NUTRITION OF LEPTOSPIRA POMONA. III. CALCIUM, MAGNESIUM, AND POTASSIUM REQUIREMENTS.

Johnson, R. C. (Fort Detrick, Frederick, Md.) and N. D. Gary. Nutrition of Leptospira pomona. III. Calcium, magnesium, and potassium requirements. J. Bacteriol. 85:983-985. 1963.-The cation requirements for Leptospira pomona Wickard were investigated employing a basal medium prepared with 10% deionized rabbit serum and containing 10(-3)m NH(4)Cl, 5 mug/ml thiamine, and 0.01 m Na(2)HPO(4) buffer (pH 7.4). Rabbit serum was deionized by passage through a column of Amberlite IRC-50 resin. This basal medium did not support growth when either Ca(++) or Mg(++) was added to it. However, when both Ca(++) (3 x 10(-5)m) and Mg(++) (5 x 10(-6)m) were present, growth was obtained. Although an absolute requirement for K(+) could not be demonstrated, an increase in the amount of growth did occur if K(+) (5 x 10(-5)m) was incorporated in addition to Ca(++) and Mg(++). When adequate concentrations of Ca(++) and K(+) were present with a limiting concentration of Mg(++) (less than 5 x 10(-7)m), filamentous cells were observed.