Showing papers in "Archives of Microbiology in 1967"

Methanobacillus omelianskii, a Symbiotic Association of Two Species of Bacteria*

Abstract: Two bacterial species were isolated from cultures of Methanobacillus omelianskii grown on media, containing ethanol as oxidizable substrate. One of these, the S organism, is a gram negative, motile, anaerobic rod which ferments ethanol with production of H2 and acetate but is inhibited by inclusion of 0.5 atm of H2 in the gas phase of the medium. The other organism is a gram variable, nonmotile, anaerobic rod which utilizes H2 but not ethanol for growth and methane formation. The results indicate that M. omelianskii maintained in ethanol media is actually a symbiotic association of the two species.

The vacuole as the lysosome of the yeast cell

Abstract: Vacuoles can be isolated by flotation from suspensions of lysed proto-plasts in the presence of Ficoll. The purity of the respective preparations is demonstrated by the complete absence of enzymes of the mitochondria and of the groundplasm, as well as by morphological observations. Hydrolytic enzymes (two acid proteases, p-nitrophenylacetate-esterase, RNase and leucylaminopeptidase) are present in high specific activities in isolated vacuoles. The vacuole therefore represents the lysosome of the yeast cell.

Hydrogen as an intermediate in the rumen fermentation.

Abstract: A method for measuring the steady state concentration of hydrogen gas dissolved in rumen contents was developed, which consisted of equilibrating the intercellular fluid with sterile salt solution within a dialysis sac immersed in the rumen or in the in vitro system under study. After about 1 hr of equilibration the contents of the sac were withdrawn and transferred without loss of hydrogen to a flask devoid of materials except water and water vapor. Carbon dioxide was absorbed with alkali and the remaining gas displaced by boiling, with condensation of vapor in a water-cooled hypodermic syringe. The hydrogen was collected in the syringe and analyzed with a gas chromatograph. The rate of methane production correlated more closely with concentration of dissolved hydrogen than with formate. At saturating formate concentrations, addition of hydrogen increased methanogenesis. It is concluded that hydrogen is a very important intermediate in the rumen production of methane.

Transport-limited fermentation and growth of Saccharomyces cerevisiae and its competitive inhibition

Abstract: The anaerobic glucose uptake (at 20°, pH 3.5) by resting cells of Saccharomyces cerevisiae followed unidirectional Michaelis-Menten kinetics and was competitively inhibited by l-sorbose; K m and K i were respectively 5.6×10-4 m and 1.8×10-1 m; V max was 6.5×10-8 moles mg-1 min-1. The aerobic uptake of glucose by resting yeast was also inhibited by l-sorbose but did not follow unidirectional Michaelis-Menten kinetics. Glucose-limited growth in the chemostat of a respiration-deficient mutant of S. cerevisiae was competitively inhibited by l-sorbose. As predicted by theory for transport-limited growth in the chemostat (van Uden, 1967) the steady state glucose concentrations were linear functions of the l-sorbose concentrations with different slopes at different dilution rates; K m and K i were respectively 7.2×10-4 m and 1.8×10-1 m. It is concluded that glucose transport was the rate-limiting step of anaerobic fermentation of S. cerevisiae and of growth of the mutant and that l-sorbose is a competitive inhibitor of active glucose transport in this yeast. The latter conclusion is accommodated in the transport model of van Steveninck and Rothstein (1965).

Zur chemischen Zusammensetzung der Zellwand der Streptokokken

Abstract: Aus Streptococcus thermophilus wurden durch Zerschlagen mit Glasperlen und anschliesender tryptischer Verdauung die Zellwande gewonnen. Sie erwiesen sich frei von Teichon- und Teichuronsaure, enthalten aber Polysaccharide und Murein. Das Polysaccharid bestand aus Rhamnose, Glucose, Glucosamin und Galaktose.

Physiologische und biochemische Beiträge zur Taxonomie der Gattung Chlorella

Abstract: Es wurde die Verwendbarkeit von Acetat, Glucose, Fructose, Galactose, Saccharose und Lactose als Kohlenstoffquelle fur das Wachstum von 72 Chlorella-Stammen, die 10 autotrophen Taxa angehoren, untersucht. Im Dunkeln zeigen mit Acetat 34 Stamme und mit Glucose 37 Stamme gutes Wachstum (Chlorella kessleri, die meisten Stamme von C. vulgaris und C. vulgaris f. tertia, sowie einige wenige Stamme von C. fusca), wahrend Fructose von 21 Stammen verwertet wird (C. kessleri, die meisten Stamme von C. luteoviridis und C. saccharophila, sowie einige Stamme von C. fusca und C. zofingiensis). Gutes Wachstum mit Galactose wurde bei 11 Stammen gefunden (C. kessleri und einige Stamme von C. vulgaris). Saccharose und Lactose ermoglichen dagegen kein intensives Wachstum. Die Verwendbarkeit der 6 gepruften organischen Verbindungen fur heterotrophes Wachstum ist als taxonomisches Merkmal zur Charakterisierung von Chlorella-Arten nicht geeignet. Lediglich Chlorella kessleri Fott et Novakova, die allgemein die ausgepragteste Fahigkeit zu heterotrophem Wachstum besitzt, unterscheidet sich durch gute Verwertung von Galactose von den ubrigen Arten.

Kefiran, a novel polysaccharide produced in the kefir grain by Lactobacillus brevis

Abstract: 1. Almost half of the material embedding the microbial population of the kefir grain consists of kefiran, a polysaccharide consisting of equal amounts of galactose and glucose with an \([\alpha ]_D ^{20^ \circ }\) of + 68.0° (C=1, H2O). 2. Kefiran is the capsular material of the large rod-shaped bacteria which predominate in the grains and have the properties of Lactobacillus brevis.

Periodicity in cell division and physiological behavior of ditylum brightwellii, a marine planktonic diatom, during growth in light-dark cycles

Abstract: Cells of Ditylum brightwellii, a large marine centric diatom, were partially synchronized by employing an appropriate light-dark cycle. At 20°C this consisted of 8 hrs of illumination at an intensity of 0.05 cal/cm2 min. A single 2.8 l culture was studied over a 20 day period by diluting the culture daily to a standard cell concentration. The sequence of events in cell development was as follows: daughter cells were formed late in the light period, in the dark they elongated and the numerous chromatophores began dividing. A minimum cell buoyancy was observed in the dark concurrent with cell elongation. Increase in cell phosphorus took place in the dark period. The photosynthetic rate of cells removed during the dark period decreased to a minimum. In the following light period photosynthetic rate increased to a maximum, photosynthetic pigments, cell carbon, nitrogen, and carbohydrate increased and cell division again took place. Cell silica content increased concomitant with cell division. Details of cell morphology during cell division, based upon light microscopy, are reported.

Enrichments of aquatic bacteria in continuous culture

Abstract: A chemostat was employed for the enrichment and eventual isolation of a variety of heterotrophic bacteria from seawater. Experimental attempts to separate single species from mixed cultures of known composition showed that successful or unsuccessful competition for the limiting substrate is based upon the particular growth parameters of the individual species under the given culture conditions. The technique appears to be suitable to enrich reproducibly for bacterial species of little substrate specificity. Applications in ecological studies are discussed.

Isolation and properties of the plasmalemma in yeast

Abstract: A method is described for the isolation of fragments of the plasmalemma based on differential and density gradient centrifugation using cell free extracts from anaerobically grown Saccharomyces cerevisiae. Electron microscopically investigated frozen-etched specimens of isolated plasmalemma revealed the presence of globular particles attached to the outer surface of the membrane; these particles correspond to those observed in situ. In isolated plasmalemma a high specific activity of Mg++-dependent ATPase, which is not sensitive to Oligomycin, is present. Yeast plasmalemma contains protein, lipids (including phospholipids) and an appreciable amount of polysaccharide. Hydrolysis of this polysacharide yields only mannose. The treatment of the isolated plasmalemma with detergents liberates the globular particles which can be isolated by density gradient centrifugation. Protein and polysaccharide occur in the respective fraction; therefore the globular particle represents a mannan-protein. It is concluded that the particles, which cover the plasma-membrane of plant cells, represent glycoproteins, that is, building stones to be incorporated into the fibrillar network of the cell walls.

The metabolism of aromatic acids by Pseudomonas testosteroni and P. acidovorans

Abstract: P. testosteroni oxidizes benzoate, m-hydroxybenzoate and p-hydroxybenzoate to protocatechuate, which is dissimilated through the meta cleavage pathway. P. acidovorans uses the same pathway for the oxidation of p-hydroxybenzoate. but employs the gentisate pathway for the oxidation of m-hydroxybenzoate. The difference between the two species with respect to m-hydroxybenzoate metabolism reflects a difference with respect to the specificity of their m-hydroxybenzoate hydroxylases: the enzyme of P. testosteroni hydroxylates in the 4 position, and that of P. acidovorans in the 6 position.

Endoplasmic reticulum as the initiator of bud formation in yeast (S. cerevisiae).

Abstract: An electron microscopical investigation of synchronously dividing yeast cells (S. cerevisiae) prepared by freeze-etching revealed that ER is inducing bud formation. In the first step, ER elements join and form a nearly-closed bag-like envelope which surrounds the nucleus and vacuoles. From the small opening of the ER-envelope, vesicles are produced by a splitting or proliferation of the ER-membranes. The vesicles fuse with the plasmalemma and release their content into the cell wall. In this limited area, bud formation starts explosively by a local evagination of the cell wall. The ER-derived vesicles are concluded to contain proteindisulfide-reductase. The limited introduction of the enzyme into the cell wall explains bud formation to be initiated by a local increase of wall plasticity caused by the reduction of disulfide bonds between cell wall proteins. The wall is forced to extrude by the internal pressure (turgor) of the cell.

Ferredoxin-dependent carbon assimilation in Rhodospirillum rubrum.

Abstract: Evidence has been presented that a soluble fraction from R. rubrum cells contains two new primary carboxylation reactions which depend on the reducing power of ferredoxin: (a) pyruvate synthase which brings about a synthesis of pyruvate from acetyl-CoA and CO2 and (b) α-ketoglutarate synthase which brings about a synthesis of α-ketoglutarate from succinyl-CoA and CO2. The soluble fraction of R. rubrum cells contains also a series of other enzymes which, together with the ferredoxin-dependent enzymes, constitutes a reductive carboxylic acid cycle—a new cyclic pathway for CO2 assimilation that was first found in the photosynthetic bacterium, Chlorobium thiosulfatophilum.

An electron microscope study of nuclear and cell division in a dinoflagellate.

Abstract: Light microscopical observations on the cell division of the small dinoflagellate Woloszynskia micra are correlated for the first time with an electron microscopical study. In prophase, whilst the nucleus enlarges and becomes pearshaped, the chromosomes divide to give pairs of chromatids. This process starts at one end and works to the other giving Y- and V-shaped chromosomes as it occurs. Cytoplasmic invaginations pass through the nucleus and by the end of prophase these are seen to contain a number of microtubules of about 180 A diameter. There is no connection between the microtubules in the nuclear in vagination and either the flagellar bases or the chromosomes. At anaphase the nucleus expands laterally and the sister chromatids move towards opposite ends. The cell hypocone is now partially divided and the two longitudinal flagella well separate. The nucleus completes its division into two daughter nuclei and for a time portions of the cytoplasmic invaginations remain visible. Cell cleavage is completed by the division of the epicone. The nuclear membrane remains intact throughout division and the nucleolus does not break down.

Beiträge zur Anwendung der Bodenwaschtechnik für die Isolierung von Bodenpilzen

Abstract: Zwei zeitsparende Modifikationen der Parkinson & Williams-Bodenwaschtechnik fur die Isolierung von Pilzen auf Bodenpartikeln werden beschrieben. Das wesentliche Merkmal beider Modelle ist der kontinuierliche Wasserdurchflus durch das Waschgefas, das von Hand oder mechanisch geschuttelt werden kann. Die Wirksamkeit der Bodenwaschung in Abhangigkeit von der verwendeten Wassermenge wurde indirekt ermittelt durch Zahlung des Sporengehalts im Waschwasser und durch Bestimmung des Kolonisationsquotienten fur die gewaschenen Partikel. Wenn der Sporengehalt des Waschwassers auf ein bestimmtes niedriges Niveau abgesunken war, blieb auch der Kolonisationsquotient konstant, unabhangig von der verwendeten Technik. Die Isolierungsfrequenz der haufigsten Pilzarten in Bodenproben derselben Herkunft lies sich zufriedenstellend reproduzieren. Jahreszeitliche Schwankungen in der Pilzflora auf gewaschenen Partikeln waren unbedeutend. Die Anzahl der Pilze auf Bodenpartikeln nahm mit der Bodentiefe stark ab. Mehr Arten wurden von gewaschenen Partikeln isoliert als aus dem Waschwasser derselben Bodenprobe. Einige Arten, wie Fusarium culmorum, F. avenaceum, F. equiseti, Mucor hiemalis, Ophiobolus graminis, wurden haufiger von organischen als von Mineralpartikeln isoliert; dagegen lies sich in der Verteilung der meisten von ca. 300 weiteren Arten kein signifikanter Unterschied fur die Partikelarten nachweisen. Nur wenige sehr langsamwuchsige Arten wurden ausschlieslich von Mineralpartikeln isoliert.

Environmental effects on the structure of the blue-green alga, Chlorogloea fritschii

Abstract: A study was made on the morphology and ultrastructure of Chlorogloea fritschii at different growth stages and under various environmental conditions. The environmental effects tested were a comparison of various light intensities, and the use of media, one with, and one without, a source of combined nitrogen. Both filamentous and endospore stages have the general ultrastructural features typical of a blue-green alga. The most marked differences found were in the arrangement of lamellae. These run parallel to the cell wall in young filaments, particularly in those grown at low light intensities. At the endospore stage these are much more scattered in arrangement. Two striking variations in this pattern were found. One cell type, possibly a spore, showed, along with other interesting features, marked reticulation of the lamellae. Material subcultured in the dark with sucrose for 3 years had the lamellae scattered throughout the cell. Differences were found also in the abundance of α-granules (probable polyglucoside bodies). These differences could to a certain extent be correlated with the growth conditions used. A brief comparison of Chlorogloea with other blue-green algae is included. Based on this, tentative hypotheses are presented concerning correlations between ultrastructural features and taxonomic groupings.

On the gas vacuoles of the halobacteria

Abstract: The cells of Halobacterium sp., strain 5, contain a large number of highly refractile bodies of the type which Petter (1932) suggested were gas-filled vacuoles. The present studies support Petter's contention, but the evidence for the exact chemical nature of the vacuole content is still indirect. It is not carbon dioxide or oxygen, but might possibly be nitrogen. “Strain 5” loses spontaneously and with a high frequency the ability to make the vacuoles. When vacuolated cells are subjected to pressure, the vacuoles disappear, but can recover upon aeration. Oxygen and the organic constituents of the growth medium stimulate the recovery, whereas 2.4-dinitrophenol inhibits it. A procedure is described for the isolation of the vacuoles. The vacuoles are bounded by a membrane which reveals itself in electron micrographs of thin sections as a 1-layered structure about 30 A thick.

Morphogenesis of thylakoids in Rhodopseudomonas palustris

Abstract: Rhodopseudomonas palustris, Stamm 11/1, kann in Dunkelkulturen durch Absenken des Sauerstoffpartialdruckes in der Submerskultur von 100 auf etwa 5 mm Hg [pO2] zur Bacteriochlorophyllsynthese und Thylakoidmorphogenese induziert werden.

Transport-limited growth in the chemostat and its competitive inhibition; A theoretical treatment

Abstract: An equation expressing the specific growth rate of heterotrophic cell populations in terms of yield factor and transport rate is proposed. From this equation expressions are derived for the specific growth rate when the transport of the energy source is growth0limiting. These expressions are applied to cell population growth in the chemostat limited by the transport of the energy source or of other substrates and simple mathematical tools are provided for obtaining estimates of the transport parameters. An equation is derived which predicts that at constant dilution rate in the chemostat the concentration of any substrate (whether or not the source of energy) the transport of which is growth limiting, is a linear function of the concentration of a competitive inhibitor of its transport. With this equation estimates of the Michaelis constants of competitive transport inhibitors can be obtained. The growth rate equation of Monod (1942) is discussed.

Some properties of the green bacterium Pelodictyon clathratiforme

Abstract: Two strains of Pelodictyon clathratiforme have been successfully maintained in culture in a partly purified state. Their maintenance under laboratory conditions requires low light intensity and low sulfide concentrations.

Rhodopseudomonas palustris and Rh. viridis--photosynthetic budding bacteria.

Abstract: Rhodopseudomonas palustris and Rh. viridis were found to reproduce by budding. The differences between budding reproduction and binary fission were discussed, and it was concluded that there was a lack of evidence to indicate a fundamental difference between the two processes in bacteria. Taxonomic and nomenclatural changes were discussed.

A continuous culture study of an obligately psychrophilic Pseudomonas species.

Abstract: The optimum temperatures for growth and respiration of an obligately psychrophilic Pseudomonas spec. were 14°C and 23°C, respectively. The maximum temperature for growth was between 19 and 20°C. When cells were grown in a chemostat with lactate as the growth-limiting substrate at a specific growth rate of 0.05 hr-1 over a temperature range of 5–19°C, it was found that RNA concentration was lowest at 14°C. At lower temperatures the cells compensated the decrease of reaction rates by increasing the concentration of RNA and of respiratory enzymes. A temperature raise above 14°C also increased cellular RNA, which probably counteracted an impairment of protein synthesis. Above 18°C the RNA increase ceased, resulting in a rapid decrease of protein synthesis, until between 19 and 20°C growth ceased entirely. Cells grown at 14°C showed a linear increase of RNA content and \(Q_{0_2 }\)values with growth rate, when this was varied from 0.025 to the maximum value of 0.2 hr-1.

A new genus of the actinoplanaceae: dactylosporanguim, gen. nov.

Abstract: Two aerobic mesophilic species of a new genus belonging to the familyActinoplanaceae are described under the nameDactylosporangium (D. aurantiacum strainD/748 type species andD. thailandensis strainD/449). The new genus is characterized by the production of finger shaped sporangia emerging directly from the vegetative mycelium. The motile sporangiospores, three to four in number are arranged in a single straight row inside the sporangium. The genusActinoplanes of the familyActinoplanaceae was described in 1950 byCouch and is characterized by the bacteria-like, flagellated spores formed in sporangia. Other members of the familyActinoplanaceae have been studied byKarling (1954),Rothwell (1957) andCross et al. (1963) in the United States, byGaertner (1955) in Germany, byVan Brummelen andWent (1957) in Holland, byNonomura andOhara (1960) in Japan, byTaig et al. (1962),Tsyganov et al. (1963), andKoniev et al. (1965) in Russia. Except for the organisms studied byKarling and byRothwell, which undoubtedly belonged to theActinoplanes but were not studied in pure culture, the organisms studied by most of the other authors belonged to the genusStreptosporangium. Three new genera having motile spores were described more recently:Ampullariella andSpirillospora described byCouch (1963, 1964), andPlanomonospora byThiemann et al. (1967b).

Nitrogen fixation by growing cells and cell-free extracts of the Bacillaceae.

Abstract: Al though Clostridium pasteurianum was the first free-living nitrogenfixing bacter ium to be isolated in pure culture (WI~OG~A])SKY, 1895), studies on the biochemistry of asymbiot ic ni trogen fixation for m a n y years were l imited almost exclusively to species of the aerobic Azotobacter. This preference likely arose f rom the relative ease of culturing and the much greater rate, extent and efficiency of the N-fixing process of the aerobe. I n the early 1950's investigations on the physiology of the elostridia provided methods t h a t overcame this technical handicap. Nevertheless, i t was somewhat unexpected t h a t the first demonst ra t ion of cell-flee fixation was obtained with a preparat ion f rom C. pasteurianum (CA~N~mtN et at., 1960). This discovery s t imulated research in m a n y laboratories resulting in notable advances in our knowledge of the biochemist ry of the nitrogen fixation process. As might be expected, mos t if no t all of this research has been done with one strain, W-5, since the biochemist usually prefers for the biological component of his sys tem one possessing an extensive backlog of research information. The bacteriologist, however, m a y choose less intensive investigation on more strains. Wi th this in mind, we have under taken a compara t ive survey of ni trogen fixation by strains of three species belonging to the Bacillaceae-C. pasteurianum, Bacillus polymyxa and B. macerans, the results of which are reported here.

Der Einfluß des Sauerstoffpartialdruckes und der Antibiotica Actinomycin und Puromycin auf das Wachstum, die Synthese von Bacteriochlorophyll und die Thylakoidmorphogenese in Dunkelkulturen von Rhodospirillum rubrum

Abstract: Die Wachstumsrate (1/p; p = Proteinverdopplungszeit) von Rhodospirillum rubrum in aeroben Dunkelkulturen ist vom Sauerstoffpartialdruck abhangig. Das Optimum liegt bei 3–5 mm Hg [O2]. Steigt die O2-Konzentration auf 150 mm Hg [O2] an, so vermindert sich die Wachstumsrate langsam um etwa 10%. Unterhalb 2 mm Hg fallt sie dagegen steil nach 0 ab. Die Ausbildung des gesamten Systems der Photophosphorylierung (Thylakoide, Chromatophoren) ist ein lichtunabhangiger, aber vom Sauerstoffpartialdruck direkt abhangiger Prozes. Die Morphogenese wird induziert, wenn der Sauerstoffpartialdruck auf etwa 20 mm Hg erniedrigt wird. Das Optimum der Bacteriochlorophyll-bildung unter aeroben Dunkelbedingungen liegt bei etwa 2 mm Hg [O2]. Die Pigmentsynthese kann durch Veranderung der Sauerstoffkonzentration induziert werden, ohne die Wachstumsgeschwindigkeit in der logarithmischen Wachstumsphase zu verandern. Eine Anderung der Wachstumsrate fuhrt zu einer relativen Verschiebung der Syntheseraten fur DNS, RNS und Protein.

Chemolithotrophes Wachstum von Hydrogenomonas H16 im Chemostaten mit elektrolytischer Knallgaserzeugung

Abstract: Ein Chemostat zur Kultur von Knallgasbakterien mit begrenzenden Konzentrationen von Wasserstoff und Sauerstoff wird beschrieben. Die Gase werden durch Elektrolyse des Mineralmediums erzeugt. Durch Verwendung von zwei Anoden, von denen die eine auserhalb des Kulturgefases angeordnet ist, last sich das Verhaltnis H2/O2 innerhalb weiter Grenzen verandern. Zur Steuerung und Veranderung der Flusrate zwischen 20 und 720 ml/Std dient ein Tropfenzahler mit Platinkontakten, ein Magnetventil und ein Impulsgeber. Wurde Hydrogenomonas H 16 in statischer Kultur mit H2 oder O2-Begrenzung herangezogen, so nahmen die Rate der Gasaufnahme und die Hydrogenase-Aktivitat mit zunehmendem Alter der Kultur ab. In kontinuierlicher Kultur mit Wasserstoff als wachstumsbegrenzendem Faktor wurden die Beziehungen zwischen Wachstumsrate, Bakterienkonzentration und Wasserstoffverbrauch untersucht. Bei gleichen Wachstumsraten unter Begrenzung des Wachstums a) durch Wasserstoff und b) durch Sauerstoff wurden einige Stoffwechsel-Aktivitaten miteinander verglichen. Wurde das Wachstum durch Wasserstoff begrenzt, so war der Gehalt an Poly-β-hydroxybuttersaure gering und die Aktivitaten von Hydrogenase und Glycerinaldehyd-3-phosphat-Dehydrogenase waren hoch. Bei Begrenzung des Wachstums durch Sauerstoff hauften die Zellen Poly-β-hydroxybuttersaure bis zu 23% des Trockengewichts an; die Aktivitaten der Hydrogenase und Glycerinaldehydphosphat-Dehydrogenase waren gering. Das H2/CO2-Verhaltnis betrug bei Begrenzung durch Wasserstoff 9,1, bei Begrenzung durch Sauerstoff 4,6. Die spezifischen Aktivitaten anderer Enzyme (Phosphoglycerokinase und NADP-spezifische Glutamat-Dehydrogenase) unterschieden sich nicht nennenswert.

A Thiococcus sp. nov. gen., its pigments and internal membrane system.

Abstract: A Thiococcus sp. nov. gen., the first Thiorhodaceae known to contain bacteriochlorophyll b, was isolated from river mud using filtered light above 900 mμ as the selecting agent in enrichments. The orange-brown colour of the immotile, Gram-negative, photolithotrophic cocci is due to two new carotenoids, 3,4,3′,4′-tetrahydrospirilloxanthin and 3,4,3′,4′-tetrahydrospirilloxanthinal. The photosynthetic pigments appear to be associated with a unique internal membrane system consisting of branched membrane tubes of even diameter (approx. 450 A) continuous with the cell membrane. The negatively stained tubes examined in the electron microscope reveal a surface fine structure of raised bodies arranged in a regular hexagonal pattern.

The isolation and preliminary characterization of a halophilic photosynthetic bacterium.

Abstract: The isolation of a photosynthetic bacterium which is apparently an obligate halophile is reported. The organism (strain SL-1) grows in a medium with either thiosulfate of sulfide and bicarbonate containing 22% NaCl but not in one containing 4% NaCl. The morphology is abnormal in media with 8% NaCl. Strain SL-1 is an obligate anaerobe. The major carotenoid pigment is spirilloxanthin. The spectrum of the chlorophyllous pigment is very similar to that of bacteriochlorophyll; however, its identity with bacteriochlorophyll has not been demonstrated. Strain SL-1 is a spirillum. Cells possess a single, polar, sheathed flagellum. The ultrastructure of the cells is depicted.

Wall structure and bud formation in rhodotorula glutinis.

Abstract: The first stage in the formation of a bud in Rhodotorula glutinis is the production of a tapered plate of new wall material between the existing wall and the plasmalemma. The parent cell wall is lysed, allowing the bud to emerge enveloped in this new wall. Mucilage is synthesised to surround the developing bud. As the bud grows a septum forms centripetally dividing the two cells. When the daughter cell reaches maximum size the septum cleaves along its axis, producing the bud scar on the parent cell and the birth scar on the daughter cell. The birth scar is obliterated later as the wall of the young cell grows. A system of endoplasmic reticulum and vesicles is found in young buds and is thought to be responsible for the transport of wall material precursors.