Fermentative production of L-proline by DL-3,4-dehydroproline resistant mutants of L-glutamate producing bacteria.

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.