THE CONSEQUENCES OF MUTATION DURING THE GROWTH OF BIOCHEMICAL MUTANTS OF ESCHERICHIA COLI II

Abstract

In unshaken cultures of E. coli, in which the pH decreases in proportion to the number of bacteria, the adaptive growth of histidine-independent back-mutants takes place until intolerable pH''s arise. The pH tolerance of these back-mutants is detd. by the proportion of parental histidineless bacteria also present in the culture. This restriction by the histidineless bacteria is not brought about by the depletion of something from the medium but rather by the production of some nonspecific substance (or substances) that is formed in proportion to the number of bacteria.