Bactericidal activity of certain fatty acids

Abstract

Summary Fatty acids in the C 9 to C 12 range are bactericidal to a number of different organisms, and this activity is markedly enhanced with increasing acidity. Optimum bactericidal activity to Staphylococcus aureus was exhibited by undecylic acid. Since the activity is of the same order as that of the quaternary ammonium germicides in alkaline solution, an explanation for both types of germicidal activity is presented in which the bacteria or some protein essential to the bacteria are considered to be “suffocated” by a “coating” of fatty groups in chemical combination with the protein. The application of these findings to bactericidal activity encountered in rancid fats is discussed briefly in connection with the oxidative degradation of oleic acid derivatives to pelargonic acid. In addition, the possible usefulness of the bactericidal activity as a microbiological assay method for certain fatty acids is pointed out.