Temperature-sensitive -Lactam-tolerant Mutants of Escherichia coli

Publisher Website
Google Scholar
Abstract
Seven temperature-sensitive penicillin-tolerant mutants of E. coli strain LD5 (thi lysA dapD) were isolated and characterized. Treatment with .beta.-lactams caused lysis of the mutants at 30.degree. C. Although growth of the mutants at 42.degree. C was inhibited by .beta.-lactams, no lysis occurred. The mutants were also slightly tolerant to D-cycloserine at 42.degree. C but lysed readily when deprived of diaminopimelate or when treated with moenomycin. The minimum inhibitory concentrations of various antibiotics were the same for the mutants and their parent. The mutations conferring penicillin tolerance were phenotypically suppressed in the presence of a variety of compounds which may act as chaotropic or antichaotropic agents. No defects in penicillin-binding proteins and peptidoglycan hydrolases were detected. Temperature-resistant revertants of the mutants were no longer tolerant to the penicillin-induced autolysis at 42.degree. C. The mutations in 5 isolates were localized to the 56-61 min region of the E. coli linkage map and to the 44-51 min region in the case of 2 other isolates.