Abstract

Updated information and services can be found at: http://jb.asm.org/content/62/2/221.citation These include: CONTENT ALERTS Receive: RSS Feeds, eTOCs, free email alerts (when new articles cite this article), more» Information about commercial reprint orders: http://jb.asm.org/site/misc/reprints.xhtml To subscribe to to another ASM Journal go to: http://journals.asm.org/site/subscriptions/ III. RoiL OF p-AUINOBENZOIC ACID IN THE FoRwrIoN OF VITAMIN Bu1 U. S. Public Health Service, Tuberculosis Research Laboratory, Cornell University Medical College, New York Si, New York Received for publication April 30, 1951 A preceding paper in this series (Davis, 1951) described mutants of Escherichia coli that require 5 growth factors: tyrosine, phenylalanine, tryptophane, pminobenzoic acid (PABA), and p-hydroxybenzoic acid (POB). These quintuple aromatic auxotrophs are blocked at various stages in aromatic synthesis; those with the earliest block (e.g., strain 83-1) are satisfied in their growth requirement by a single nonaromatic intermediate, shikimic acid (a 3,4,5-trihydroxycyclohexenecarboxylic acid), or by its precursor, Compound X. In applying these mutants to the problem of it seemed likely that all aromatic metabolites might arise through a common path. A mutant blocked early enough in aromatic synthesis would be unable to make any of these compounds unless supplied with a precursor of it, or a compound that the cell