Abstract
In high (45 mM)-phosphate medium, Methanospirillum hungatei strains GP1 and JF1 grew as very long, nonmotile chains of cells that did not possess flagella. However, growth in lower (3 or 30 mM)-phosphate medium resulted in the production of mostly single cells and short chains that were motile by means of two polar tufts of flagella, which transected the multilayered terminal plug of the cell. Electron microscopy of negatively stained whole mounts revealed a flagellar filament diameter of approximately 10 nm. Flagellar filaments were isolated from either culture fluid or concentrated cell suspensions that were subjected to shearing. Flagellar filaments were sensitive to treatment with both Triton X-100 and Triton X-114 at concentrations as low as 0.1% (vol/vol). The filaments of both strains were composed of two flagellins of Mr 24,000 and 25,000. However, variations in trace element composition of the medium resulted in the production of a third flagellin in strain JF1. This additional flagellin appeared as a ladderlike smear on sodium dodecyl sulfate-polyacylamide gels with a center of intensity of Mr 35,000 and cross-reacted with antisera produced from filaments containing only the Mr-24,000 and -25,000 flagellins. On sodium dodecyl sulfate-polyacrylamide gels, all flagellins stained by the thymol-sulfuric acid and Alcian blue methods, suggesting that they were glycosylated. This was further supported by chemical deglycosylation of the strain JF1 flagellins, which resulted in a reduction in their apparent molecular weight on sodium dodecyl sulfate-polyacylamide gels. Heterologous reactions to sera raised against the flagella from each strain were limited to the Mr-24,000 flagellins.