Masatoshi Enomoto

Composition of chromosome fragments participating in phage P22-mediated transduction of Salmonella typhimurium.

Abstract It was demonstrated quantitatively that the chromosome fragments carried by phage P22 and concerned in abortive transduction of motC - H 1- flaK region of Salmonella typhimurium are heterogeneous in genetic composition. When the total number of fragments carrying motC , flaK , or both was taken as 100, those carrying motC + , motC + H 1, motC + H 1 flaK + , H 1 flaK + , and flaK + were approximately 2, 27, 0.2, 4, and 67%, respectively. These proportions indicate that the chromosome fragments having termini between H 1 and flaK are 94% and those between H 1 and motC are 6%. This result was obtained from the number of trails (motile heterogenotes) produced in the transduction from a motile donor strain in phase 1 ( gp ) to three kinds of nonmotile mutants in expressed or latent phase 1 ( i ) on NGA medium containing both anti- gp and anti- 1.2 sera or anti- 1.2 serum for the phase 2 flagellar antigen. The three nonmotile mutants, motC 244, flaK 48, and motC 244 flaK 48, have mutational sites cotransducible with H 1, and presumably satisfy the working premise that the exogenotic H 1 allele in motile heterogenotes is always expressed when present and motility of the heterogenotes is inhibited by the antiserum for the phase 1 flagellar antigen of the donor.

Different frequencies of cotransduction of motC and H1 in Salmonella

The frequency of cotransduction of motC and H1 in Salmonella has been investigated, using four Salmonella serotypes and many serotypic recombinants as donors and S. typhimurium motC mutant as recipient. The frequency varied with the four serotypes from 7% to 52%. It is suggested that the difference in frequency arises from not only differences in genetic homology between the chromosome of the recipient and the fragment from the donor, but also from differences in genetic composition of the chromosome fragments carried by the phage. The frequency of serotypic recombinants selected for motC + and H1 gene of the donor is generally higher than with recombinants selected for flaK + and H1 . The difference in genetic homology between S. typhimurium and other species is more marked in the region between H1 aud flaK than between motC and H1 .

Chapter IV Motility

Publisher Summary In the microbial world, motile organisms are distributed in most of the phyla. The mode of movement differs in different microbial groups and has been regarded as an important characteristic for the identification of microbes. Myxomycetes, slime moulds, and some unicellular protozoa move over the surface of solid substances as a result of cytoplasmic movement. This kind of movement is commonly called amoeboid movement. Another movement that is possible only when organisms are in contact with a solid surface is the gliding movement, such as seen with myxobacteria, blue-green algae, and some of the filamentous bacteria such as the Beggiatoales. Many motile micro-organisms can move actively in a liquid medium. This swimming movement is brought about by locomotive organelles known as flagella or cilia. Flagella of eubacteria differ in their fine structure from those found in eukaryotic micro-organisms, such as flagellates or protozoa. Among the bacteria, spirochetes swim in a liquid medium with the aid of an axial filament. This chapter describes the techniques that concern the observation of motility and locomotive organelles of eubacteria.