panD, a new chromosomal locus of Salmonella typhimurium for the biosynthesis of beta-alanine.

Three mutants of Salmonella typhimurium LT2, which required either pantothenate or beta-alanine for growth, were obtained after treatment with N-methyl-N'-nitro-N-nitrosoguanidine. Their phenotype was: SM30 Pan-, SM31 Pan- Met-, SM32 Pan- Thi- (requirement for the thiazole-moiety of thiamine). Neither aspartate, dihydrouracil, nor beta-ureidopropionate replaced beta-alanine as growth factor. By conjugation it was found that the three genetic lesions (Pan-, Met-, Thi-) were located at about minute 128 of the bacterial chromosome. By transduction 63% linkage was found between the Pan and Met loci, and 84% between the Thi and Pan loci. Probably the thiazole auxotrophy was due to a lesion in the thiG locus. The new genetic locus responsible for the synthesis of beta-alanine was named panD.