- Volume 114, Issue 1, 1979

Summary: At an external pH of 3·5, nigericin (which catalyses an electroneutral H+/K+ exchange) abolished the transmembrane proton gradient (∆pH) of Bacillus acidocaldarius, causing a rapid acidification of the cytoplasm from approximately pH 6·0 to pH 3·5. A pronounced loss of viability and fine-structural changes rapidly followed treatment with nigericin. A marked decline in respiration and an even more rapid decrease in cytoplasmic ATP were observed. Activity of at least one cytoplasmic enzyme decreased more slowly. There was no generalized loss in the integrity of the cytoplasmic membrane, as assayed by permeability to inulin or Na+ or by release of ultraviolet light-absorbing compounds. The loss of viability upon treatment with carbonyl cyanide m-chlorophenylhydrazone was similar to that observed with nigericin, so proton influx alone, rather than together with K+ efflux, was probably involved in the death of the organism. Moreover, acidification of the cytoplasm rather than abolition of the ΔpH was the lethal event, since no loss of viability was observed when the ΔpH was abolished by elevation of the external pH.

SUMMARY: A Chlamydia psittaci strain grown on McCoy cell monolayers showed endotoxin-like activity by both the limulus amoebocyte lysate assay and the rabbit pyrogen test.

Summary: The isoprenoid quinone contents of streptococci of serological groups D and N were investigated. Streptococcus faecalis, S. faecalis subsp. liquefaciens and S. faecalis subsp. zymogenes strains contained demethylmenaquinones with nine isoprene units as their major isoprenologues. Menaquinones with eight isoprene units predominated in S. faecium subsp. casseliflavus and S. faecium subsp. mobilis whereas menaquinones with nine isoprene units constituted the major components in strains of S. cremoris, S. cremoris subsp. alactosus, S. lactis and S. lactis subsp. diacetylactis. Strains of S. avium, S. bovis, S. durans, S. equinus, S. faecium, S. raffinolactis and S. suis contained neither menaquinones nor ubiquinones. The isoprenoid quinone data correlate well with other kinds of data on these organisms and are of value in the classification of these bacteria.