Chemotaxis toward amino acids by Bacillus subtilis

Conditions for assaying chemotaxis in B. subtilis are described. The chemotaxis medium that was 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°C and 42°C. Chemotaxis was observed toward all 20 common amino acids, with thresholds varying from 3 nM for alanine to 0.1 mM for glutamate, in the capillary assay, and from 0.1 μM for alanine to 0.32 mM for glutamate in the microscope assay.