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A Mutant of Salmonella Possessing Straight Flagella
Abstract
SUMMARY
A mutant of Salmonella typhimurium produced straight flagella in phase 2 (antigen-1,2) and normal flagella in phase 1 (antigen-i). The straight flagella were observed by light microscopy and electron microscopy either with or without formalin fixation. Flagellar bundles of the mutant bacteria prepared in 0·25% methylcellulose (w/v) and examined by dark-field microscopy were also found to be straight. It was shown by electron microscopy that the component flagella of the straight flagellar bundle were in most instances irregularly twisted about each other. Heteromorphous bacteria which had straight flagella and either normal or mini-small-amplitude flagella were seen at a frequency of 10–13 % among the bacterial clones in phase 2. The bacteria with straight flagella were non-motile but they were sensitive to bacteriophage χ, which is known to infect motile bacteria of Salmonella species. In transduction, using phage P22 grown on a normal flagellar strain and the phase 2 straight strain as recipient, transductional clones with normal flagella in both phase 1 and phase 2 were obtained. The transductional clones showed the antigen of the recipient in phase 1 and that of the donor in phase 2. This indicated that the straight mutant originated by a mutation of the structural gene of phase 2 flagellin. In absorption-agglutination experiments with antisera prepared against flagella of either normal-1,2 or straight-1,2 no antigenic difference between normal and straight flagella could be detected.
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