A study of the effect of growth substrate on the respiration of Azotobacter.

It is well known that the medium upon which bacteria are grown has a definite influence on the properties of the resulting cells. Several investigators (l-3) have reported that the physiological activities of species of Azotobacter may be altered by t,he growth medium. This investigation was undertaken to determine the response of Axotobacter cells to different organic compounds available for respiration. The problem was divided into two parts: (a) growing the organisms on different energy sources and studying their physiological activity to determine whether the substrate had any effect upon the enzymatic constitution of the cells, and (b) determining whether the Axotobacter cells could adapt themselves to the utilization of a substrate other than the compound serving as the energy source for the growth of the organisms.