ISOLATION OF URACIL AUXOTROPHS FROM BURKHOLDERIA-CEPACIA ATCC-25416

TWO uracil auxotrophs of the phytopathogen Burkholderia cepacia ATCC 2 5416, which is known to be involved in food spoilage, were isolated by a combination of ethylmethane sulphonate and D-cycloserine countersel ection. One mutant exhibited depressed orotate phosphoribosyltransfera se activity while the other mutant lacked orotidine 5'-monophosphate d ecarboxylase activity. Pyrimidine limitation of either auxotroph eleva ted aspartate transcarbamoylase and dihydroorotase activities by at le ast 1.5-fold indicating that these pathway enzymes may be repressible by a uracil-related compound in B. cepacia. Overall, regulation of de novo pyrimidine synthesis in the uracil auxotrophs of B. cepacia ATCC 25416 was observed.