No abstract

1970. Proflavine binding and release by sensitive and resistant BaciNlrs sublilis. Can. J. Microbiol. 16: 973-981. Proflavine binding of a sensitive strain of Bacilllis slrbiilis and of a resistant strain derived from it was compared. Proflavine was bound very rapidly and more was bound at 0 "C than at 37 "C. Boiling increased the proflavine-binding capacity at 37 "C of sensitive but not of resistant cells. The binding capacity of sensitive and resistant cells suspended in buffer was the same; this was also true in various growth media. If cells were able to grow in the presence of proflavine their proflavine content decreased.Bound proflavine was released when cells were treated with growth media or with the salts of growth media. Sodium salts of organic acids also caused a release. This effect seemed due to thcir Na+ content, and was somewhat higher for resistant than for sensitive cells. The mechanism of proflavine resistance in B. slrblilis is probably different from that of Escllerichia coli, which is thought to depend on an energydriven release of bound proflavine.

Previous studies showed that some lactones have beta-lactamase inhibitory or antibacterial effects, others--like A-factor (a gamma-butyrolactone) and its derivatives--stimulate sporulation in Streptomyces griseus strains. Our experiments were aimed at exploring whether synthetic gamma-lactones had such effects. None of the seven gamma-lactones studied showed antibacterial activity, but two of them inhibited beta-lactamases isolated from various bacteria. These two gamma-lactones did not reduce colony formation of murine bone marrow cells in vitro, indicating that they were not toxic to proliferating mammalian cells. Four gamma-lactones, including the two inhibiting beta-lactamase, stimulated sporulation in the non-sporulating S. griseus bald 7 mutant. Further studies of gamma-lactones as potential inhibitors of beta-lactamase seem to be warranted.