THE RELATIONSHIP BETWEEN GROWTH AND MUTATION IN PSEUDOMONAS FLUORESCENS

Abstract

A mutant of P. fluorescens was discovered which uses itaconate (methylene succinate) as the sole source of C for growth, the parent being unable to do so. By means of a simplified tube fluctuation test the random origin of the mutation was established, and a high positive correlation between growth of the wild type and the mutation to itaconate utilization was demonstrated. Furthermore it was shown that P. fluorescens can grow for many generations to a population density below the visible level in a medium devoid of any deliberately added utilizable carbon source. A new simplified method was used for the detn. of the mutation rate based upon a modification of the tube fluctuation test, employing an equation derived by Luria and Delbriick. The mutation rate so calculated, based upon the averaging of 3, is 1.9 x 10-8. This method may be used in detn. of mutation rates involving mutations which are expressed phenotypically by "added" biochemical properties.