Effect of carbon source on pyrimidine formation in Pseudomonas fluorescens ATCC 13525

The effect of carbon source on the regulation of the de novo pyrimidine biosynthetic enzymes in the type strain of Pseudomonas fluorescens was investigated. The de novo pyrimidine biosynthetic enzyme activities were measured in P. fluorescens ATCC 13525 cells and in cells from an auxotroph deficient for orotate phosphoribosyltransferase activity where glucose or succinate served as the carbon source. Pyrimidine supplementation to the culture medium affected the biosynthetic enzyme activities in ATCC 13525 cells. Pyrimidine limitation of the mutant strain indicated transcriptional regulation of the biosynthetic pathway by pyrimidines that was influenced by carbon source. Transcriptional regulation of pyrimidine synthesis in P. fluorescens appeared to be more highly regulated than was observed for the taxonomically related species Pseudomonas aeruginosa or Pseudomonas putida.