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K B RAPER

Publications and source records attributed to K B RAPER.

At least 19 recordsLinked to original sources
PubMed1963

Nutrition of cellular slime molds. I. Growth on living and dead bacteria.

Hohl, Hans-Rudolf (University of Wisconsin, Madison) and Kenneth B. Raper. Nutrition of cullular slime molds. I. Growth on living and dead bacteria. J. Bacteriol. 85:191-198. 1963.-Methods for growing selected species of cellular slime molds in liquid culture on living and dead bacteria are described. Species investigated included Polysphondylium pallidum, P. violaceum, Dictyostelium discoideum, and D. purpureum. Maximal growth of myxamoebae occurred in suspensions of 10(10) living bacteria (Escherichia coli B/r)/ml in Sörensen's phosphate buffer (pH 6.0), reaching a density of 10(7) to 2 x 10(7) cells/ml in 48 hr. The generation time for the different slime molds ranged from 2.4 hr for P. violaceum to 2.9 hr for D. discoideum (strain V-12). Good growth of P. pallidum occurred between pH 3.6 and 7.8. The slime molds grew less well on dead (autoclaved) than on living bacteria and, except for P. pallidum, the amount and rate of growth decreased markedly as the time of autoclaving was increased from 2.5 to 80 min. Bacteria killed with propylene oxide supported growth equal to those autoclaved for a few minutes. The myxamoebae were very sensitive to the osmotic pressure of the culture medium, especially in the presence of living bacteria, and addition of as little as 0.01 m NaCl caused a measurable decrease in slime mold growth. The culture techniques employed afford useful methods for investigating the nutritional requirements of the cellular slime molds, and the experiments described provide the bases for subsequent studies relating to the axenic cultivation of these singular microorganisms.

Bacteria↗
PubMed1963

Nutrition of cellular slime molds. II. Growth of Polysphondylium pallidum in axenic culture.

Hohl, Hans-Rudolf (University of Wisconsin, Madison) and Kenneth B. Raper. Nutrition of cellular slime molds. II. Growth of Polysphondylium pallidum in axenic culture. J. Bacteriol. 85:199-206. 1963.-Several strains of Polysphondylium pallidum were grown on a liquid soluble medium in axenic culture. The medium contained embryo extract, serum albumin, Tryptose, dextrose, vitamins, and salts. The final cell yield was about 6-11 x 10(6) cells/ml, depending on the strain. The generation time was usually about 5 to 6 hr. The myxamoebae were grown for over 125 generations on this soluble complex medium without decrease in growth vigor or loss of their capacity to form normal fructifications when removed to an appropriate surface (e.g., agar). Thus the whole life cycle of this species was completed in the absence of any bacteria or bacterial products. Other species of the Dictyosteleaceae grew less well or failed to grow in the liquid medium described.

Agar↗
PubMed1963

NUTRITION OF CELLULAR SLIME MOLDS. III. SPECIFIC GROWTH REQUIREMENTS OF POLYSPHONDYLIUM PALLIDUM.

Hohl, Hans-Rudolf (University of Wisconsin, Madison), and Kenneth B. Raper. Nutrition of cellular slime molds. III. Specific growth requirements of Polysphondylium pallidum. J. Bacteriol. 86:1314-1320. 1963.-Soluble media for the axenic growth of certain strains of Polysphondylium pallidum are described. One of the media, referred to as the complex medium, was composed of 2% tryptose and 4% serum albumin in an inorganic salt solution. Cell densities of up to 10(7) myxamoebae per ml were obtained. Supplementing this medium with amino acids, vitamins, nucleic acid bases, and glucose resulted in growth of strain Pan-17 up to 3 x 10(7) cells per ml with a generation time during the log phase of about 4.5 hr. A defined medium was subsequently developed that allowed growth of strain Fr-47 up to 2 x 10(6) to 5.5 x 10(6) myxamoebae per ml in the presence of 1% serum albumin. The base medium contained the following essential nutrients: six amino acids (glycine, methionine, lysine, isoleucine, tryptophan, and tyrosine), riboflavine, purines and pyrimidines, and a carbohydrate (dextrose) dissolved in an inorganic salt solution containing trace elements.

Amino Acids↗
PubMed1962

Antibiotic activity of myxobacteria in relation to their bacteriolytic capacity.

Norén, Börge (University of Wisconsin, Madison) and Kenneth B. Raper. Antibiotic activity of myxobacteria in relation to their bacteriolytic capacity. J. Bacteriol. 84:157-162. 1962-Myxococcus virescens, M. fulvus, M. stipitatus, M. lacteus, Chondrococcus blasticus, and Chondromyces crocatus were tested for antibacterial activity, and all were found to secrete products that inhibited the growth of gram-positive eubacteria. The amount of inhibition varied with the myxobacterium employed and with the eubacterium used as a test organism. The growth of gram-negative eubacteria was in no case visibly affected by the antibiotic products. The experiments performed failed to indicate any positive relationship between the antibacterial activity and the bacteriolytic capacity of the six myxobacteria investigated.

Anti-Bacterial Agents↗