%0 Journal Article %A De Graaff, J. %A Stouthamer, A. H. %T Citrobacter freundii Mutants Deficient in Host Specificity Functions and Their Recipient Ability for Foreign Deoxyribonucleic Acid %D 1971 %J Microbiology, %V 67 %N 1 %P 91-97 %@ 1465-2080 %R https://doi.org/10.1099/00221287-67-1-91 %I Microbiology Society, %X Summary: The isolation and properties of mutants of Citrobacter freundii deficient in host specificity functions is described. Two mutant types have been isolated, one deficient in restriction (hsr) and another one deficient in both restriction and modification (hss). These non-restricting mutants are good recipients for plasmid DNA in conjugation experiments with Escherichia coli donor strains. Transfer of chromosomal markers was observed in crosses between E. coli Hfr strains and non-restricting mutants of C. freundii, and in crosses between Salmonella typhimurium Hfr or S. abony Hfr strains and non-restricting C. freundii recipients. Recombinants from these crosses are unstable, partially diploid strains. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-67-1-91