The Growth of Bacterial Cultures

The study of the growth of bacterial cultures does not consti­ tute a specialized subject or branch of research: it is the basic method of Microbiology. It would be a foolish enterprise, and doomed to failure, to attempt reviewing briefly a "subject" which covers actually our whole discipline. Unless, of course, we considered the formal laws of growth for their own sake, an ap­ proach which has repeatedly proved sterile. In the present review we shall consider bacterial growth as a method for the study of bacterial physiology and biochemistry. More precisely, we shall concern ourselves with the quantitative aspects of the method, with the interpretation of quantitative data referring to bacterial growth. Furthermore, we shall consider exclusively the positive phases of growth, since the study of bacterial "death," i.e., of the negative phases of growth, involves distinct problems and meth­ ods. The discussion will be limited to populations considered genetically homogeneous. The problems of mutation and selection in growing cultures have been excellently dealt with in recent review articles by Delbriick (1) and Luria (2). No attempt is made at reviewing the literature on a subject which, as we have just seen, is not really a subject at all. The papers and results quoted have been selected as illustrations of the points discussed.