No abstract

The influence of various nutritional and environmental factors on the dissimilation of streptomycin by a pseudomonad isolated from soil was investigated, and conditions most suitable for growth of the bacterium, in a medium that contained streptomycin as a sole source of energy, nitrogen, and organic carbon, were determined. Development of the bacterium as measured by plate counts was correlated with degradation of streptomycin as measured by both biological and spectrophotometric assay procedures. Periodic analyses of culture filtrates indicated that the three constituent moieties of the streptomycin molecule underwent simultaneous transformation when the antibiotic was degraded microbiologically. Washed cell suspensions were capable of immediate and rapid oxidation of streptomycin, dihydrostreptomycin, and hydroxystreptomycin, but cell-free sonic extracts, in the absence and presence of cofactors, did not oxidize streptomycin or any of a number of derivatives or degradation products of the antibiotic. Evidence was obtained that the bacterial dissimilation of streptomycin involves an oxidation system in which methylene blue can act as hydrogen acceptor.

No abstract

Ammonia, methylamine, and pyridine were detected in broth filtrates of a streptomycin-degrading strain of Pseudomonas maltophilia during growth on streptomycin as a sole carbon and nitrogen source. Ammonia and methylamine, quantitatively measured by conversion to chromophores with picryl sulfonic acid, were found to accumulate in broth, whereas pyridine concentration increased in the early stages of streptomycin degradation and then decreased as the degradation of the antibiotic neared completion. Exogenous pyridine was metabolized by washed-cell suspensions. Use of N-streptomycin-methyl-14C showed that the methylamine arose from the N-L-glucosamine-methyl moiety of streptomycin. Methylamine was an end product and was not further metabolized by cells.

No abstract