Abstract
SUMMARY: A simple chemically defined medium for examining the motility of Escherichia coli K12 was designed. The essential components were: (1) a chelating agent to protect the motility against inhibition by traces of heavy metal ions; (2) a buffer to keep the pH value at the optimum between pH 6·0 and 7·5; (3) an energy source to stimulate the motility above that allowed by an endogenous energy source. Oxygen was required unless an energy source was provided which yielded energy anaerobically. A temperature optimum was determined.
A chemically defined growth medium capable of producing motile bacteria was devised. It was found that the presence of glucose or growth above 37° prevented synthesis of flagella.