Amino acid utilization by Aerobacter aerogenes and Escherichia coli

Abstract

A considerable amount of work has been done on the growth of A. aerogenes and E. coli in synthetic media, but little work has been undertaken on the utilization by these organisms of amino acids as comparative sources of nitrogen. The most valuable study of this subject was made by Koser and Rettger in 1918, but it is incomplete due to the fact that only a few amino acids were tried and it also seems to lack in scientific precision. J. Howard Mueller more recently worked extensively with amino acids but he was interested in pathogenic organisms (Pneumococcus, Streptococuss hemolyticus and diphtheria Bacillus) more than in the two species we are studying and, furthermore, we do not approve completely of the methods of inoculation and of growth measurement he used. (See under these headings in the following pages.) Thus there appears to be a great opportunity for further investigation in this field leading to the acquirement of more knowledge with regard to differentiation, classification, intermediate metabolism, and essential growth factors of bacteria. The object of this thesis is to study the relative availability of the amino acids as sole source of nitrogen in the growth of A.aerogenes and E.coli, when used individually for this purpose and in varying concentrations.