- Volume 20, Issue 1, 1959
Volume 20, Issue 1, 1959
- Article
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Krassilnikoviae: A New Class of Micro-Organisms found in Sea and Ocean Depths
More LessSummary: A new class of micro-organisms, the Krassilnikoviae, found in the Black Sea, the Pacific and the Arctic Oceans, is described. These organisms developed on slides immersed in the waters; they have not been cultivated in the laboratory. They consist of non-branching, non-septate filaments with a head at one end consisting of a cluster of round bodies. The filaments often become interlaced and form strings which can just be seen by the naked eye. They may or may not be contained in a sheath.
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Some Physioloǵical Characters of Yeasts from Soils and Allied Habitats
More LessSummary: An investigation has been made of some physiological properties of yeasts from soil and from the leaf surfaces of pasture plants. Almost all the species tested could use cellobiose, and the majority could synthesize growth factors and use a range of organic acids as carbon sources. Some species, including all the pigmented ones examined, could use aromatic compounds as carbon sources. A few species could liquefy gelatin. Only two were able to degrade pectin completely under the conditions used. Almost all could grow within a wide range of hydrogen ion concentrations and at osmotic pressures of at least 30 atmospheres. Ability to survive desiccation varied greatly. Only one species showed any ability to grow at low oxygen tensions. No marked or consistent differences could be seen between soil and leaf yeasts. As both groups are competent to grow in substrates which supply low concentrations of complex foodstuffs, it seems likely that antagonistic factors originating from other members of the soil and leaf populations are responsible for keeping the two floras distinct.
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Nadsonia slovaca n.sp. Isolated in Slovakia
More LessSUMMARY: In the region of the mountains of Malé Karpaty and Harmanec in Slovakia a new species, Nadsonia slovaca, was isolated. The species was found on the surface of the fruits of Comus mas, on the surface of the fruiting bodies of Amanita muscaria, Nematoloma lateritium and N. fasciculare and in the water of the brook Bystrica. The new species differed from those described hitherto by the formation of abundant pseudomycelium on the margin of slimy streaks and by the formation of big, bag-like, granulated cells. The new species did not ferment any sugars.
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The Freezing Points of Bacterial Cells in Relation to Halophilism
More LessSUMMARY: The hypothesis that halophilic bacteria achieve a high degree of salt tolerance by exclusion of much of the external solutes of the growth medium has been tested. Organisms were grown in media containing from 1 to 4 m salts. For both halophilic and non-halophilic bacteria the freezing points of the cells were close to those of the media in which they were grown. It is concluded that halophilic bacteria do not maintain the intracellular aqueous phase at a water activity greater than in the surrounding growth medium.
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Lysis of Vibrio costicolus by Osmotic Shock
More LessSUMMARY: Suspensions of the halophilic organism Vibrio costicolus lysed when subjected to sufficient osmotic shock; this was revealed as a marked fall in optical density. Organisms in the logarithmic phase of growth, grown in media containing m-NaCl, when suspended in NaCl or LiCl solutions with concentrationsm or lower lysed when the concentration was below 0·33 m: when the organisms were suspended similarly in KCl or NH4Cl solutions, lysis began at a concentration above 0·8 m. Older organisms were more resistant to lysis. Lysis was little affected by replacement of chloride by other univalent anions, by pH values from 4 to 10 or by previous incubation with 10𢄥 m-mercuric chloride. Addition of cetyltrimethylammonium bromide (200 μg./ml.) increased resistance to lysis in both NaCl and KCl solutions.
Organisms grown in media of NaCl concentrations ranging from 0·5 to 3·0 m began to lyse at a NaCl concentration one-third of that present during growth. Organisms suspended in NaCl solutions of one-half the concentration in which they had been grown equilibrated promptly to the new environment; this was shown by a decrease of 50 % in the salt concentration at which lysis then began. When organisms were transferred to salt concentrations higher than that of the growth medium, the osmotic sensitivity was not affected. It is concluded that the osmotic status of these organisms is controlled chiefly by small ions or molecules which leak rapidly from the cells on transfer to dilute environments.
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A Gene Modifying the Thiamine-requirement of Strains of Neurospora crassa
More LessSummary: A new gene, thi-1o, is described in Neurospora crassa. This gene is shown to be a modifier of the nutritional response of strains containing the thi-1 gene, and is not nutritionally detectable in the absence of the thi-1 mutant locus. The gene thi-1o is additionally characterized by a decreased ability to synthesize thiamine from thiazole and pyrimidine; thi-1o appears to modify only thi-1 strains because of their unusually high thiamine requirements. The nutritional responses of strains containing either thi-2 or thi-3 loci are not affected by the presence of thi-1o. Both thi-1o and thi-4 are anomalous in the condensation of pyrimidine and thiazole. The probability that thi -1o may be an isoallele of thi-4 is based upon a similarity of metabolic pattern and upon location on chromosome III. The failure to obtain recombination in crosses between strains containing thi-1o and thi-4 constitutes additional support for their allelism.
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Investiǵation on Streptomycin Inhibitors with the Aid of a Streptomycin-dependent Vibrio comma
More LessSUMMARY: The growth and amylase activity of a streptomycin-dependent Vibrio comma on starch agar plates was gradually decreased with decrease of the streptomycin-concentration. The concentrations of streptomycin and the streptomycin- antagonizing properties of bacterial products also could be assayed by a cup plate method. The diameters of the zones of decomposed starch around the cups were proportional to the logarithms of streptomycin concentration. In the presence of a constant concentration of streptomycin they were inversely proportional to the concentration of bacterial antagonist. The following species and genera of microorganisms produced antagonists (in decreasing order of their activity): Pseudomonas sp., Proteus morganii, Clostridium botulinum, C. parabotulinum, C. welchii, C. septi- cum, Bacillus megaterium, B. subtilis, Rhodotorula sp., and some strains of the genera Escherichia, Shigella and Klebsiella. No inhibitory effects were observed with products of Salmonella paratyphi A and B, Serratia marcescens, Staphylococcus aureus, S. albus, Streptococcus faecalis, S. lactis, Brucella abortus, B. melitensis, Pasteurella pestis, P. pseudotuberculosis, Alkaligenes faecalis, Saccharomyces sp., Candida albicans.
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Some Applications of Deterǵents to the Study of the Virus of Foot-and-Mouth Disease
More LessSUMMARY: The virus of foot-and-mouth disease is highly resistant to the detergents sodium dodecyl sulphate (SDS), cetyl trimethyl ammonium bromide (CTAB) and Tween 80. Results are recorded which show the possibilities of using SDS in the extraction of virus from infected cells, in concentrating virus by elution from adsorbents, and in increasing yields in the filtration and ultracentrifugation of virus suspensions.
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Amino Acid Requirements for Formation of the Reductive Amination System in Bacillus subtilis
P. C. Shah and H. K. KingSUMMARY: Bacillus subtilis, grown on nutrient broth, casein hydrolysate, or on a mixture of amino acids simulating casein hydrolysate, yielded washed suspensions with an active reductive amination system. On simple defined media the activity of the organisms was relatively low. Additions of a variety of amino acids, singly or in simple mixtures, yielded suspensions with activities up to about half of that attained with complex media. The performance of 18 amino acids in about 200 different combinations was analysed statistically; no amino acid showed marked and significant stimulation of enzyme formation. It was concluded that a high enzyme yield requires a medium with a complex amino acid relationship, and that the performance of complex media cannot be explained directly in terms of a few active components.
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Some Characters of Rhizobium Strains from Tropical Legumes
More LessSUMMARY: Twelve strains of Rhizobium sp. from wild and cultivated leguminous plants growing in the Belgian Congo were examined. All were bacillary or filamentous, weakly Gram-positive, and produced occasional retractile, heat-resistant spores; all grew alternatively in the form of very tiny, Gram-negative rods with polar flagella (if motile), and without spores. Botanical evidence suggests that the host plants are primitive members of the family Leguminosae, and if the characters of these strains of Rhizobium are also to be regarded as primitive, this evidence supports the view that Rhizobium is related to Azotobacter and the Bacillaceae.
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Some Properties of a Pectolytic Soil Flavobacteriurn
More LessSummary: A pectolytic Flavobacterium sp. isolated from soil is described. It possesses a typical bacterial polygalacturonase but no pectin methyl esterase.
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Release of Herpes Virus from Solitary HeLa Cells
More LessSUMMARY: A study has been made of the release of herpes virus (strain HFEM) from solitary HeLa cells which had been infected en masse. Under the conditions used, small amounts of infective virus were released from a few cells as early as 10 hr. after infection. Evidence is given suggesting that such virus is a remnant of the inoculum. A greater proportion of cells released infective virus (considered to be new virus) between 16 and 34 hr. after infection. The results suggest that: (a) the yield of virus is low (average 13 pock-forming units/cell); (b) liberation of virus from one cell extends over a period of several hours; (c) there is some scatter in the time of release by different cells. The proportion of solitary cells liberating virus 28–35 hr. after infection was lower than expected (19–35 %) considering the virus/cell ratios used, but was not affected by treating the cells with herpes antiserum after they had been exposed to virus. This proportion was compared with the proportion of cells able to initiate pocks on the chorioallantois.
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Some Properties of an Inhibitor of Virus Infection from Leaves of Raspberry
More LessSUMMARY: Raspberry leaves contain a substance which prevents the infection of plants by viruses when it is mixed with the inoculum. It is lost on dialysis, precipitated by nicotine or added protein, unaffected by boiling or freezing, and is probably a phenolic tanning agent. Extracts from peach or apple leaves contain less of such substances than do those from leaves of plum, cherry, raspberry or strawberry. The degree to which virus infection is inhibited by tanning substances from raspberry or other sources depends on the virus and not on the species of test plant. Raspberry tannin and tannic acid combine irreversibly with some viruses but with others the combination is readily reversed by dilution or increase in pH value. With potato ring necrosis, tobacco mosaic and tobacco necrosis viruses, there seems to be a fixed ratio between the amount of virus and the amount of tannin needed to decrease infectivity by a fixed proportion. The infectivity of extracts made from raspberry leaves containing raspberry ring spot or beet ring spot viruses varied with the concentration of tannin present and the pH value. The amount of virus sedimented by centrifuging such extracts at low speed decreased with increase of pH value. Extracts made with 2·5 % nicotine in water were usually more infective than those made with alumina or phosphate buffer (pH 8), and much more infective than those made with water. Both viruses are precipitated by acetone or ammonium sulphate from extracts of infected raspberry leaves made with nicotine or alumina; beet ring spot virus was detected serologically in such preparations from infected raspberry leaves.
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A Comparison of Nocardia asteroides and Nocardia brasiliensis
More LessSUMMARY: A description of Nocardia asteroides (Eppinger) Blanchard, based on the examination of 98 strains, is presented and compared with a description of N. brasiliensis (Lindenberg) Castellani and Chalmers, based on 50 strains. Characteristics common to freshly isolated strains, variants of the same strain, and old stock strains are used in the delineation of each species.
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Reversion of Transduced Antigenic Characters in Salmonella typhimurium
More LessSUMMARY: A strain of Salmonella typhimurium, in which the H antigens had been altered by transduction with a bacteriophage lysate of S. abony to the form b ⟷ enx has been found to revert in the first or second phases giving rise to organisms with the structure i ⟷ enx and 6 ⟷ 1.2. No reversions in both phases have so far been detected. This phenomenon has been observed only in non-lysogenic strains; lysogenic varieties have remained stable.
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Evidence for the Occurrence of Permeases for Tricarboxylic Acid Cycle Intermediates in Pseudomonas aeruginosa
More LessSUMMARY: Washed suspensions and cell-free extracts of Pseudomonas aeruginosa grown on Lemco agar, to which intermediates of the tricarboxylic acid cycle had been added, were tested for their ability to oxidize succinate, fumarate, malate, pyruvate, acetate, α-oxoglutarate and citrate. Whole organisms had lag periods of 2–3 hr. before citrate was oxidized rapidly, except when citrate or acetate had been added to the growth medium. There were lag periods of about 10 min. before rapid and linear oxidation of succinate by organisms grown on acetate; of fumarate by organisms grown on acetate or pyruvate; and of acetate by organisms grown on malate, pyruvate, α-oxoglutarate, fumarate or succinate. There were no lags for malate, pyruvate or α-oxoglutarate by organisms grown on any of the substrates tested. Organisms grown on malonate or Lemco agar to which no additions had been made had lags for all the substrates. Glucose-grown organisms had lags for all the intermediates except succinate. Only malonate-grown organisms oxidized malonate rapidly and linearly, and organisms grown without malonate had lag periods of 2–3 hr. before oxidizing this substrate.
Cell-free extracts from organisms with lag periods before the oxidation of citrate, acetate, fumarate, malate, succinate and α-oxoglutarate were shown to oxidize these substrates without a lag period. Pyruvate and malonate were not oxidized by any of the extracts including those from organisms grown on these substrates. Chloramphenicol inhibited the adaptation to substrates by whole organisms but was without effect on the oxidation by cell-free extracts. The significance of these findings in relation to the hypothesis of specific permeases for the transport of organic molecules into the cell is discussed.
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The Occurrence of Polyol Derivatives of Cytidine Diphosphate in Micro-organisms
More LessSUMMARY: A survey of cytidine diphosphate compounds in representative species of Gram-positive and Gram-negative bacteria has been made. Cytidine diphosphate glycerol and cytidine diphosphate ribitol, first discovered in Lactobacillus arabinosus 17/5, were also found in L. plantarum. Cytidine diphosphate glycerol was found in L. bulgaricus and cytidine diphosphate ribitol in Bacillus subtilis. No correlation between the presence of cytidine nucleotides and the Gram reaction was found.
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A New Type of Acetobacter: Acetobacter acidophilum prov. sp.
More LessSUMMARY: A new type of Acetobacter, provisionally named Acetobacter acido- philum, has been isolated in pure culture from an experimental vinegar generator originally inoculated with active industrial beechwood shavings. In contrast to other bacteria, this organism needs an acidic medium for growth and has a very specific oxidizing capacity. It does not grow above pH 4·3 and oxidizes only primary alcohols. Other substrates, including glucose and acetic acid, are not oxidized at a rate higher than 1 % of the oxidation rate for ethanol. The new isolation procedure, which has been applied for the strain described in this paper, allows the isolation of the bacteria present on active shavings, suggesting that this type of bacteria belongs probably to the group of organisms responsible for the acetification in the ‘quick vinegar process’.
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