Chemotaxis toward amino acids by Bacillus subtilis.

Conditions for assaying chemotaxis in Bacillus subtilis are described. The chemotaxis medium we used afforded excellent motility for hours. In it, chemotaxis measured by capillary assays was insensitive to pH between 5.5 and 9, and to temperature between 28 degrees C and 42 degrees C. Chemotaxis was observed toward all 20 common amino acids, with thresholds varying from 3nM for alanine to 0.1 mM for glutamate, in the capillary assay, and from 0.1 muM for alanine to 0.32 mM for glutamate in the microscope assay.