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R S BERK

Publications and source records attributed to R S BERK.

11 recordsLinked to original sources
PubMed1964

BIOELECTROCHEMICAL ENERGY CONVERSION.

The interaction between photosynthetic microorganisms and an inert electrode material was examined. Cathodic polarization values of platinum-bearing marine algae were obtained over a wide current-density range under both illumination and dark conditions. A potential shift of 0.6 v in the cathodic direction occurred upon illumination at a current density of 4.3 mua/cm(2). Similar photo-induced results, involving anodic polarization, were obtained by use of resting cells of Rhodospirillum rubrum supplemented with malate. Appropriate combinations of such bioelectrodes were used to assemble an electrochemical cell capable of light-dependent production of electrical energy.

Electrophysiology↗
PubMed1964

PARTIAL PURIFICATION OF THE EXTRACELLULAR HEMOLYSIN OF PSEUDOMONAS AERUGINOSA.

Berk, Richard S. (Wayne State University, College of Medicine, Detroit, Mich.). Partial purification of the extracellular hemolysin of Pseudomonas aeruginosa. J. Bacteriol. 88:559-565. 1964.-Through a series of chemical fractionation steps, the extracellular hemolysin of Pseudomonas aeruginosa was purified 126-fold with a recovery of 49%. Hemolytic activity of crude preparations was irreversibly lost upon contact with anionic exchange materials such as diethylaminoethyl Sephadex or ECTEOLA-Cellulose, but traveled with the solvent front during passage through Sephadex G-200 and carboxymethyl Sephadex. The hemolysin was soluble in water and ethanol, and was partially extractable with ether, but not with trichlorotrifluoroethane (Freon). Although normal serum and serum albumin blocked hemolytic activity, it was unaffected by trypsin, deoxyribonuclease, or ribonuclease. Partially purified hemolysin was studied in vivo, but did not exert dermonecrotic activity in mice or rabbits in the concentrations tested. Although preparations were toxic to mice, lethality appeared to be more a reflection of the nonhemolytic protein content of the preparations rather than of hemolytic activity.

Animals↗
PubMed1963

INTRACELLULAR HEMOLYSIN OF PSEUDOMONAS AERUGINOSA.

Berk, Richard S. (Wayne State University, Detroit, Mich.). Intracellular hemolysin of Pseudomonas aeruginosa. J. Bacteriol. 85:522-526. 1963.-Disruption of cells (2 to 6 days old) of Pseudomonas aeruginosa grown in Tryptose Broth devoid of blood yielded an intracellular hemolysin active on sheep and human erythrocytes. The intracellular agent was not usually detectable in cells grown under highly aerobic conditions. However, activity was observed after 48 hr of growth and appeared to reach a peak at 96 hr when grown under static conditions. Centrifugation of hemolytic extracts at 20,000 x g for 30 min resulted in a fractionation of activity into particulate and soluble components. Similar fractionation of activity occurred after adjustment of the pH of crude extracts to 1.40. In addition, hemolytic preparations were not inactivated by boiling for 90 min, by treatment with ethylenediaminetetraacetate, or by heating in equal volumes of 20% KOH. Activity over a wide pH range was noted, with a maximum occurring at approximately 6.0. However, some preparations occasionally exhibited a second peak on the alkaline side.

Animals↗
PubMed1963

NUTRITIONAL STUDIES ON THE "AUTO-PLAQUE" PHENOMENON IN PSEUDOMONAS AERUGINOSA.

Berk, Richard S. (Wayne State University, Detroit, Mich.). Nutritional studies on the "auto-plaque" phenomenon in Pseudomonas aeruginosa. J. Bacteriol. 86:728-734. 1963.-Examination of 20 cultures of Pseudomonas aeruginosa indicated that 18 cultures possessed the common property of spontaneously lysing to form "plaques" or erosions on themselves in the absence of a sensitive indicator strain. Maximal lysis and plaque production was found to occur on a medium with a Tryptone concentration of 2.0 to 2.5%. Reduction of the Tryptone concentration to 0.5% or less supported growth, but was usually inadequate for support of lysis. However, addition of l-asparagine or l-arginine to 0.5% Tryptone induced lysis. Examination of five strains of Pseudomonas, which routinely exhibited the autolytic phenomenon, indicated that all were both lysogenic and pyocinogenic when tested against other Pseudomonas strains on both 2 and 0.5% Tryptone. Culturing of autolytic strain Pa-1 on a simple medium composed of glucose and inorganic salts appeared to be inadequate for "auto-plaque" formation, although lysis occurred occasionally when a yeast extract concentration of 1% was incorporated into the medium. Suppression of auto-plaque formation was also effected by growing the culture on Technicon dialyzing membrane D3 overlaid on 2% Tryptone, although lysogenic lysis of an indicator strain was demonstrable on the membrane.

Arginine↗
PubMed1962

Production and characterization of Pseudomon as aeruginosa hemolysin.

Berk, Richard S. (Wayne State University, Detroit, Mich.). Production and characterization of Pseudomonas aeruginosa hemolysin. J. Bacteriol. 84:1041-1048. 1962.-Hemolysin from Pseudomonas aeruginosa was obtained by either extraction of blood agar media after bacterial growth or by saline washing of cellophane plate-grown cells, hemolytic activity being greatest in the latter preparations. Except for variations in heat stability, both types of preparations appeared to be similar if not identical. Complete hemolysis of red blood cells was observed over a wide pH range, although the optima appeared to be below 6.0. Acidification of agar extracts resulted in a coarse precipitate which appeared to be a hemolysin-agar complex. Partial purification of hemolysin present in cellophane washings was obtained by fractionation with ammonium sulfate or by gel filtration. Further characterization of hemolysin is described.

Agar↗