Restoration of Growth Phenotypes of Escherichia coli DH5α in Minimal Media through Reversal of a Point Mutation in purB

A point mutation (E115K) resulting in slower growth of Escherichia coli DH5α and XL1-Blue in minimal media was identified in the purB gene, coding for adenylosuccinate lyase (ASL), through complementation with an E. coli K-12 genomic library and serial subcultures. Chromosomal modification reversing the mutation to the wild type restored growth phenotypes in minimal media.