PubMed · 13242215
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W E HERRELL. 1955. Carbomycin.. https://pubmed.ncbi.nlm.nih.gov/13242215/
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A stable mutant No. 68 was obtained by treatment of S. mycarofaciens 1748 spores at high temperature. The electromicroscopic examination has shown that the mutant No. 68 and parent strain 1748 both have the spore chains of the spiratype. The spores of both strain are cylindrical in shape. The only difference is that the spores of the mutant No. 68 are of smooth surface, but the 1748 are of thorny. The physiological characteristics of both strains are also very similar with slight differences in utilization of few carbon sources and in cultural characters in few medium. Feeding experiment has shown that the mutant No. 68 was blocked in the formation of the macrolide lactone in the midecamycin biosynthetic pathway. This suggested that the mutant No. 68 might be a polyketide synthase genes deficient mutant. The ability of the mutant No. 68 to convert spiramycin into 4"-propionylspiramycin indicated that the mutant No. 68 contained the midecamycin 4"-propionyltransferase and could be used for microbial bioconversion of spiramycin into 4"-propionylspiramycin.
This in-vitro study of susceptibility to spiramycin of 103 strains of Branhamella catarrhalis isolated between 1982 and 1987 was performed by evaluation of their MICs. More than 97% of strains remained susceptible with MIC less than or equal to 8 mg/l (two strains). One strain presented a MIC of 16 mg/l. There were no significant differences of susceptibility to spiramycin between penicillinase-producing and non-producing strains.
Derivatives of mycaminosyl tylonolide (1) and 4'-deoxymycaminosyl tylonolide (2) containing N-ethyl-2-fluoro-, 2,2-difluoro- and 2,2,2-trifluoroethylamino groups at their C-23 have been prepared by treating 23-deoxy-23-ethylaminomycaminosyl tylonolide diethyl acetal (14) and its 4'-deoxy analog 15 with 2-fluoro-, 2,2-difluoro- and 2,2,2-trifluoroethyl trifluoromethanesulfonates. The relationship between the antibacterial activity and the numbers of the fluorine atoms introduced in the final products is discussed.