bluuebunny/crossref_metadata_2025 huggingface dataset:
Sequential action of cell wall hydrolases in the germination and outgrowth of Microsporum gypseum macroconidia
Authors: Page W. J. , Stock J. J.
Published: April 2010

The spore coats of mature macroconidia of Microsporum gypseum contained greater carbohydrate–protein ester, disulfide, acid-soluble phosphate, and acid-insoluble phosphate content than mycelial walls. Phosphate was a major constituent of the spore coat, accounting for 6.8% of the dry weight. Spore coat phosphates were located internally as acid-insoluble phosphate, or externally on the spore surface as acid-soluble phosphate. Upon spore germination, the carbohydrate–protein ester, acid-insoluble phosphate, and acid-soluble phosphate content of the spore coats decreased, resulting in considerable alteration of spore coat internal and external properties. Germination was initiated by early alkaline protease and β-1,3-glucanase action, followed by ethyl-esterase, phosphodiesterase, and chitinase activities. These hydrolases were compartmentalized in lysosomal vesicles, which appeared to be delivered to the germinating spore in a coordinated manner.
Characteristics of a reserve α-glucan from Clostridium pasteurianum
Authors: Laishley E. J. , Brown Robert G. , Otto M. C.
Published: April 2010

An iodophilic intracellular polysaccharide has been isolated from cells of Clostridium pasteurianum. This polysaccharide has been shown to be unbranched and to contain α[1 → 4]-and α[1 → 6]-linked glucopyranose residues in a ratio of 3:2.
Survival of Escherichia coli from freeze–thaw damage: a theoretical and practical study
Authors: Calcott Peter H. , MacLeod Robert A.
Published: April 2010

The effect of cooling and warming rates on the cryosurvival of chemostat populations of Escherichia coli was investigated. Survival curves were obtained which were similar in shape to those obtained by others for other cell types, with saline always a more lethal environment than distilled water.For organisms frozen in either distilled water or saline, as the cooling rate was increased survival increased to a maximum at 6 C/min, decreased to a minimum at 100 C/min, and then continued to increase as the cooling rate was increased to ultrarapid rates (about 6000 C/min). At these ultrarapid rates of cooling but not at lower rates, increasing the rate of warming enhanced survival; slow warming rates were detrimental to survival and eliminated the increase in survival associated with these cooling rates. Solution of a theoretical equation predicted that supercooling of cell water, and thus the likelihood of internal freezing, should increase as the cooling rate was increased from 3.5 to 350 C/min. This increase in probability of internal freezing was paralleled by a decrease in viability of cells as the cooling rate was increased from 6 to 100 C/min.The effectiveness of three protectants was investigated over the whole cooling rate range. Glycerol or sucrose added to suspensions of cells in distilled water protected over the whole range; but at lower cooling rates (less than 6 C/min) they did so with an altered stoichiometry. Sucrose protected organisms frozen in saline and Tween 80, a non-ionic detergent, protected organisms frozen either in saline or distilled water from rapid or ultrarapid cooling only. The evidence supports a two-factor hypothesis to explain cryoinjury.
Survival of Escherichia coli from freeze–thaw damage: influence of nutritional status and growth rate
Authors: Calcott Peter H. , MacLeod Robert A.
Published: April 2010

The influence of nutritional status and growth rate on the cryosurvival of Escherichia coli was investigated. Organisms grown at rates between 0.1 and 0.6 h−1, under carbon- or nitrogen-limiting conditions all showed a basically similar cooling rate – survival profile; a peak of survival was noted in the lower cooling rate range (less than 100 C/min), a trough of minimum survival at 100 C/min, and increased survival as the cooling rate was increased to ultrarapid rates. Carbon-limited organisms showed a shift of the peak from 6 C/min for slowly grown organisms (D = 0.11) to 40 C/min at higher growth rates (D = 0.60 h−1); their survival at these peaks also showed a slightly upward trend. Nitrogen-limited organisms showed a similar trend of a shifting of the peak of survival. However, as the growth rate was increased, survival at this peak, and at other regions, decreased. For carbon-limited organisms, above 100 C/min, survival was growth rate independent, unlike nitrogen-limited organisms, which exhibited lower survivals as the cooling rate was increased in the ultrarapid range. The survival of both carbon-and nitrogen-limited organisms at the peak of survival showed a correlation with their carbohydrate and protein contents. The relevance of these findings is discussed.
A new species of Arthrobacter which degrades picolinic acid
Authors: Tate R. L. , Ensign J. C.
Published: April 2010

A bacterium which utilizes picolinic acid as a carbon and energy source is identified as a new member of the genus Arthrobacter. The name Arthrobacter picolinophilus is proposed.
Picolinic acid hydroxylase of Arthrobacter picolinophilus
Authors: Tate R. L. , Ensign J. C.
Published: April 2010

Picolinic acid is oxidized by cells and extracts of Arthrobacter picolinophilus to 6-hydroxypicolinic acid. The enzyme involved is a particulate hydroxylase which appears to incorporate the hydroxyl group of water into the substrate. The enzyme was purified about 60-fold. The molecular weight as determined by gel filtration was 230 000 daltons. Activity of the purified enzyme was stimulated by ferrous ions and was inhibited by quinacrine. Flavin mononucleotide reversed the inhibition by quinacrine.
Somatic nuclear division in the sporidia of Ustilago violacea. II. Observations on living cells with phase-contrast and fluorescence microscopy
Authors: Poon N. H. , Day A. W.
Published: April 2010

Somatic nuclear division in living cells is described under both phase-contrast and acridine orange fluorescence microscopy. The observations confirm a previous description of the division in fixed cells stained with acetic orcein. Acridine orange at the optimum concentration of 75–250 mg/liter complete medium clearly differentiated the nucleolus, chromatinic granules, nucleoplasm, and spindle pole body, as well as indicating changes in RNA content in the cytoplasm during budding. Acridine orange fluorescence was identical in both living and fixed cells. The fluorescence of the spindle pole body indicated that it contains DNA, which may initiate RNA synthesis. Time-lapse phase-contrast observations confirmed that neither the fixation technique nor acridine orange or acetic orcein staining caused noticeable artefacts during division, and provided indisputable evidence for the sequencing of stages. Estimates from the time-lapse observations indicated that the division is quite slow (about 45 min) and that 'prophase' takes about 12 min, 'metaphase' 5 min, and 'anaphase–telophase' about 28 min.
Artifacts induced by preparation for scanning electron microscopy in Proteus mirabilis exposed to carbenicillin
Authors: Prior Richard B. , Perkins Robert L.
Published: April 2010

Proteus mirabilis exposed to carbenicillin and subsequently washed before fixation for scanning electron microscopy showed morphologic alterations that were not attributed to the drug.
Sulfate uptake as a measure of planktonic microbial production in freshwater ecosystems
Authors: Monheimer Richard H.
Published: April 2010

A method is needed by which biomass production resulting from non-photosynthetic micro-organisms in natural aquatic ecosystems can be included in microbial production measurements. Both laboratory cultures and field samples were used for examining the suitability of measuring sulfate uptake as a yardstick of microbial production. Sulfate uptake, using 35SO4, was com pared with 14CO2 uptake and it was found that sulfate uptake measures significantly more microbial production than does 14CO2 uptake. With further study, the use of sulfate uptake may become a very satisfactory method for better estimating the total planktonic microbial production under aerobic conditions.
Cytochemistry of acid mucosubstance and acid phosphatase in Cryptococcus neoformans
Authors: Mahvi Thomas A. , Spicer Samuel S. , Wright Nancy J.
Published: April 2010

At the ultrastructural level, dialyzed iron stains only the mucoid capsule in Cryptococcus neoformans, converting it from the most lucent to an extremely dense layer and thus demonstrating its content of acid mucosubstance. After lead staining of thin sections of dialyzed iron treated specimens, the wall exhibits a dense inner and translucent outer layer. The inner layer and mucoid capsule appear thicker in the mother than the daughter cell of budding organisms. C. neoformans cells fixed in suspension and incubated in acid phosphatase substrate medium exhibit at the ultrastructural level activity confined to the mucoid capsule, cell wall, and internal extensions presumed to be plasmalemmasomes. Organisms in small blocks or cryostat sections of pellets fixed in clotted fibrin, when incubated for acid phosphatase, reveal moderate to no reactivity in cell wall and mucoid capsule but strong activity in surrounding fibrin aggregates. In the latter specimens, reaction product indicative of acid phosphatase also is evident in the nuclear envelope, in some of the profiles of presumed granular reticulum, in complex lamellar profiles presumed to be Golgi elements, and in small cytoplasmic bodies and large vacuoles. The morphological specimens disclose counterparts of acid phosphatase reactive structures and show lucent cytoplasm segregated by circular mitochondrial profiles and a difference between the thickness and density of the plasmalemma and other cell membranes.
Acetylene reduction by non-symbiotic bacteria in artificial soil aggregates amended with glucose
Authors: Mayfield C. I. , Aldworth R. L.
Published: April 2010

The C2H2-reduction assay was used to study the activity of non-symbiotic N2-fixing bacteria in glucose-amended artificial soil aggregates prepared from a sandy clay loam and a sandy loam soil. Anaerobic incubation under nitrogen resulted in significantly higher rates and greater total quantities of C2H2 reduction than did incubation in air. In the sandy clay loam soil activity under both incubation conditions was due to anaerobic N2-fixing bacteria, whereas in the sandy loam soil aerobic N2-fixing bacteria also proliferated in the aggregates. Direct observation of sectioned aggregates by fluorescence microscopy showed that peripheral zone 1 mm thick sup ported the growth of aerobic microorganisms. The anaerobic microsites in the interior of the aggregates were well protected since disruption procedures involving vigorous shaking with aerated water were required to allow O2 to penetrate and inhibit the anaerobic activity.
Peptidoglycan structure in cell walls of parental and filamentous Streptococcus cremoris HP
Authors: Johnson K. G. , McDonald I. J.
Published: April 2010

Cell walls were prepared from parental and filamentous cells of Streptococcus cremoris HP. In addition to aspartic acid, glutamic acid, alanine, and lysine in a 1:2:3:1 ratio, such preparations contained hot formamide-extractable material composed of glucosamine, glucosa-mine-6-phosphate, glucose, galactose, and rhamnose. Parental and filamentous cell walls contained, respectively, 210 and 225 disaccharide units per milligram. The ratio of muramic acid: peptide subunits was about 1.3 for both preparations.Enzymic and chemical analyses revealed that glycan strands are incompletely substituted, peptide cross-bridging is not mediated by D-alanyl-L-alanyl linkages, peptide subunits are linked together to form large moieties, and no significant differences in peptidoglycan structure exist between parental and filamentous cell walls.Analysis by dinitrophenylation techniques disclosed the presence of significant quantities of glucosamine and muramic acid residues with free amino groups in the peptidoglycans of both cell wall preparations. Conversion of such groups by dinitrophenylation or N-acetylation greatly enhanced the response of cell walls to lysozyme digestion.
Biodegradability and crude oil composition
Authors: Westlake D. W. S. , Jobson A. , Phillippe R. , Cook F. D.
Published: April 2010

Four crude oils (Prudhoe Bay, Norman Wells, Atkinson Point, and Lost Horse Hill) of different chemical composition were tested as to their biodegradability under mesophilic and psychrophilic conditions. Changes in bacterial numbers and chemical composition of the oils were monitored using a plate count and chromatographic technique respectively. Populations induced under psychrophilic conditions readily metabolized similar quality oils under mesophilic conditions. Mesophilic populations, however, only showed a limited metabolic capability on similar quality oils under psychrophilic conditions. Gram-negative rods were predominant in all the populations obtained under these experimental conditions. The ability of the mixed populations to use crude oil as a sole carbon source was dependent not only on the composition and amount of the n-saturate fraction but also on that of the asphaltene and NSO (i.e. nitrogen-, sulfur-, and oxygen-containing) fraction. Growth on an oil which lacked a normal n-alkane component indicated that the aromatic fraction of oil was capable of sustaining bacterial growth. Oil quality and temperature of incubation affected the generic composition of populations obtained which would use crude oil. The isoprenoids, phytane and pristane, while readily used under mesophilic conditions, were more resistant to bacterial metabolism under psychrophilic conditions.
The cytochrome system in Mycobacterium lepraemurium
Authors: Ishaque M. , Kato Laszlo
Published: April 2010

The respiratory chain system of cell suspensions of Mycobacterium lepraemurium was investigated spectrophotometrically. The results obtained indicated that whole cell preparations contained flavins, cytochromes of the a + a3 and b type, as well as two CO-binding pigments; cytochromes a3–CO and a second pigment similar to cytochrome o. The cytochromes were found to be in the reduced form. The presence of cytochrome systems could only be shown after the cell suspensions in the reference cuvette were exposed to oxygen. The positions of the peaks in the difference spectra were similar when the cell suspensions were reduced anaerobically without added substrate or treated with dithionite. The whole cell suspensions of M. lepraemurium were not found to contain detectable quantities of cytochrome c.
Large-scale production of staphylococcal delta hemolysin by the dialysis membrane technique
Authors: Murphy Richard A. , Haque Riaz-Ul
Published: April 2010

A procedure has been developed which uses the dialysis membrane technique for producing and rapidly harvesting staphylococcal delta hemolysin from several hundred plates of culture medium.
Comparison of selective media for the enumeration of sublethally heated food-poisoning strains of Staphylococcus aureus
Authors: Collins-Thompson D. L. , Hurst A. , Aris B.
Published: April 2010

Staphylococcus aureus strains (19 food-poisoning strains) were heated at 52C for 15 min in 100 mM potassium phosphate buffer. The sublethally heated organisms were enumerated on seven selective media commonly used for quantitating S. aureus. Compared to trypticase soy agar, Baird-Parker agar was the only medium which was satisfactory with all cultures tested. The remaining selective media gave unsatisfactory recoveries with one or more of the strains tested and are listed in the following order of decreasing acceptability: tellurite glycine agar, egg yolk azide agar, phenolphthalein phosphate agar with polymyxin, mannitol salt agar, Vogel Johnson agar.
The metabolism of carbohydrates by extremely halophilic bacteria: glucose metabolism via a modified Entner-Doudoroff pathway
Authors: Tomlinson Geraldine A. , Koch Thomas K. , Hochstein L. I.
Published: April 2010

Crude extracts prepared from the extremely halophilic bacterium M6 catalyzed the conversion of glucose to gluconic acid. The latter compound was dehydrated to 2-keto-3-deoxygluconic acid, which in the presence of ATP, was converted to equimolar amounts of pyruvate and 3-phosphoglyceraldehyde, presumably through the intermediate compound 2-keto-3-deoxy-6-phosphogluconic acid. Additional enzymes catalyzing the conversion of 3-phosphoglyceraldehyde to pyruvic acid were also present. These data are consistent with the operation of a modified Entner-Doudoroff pathway in this organism.
Uptake of amino acids by the marine centric diatom Cyclotella cryptica
Authors: Liu Ming Sai , Hellebust Johan A.
Published: April 2010

The transport systems for all of the amino acids studied, with the exception of isoleucine, obey saturation kinetics. The strong inhibition of the process by cyanide and dinitrophenol provides evidence that energy is required. Additional evidence for the requirement of energy for amino acid transport is the strong temperature dependence (Q10 about 2) and the high concentration ratios measured for transported amino acids.Transport parameters (Ks and Vmax) for several amino acids were determined from data for two different concentration ranges. The results of the kinetic studies indicate the presence of two or more transport systems that become saturated at different substrate concentrations for each of the amino acids. The presence of a high affinity – high capacity transport system for arginine indicates that this amino acid may be utilized efficiently by the diatom when present at low concentrations in the natural environment.Interactions between pairs of amino acids suggest that several transport systems are available. There appears to be one system for ornithine and arginine, one for glutamate and aspartate, and several for neutral amino acids.Restriction of nitrogen in the growth medium produces a marked increase in the rate of amino acid uptake, indicating that amino acids are acquired more rapidly from the medium by nitrogen-limited cells.
Rough mutants of Salmonella typhimurium with defects in the heptose region of the lipopolysaccharide core
Authors: Sanderson Kenneth E. , Wyngaarden John Van , Lüderitz Otto , Stocker B. A. D.
Published: April 2010

Six rough mutants of Salmonella typhimurium LT2 with defects in the heptose region of the lipopolysaccharide were isolated and analyzed for phage sensitivity, for sugar composition and serological specificity of the lipopolysaccharide, and for genetic properties. Three of the mutants were of chemotype Rd2, with mutations presumably in the rfaF gene. Three mutants of chemotype Re represent mutants in at least two separate genes, one perhaps rfaE and the other a previously undescribed gene rfaC, which maps in the cluster of rfa genes at 116 min on the linkage map.
Permeability of lipopolysaccharide-deficient (rough) mutants of Salmonella typhimurium to antibiotics, lysozyme, and other agents
Authors: Sanderson K. E. , MacAlister T. , Costerton J. W. , Cheng K.-J.
Published: April 2010

Six mutants of Salmonella typhimurium LT2 with defects in the heptose region of the lipopolysaccharide (LPS) ("rough" mutants) were more sensitive to the growth-inhibitory effects of erythromycin, bacitracin, vancomycin, novobiocin, kanamycin, and cloxacillin and of deoxycholate than smooth strains, but less sensitive to tetracycline and ampicillin. In general, growth of the three rough mutants of chemotype Rd2, which lack the distal but not the proximal heptose unit in the LPS, was less inhibited than the three mutants of chemotype Re, which are heptose-deficient. In addition, inhibition of uracil-1-14C incorporation in the presence of actinomycin D and spheroplast formation in the presence of lysozyme occurred in the rough mutants without ethylenediaminetetraacetate (EDTA) treatment of the cells, while actinomycin D and lysozyme were effective on smooth strains only after EDTA treatment. Since the major part of the LPS is in the outer membrane of the cell envelope, and since the target of the toxic agents used is located inside this layer, these data indicate that the carbohydrate part of the LPS component of the outer membrane is an essential part of a barrier layer preventing penetration of large molecules.
A new tremorgenic metabolite from Penicillium paxilli
Authors: Cole Richard J. , Kirksey Jerry W. , Wells John M.
Published: April 2010

A new tremorgenic metabolite was found in the chloroform extracts of cultures of Penicillium paxilli. Purified tremorgen had a molecular formula of C27H33NO4 and data supported the presence of an indole moiety. Administration of the tremorgen orally to 1-day-old cockerels and intraperitoneally to mice caused sustained tremors that persisted for about 24 h. The tremorgen also caused mice to overreact to sound stimuli.
Etude ultrastructurale et cytochimique de la différenciation des bactéroïdes de Rhizobium trifolii Dangeard dans les nodules de Trifolium repens L.
Authors: Gourret Jean-Pierre , Fernandez-Arias Hector
Published: April 2010

An ultrastructural and cytochemical study of the mature nodules from Trifolium repens L. indicates that bacteroid formation may be considered as a differentiation of the bacteria Rhizobium trifolii which, after invading the leguminous cell cytoplasm, undergo significant modifications including essentially: (a) progressive increase of the volume (about fortyfold), (b) modification of the shape of the bacteria which are successively short, rod-shaped, filamentous, pear-shaped, then spherical, and sometimes polyhedric, (c) dispersion of the initial nucleoid and appearance of granular bodies, (d) formation of a plasma membrane derived vesicular system, bearing or bounding oxydoreductive enzymes, which react with diaminobenzidine (DAB) at pH 6, 8, and 9. Bacteria to bacteroid transformation is related to host-cell differentiation which is mainly characterized by organelles distributed in concentric layers (peripheral starch-containing plastids, mitochondria, bacteroids, nucleus, and central vacuole) and by leghaemoglobin formation in the vacuolar space surrounding the bacteroids. Leghaemoglobin is detected by its electron density and positive reaction with DAB after incubation at alcaline pH in the presence of H2O2. The cytological events preceding or following the functional state of differentiation are also illustrated and discussed: infection of the host-cells by bacteria released from the threads, senescence of the bacteroids with formation of voluminous drops of poly-β-hydroxybutyrate (PHB), concomitant death of the host-cells, and the bacteroids at the base of the nodule.
Phosphate metabolism in blue-green algae. I. Fine structure of the "polyphosphate overplus" phenomenon in Plectonema boryanum
Authors: Jensen Thomas E. , Sicko Linda M.
Published: April 2010

Changes in cell architecture at the electron microscope level have been followed in P. boryanum during conditions of phosphate starvation and rapid uptake. Cells from 14-day-old cultures were starved of phosphorus for 5 days and then inoculated into a medium containing 10 mg PO4/liter. Polyphosphate bodies developed in five different areas of the cells: (1) in ribosomal areas, (2) on strands of DNA, (3) intrathylakoidally, (4) in polyhedral bodies, and (5) in areas of medium electron density which develop in nucleoplasmic areas. In control cells types 1 and 2 predominate. In phosphate-starved cells types 1, 2, and 5 predominate, and under conditions of rapid uptake types 4 and 5 are predominant. Details of the development process and its significance are discussed. In addition to the described variations in polyphosphate bodies during phosphorus starvation, the number of cyanophycean granules and lipid-like inclusions increase. Cell division is also abnormal in many of the phosphorus-starved cells, with both small cells and abnormally large cells being common. Thylakoid structure is altered under different phosphate concentrations. Expanded thylakoids are found in control algae; the frequency increases during starvation with the greatest number occurring during a rapid uptake. Other aspects of cell architecture are discussed in relation to the "overplus phenomenon."
Chitinolytic Clostridia isolated from marine mud
Authors: Timmis K. , Hobbs G. , Berkeley R. C. W.
Published: April 2010

Anaerobic chitinolytic bacteria were isolated from chitin-enriched marine sediments. All isolates were species of Clostridia and 9 out of a total of 15 were identified with established species. Although most of the isolates failed to produce detectable chitinase when grown in the absence of chitin, all caused breakdown of chitin to N-acetylglucosamine when grown in chitin-containing media. Thus, chitinase synthesis in these bacteria appears to be inducible.
Chelating agents and blue-green algae
Authors: Lange Willy
Published: April 2010

Many planktonic blue-green algae produce natural chelators which enable them to grow at high pH's in the absence of artificial chelators. The growth of 10 cyanophytes without an added chelator was found to differ widely with the algal species. Bacteria-containing cultures of Anabaena cylindrica, Anacystis nidulans, Lyngbya sp., Microcystis aeruginosa, Nostoc muscorum, and Phormidium foveolarum produced their own chelators and grew just as well as the controls with artificial chelating agents. Bacteria-containing cultures of Anabaena circinalis, Gloeotrichia echinulata, Oscillatoria rubescens, and Aphanizomenon flos-aquae did not produce chelators and, in the absence of artificial agents, grew poorly or perished early. The alga-produced, extracellular chelators were water-soluble and capable of chelating and controlling metal compounds that would exist in colloidal form at pH's above 7. Accordingly, in the absence of artificial chelators, the non-chelator-forming species grew in the filtrates of the chelator-forming algae the same as in the presence of artificial agents. Bacteria were not involved in the formation of natural chelators, since axenic cultures of Anabaena circinalis, Anacystis nidulans, Microcystis aeruginosa, Nostoc muscorum, and Phormidium foveolarum in the absence of artificial chelators performed about the same as the bacteria-associated species. Also, the filtrates of axenic, chelator-forming Anacystis cultures had the same growth-stimulating effect on non-chelator-forming species as filtrates from bacteria-associated cultures. The natural chelators showed partial thermolability.While the growth of chelator-forming species in the absence of artificial chelators was normal during the logarithmic phase, a peculiar, continuing production of total organic matter was observed with strongly declining cell numbers of Lyngbya, Microcystis, and Phormidium. The terminal cultures of these species were gelatinous, owing to the presence of extracellular matter, probably consisting of polysaccharides.
Effet du régime alimentaire sur l'équilibre entre 14 souches microbiennes ensemencées dans le tube digestif de souris axéniques adultes et sur l'établissement de ces souches chez leurs descendants entre la naissance et le sevrage
Authors: Chopin A. , Ducluzeau R. , Raibaud P.
Published: April 2010

Ten strictly anaerobic bacterial strains belonging to the genera Inflabilis (I), Zymobacterium (Z), Acuformis (A), Streptococcus (S1, S2), Ristella (R), Clostridium (C), Eubacterium (E), Pasteurella (P), and Veillonella (V); three facultatively anaerobic strains belonging to the genera Actinobacillus (Ac), Lactobacillus (L), and Staphylococcus (St); and one yeast strain of the genus Torulopsis (T) were inoculated into adult male and female axenic mice fed either a commercial diet A or a semisynthetic diet B.Three strains (I, Z, St) did not establish in any "gnotoxenic" animals. One strain established only in animals fed diet B (S2). The average number of each of the other 10 strains is 10 to 100 times less in animals receiving diet B than in those given diet A. The microflora of the stomach and the small intestine is more variable and less abundant in mice fed diet B than in those receiving diet A. For strains A and C there is a net decrease in colon populations as related to those of the caecum or the feces, especially in mice receiving diet B.In the digestive tract of young "gnotoxenic" mice sacrificed before weaning, the facultatively anaerobic microflora is always established before the strictly anaerobic flora but does not change the establishment of the latter. Finally, the diet of the mother affects appreciably the establishment kinetics of strains L, St, and T in the young mice.
The effects of temperature upon the reproduction and respiration of a marine obligate psychrophile
Authors: Christian R. R. , Wiebe W. J.
Published: April 2010

The growth and respiration rates of a marine obligate psychrophile, Vibrio sp., were determined in a complex medium using optical density and viable counts and a polarized oxygen-electrode system. Growth rate was optimal at 7C and decreased at 10C, the maximum temperature for growth. Respiration increased continually from 1to 10C. Both growth and respiration rates were highly sensitive to small changes in temperature. For example, rates at 4C were 1.8 and 4.4 times higher than at 1C for growth and respiration, respectively. Growth efficiencies were calculated as generations per hour divided by respiration rate. Results indicated that the growth efficiency of this bacterium was much greater at the lower temperature range of growth.
The location and analysis of melanins in the cell walls of some soil fungi
Authors: Ellis D. H. , Griffiths D. A.
Published: April 2010

Electron-dense particles of melanin were located in ultrathin sections of: the hyphal walls of Amorphotheca resume; the aleuriospore walls of Epicoccum nigrum and Humicola grisea; the sclerotial walls of Colletotrichum coccodes; and both within and between the microsclerotial cell walls of Verticillium dahliae. Melanin was extracted with KOH from each of the fungi, but, because of rapid oxidation of the pigment in air, extraction and analysis was carried out under nitrogen. The pigments were examined spectrophotometrically under UV and IR radiation and by means of x-ray diffraction. Characterization of the melanin in terms of its degradation products indicated it to be indolic in nature. These results are compared with published data on other melanins extracted from animal and plant sources.
Serum-mediated protection of microtissue cultures against gonococcal infection
Authors: Ashton F. E. , Wallace R. , Diena B. B.
Published: April 2010

A microtissue culture technique has been developed to study the ability of animal and human sera to inhibit infection and destruction of Rhesus monkey kidney cells by Neisseria gonorrhoeae.
Germination studies on pure yeast ascospores
Authors: Savarese John J.
Published: April 2010

Pure ascospore suspensions of three strains of Saccharomyces cerevisiae have been prepared by sequential treatment with 2-mercaptoethanol, Glusulase, and sonication. Light microscopy and acid-fast staining revealed the presence of only ascospores. Various germination media tested using the ascospore preparation revealed different nutritional requirements for the germination of auxotrophic and prototrophic yeast strains. Acid-fast staining of the germinating ascospores was shown to be an effective method for studying the kinetics of ascospore germination. The anaerobic nature of ascospore germination was demonstrated using this staining technique.
Aerosol survival of Serratia marcescens as a function of oxygen concentration, relative humidity, and time
Authors: Cox C. S. , Gagen S. J. , Baxter Jean
Published: April 2010

Previously the kinetics of loss of viability of freeze-dried Serratia marcescens 8UK were determined by Cox and Heckly as a function of oxygen concentration and time. Results are presented here when dehydration is brought about by aerosolization into atmospheres of low relative humidity (RH) rather than by freeze-drying. As for freeze-dried S. marcescens, oxygen was toxic and viable decay followed the same kinetics with respect to oxygen concentration and time. The influence of RH upon viable decay (which was not studied in the previous report) was that above 65% RH oxygen was not toxic but was progressively more toxic as the humidity was further reduced. Kinetic analyses of the results indicate that the site for the toxic action of oxygen lies in the interspace between the cytoplasmic membrane and the cell wall. Such a finding is consistent with other data which suggest that cell division and (or) cell wall synthesis in bacteria are inhibited by oxygen.
Intrageneric clustering and divergence of Erwinia strains from plants and man in the light of deoxyribonucleic acid segmental homology
Authors: Murata Nobuo , Starr Mortimer P.
Published: April 2010

The relationships among Erwinia species (originating from plants and man) and other enterobacteria were examined in terms of DNA–DNA segmental homology. All of the organisms studied show a "core homology" amounting to about 10–15%, thus supporting the inclusion of the erwinias in the taxonomic vicinity of the other enterobacteria, and also revealing that the present genus Erwinia is hardly separable from the other enterobacterial genera solely on the extent of DNA–DNA segmental homology. Genetic clusters based on DNA–DNA segmental homology are found within all of Dye's "natural" (phenotypic) groups of the genus Erwinia. However, these genetic clusters are not coextensive with any entire natural group, and designation of any of them as genera seems implausible at present. Except for a few cases of obvious synonymy, the several Erwinia nomenspecies generally showed significant nomen-species-specific segments of DNA, but a taxonomic revision at the species level based only on DNA–DNA segmental homology would seem premature. The Erwinia strains isolated from human clinical sources are essentially indistinguishable on the basis of DNA–DNA segmental homology from the epiphytic and related Erwinia strains derived from plants.
Demonstration in Aspergillus niger of adenyl cyclase, a cyclic adenosine 3′,5′-monophosphate-binding protein, and studies on intracellular and extracellular phosphodiesterases
Authors: Wold William S. M. , Suzuki Isamu
Published: April 2010

Aspergillus niger was found to possess adenyl cyclase, one or more cyclic adenosine 3′,5′-monophosphate (cAMP) binding proteins, and two apparently distinct cAMP phosphodiesterases, one intracellular (I-PDE) and the other extracellular (E-PDE). All these activities except E-PDE were located in the soluble fractions of the cells. The I-PDE was partially purified by protamine sulfate treatment, ammonium sulfate precipitation, ethanol precipitation, and DEAE-cellulose chromatography. The I-PDE had a pH optimum of 7.5, was activated by magnesium ions, and was inhibited by EDTA. The Km for cAMP was 2.5 mM, and for cyclic guanosine 3′,5′-monophosphate (cGMP), 0.5 mM. The E-PDE had a pH optimum of 3.5 and was inactive at pH 7.5. The Km for cAMP was 18 μM. Preliminary evidence was obtained that the activity of the E-PDE may be regulated by endogenous inhibitor.
CO2 fixation by the facultative autotroph Thiobacillus novellus during autotrophy–heterotrophy interconversions
Authors: McCarthy J. T. , Charles A. Michael
Published: April 2010

During conversion of Thiobacillus novellus to a heterotrophic mode of growth, 14CO2 incorporation declined in freshly grown cells by about 67% of the autotrophic amount within 15 min after transfer to glucose – mineral salts medium. At later times this activity increased until it was about 350% of the original amount. Enzyme assays of freshly prepared crude extracts revealed that initially RuDP carboxylase accounted for 77 ± 4.7% of the total specific activities of the CO2-fixing enzymes studied. PEP carboxylase was 6.7 ± 1.3%; PEP carboxykinase, 8.2 ± 1.8%; and pyruvate carboxylase, 8.2 ± 1.8%. The decline in specific activity of RuDP carboxylase during growth on glucose was relatively slow, accounting for about 8% of the original activity after 18 h. None was detectable after 24 h growth. Decline in the specific activity of phosphoribulokinase and alkaline fructose diphosphatase was also observed. On the other hand, there was an increase in the specific activities of PEP carboxylase, PEP carboxykinase, and pyruvate carboxylase respectively. Conversion of the organism to an autotrophic mode of growth initially resulted in high incorporation of 14CO2. This, however, declined with increased exposure to S2O32− and CO2. The specific activities of the various enzymes also showed a reversal of the patterns noted during heterotrophic development. Phosphoribulokinase reached its maximum (specific activity) earliest. It was followed about 2 h later by RuDP carboxylase, and another 2 h elapsed before alkaline fructose diphosphatase attained its maximum. Finally, S2O32− was found to be necessary for RuDP carboxylase induction; HCO3−, SO32−, or SO32− and HCO3− were ineffective.
Action of streptomycin on the growth of Streptomyces griseus
Authors: Cella R. , Vining L. C.
Published: April 2010

A streptomycin-producing culture of Streptomyces griseus was sensitive to streptomycin, but inhibition was temporary, and cultures supplemented with the antibiotic up to 100 μg/ml grew after a lag. Streptomycin tolerance developed, not by inactivation of the antibiotic but by selection of resistant variants in the natural population. Addition of streptomycin to growing cultures caused a drastic reduction in protein synthesis and an accumulation of "stuck" (70 S) ribosomes within the mycelium. Although the effect on protein synthesis could not be confirmed in vitro because cell extracts from S. griseus contained an inhibitor of polyuridylic-acid-directed polymerization of L-phenylalanine, it is concluded that streptomycin prevents the growth of this organism by a mechanism similar to that observed with other bacteria and that the tolerance of producing cultures cannot be attributed to the presence of streptomycin-resistant ribosomes.
Growth abnormalities in microorganisms exposed to tobacco leaf extracts
Authors: Ghabrial S. A.
Published: April 2010

Unusual cultural changes were observed when several bacterial and yeast strains were grown on a medium containing aqueous extracts of tobacco leaves. In 24–48 h incubation on such a medium, several dark-brown papilla-like structures developed on the surface of normally smooth colonies. Moreover, smaller dark-brown refractile globular bodies were observed in the medium in areas beneath and surrounding the microbial colonies with papilla-like structures. Attempts to demonstrate the viability of these globular bodies failed. The cultural abnormalities observed on tobacco extract medium were unique to this medium since they were not detected in a wide variety of culture media tested. The lowest concentration of tobacco extract (dry wt. basis), which is required for the development of this phenomenon, was determined to be 0.5 mg/ml of medium.
Relationship of soil constituents to spore counts and heat resistance of Bacillus stearothermophilus
Authors: Fields M. L. , Lee P. P. Chen , Wang David
Published: April 2010

Spore counts and heat resistance of Bacillus stearothermophilus and thermophilic actinomycetes were influenced by types of crops and were correlated positively with Mn, Ca, P, pHw, and pHs of soil from Sanborn Field, Columbia, Mo. In greenhouse soil, positive correlations were found between thermophilic aerobes and Mg, Ca, K, and cation-exchange capacity. Also, in the greenhouse soil, negative correlations occurred between counts for thermophilic aerobes and pHw and pHs. Spores in soils in Sanborn Field were more heat- resistant than spores in greenhouse soil. The number of germinating spores in dry soil stored at 25Cand 1.1C increased after 1 month and remained at the same relative number for 9 months at which time counts declined at both temperatures.
Photosynthesis and nitrogenase activity in the blue-green alga Gloeocapsa
Authors: Gallon J. R. , LaRue T. A. , Kurz W. G. W.
Published: April 2010

In a young culture, photosynthetic-oxygen evolution by Gloeocapsa is at a low level while nitrogenase activity is at its greatest. When the culture ages, there is a rapid increase in photosynthetic pigments and oxygen evolution, and nitrogenase activity decreases. The temporal separation of nitrogen fixation and photosynthesis may serve to protect nitrogenase from oxygen denaturation.
Iron oxidation by cell envelopes of Thiobacillus ferrooxidans
Authors: Bodo Carl , Lundgren D. G.
Published: April 2010

The parameters for iron oxidation by isolated cell envelopes of Thiobacillus ferrooxidans were studied using a Clark oxygen electrode. Envelopes were obtained by breaking thoroughly washed cells in a French pressure cell and by sedimenting the envelope fraction by ultracentrifugation. The envelopes were partially purified by sucrose density-gradient centrifugation. A broad band was separated at a specific gravity of about 1.21 g/cm3 which coincided with the major protein peak and iron oxidation activity. Electron micrographs confirmed that the active preparations were cell envelopes consisting of the cytoplasmic membrane, peptidoglycan layer, and the outer lipopolysaccharide–lipoprotein double track layer of gram-negative bacteria. Numerous membrane vesicles were also present. Lysozyme had little effect upon iron oxidation activity whereas treating cell envelopes with Triton X-100 destroyed activity. Iron oxidation by cell envelopes was completely inhibited by heating in boiling water or by adding 1% trichloroacetic acid to the reaction cuvette.Kinetic analysis of iron oxidation by envelopes in β-alanine-SO42− buffer (pH 3.5) showed an apparent Km of 5.4 × 10−3 M. The apparent Km with whole cells was 2.1 × 10−3 M. The pH optimum for iron oxidation by cell envelopes was between pH 3.0 and 3.5 while for whole cells the optimum was pH 2.0–2.5.Spectrophotometric studies identified the membrane-bound cytochromes as cytochromes c and a; cytochrome b was also present but its function is unknown at this time.
Chemotaxonomic fatty-acid fingerprints of some streptococci with subsequent statistical analysis
Authors: Drucker D. B.
Published: April 2010

Cellular fatty-acid profiles were obtained for streptococci of Lancefield groups A, B, C, D, N and O, and Streptococcus salivarius. The major fatty acids above isomyristate had the retention characteristics of n-myristate, myristoleate, n-palmitate, palmitoleate, anteisostearate, n-stearate, and oleate (or cis-vaccenate). Profiles were quantitatively and qualitatively similar. Strains could be identified as members of a particular Lancefield group by computer analysis with the Bravais–Pearson coefficient of linear correlation being used as a measure of association of strain pairs, since strains of the different Lancefield groups examined had distinct fatty-acid profiles.
Trimethylamine oxide reduction by Salmonella
Authors: Kim Kyung Eun , Chang George W.
Published: April 2010

Trimethylamine oxide (TMAO) allows the anaerobic growth of Salmonella on glycerol and is thereby reduced to trimethylamine, a volatile indicator of fish spoilage. A mutant strain, TA1530, is unable to reduce either TMAO or nitrate; this suggests that the TMAO and nitrate reductase systems have common components.
Inhibition and amplification of the radiation-induced degradation of DNA in Escherichia coli
Authors: Myers D. K.
Published: April 2010

The degradation of DNA in a repair-proficient strain (B/r) and in two repair-defective strains (Bs–1 and pol A) of Escherichia coli was studied in the presence and absence of three metabolic inhibitors after exposure of the cells to X-radiation. The radiation-induced degradation of DNA was dependent on energy production in freshly harvested log-phase cells and was closely related to the repair capacity of the cells. A different system, probably involving nonspecific deoxyribonucleases acting at radiation-induced strand breaks, appeared to be responsible for the degradative processes in stationary-phase cells or in log-phase cells which had been aged by standing in buffered saline for 2 days before irradiation. The three inhibitors tested (caffeine, rifampin, and carbonyl cyanide m-chlorophenyl hydrazone) were all found to inhibit partially the radiation-induced degradation of DNA in E. coli cells. Under other conditions, the same three compounds amplified the degradative process. The data suggested that the amplification was due to a selective inhibition of repair processes. The degradative processes which were stimulated by X-radiation of E. coli cells show many parallels to those which are evoked by phleomycin or colicine.
Yeast-like growth of Mucor alternans (van Tieghem) in tissue-culture medium 199
Authors: Leyritz M. , Kapica L.
Published: April 2010

Mucor alternans (van Tieghem) was found to be a diphasic species in that it grew exclusively in the yeast-like budding phase under anaerobic conditions in the complex medium yeast extract – peptone – glucose broth and in tissue-culture medium 199. In the latter medium this growth form occurred also at 37C, at an initial pH of 7.2, and at glucose concentrations of 0.1 and 1.0%. The authors suggest that because of its synthetic nature the tissue-culture medium could be used with advantage in the study of nutritional requirements of dimorphic mucors.
Theoretical studies on the coexistence of competing species under continuous-flow conditions
Authors: Taylor P. A. , Williams P. J. LeB.
Published: April 2010

In continuous-flow environments, such as a chemostat, we find that, in theory, stable mixed populations of competing species obeying Monod/Michaelis–Menten growth kinetics (extended to more than one limiting substrate) cannot coexist unless the number of growth-limiting substrates is equal to or greater than the number of species. Additional restrictions on the relative values of the growth-yield constants and input-substrate concentrations must also be satisfied. Examples of the theoretical growth of mixed cultures after initial inoculation in stable and unstable cases are presented. The ecological consequences of these findings are briefly discussed.
Antibacterial properties of a peroxidogenic strain of Streptococcus mitior (mitis)
Authors: LeBien Tucker W. , Bromel Mary C.
Published: April 2010

An antibacterial substance produced by a strain of Streptococcus mitior, and isolated from a human throat culture, was found to inhibit the growth of streptococci and staphylococci. The substance was characterized as hydrogen peroxide.
Influence of temperature and salt concentration on the growth of a facultatively halophilic "Micrococcus" sp.
Authors: Novitsky T. J. , Kushner D. J.
Published: April 2010

Growth characteristics of a facultatively halophilic strain of Micrococcus, capable of growth in medium containing no added NaCl and in medium containing 5.5 M NaCl, were studied over a range of salt concentrations and temperatures. Optimal growth occurred at 35C in a medium containing 1.0 M NaCl. In a medium containing 0.1 M NaCl, growth only occurred if the incubation temperature was less than 30C. No growth occurred if KCl, LiCl, NH4Cl, MgCl2, or sucrose was substituted for NaCl at 35C. A reexamination of bacteria previously described as moderate halophiles is suggested.