Warm-Water Strain of Leucothrix mucor

The physiological properties and temperature responses of the first strain of Leucothrix mucor ever to be isolated from a warm, tropical seacoast area are described.     

Electron microscope studies on Leucothrix mucor

Summary Electron microscopic studies of thin sections of filaments, knots, resettes, gonidia, and gonidial-forming filaments of Leucothrix mucor were carried out. The cell wall is typical of gram-negative bacteria, with a double outer layer of variable thickness, a single thin middle layer which is probably peptidoglycan, and a double inner layer which is the cell membrane. The transverse septa of these filaments show two peptidoglycan layers, and no clearly demarked outer layer. During gonidial formation, there is a gradual rounding up of the cells, and the transverse septa become part of the gonidial wall. The cell membrane contains many invaginations, both along the outer wall and along the transverse septa. Thin sections through rosettes show the holdfast as material which is a heavily-staining amorphous material peripheral to the outer wall layer. Sections through knots show highly contorted cell walls, closely appressed. Fibrillar nuclear material, ribosomes, and storage granules can be seen within the cytoplasmic matrix.     

Molecular Heterogeneity of Isolates of the Marine Bacterium Leucothrix mucor

Two collections of strains of Leucothrix mucor were isolated, one of world-wide origin and the other originating from a restricted area around San Juan Island, Friday Harbor, Washington. These two collections were compared on the basis of morphological, nutritional, and physiological properties, deoxyribonucleic acid base composition, and mobility by starch-gel electrophoresis of isocitric dehydrogenase and malic dehydrogenase. Despite the fact that all the strains were similar in most characteristics, significant molecular heterogeneity was found in the enzyme electrophoresis studies. This heterogeneity was just as great in the local collection as it was in the world collection. Even strains originating from the same microenvironment exhibited molecular heterogeneity.     

Effect of Several Algicides and Surfactants on the Filamentous Bacterium Leucothrix mucor Oersted

Leucothrix mucor Oersted, the primary cause of filamentous gill disease in cultured shrimp, was treated with algicides and surfactants by a serial dilution method. It was found to be highly sensitive to those algicides containing quaternary ammonium compounds. Copper-containing compounds and Formalin were less effective, whereas potassium permanganate and two surfactants, Dreft and Alconox, were ineffective.     

Mode of Filamentous Growth of Leucothrix mucor in Pure Culture and in Nature, as Studied by Tritiated Thymidine Autoradiography

Mode of growth of Leucothrix mucor filaments was measured by autoradiography with tritiated thymidine. Studies were performed on L. mucor in pure cultures in free suspension, as an epiphyte of pure cultures of the red alga Antithamnion sarniense, and as an epiphyte of red algae in the sea. Statistical analyses of the distribution of growing cells was done by use of the nonparametric One-Sample Runs Test and a Cluster analysis adapted from quadrat analyses of plant ecologists. No evidence of preferential growth at base or tip of L. mucor filaments was obtained in any of these studies. However, in nature, but not in the laboratory, there were regions of L. mucor filaments which were nongrowing or dormant. Such nongrowing regions could incorporate tritiated glucose.     

Zur Kenntnis von Leucothrix,einer Gattung farbloser Cyanophyceen

Zusammenfassung Leucothrix ist eine marine, fädige, apochlorotische Cyanophycee. Wo Meeresalgen in Zersetzung übergehen, ist sie fast immer zu finden. Durch Ausstreichen auf Seewasseragar mit wenig Fleischextrakt können Reinkulturen hergestellt werden.Die meisten Stämme von verschiedenen Küsten sind einander morphologisch und physiologisch so ähnlich, daß sie zur selben Art Leucothrix mucor Oersted zu stellen sind, wenn auch unbedeutende Unterschiede bestehen.Ein Ammonsalz in Seewasser mit den üblichen Nährsalzen und einer Hexose oder Salzen einiger organischer Säuren ermöglicht gutes Wachstum. Vitamine sind nicht nötig.Die Zugehörigkeit zu den Cyanophyceen ist durch die Bildung von Hormogonien mit Gleitvermögen, die Beschaffenheit der Zellfäden und das Auftreten von Nekridien gesichert.

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Summary A colourless marine filamentous organism occurring frequently on decaying seaweeds has been repeatedly described under various names until Harold u. Stanier (1955) identified it with Leucothrix mucor (Oversted, 1844). They also demonstrated its morphological features which show that the organism belongs as an apochlorotic member to the Cyanophyceae.The present author, after adding a few morphological details, described a second species as Leucothrix cohaerens (Pringsheim, 1957). The strains derived from a number of coastal localities newly isolated for nutritional investigations or given to me by other authors, all belong to the original type. If there are differences they are very small.Clonal axenic strains were prepared by streaking on seawaterbeefextract agar plates. They were tested for their nutritional requirements in liquid media with artificial seawater, the customary nutrient salts and organic substrates. With an ammonium salt as nitrogen source glucose and other hexoses supported the growth of Leucothris mucor, various organic acids to a lesser degree. Vitamins are not required but substances like beefextract and yeast-autolysate make the growth richer.The taxonomic position of Leucothrix as related to the Cyanophyceae is established by the production of hormogonia with gliding motility, the structure of the trichomes, and the occurrence of necridia.

     

Improved Double-Vial Radiorespirometric Technique for Mineralization of 14C-Labeled Substrates

New procedures which simplify sample preparation and improve counting efficiency were developed for double-vial radiorespirometry. Under certain conditions, efficiency of fluor-NaOH-impregnated wicks was not stable, but was adversely affected by water vapor, NaOH concentration, and CO₂ loading. Glass fiber wick material treated with a methanolic fluor-NaOH solution showed improved ¹⁴C counting efficiency (58%) compared with previous methods.     

Radiorespirometric studies of carbohydrate metabolism by washed spermatozoa of various species.

1. The patterns of 14CO2 evolution from specifically labeled glucose substrates by washed bull, ram, boar, rabbit, dog, rooster and turkey spermatozoa were similar and indicated the Embden-Meyerhof and Kreb's cycle pathways as the major route of energy metabolism. 2. Honey bee spermatozoa metabolized glucose-3,4-[14C], glucose-[U-14C] or fructose-[U-14C], but not glucose-1-[14C], glucose-2-[14C]or glucose-6-[14C], indicating the presence of the glycolytic pathway, but the absence of respiration via the Kreb's cycle. 3. The rate of glycolysis exceeded the rate of respiration in the spermatozoa of all the species studied. 4. A preferential utilization of glucose-1-[14C] over glucose-6-[14C] was evident in some sperm samples, but no consistent indication of pentose cycle metabolism was observed, due to considerable variability between samples within each group. 5. Fructose metabolism was greater than glucose metabolism in the rooster, less in the dog, boar and turkey, and similar in the spermatozoa from the other species examined. 6. Only ram and bull spermatozoa metabolized acetate-1-[14C] to any extent.     

Method for Radiorespirometric Detection of Bacteria in Pure Culture and in Blood

Methods are described for the detection of low numbers of bacteria by monitoring (14)CO(2) evolved from (14)C-labeled substrates. Cell suspensions are filtered with membrane filters, and the filter is then moistened with 0.1 ml of labeled medium in a small, closed apparatus. Evolved (14)CO(2) is collected with Ba(OH)(2)-moistened filter pads and assayed with conventional radioactivity counting equipment. The kinetics of (14)CO(2) evolution are shown for several species of bacteria. Fewer than 100 colony-forming units of most species tested were detected in 2 h or less. Bacteria were inoculated into blood and the mixture was treated to lyse the blood cells. The suspension ws filtered and the filter was placed in a small volume of labeled medium. The evolved (14)CO(2) was trapped and counted. A key development in the methodology was finding that an aqueous solution of Rhyozyme and Triton X-100 produced lysis of blood but was not detrimental to bacteria.     

Lipid content during sexual development in the homothallic mucor Zygorhynchus moelleri

In Zygorhynchus moelleri, a homothallic Mucor, triglycendes are the main components of chloroform/methanol extractable lipids. The triglycerides accumulate in the aerial hyphae, particularly in the developing zygospores and in the lateral suspensors, but only after zygospore maturation. They are probably transported from the submerged mycelium to the aerial hyphae. Most of the fatty acid synthetase activity is found in the submerged mycelium. The fatty acid composition of the triglycerides does not change appreciably during sexual development. No influence of trisporic acids has been found on triglyceride synthesis or transport.