SELECTION AND BIOCHEMICAL-STUDIES OF PYRIMIDINE-REQUIRING MUTANTS OF LACTOBACILLUS-PLANTARUM

Mutagenesis and mutant enrichment in Lactobacillus plantarum, a lactic acid bacterium used in silage, sauerkraut and sausage fabrication, we re studied. In optimal conditions, auxotrophic mutants were obtained t hat permitted investigation of the de novo pyrimidine biosynthesis. Ur acil-requiring mutants were characterized for their enzymatic defect, in aspartate transcarbamylase (ATCase), dihydro-orotase (DHOase), dihy dro-orotate dehydrogenase (DHOdehase), orotidine monophosphate pyropho sphorylase (OMPppase) or in orotidine monophosphate decarboxylase (OMP decase). The five enzymatic activities are totally repressed by uracil in the growth medium.