Sodium Azide Resistance in Proteus hauseri

Abstract

SUMMARYThe sodium azide resistance pattern of Proteus hauseri is not of the allor-none unilocal type reported for Escherichia coli but rather of the obligatory multi-step or penicillin variety. Independently isolated 1st-step resistant variants possessed similar degrees of resistance to sodium azide. Some properties of azide-resistant variants of P. hauseri are described. In support of the above finding it was possible to transduce 1st-step (and only 1st-step) resistance into the wild-type by phage grown on either 1st-, 2nd-, 3rd-or 4th-step resistant organisms. It was also possible to transduce 2nd-step resistance into 1st-step resistant organisms by phage developed on independently isolated 1st-step resistant organisms or by phage from multi-step resistant variants. About 60 yo of transduced genes expressed their phenotype in platings done immediately after the adsorption period. It is concluded that a number of loci, not closely linked, and possibly equipotent, control sodium azide resistance in P. hauseri and that resistance could be dominant to the wild allele.

Mutations Determining Mitomycin Resistance in Bacillus subtilis

“…It would appear that in E. coli the development of resistance to this antibiotic follows a different pattern, since the resistance of first-step mutants ranges from 1.4 to 31 times that of the parent strain and multistep mutants with intermediate levels of resistance have been observed (9). Only a genetic analysis of the E. coli mutants would clarify this issue, but it may be pointed out that there are other examples (5,20) of different patterns of resistance shown by different bacterial species. The mutations that enhance the effect of the primary mutations in B. subtilis do not by themselves appear to confer any detectable level of resistance.…”