Open AccessThe Isolation and Characterization of Three Types of Vitamin B6 Auxotrophs of Escherichia coli K12
Author(s) -
Robert C. Hockney,
Thomas Allan Scott
Publication year - 1979
Publication title -
journal of general microbiology/journal of general microbiology
Language(s) - English
Resource type - Journals
eISSN - 2059-9323
pISSN - 0022-1287
DOI - 10.1099/00221287-110-2-275
Subject(s) - auxotrophy , pyridoxine , escherichia coli , mutant , biology , pyridoxal , oxidase test , gene , genetics , biochemistry , sulfathiazole , strain (injury) , pyridoxal phosphate , genetic linkage , microbiology and biotechnology , enzyme , cofactor , anatomy
Approximately 500 vitamin B6 auxotrophs were isolated from 18 independent cultures of Escherichia coli strain CR63. None grew in minimal medium supplemented with 2'-hydroxypyridoxine. Eighteen auxotrophs which had arisen independently were further characterized. All of them were defective in vitamin B6 synthesis rather than in an aminotransferase involved in vitamin B6 utilization. Two different phenotypes were recognized: 'Oxidase' mutants which grew only when supplied with pyridoxal or pyridoxal 5'-phosphate and 'Pre Pn' mutants which would also grow with pyridoxine or pyridoxine phosphate. "Oxidase' mutants were confined to a single linkage group, but data from interrupted mating experiments established that 'Pre Pn' mutants fall into two linkage groups which are possibly identical to pdxA and pdxB. All mutations in the in the pdxA region were allelic rather than located in two closely linked genes.