Transponson Tn916 Mutagenesis in 'Bacillus anthracis'

摘要

Mutagenesis of Bacillus anthracis by the streptococcal tetracycline resistance transponson, Tn916, is described. Tn916 was transferred from Streptococcus faecalis strain DS16C1 to B. anthracis VNR-1 by conjugation in a standard filter mating procedure. Tetracycline-resistant (Tcr) transconjugants were obtained at a frequency of 1.6 X 10 to the minus 8 per donar CFU. When donor and recipient cells were treated with nafcillin prior to conjugation, this frequency was increased nearly tenfold. Nafcillin pretreatment of donor and recipient strains was used in all subsequent conjugation experiments. S. faecalis strain CG110, containing multiple chromosomal insertions of Tn916, transferred the transponson to B. anthracis VNR-1 at a frequency of 9.3 X .000 001 A Tcr B. anthracis transconjugant, strain VNR-1-tet-1, transferred Tn916 to B. anthracis strain UM23-1 and Bacillus subtilis BST1 at frequencies of 2.1 X .00001 and 5.8 X .0000001 respectively. The transfer of Tn916 occurred only on membrane filters, since no Tcr transconjugants were obtained when strains VNR-1-tet-1 and UM23-1 were mixed and incubated in broth culture. Of 3000 B. anthracis UM23-1 Tcr transconjugants tested, 21 were phenylalanine auxotrophs, and two were auxotrophic for phenylalanine, tyrosine, and tryptophan.