.A.,
MurrayR. G. E.1970; Studies on the cell wall of Spirillum serpens. 1. Isolation and partial purification of the outermost cell wall layer. Canadian Journal of Microbiology 16:1011–1022
HowardL.,
TipperD. J.1973; A polypeptide bacteriophage receptor: modified cell wall protein subunits in bacteriophage-resistant mutants of Bacillus sphaericus strain P-1. Journal of Bacteriology 113:1491–1504
MasudaK.,
KawataT.1981; Characterization of a regular array in the wall of Lactobacillus buchneri and its reattachment to the other wall components. Journal of General Microbiology 124:81–90
SleytrU. B.1978; Regular arrays of macromolecules on bacterial cell walls: structure, chemistry, assembly and function. International Review of Cytology 53:1–64
SleytrU. B.,
ThorneK.J.I.1976; Chemical characterization of the regularly arranged surface layers of Clostridium thermosaccharolyticum and Clostridium thermohydrosulfuricum. Journal of Bacteriology 126:377–383
ThornleyM. J.,
GlauertA. M.,
SleytrU. B.1974; Structure and assembly of bacterial surface layers composed of regular arrays of subunits. Philosophical Transactions of the Royal Society. Series B 268:147–153
WeberK.,
OsbornM.1969; The reliability of molecular weight determinations by dodecyl sulfate- polyacrylamide gel electrophoresis. Journal of Biological Chemistry 244:4406–4412