Abstract
Mutants resistant to growth inhibition by DL-3, 4-dehydroproline, an analog of L-proline, were derived from the wild type L-glutamate producing bacteria, Brevibacterium flavum, Brevibacterium lactofermentum, Corynebacterium glutamicum and Microbacterium ammoniaphilum. Among these mutants, potent L-proline producers were obtained.
The production of L-proline by Brevibacterium flavum No. 199, which was obtained as an isoleucine auxotrophic and sulfaguanidine resistant mutant from the wild strain, was improved by deriving DL-3, 4-dehydroproline resistant mutants under the condition, in which the overproduction of L-proline was reduced by adding excess L-isoleucine, i.e. more than necessary for growth. Among mutants thus obtained, strain P-390 produced 40 g of L-proline per liter, which was 30% more than that of parental strain No. 199, in medium containing 10% glucose, 6% ammonium sulfate, inorganic salts and other components. This yield was the highest among yields so far reported.
