The Inheritance of Environmentally Induced Characters in Bacteria

Abstract

The problem of environmentally induced characters in bacteria is important both in theoretical and applied bacteriology. It is of special significance in chemotherapy, particularly as regards the development of sulfonamide and other drug-resistant forms. It is also of fundamental importance because of its bearing on microbic heredity. A vast amount of literature is available indicating that bacteria and related organisms can become adapted to a wide range of environmental conditions. It is well established that by gradual progressive cultivation of bacteria in media containing increasing amounts of a toxic substance, a tolerant or resistant strain can in most cases be produced. On the other hand very little information is available on some of the fundamental questions which this phenomenon of adaptation raises. Can single cell cultures, therefore genetically pure, become adapted to different environments merely by being subjected to them? If so, what are the limits of their adaptive powers? Are the induced characters permanent and transmissible to subsequent generations, or are they of a temporary nature? What is the mechanism of adaptation? Is it a result of the selection to certain individuals occurring in the population, or do the toxic substances act as a direct stimulus upon the hereditary material of the cell, causing a new character or characters to appear?