CHARACTERIZATION AND GENETIC-MAPPING OF PHOSPHOGLUCOISOMERASE MUTATIONS IN MANNITOL-NEGATIVE MUTANTS OF PSEUDOMONAS-AERUGINOSA

Phosphoglucoisomerase (pgi) mutations in a number of independently iso lated mannitol-negative mutants of Pseudomonas aeruginosa PAO1 were ma pped on the chromosome by plasmid FPS-mediated conjugation and by cotr ansduction with the generalized transducing phages G101 and F116L. Mut ant allele pgi-9001 exhibited linkage to ilvB, C-9059 (46-85%), car-90 03 (93-100%), and pur-9047 (70%), but not with met-9011, in FPS-mediat ed conjugational crosses. All known pgi mutations and several previous ly uncharacterized mannitol-negative mutations exhibited transductiona l linkage to two independent car mutations at frequencies ranging from 13% to 42% and 53% to 99%, in transductional crosses mediated by phag es G101 and F116L respectively. These pgi and mannitol-negative mutati ons also were cotransducible at very low frequencies (<1%) with two in dependent ilv mutations. Cotransduction of the car and ilv loci could not be detected, These data suggest the location of pgi within the fir st minute of the P. aeruginosa chromosome closely linked to the car ma rker and probably between the ilv and car loci. All of the mannitol-ne gative mutations that exhibited linkage to the car and ilv loci were c haracterized as pgi mutations by enzyme assays. A phenotypically simil ar, mannitol-negative mutatant was shown to contain a mutation in gluc ose-6-phosphate dehydrogenase (zwf-9012) that maps to a different regi on on the chromosome.