GROWTH OF A GLUTAMIC ACID PRODUCING BACTERIUM AND RELATED BACTERIA

II. EFFECT OF CHELATING AGENT AND ITS RELATION TO INORGANIC SALT

Abstract

Growth response of a strain of Micrococcus glutamicus to ferrichrome or related compounds, a large amount of ascorbic acid and iron salt were further studied with the consideration about the relationship between these substances, and following results were obtained.
(1) Rutin and 8-hydroxyquinoline supported the growth at very low concentrations, and the effectiveness of some other chelating agents was confirmed.
(2) The growth of the bacterium was supported also by autoclaving glucose in the medium, and the active factor produced in the medium was speculated to be a chelating agent in view of other literature reports.
(3) The effect of iron salt is specific and could not be replaced by other metals.
(4) A very minute amount of maganese specifically competed with iron in supporting the growth of the bacterium.
(5) Synergistic action between iron and rutin was noticed, while the mutual action between manganese and rutin was obscure.
From these results, the mode of the action of these growth supporting compounds were suggested as follows. In the basal medium, manganese competes the iron and retards the utilization of iron by the bacterium. The iron in the medium can be utilized by chelation with some chelating agent. The chelating agent also accelerates the utilization of iron by excluding the harmful action of some metals (for example, manganese, copper and zinc) by chelating them. Autoclaving glucose in the medium produces a chelating agent which acts in the same manner as described above. A large amount of iron salt overcomes the action of manganese and supports the growth of the bacterium.
The effect of iron salt or some chelating agent or autoclaving glucose in the medium was also confirmed in some other coryneform bacteria.
From these results, the singnificance of chelating agents in the growth of microorganisms was discussed.