FIG. 1.

Chemotactic response of R. eutropha JMP134(pJP4). (A) Chemotactic rings formed by wild-type cells on soft agar swarm plates containing 0.5 mM succinate (left) or 0.25 mM 2,4-D (right). Plates were inoculated by stabbing motile cells in the center of the plate at a point corresponding to the center of the swarm ring and incubated for 24 to 48 h at 30°C. (B) Attraction of wild-type cells in a modified capillary assay. Cells were grown on 3 mM 2,4-D. Capillaries contained 10 mM 2,4-D, 1% Casamino Acids, or no attractant (chemotaxis buffer). Chemotactic responses are shown in photographic form (top) and illustrative form (bottom). Illustrations for chemotaxis buffer were omitted because no response was observed.