Inactivation of dihydrostreptomycin by Staphylococcus aureus

Protoplast transformation of glutamate-producing bacteria with plasmid DNA

A method for polyethylene glycol-induced protoplast transformation of glutamate-producing bacteria with plasmid DNA was established. Protoplasts were prepared from cells grown in the presence of penicillin by treatment with lysozyme in a hypertonic medium. The concentration of penicillin during growth affected the efficiency of formation, regeneration, and polyethylene glycol-induced DNA uptake of protoplasts. Regeneration of protoplasts was accomplished on a hypertonic agar medium containing sodium succinate and yeast extract. The spectinomycin and streptomycin resistance plasmid pCG4, originally from Corynebacterium glutamicum T250, could transform various glutamate-producing bacteria such as C. glutamicum, Corynebacterium herculis, Brevibacterium flavum, and Microbacterium ammoniaphilum. The plasmid was structurally unchanged and stably maintained in new hosts. The transformation frequency of most competent protoplasts with pCG4 DNA isolated from primary transformants was high (ca. 10(6) transformants per microgram of covalently closed circular DNA) but was still two orders of magnitude below the frequency of transfection with modified DNA of the bacteriophage phi CGI. The difference was ascribed to the involvement of regeneration in transformation.

Antiviral activity of alpha-methyl-1-adamantanemethylamine hydrochloride

Three types of Staphylococcus aureus strains were isolated with respect to streptomycin (SM) and spectinomycin (SPC) resistance, namely, SM r SPC r , SM r SPC s , and SM s SPC r (r, resistant; s, sensitive). Curing experiments and transduction analysis of strain MS7990 (SM r .SPC r .EM r ) (EM, erythromycin) disclosed that the loci governing SM and SPC resistance are different and exist on different nontransferable plasmids ( r factor), one plasmid carrying the genes governing SM resistance and another possessing the genes governing resistance to both SPC and EM. Strain MS7990 (SM r .SPC r ) inactivated both drugs by adenylylation. Similarly, the SM r SPC s and SM s SPC r strains inactivated SM and SPC, respectively, by adenylylation, although the adenylylated positions of both drugs have not been established as yet. The adenylylated SM in staphylococci was shown to be different from 3″-adenylyl-SM, indicating the possibility of the existence of a different enzyme from SM3″-adenylyl transferase demonstrated in Escherichia coli strains.

Lividomycin resistance in staphylococci by enzymatic phosphorylation

Enzymatic inactivation of lividomycin (LV) was attempted with nine clinical isolates of staphylococci including LV-susceptible and -resistant strains. LV inactivation and the incorporation into LV of (32)P from gamma-(32)P-adenosine triphosphate were demonstrated in the presence of cell-free extracts from LV-resistant strains but not from LV-susceptible ones. The enzyme was purified approximately 82-fold from a resistant Staphylococcus aureus strain by means of ammonium sulfate fractionation and column chromatography. Some properties of the partially purified LV-phosphorylating enzyme were quite similar to those of an enzyme from Escherichia coli carrying an R factor conferring LV resistance, and the phosphorylated product of the drug was also found to be identical with that produced by E. coli carrying an R factor, i.e., 5''-phosphoryl-LV.