Isolation of uracil auxotrophs from Burkholderia cepacia ATCC 25416.

Two uracil auxotrophs of the phytopathogen Burkolderia cepacia ATCC 25416, which is known to be involved in food spoilage, were isolated by a combination of ethylmethane sulphonate and D-cycloserine counterselection. One mutant exhibited depressed orotate phosphoribosyltransferase activity while the other mutant lacked orotidine 5'-monophosphate decarboxylase activity. Pyrimidine limitation of either auxotroph elevated aspartate transcarbamoylase and dihydroorotase activities by at least 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.