Abstract
Effect of carboxylic acids and Tweens on the growth of Rhizobium trifolii was examined. 1) All fatty acids tested exerted the inhibitory effect on the growth with the exception of acetic acid, their action increasing with carbon chain length. Inhibitory effect of higher fatty acids decreased with the degree of unsaturation. The action of unsubstituted aliphatic dicarboxylic acids on the growth increased with carbon chain length. Substituted mono- and di-carboxylic acids, and aromatic acids were also inhibitory. 2) Inhibitory effect of glycolic and propionic acids increased as pH of the medium lowered, suggesting that the acid at unionized state is responsible for the inhibition. 3) Tweens 40 and 60 were inhibitory for the growth, but Tweens 80 and 85 were rather stimulative. 4) Oxidations of succinate and glucose were repressed by the addition of crotonic or acrylic acid after ca. 30 min reaction.
