LYSIS OF BACTERIA

Selective release of the periplasmic enzyme beta-lactamase from Escherichia coli with tetradecyl betainate

The periplasmic enzyme beta-lactamase was selectively released from Escherichia coli K12 by the amphiphilic quaternary ammonium compound tetradecyl betainate at certain concentration intervals. At low concentrations little enzyme was released, and at high concentrations enzyme inactivation occurred. Greater effects of tetradecyl betainate were seen both with respect to release and inactivation at higher pH. At intermediate concentrations of tetradecyl betainate high yields of beta-lactamase were obtained with no detectable contribution of the cytoplasmic marker beta-galactosidase. The highest yields of beta-lactamase activity were obtained when high concentrations of salt were added 1 min after permeation of the bacteria with tetradecyl betainate.

Influence of salts and gelatin on disintegration of Saccharomyces cerevisiae by freeze-pressing

The disintegration by freeze-pressing of a low concentration of Saccharomyces cerevisiae suspended in aqueous solutions of gelatin and different salts has been studied at different temperatures. In the freeze-pressing process deionized water and salt solutions flow in pulses, whereas samples with increasing concentrations of gelatin or cells tend to flow more smoothly. This smooth flow enhances the disruption efficiency particularly at lower temperatures, which seems to be of great practical importance. The addition of salts also promotes disintegration. The presence of both gelatin and salts works antagonistically on disintegration presumably because of different modes of action at disruption of cells.

Isolation of mycoplasma membranes by digitonin

The cell membrane of Mycoplasma hominis was isolated by lysing the cells with digitonin. Electron microscopy and chemical, density gradient, and electrophoretic analyses of the membrane proteins showed the membranes so obtained, like those isolated by osmotic lysis, to be relatively free of cytoplasmic contaminants. Sensitivity to digitonin lysis depended on temperature but was not affected by Mg(2+) ions and was only slightly affected by the age of the culture. Accordingly, it seems that digitonin may be used for the isolation of cell membranes from sterol-requiring mycoplasmas that tend to be fairly resistant to osmotic lysis.

BACTERIOLYSIS OF THE PSEUDOMONADS: II. CHEMICAL TREATMENTS AFFECTING THE LYTIC RESPONSE

Various chemical treatments altered the lytic response of the pseudomonads to EDTA–lysozyme–buffer systems. Under acidic conditions (pH 6.0) lysis was impaired; alkaline conditions (pH 8.0) released this impairment. Shrinking and swelling of the cells paralleled the changes in pH. Lysis was inhibited by NaCl (0.1 to 2.0%); the degree of inhibition varied individually with the species. The addition of NaCl resulted in more compact cells. Growing the cultures in a medium containing increased levels of NaCl (1.0 to 5.0%) released the inhibition. Ten percent starch or sucrose, but not glycerol, also inhibited lysis.