Bacterial utilization of dodecyl sulfate and dodecyl benzene sulfonate

Two unknown bacterial isolants (C12 and C12B) were obtained from enriched soils and cultured on media containing detergent compounds as sole sources of carbon. Either isolant destroyed the foaming capacity of cultures containing dodecyl sulfate; but C12B, which could grow on dodecyl benzene sulfonate (DBS) whereas C12 could not, did not destroy the foaming capacity of this surfactant. The source of DBS available in quantity was a mixture of isomers derived from kerosene, and the bacteria utilized only one-fifth to one-fourth of this material during growth. Both isolants grew on short- or long-chained organic acids, and resting cells of both rapidly oxidized several long-chain acids and alcohols. Three of five phenyl-placement isomers of DBS (with the phenyl group at carbon 2, 3, or 6 on the alkyl chains) were excellent substrates for growth of C12B, but isomers with phenyl placement at carbon 4 or 5 were toxic and killed the bacteria.

EFFECT OF DETERGENT ON ELECTRICAL PROPERTIES OF SQUID AXON MEMBRANE

The effects of detergents on squid giant axon action and resting potentials as well as membrane conductances in the voltage clamp have been studied. Anionic detergents (sodium lauryl sulfate, 0.1 to 1.0 mM; dimethyl benzene sulfonate, 1 to 20 mM, pH 7.6) cause a temporary increase and a later decrease of action potential height and the value of the resting potential. Cationic detergent (cetyl trimethyl ammonium chloride, 6 x 10^-5M or more, pH 7.6) generally brings about immediate and irreversible decreases in the action and resting potentials. Non-ionic detergent (tween 80, 0.1 M, pH 7.6) causes a slight reversible reduction of action potential height without affecting the value of the resting potential. Both anionic and cationic detergents generally decrease the sodium and potassium conductances irreversibly. The effect of non-ionic detergent is to decrease the sodium conductance reversibly, leaving the potassium conductance almost unchanged.

THE CLEANING OF INSTRUMENTS AND SYRINGES

The dangers to the handler of syringes used for routine injections were found to be negligible, but known infected syringes and those contaminated with antibiotics should be autoclaved before handling as a high proportion of these carry pathogenic organisms. Mechanical methods of cleaning syringes and instruments are assessed. The use of an artificial soil for testing purposes is described. Using this soil, ultrasonics by themselves are inadequate for cleaning syringes and instruments. Agitation with ultrasonics is essential for syringes, but is insufficient for instruments. Detergents are therefore an essential adjunct to the cleaning process. For syringes Pyroneg proved to be the most satisfactory, particularly if they had been previously siliconized. The best detergent for instruments contaminated with these types of soil was Penesolve 814 at a temperature of 95 degrees C. but the instruments must be adequately rinsed after this treatment. A number of other detergents and cleaning agents are discussed.

CHARACTERIZATION OF THE HUMAN GASTRIC PARIETAL CELL AUTO-ANTIGEN

The gastric parietal cell auto-antigen is localized essentially in the microsomal fraction of mucosal homogenates obtained by centrifugation over a sucrose density gradient. The fractionation is facilitated by digestion of gastric mucus with ficin before disruption of the tissue. The antigen was assayed by a quantitative complement-fixation method. The effect of a number of enzymes and chemical treatments upon the serological reactivity of a gastric microsomal preparation was studied. The properties of the gastric antigen suggest an intimate association with insoluble lipoprotein elements of the microsomal membranes. Although immunologically distinct and strictly organ specific, the cytoplasmic auto-antigens of the stomach, and of the thyroid gland, show a remarkable resemblance in their biochemical characteristics. This similarity has a parallel not only in the embryo-logical origin and the iodide trapping mechanisms which the two organs share in common but also in the close serological and clinical associations that have been demonstrated between auto-immune atrophic gastritis and thyroiditis.