Abstract
The growth-promoting action of Tween 80 on Ery. incidiosa was investigated with the following results: 1. When the concentration of Tween 80 in the medium was 0.1% the greatest growth promotion was noted regardless of whether the medium was liquid or solid.2. The growth-promoting effect of Tween 80 was dependent on the kind of peptone used. 3. Tween 80 had a more remarkable growth-promoting action than horse serum, but the turbidity of medium containing the former was lower than that of medium containing the latter. 4. A growth-promoting effect of Tween 80 in casamino acids medium was nut observed when yeast extract was added, but definitely observed when glucose was added. 5. Tween 80 did not show an inhibitory effect even when a minute inoculum of bacteria used. 6. Cultures grown in agar medium containing Tween 80 showed considerable changes both in morphology and colony form. 7. Tween 80 had a growth-promoting effect not only on Ery. incidiosa but also on Corynebact. pyogenes. Tween 60 was accelerative on Ery. incidiosa, but was weaker than Tween 80. 8. The mechanism of growth-promoting action of Tween 80 on Ery. incidiosa was discussed. It was assumed that partly it may neutralize the toxicity of the medium, in addition to its wetting and spreading action.
