bluuebunny/crossref_metadata_2025 huggingface dataset:
Further properties of P-2 R-factors of Pseudomonas aeruginosa and their relationship to other plasmid groups
Authors: Shahrabadi M. S. , Bryan L. E. , Elzen H. M. Van Den
Published: April 2010

R-factors of the P-2 (prototype R-factor R931) incompatibility group pf plasmids detected in Pseudomonas are compatible with group P, C, W, and N R-factors which are plasmids that can be transferred to Pseudomonas aeruginosa recipients. Members of the P-2 group (R130, R931) have significant homology by DNA–DNA hybridization. R-factors of the P-group (RP1, RP9) and F-group (R1) exhibited homology with P-2 R-factors but to a lesser extent than R130 with R931. Members of the 1, C, and W groups showed no significant homology with P-2 R-factors. Minicircular DNA of strain 931(R931) was not homologous with R931 DNA. The host range of R931 and R130 is limited mainly to certain Pseudomonas species including P. aeruginosa, P. fluorescens, P. putida, and P. stutzeri. These R-factors could not be transferred at detectable frequencies to any member of the Enterobacteriaceae examined. R-factor-specified pili were strongly suggested by the detection of pili by electron microscopy in R+ but not R− non-piliated mutants of P. aeruginosa strain PA01. The combined properties of R-factors 931 and similar R-factors reported before and in this study strongly support our previous contention that this group of R-factors form a significant new group of plasmids. A classification scheme previously proposed for plasmids occurring in Pseudomonas has been modified and four groups have been specified.
Hydrogen cyanide, a secondary metabolite of Pseudomonas aeruginosa
Authors: Castric Peter A.
Published: April 2010

Seventy-four of 110 strains of Pseudomonas aeruginosa tested produced detectable amounts of HCN from growth in 2% peptone or nutrient agar. Of the 25 species of 12 bacterial and fungal genera tested, other than P. aeruginosa, only P. fluorescens and P. polycolor gave positive HCN tests. Cyanide is produced after cessation of active growth. Iron was stimulatory to cyanogenesis in concentrations above 1 μM, while copper, zinc, cobalt, and manganese at concentrations of 20 μM had no effect. Cyanogenesis is dependent on the temperature of incubation within ranges which allow complete growth. Inorganic phosphate in concentrations between 90 and 300 mM allows growth but inhibits HCN production. Growth of cells anaerobically, using nitrate as the electron acceptor, results in low cyanide yields, which can be partially reversed by subsequent aerobic incubation. These results indicate that HCN is a secondary metabolite of P. aeruginosa.
Basis for the susceptibility of several algae to microbial decomposition
Authors: Gunnison Douglas , Alexander Martin
Published: April 2010

Partially purified cellulase and a cellulase-containing polygalacturonase but not lysozyme extensively degraded the walls of Chlamydomonas reinhardtii and Ulothrix fimbrata and converted intact cells of the algae to spheroplasts. A streptomycete cellulase cochromatographed with the enzyme system releasing glucose from walls of these organisms, and this preparation also converted the algal cells to spheroplasts. The dominant constituent in the walls was carbohydrate, and glucose and small quantities of galacturonic acid but no amino sugars were present in acid hydrolysates of the walls. Glucose accounted for essentially all of the material solubilized by the cellulase preparation. Lysozyme acted on Cylindrospermum sp. walls, and it, but not the other enzymes, converted some of the Cylindrospermum sp. cells to spheroplasts. Streptomycete enzymes lysing Micrococcus lysodeikticus cochromatographed with the proteins releasing reducing sugars from Cylindrospermum sp. walls, and components in the active fraction converted cells of this alga into spheroplasts. X-ray diffraction revealed that the walls of C. reinhardtii and U. fimbrata but not those of Cylindrospermum sp. contained cellulose. The data suggest that the susceptibility of the first two species to microbial degradation in natural ecosystems results from an attack on the cellulose in their walls, and the susceptibility of the third is linked with the microbial production of a lysozyme.
N6-(Δ2-isopentenyl)adenosine: hydrolysis by a nucleosidase isolated from Lactobacillus acidophilus cells
Authors: Hordern J. , Johnson R. H. , McLennan B. D.
Published: April 2010

A nucleosidase activity has been isolated from Lactobacillus acidophilus which rapidly hydrolyses N6-(Δ2-isopentenyl)adenosine to its corresponding base, N6-(Δ2-isopentenyl)adenine. The activity can be distinguished from the spleen exzyme (EC. 2.4.2.1), a purine nucleoside transferase, on the basis of its substrate specificity, electrophoretic behavior, and non-dependence on phosphate. The bacterial enzyme hydrolyzes both inosine and isopentenyl adenosine, giving Km values of 63.3 μM and 177 μM respectively. The presence of this enzyme in bacteria accounts for the rapid conversion of the parent nucleoside to isopentenyl adenine, which has been observed in these cells. The enzyme thus assumes importance as one of the catabolic activities available to the cell for metabolizing the cytokinin, N6-(Δ2-isopentenyl)adenosine.
Relationship between DNA content and mesosome number in cells of Bacillus
Authors: Johnston Gerald C.
Published: April 2010

In cells of Bacillus there is evidence that deoxyribonucleic acid forms an association with some membranous structure within the cell, possibly mesosomes. Cells of varieties of Bacillus cereus and Bacillus subtilis were examined to see if any quantitative relationship existed between the numbers of mesosomes and DNA content. No direct relationship could be demonstrated. However, cells of Bacillus cereus var. alesti A(−) maintained a characteristic and constant DNA content and number of mesosomes regardless of growth conditions.During sporulation, a variant of A(−), termed A(−)3, sequesters its DNA at both ends of the cell, leaving a small amount of DNA but no mesosomes in the center compartment. Since this center compartment is capable of growth and division upon replacement in fresh medium (rejuvenation) it was examined for mesosome content as DNA synthesis and division were initiated. In most cells, a central mesosome was formed at the site of cell septum formation; however, the presence of a mesosome was not an absolute prerequisite for cell division.We propose that at the onset of cell growth, mesosomes primarily function in the process of cell septum formation. As growth and division proceed, mesosomes are produced in characteristic numbers and may act as the site of DNA synthesis and (or) segregation.
Lethality of Candida strains as influenced by the host
Authors: Saltarelli Cora G. , Gentile Kathi Ann , Mancuso Susan C.
Published: April 2010

A comparative study of the pathogenicity of Candida albicans morphological mutant strains was made to relate chlamydospore production, germ tube formation, and proteolytic activity to candidiasis in mice. It was observed that the mycelium strains were more lethal than the yeast-like strains and that neither chlamydospore production, germ tube formation, nor nutritional requirements was related to pathogenicity in mice. Statistical analysis indicated that the culture media of the organisms and the strain and sex of the mice into which the cells were injected were important factors in the development of pathogenicity.
Differentiation of Arthrobacter soil isolates and named strains from other bacteria by reactions on dye-containing media
Authors: Hagedorn Charles , Holt John G.
Published: April 2010

Twenty-five gram-negative and 62 gram-positive bacterial cultures, of which 37 were arthrobacters, were tested, using a multipoint inoculation device, for responses on varying concentrations of 35 dyes. Both selective (growth vs. no growth) and differential (dye absorption) responses were obtained. It was possible to differentiate the arthrobacters from the other gram-positive bacteria tested as well as to distinguish separately each Arthrobacter -named strain. The results indicated that dyes have a greater potential for use in selective and differential media than has been presently realized; and the possibility of using dye-reactions as features in taxonomic schemes to differentiate rapidly many of the common genera of soil bacteria is discussed.
Preservation of mycobacterial suspensions at −55 °C
Authors: Boulanger R. P. , Portelance V.
Published: April 2010

Suspensions in dilute Sauton's medium of 14 mycobacterial strains grown under identical conditions were prepared with bacilli harvested at their midlog phase of growth, and were frozen and stored at −55 °C. Survivals, estimated by CFU determinations after periodic intervals of storage, showed no adverse effect of freezing and thawing on any of the strains. Effectiveness of preservation, however, varied from strain to strain and no correlation existed between effectiveness and species of mycobacteria. No noticeable changes in the virulence of the H37Rv strain and in the immunizing activity of BCG were detected after prolonged storage. Results of experiments performed with two strains suspended in seven diluents suggest that some are more suitable for long-term preservation, particularly so for the more sensitive one.
Determination of guanine plus cytosine content in Streptococcus pyogenes
Authors: Stuart James G. , Ferretti Joseph J.
Published: April 2010

The guanine and cytosine content of Streptococcus pyogenes DNA was determined by thermal denaturation and buoyant density analysis to be 36.7% and 38.7%, respectively.
Amino acid requirements of staphylococci isolated from human skin
Authors: Emmett Merrill , Kloos Wesley E.
Published: April 2010

Amino acid requirements and auxotrophic reversion properties were determined for 823 Staphylococcus strains isolated from natural populations on human skin. Ten species of Staphylococcus exhibited distinct amino acid requirement patterns. Proline, arginine, and valine were the most frequently required amino acids for the genus Staphylococcus.
Effect of nitrogen source on carbon metabolism by Azotobacter vinelandii OP grown in chemostat and batch culture
Authors: Kurz W. G. W. , LaRue T. A.
Published: April 2010

Azotobacter vinelandii growing under nitrogen-fixing conditions has higher specific activities of isocitric and malic dehydrogenase than do cells growing on nitrate or ammonia. Results show that the source of nitrogen has an effect on carbon metabolism.
The participation of common and species-"specific" antigens of mycobacteria in the tuberculin skin reaction
Authors: Turcotte Raymond
Published: April 2010

Protoplasmic extracts isolated from four different species of mycobacteria contained common and species-specific antigens. Both the common and the specific antigens were involved in the elicitation of the tuberculin reaction in sensitized guinea pigs. The elimination of the common antigens from the extracts by means of cross absorption with heterologous mycobacterial antibodies led to preparations which, at the doses used in this study, elicited a cutaneous reaction in animals sensitized with the corresponding strains only. Moreover, the tuberculin activity of the common antigens was about the same in animals sensitized either with homologous or heterologous strains.
Nitrate utilization and growth in biotin-deficient Aspergillus nidulans
Authors: Desai J. D. , Modi V. V.
Published: April 2010

A marked increase in the cellular synthesis accompanied by a decrease in the total fatty acid content was observed when Aspergillus nidulans was grown on NH4NO3 as a sole nitrogen source, in the medium containing avidin. Because of the increased uptake of NH4+, the level of NH4+ was lowered in the medium; as a result there is early uptake and assimilation of nitrate by a biotin-deficient culture as compared with the normal culture of A. nidulans. At about 17 mM concentration, NH4+ repressed the activity of nitrate reductase. The regulation of NO3− uptake and its assimilation with respect to the growth of A. nidulans have been discussed.
Some physiological effects of near-maximum growth temperatures on an obligately psychrophilic marine bacterium
Authors: Geesey Gill G. , Morita Richard Y.
Published: April 2010

The heat inactivation of the obligately psychrophilic marine bacterium Ant-300 was investigated in terms of glucose uptake, the oxidation of glucose to CO2, and permeability control. At 13C, the maximum temperature for growth, and at slightly higher temperatures, CO2 evolution decreased with time during the oxidation of exogenously supplied glucose. The decrease in CO2 evolution appeared to be a result of heat-induced restrictions on glucose uptake. Leakage of intracellular metabolites apparently contributed to the cells decreased ability to take up glucose at elevated temperatures. A consequence of these heat-induced changes seemed to be the acceleration of cell starvation.
Aerobic adaptation in yeast. II. Changes in enzyme profiles during a step-down anaerobic–aerobic transfer
Authors: Ball A. J. S. , Bruver Rita M. , Tustanoff E. Reno
Published: April 2010

The levels of various enzymes and components of the glycolytic and respiratory pathways of the yeast Saccharomyces cerevisiae have been determined during a step-down, anaerobic-to-aerobic transition. These activities were determined as an adjunct to the respective metabolite data reported in the first paper in this series. It is clear from the data that anaerobic conditions induce an environment conducive to express glycolytic enzyme activities, while manifesting a differential induction/repression effect on oxidative enzymes. An NAD/NADH mediated mechanism is proposed to explain this difference. Of the enzymes assayed only cytochrome c oxidase shows any direct response to oxygen challenge and consequently it is suggested that the assembly of this enzyme is the trigger mechanism and rate-limiting step in aerobic adaptation.
Protozoa and the decline of Rhizobium populations added to soil
Authors: Danso S. K. A. , Keya S. O. , Alexander M.
Published: April 2010

A fall in Rhizobium abundance occurred in nonsterile soil inoculated with large numbers of the root-nodule bacteria, but many of the rhizobia still survived. No such decline was evident in sterile soil. Protozoa feeding on these bacteria were isolated from soil and other environments. As the abundance of Rhizobium meliloti and a cowpea Rhizobium strain in soil decreased, the protozoan density increased. The inability of the predators to eliminate their prey from soil was not the result of the presence of organisms feeding on the protozoa because many rhizobia survived in sterile soil inoculated with the prey and cultures of individual protozoa, nor was it the result of the rapid multiplication of the bacteria to replace those consumed because survivors were still numerous in essentially organic matter free soil in which the bacteria did not grow appreciably. The lack of elimination also was not associated with a protective effect of soil particles because survivors were still abundant in solutions inoculated with protozoa and bacteria. It is suggested that the size of the prey population diminishes until a density is attained at which the energy used by the predator in hunting for the survivors equals that obtained from the feeding.
Aeromonas proteolytica—a halophilic aeromonad?
Authors: McCarthy D. H.
Published: April 2010

Aeromonas proteolytica, a halophilic bacterium originally isolated from the intestine of a marine isopod, was compared with 93 strains of Aeromonas hydrophila and representative strains of five similar genera in a computer and serological analysis.Aeromonas proteolytica was peritrichate and non-reactive with six A. hydrophila antisera, and possessed a percentage guanine + cytosine ratio (49.5) outside the range for other aeromonads (55–62%). Moreover, in the computer analysis it shared a lower level of similarity with other aeromonads than with both strains of Vibrio anguillarum tested.
The isolation and characterization of a temperate phage, Y46/(E2), from Erwinia herbicola Y46
Authors: Harrison Anne , Gibbins L. N.
Published: April 2010

A temperate phage was induced from exponential phase cells of Erwinia herbicola Y46 by treatment with mitomycin C. The phage was purified by single plaque isolation, and produced in bulk by successive cultivation in young cultures of E. herbicola Y178. Phages were concentrated from culture filtrates by rate zonal centrifugation and resuspension in 0.02 M Tris buffer, pH 7.2, twice, yielding suspensions of about 5 × 1011 PFU/ml. Purification was achieved by centrifugation in buffered sucrose solutions. The band at the 30/40% sucrose interface yielded intact particles having regular hexagonal heads and long contractile tails, with base plates. Fibers were not seen. The mean dimensions were head, 51 nm; neck length, 11 nm; overall tail length, extended, 98 nm and contracted, 75 nm; diameter of tail sheath, 24 nm. The phage was stable from pH 4.0 to 11.0, but unstable at pH 3.0, the response being independent of the suspending medium used. At pH 3.0, a survival curve having a biphasic appearance was observed, which was not due to a mixed population of phages. Stability to heat was good up to 45 °C, above which a logarithmic decline with temperature increase occurred. The average inactivation rate constant at 50 °C and pH 6.8 was 0.15 min−1. Adsorption to E. herbicola Y178 cells exhibited first-order kinetics, the adsorption rate constant being 2.5 × 10−10 ml/min. One-step growth-curve experiments indicated a burst size of 35–40, and a minimum latent period of 80 min. Probit analysis gave a mean latent period of 140 min (SD 25). The phage caused lysis of only E. herbicola strains Y178 and Y186.
Electron microscopy of the in vivo internalization of virulent Chlamydia psittaci 6BC strain
Authors: Kordová Nonna , Wilt John C. , Burton Lynn , Martin Caroline
Published: April 2010

The internalization of virulent Chlamydia psittaci 6BC particles by wandering mononuclear phagocytes in the peritoneal cavity of intraperitoneally inoculated mice occurred asynchronously, i.e., fragile reticulate bodies (RB) appeared to be more readily phagocytized than the rigid elementary bodies (EB). Early damage of mononuclear phagocytes occurred after internalization of chlamydiae. This was followed by a decreased uptake of particles, and may explain the relatively long persistence (up to 6 h after inoculation) of free, extracellular, "swollen," and RB-like particles. Internalized particles within phagolysosomes showed varying degrees of disintegration. The subsequent influx of polymorphonuclear phagocytes and monocytes into the inflammed peritoneal cavity may explain the rapid disappearance of chlamydiae and their antigens from the peritoneal fluid. The alteration in ultrastructure of peritoneal cells and chlamydial parasites during the inflammatory process are discussed.
Natural infections of Richardson's ground squirrels with western equine encephalomyelitis virus, Saskatchewan, Canada, 1964–1973
Authors: Leung Man-Kit , Burton Althea , Iversen John , McLintock John
Published: April 2010

A survey (1964–1973) was conducted on naturally occurring western equine encephalomyelitis (WEE) virus infections of Richardson's ground squirrels (RGS) in agricultural areas of Saskatchewan. The survey included both serology and virus isolation attempts on live-trapped wild squirrels. Throughout the study, seropositive squirrels were found in the known enzootic regions of the province each summer. The infection rate was high (11.6% of 250) in the epidemic year of 1965 and low (less than 2% of 681) in the subsequent non-epidemic years. The maximal seasonal prevalence of seropositive RGS coincided with the time when the squirrel population and aedine mosquito abundance reached their seasonal peaks. Five virus isolations were obtained from the blood and brains of naturally infected squirrels. All isolations were from squirrels collected in June. The early seasonal infections in squirrels could provide a source of virus for Culex tarsalis, the epidemic vector. In view of their abundance in the enzootic agricultural areas and the high annual population turnover, the RGS may play an important role in the natural history of WEE virus in the Canadian prairies.
A simple method for storing cellular slime mold amoebae
Authors: Laine Joanne , Roxby Nancy , Coukell M. B.
Published: April 2010

A simple procedure has been developed for freezing of vegetative amoebae of various cellular slime mold species. This procedure can be used to store stocks of both developmentally competent and developmentally defective strains of cellular slime molds for periods up to at least 1 year.
The inhibition of bacterial growth by ochratoxin A
Authors: Heller K. , Schulz C. , Löser R. , Röschenthaler R.
Published: April 2010

A series of bacterial species was examined for their sensitivity to ochratoxin A. Only gram-positive bacteria could be inhibited, generally at a pH lower than 7.0. Bacillus subtilis did not show any reduction of growth rates in presence of ochratoxin A, but had a prolonged lag phase. With Staphylococcus pyogenes var. aureus and Streptococcus faecalis, a prolonged lag phase and a reduction of the growth rates was observed. Most sensitive was Streptococcus faecalis in the exponential-growth phase. The inhibition could be diminished by changing the pH to neutral, or by addition of yeast extract, tetrahydrofolate, or MgSO4. With MgSO4 a complete abolition of the inhibitory effect was achieved, but not with CaCl2. During growth inhibition, protein and RNA synthesis were reduced simultaneously, but not DNA synthesis. Even with the very high concentration of 1 mg/ml, no lethal effect was observed.
Continuous non-destructive determination of nitrogenase activity in microbial cultures
Authors: Larue T. A. , Kurz W. G. W. , Mallard C.
Published: April 2010

The dinitrogen fixing enzyme nitrogenase (nitrogen:(acceptor) oxidoreductase) (EC 1.7.99.2) is monitored by its ability to reduce acetylene to ethylene. Low, non-inhibitory concentrations of acetylene (~10−7 mol/litre) are mixed with the gas flow aerating microbial cultures, and acetylene and ethylene in the effluent gas are determined by gas chromatography. The procedure is safe, simple and is carried out in situ without disturbing the growing culture. Transient changes in nitrogenase activity are easily detected. The technique may be automated.
Electron microscopy of vesicular-arbuscular mycorrhizae of yellow poplar. I. Characterization of endophytic structures by scanning electron stereoscopy
Authors: Kinden Darrell A. , Brown Merton F.
Published: April 2010

Vesicular-arbuscular mycorrhizae of yellow poplar (Liriodendron tulipifera L.) were examined by scanning electron microscopy. The morphology and spatial distribution of endophytic structures are illustrated. The use of stereoscopic techniques in conjunction with removal of host cytoplasm permits detection of subtle morphological alterations and progressive deterioration of the fungal component.
Changes in patterns of respiration and glucose utilisation in Candida utilis during the cell cycle: some variations with growth rate
Authors: Dawson P. S. S. , Westlake D. W. S.
Published: April 2010

The release of 14CO2 from 14C-labelled glucose (G-1-14C, G-3,4-14C, G-6-14C) was followed in phased cultures of Candida utilis grown in a glucose – mineral salts medium under altered conditions of carbon:nitrogen limitation at doubling times of 2, 4, and 6 h. Changes in oxygen uptake and CO2 evolution were observed and respirometric studies showed that the relative contributions of the Embden-Meyerhof-Parnas and hexose monophosphate pathways varied over the cell cycle and changed with growth rate. The results are discussed in relation to the growth metabolism of the cells.
Enhancement of adhesion of the marine Chlorella vulgaris to glass
Authors: Tosteson T. R. , Corpe W. A.
Published: April 2010

The adhesion of washed cells of a marine Chlorella vulgaris to solid surfaces was enhanced by non-diffusible material recovered from Chlorella exudate, marine bacterial cultures, natural seawater, and fouled marine surfaces. Materials isolated from certain bacterial cultures and from particulate materials filtered from seawater were three orders of magnitude more active than Chlorella exudate per unit weight. Active polymer materials from several sources were chromatographed on DEAE cellulose. The major fraction eluted with dilute base contained both protein and carbohydrate and enhanced adhesion more than the unchromatographed material.
Contamination of shellfish with strains of Pseudomonas aeruginosa and specific bacteriophages
Authors: Denis F. A.
Published: April 2010

Pseudomonas aeruginosa and its corresponding bacteriophages were sought in oysters and mussels throughout 1973. Forty-eight percent of the oysters and 74% of the mussels examined during the last half of the year contained P. aeruginosa; serotype P3 was predominant.The percentage of oysters contaminated by bacteriophages active on P. aeruginosa increased throughout the year, from 0 to 4% between January and May to 69% in November. We were unable to establish a significant relationship between the presence of the bacterium and that of its specific bacteriophages in the shellfish.
Characteristics of Staphylococcus aureus associated with lysogenic conversion to loss of beta-hemolysin production
Authors: Mason Richard E. , Allen Wendall E.
Published: April 2010

Staphylococcus aureus strains 7-8 and 57 that produce β-hemolysin but not staphylokinase (β+K−) were lysogenically converted by certain serological group F bacteriophages to the loss of β-hemolysin production and the gain in staphylokinase production (β+K−). Serological group A phage 42E was found to convert S. aureus strains 7-8 (β+K−) and 57 (β+K−) to β − K−. Conversion of β-hemolysin by lysogenization of a serological group A phage has not previously been reported. Phage 42E conversions differed from the group F conversions since staphylokinase was not affected. This indicates that conversion to β − K+ involves separate loci on the phage chromosome. Several characteristics associated with virulence of staphylococci of human or animal origin other than staphylokinase production (coagulase, DNase, lipase, gelatinase, mannitol fermentation, and phage-sensitivity patterns) were not correlated with lysogenic conversions to loss of β-hemolysin.
Preservation of stained and unstained tissue impressions for the rabies fluorescent antibody test
Authors: Lewis Vester J. , Engelman Helen M. , Thacker W. Lanier
Published: April 2010

Rabies impression slides held at selected temperatures unstained or stained and mounted with Elvanol or buffered glycerol were evaluated for reliability in the rabies immunofluorescence test.
The effect of glucose and lactose on β-D-galactosidase activity and formation of sclerotia in Sclerotium rolfsii
Authors: Okon Y. , Chet I. , Henis Y.
Published: April 2010

Addition of 0.5% (w/v) lactose to a glucose–mineral medium (SM) induced formation of sclerotia and β-D-galactosidase (β-D-galactoside galactohydrolase) (EC 3.2.1.23) synthesis in Sclerotium rolfsii types A and R. These effects as well as lactose uptake were inversely related to glucose concentration within the tested range of 0.5 to 2.5% (w/v). Transfer of lactose-grown colonies to a glucose-supplemented medium nullified the inducible effect of lactose on formation of sclerotia, whereas transfer to water agar did not. It is concluded that glucose nullifies the effect of lactose on S. rolfsii by interfering with its active uptake.
Ultraviolet sensitivity and photoproducts in spore-like bodies of an excision-repair-deficient and dipicolinic-acid-less strain of Bacillus subtilis
Authors: Munakata N. , Fitz-James P. C. , Young I. E.
Published: April 2010

Bacillus subtilis strain UVS-42DPA is defective in both excision-repair capability and dipicolinic acid (DPA) accumulation. In sporulation medium, it forms spore-like bodies, which are as sensitive to ultraviolet light (UV) as the vegetative cells and produce mostly cyclobutane dimers instead of "spore photoproduct" upon UV irradiation. The results suggest that the drastic change in the photochemical reactivity of DNA during sporulation might be induced and (or) maintained by the accumulation of DPA.
Cell surface protein of Salmonella typhimurium
Authors: Kabir S.
Published: April 2010

Lactoperoxidase-catalyzed radioiodination with Na125I was performed both on intact Salmonella typhimurium 1195 and on ghost membrane isolated from the same bacterial strain. Ghost membrane was also prepared from radioiodinated whole bacteria. The labelled proteins from both these ghost membrane preparations were compared by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate to identify the cell surface protein. From the results obtained it was concluded that one major protein with an apparent molecular weight of 12 000 – 13 000 was exposed on the exterior surface of the ghost membrane.
Characterization of two reserve glucans from Clostridium pasteurianum
Authors: Brown Robert G. , Lindberg Bengt , Laishley Edward J.
Published: April 2010

The reserve glucans of C. pasteurianum, previously assumed to be a single polysaccharide, have been fractionated into two polysaccharides which resemble amylopectin and dextran. Both polysaccharides are produced when cells are grown with sucrose, D-glucose, or D-fructose as carbon sources.
Genetic recombination in a chloramphenicol–producing strain of Streptomyces species 3022a
Authors: Francis M. M. , Cella R. , Vining L. C.
Published: April 2010

Mutation with ultraviolet light and chemical mutagens yielded strains with auxotrophic and streptomycin-resistance markers. These were used to show the existence of genetic recombination in Streptomyces species 3022a and to construct a linkage map for 17 marker loci.
Interactions between Azotobacter and "phosphobacteria" and their establishment in the rhizosphere as affected by soil fertility
Authors: Ocampo J. A. , Barea J. M. , Montoya E.
Published: April 2010

The effects on plant growth of "bacterial fertilizers" prepared from Azotobacter spp. and phosphate-solubilizing bacteria ("phosphobacteria") have been the subject of much controversy. Cases where no plant-growth stimulation occurred may often be accounted for by the failure to establish the bacterial inocula in the rhizosphere.Three factors that may influence inocula establishment, i.e. soil fertility, manuring, and interactions between Azotobacter and "phosphobacteria," were examined in pot experiments, designed for statistical analysis, in two neutral–alkaline soils, using lavender plants (Lavandula spica L.). During the experiments the numbers of Azotobacter and "phosphobacteria" were counted. Dry weights of roots and shoots were recorded after 16 weeks of growth.At the end of the experiments there were always more Azotobacter and "phosphobacteria" in the rhizospheres when plants were inoculated with both groups of organisms together than when they were inoculated singly. Addition of 2% farmyard manure to the richer soil enhanced this effect.Plant growth was greatest when seedlings were inoculated with both Azotobacter and the "phosphobacteria."
Effective selection of Proteus mirabilis clones producing mirabilicin D-52
Authors: Tikhonenko Anna S. , Belyaeva Nina N. , Bespalova Iraida A.
Published: April 2010

From a defective-lysogenic Proteus mirabilis strain we isolated several clones differing in the pattern of their growth on agar plates. Using electron microscopy we have shown some of the selected clones to be efficient in producing mirabilicin D-52 after UV induction, while other clones produced defective mirabilicin polysheaths and polycores. Clones producing polysheaths and polycores can be detected electron microscopically only, since these defective particles are biologically inactive.
Influence of albumin on rubella virus hemagglutination and the hemagglutination-inhibition test
Authors: Campbell J. B. , Grunberger T. , Ellins Mary L.
Published: April 2010

The HEPES–saline–albumin–gelatin (HSAG) diluent found optimal for agglutination of fowl erythrocytes by rubella virus antigen is also optimal for agglutination of trypsin-treated human group O cells. Albumins from different commercial sources, however, can have varying inhibitory effects on rubella hemagglutination titers. This can have a significant effect on the hemagglutination-inhibition test since antibody titers measured by this procedure are related to the amount of antigen used.
The development of an increased rate of Cl− uptake in the ascomycete Neocosmospora vasinfecta
Authors: Miller A. G. , Budd K.
Published: April 2010

Freshly harvested mycelium of the filamentous ascomycete Neocosmospora vasinfecta accumulated Cl− against a concentration gradient by a process probably requiring the expenditure of metabolic energy. When mycelium, washed free of growth medium, was incubated in deionized water or tris(hydroxymethyl)aminomethane sulfate at pH 7.5 for 4 h and then transferred to K36Cl solutions, the Cl− uptake rate was, on the average, 3.77 ± 0.26 (± SE, N = 20) times the uptake rate exhibited by freshly harvested mycelium. This development of an increased rate of Cl− uptake could be blocked by the presence of an inhibitor of ribonucleic acid synthesis (azaguanine) or of protein synthesis (cycloheximide, fluorophenylalanine, or puromycin). The combined presence of glucose and a potassium salt in the preincubation solution virtually arrested the development of enhanced Cl− uptake. The rate of Cl− uptake by freshly harvested mycelium did not vary greatly with the age of the culture on harvest but the ability to develop an increased rate declined with age. The fact that it is possible to obtain mycelium possessing widely different capacities for Cl− uptake should assist in biochemical characterization of the Cl− uptake system.
Repair of heat injury in thymine auxotrophs of Escherichia coli
Authors: Bhaumik Gayaram , Bhattacharjee Sukhendu B.
Published: April 2010

Heat-induced damage in four strains of bacteria has been studied. It has been shown that the damage is repairable on incubation at 37 °C in a medium not supporting growth. The extent of repair is dependent upon the strain of bacterium chosen. Recovery from the damage is prominent in the case of filament-forming bacteria, and in non-filament formers, recovery is not totally absent.
Electron microscopy of T1-bacteriophage adsorbed to clay minerals: application of the critical point drying method
Authors: Bystricky Vojtech , Stotzky G. , Schiffenbauer Milton
Published: April 2010

A T1-bacteriophage appears to be strongly adsorbed by clay minerals. The critical point drying method has been used to facilitate visualization of this surface interaction by electron microscopy.
Assembly of the enveloped bacteriophage ϕ6 in environments which perturb the host cell membranes
Authors: Sands J. A. , Lowlicht R. A. , Cadden S. C. , Haneman J.
Published: April 2010

The effects of known membrane-perturbing agents (pH, Na+, Ca2+, and a small lipid-soluble molecule) on the enveloped bacteriophage ϕ6 host cell system were investigated at the levels of cellular growth, virus assembly and stability, and the physical and chemical properties of host cell membranes. Spin-label probes of cellular membranes indicate that growth in high levels of Na+ or the small spherical hydrophobic molecule adamantanone results in membranes having increased "fluidity," while growth in high levels of Ca2+ results in slightly greater rigidity of the membranes. In addition, the phospholipid composition of the cellular membranes is dependent on the NaCl concentration in the growth medium. None of these membrane alterations, however, prevent the production of infectious ϕ6 virus particles.
Sequential production of polygalacturonase, cellulase, and pectin lyase by Rhizoctonia solani
Authors: Lisker N. , Katan J. , Henis Y.
Published: April 2010

The sequence of appearance of cell wall degrading enzymes of Rhizoctonia solani propagules was followed. Polygalacturonase (PG; EC 3.2.1.15) was induced earlier by sodium polypectate (NaPP) as compared with the induction of cellulase (Cx; EC 3.2.1.4) by carboxymethyl cellulose (CMC), cellobiose, or fibrous cellulose powder. Increasing CMC concentration to 0.5% shortened the time of Cx appearance. In Czapek medium containing citrus pectin, pectin lyase (PL; EC 4.2.2.10) was produced faster and at higher amounts than in a medium containing NaPP as the sole carbon source. PG appearance also preceded that of PL in media simultaneously supplemented with their respective inducers. NaPP, which induced production of PG, repressed Cx production. Among the Cx inducers, only CMC and cellobiose repressed PG production to any extent. At pH 6.0, either in a synthetic medium or on autoclaved bean hypocotyl segments, a delay in PG production as compared with Cx and PL production was observed. Optimal pH levels for enzyme production and activity were 4.0 and 5.0 for PG, 4.0 and 5.5 for Cx, and 8.0 and 7.5 for PL. PG was less repressed than Cx by glucose, cellobiose, and monogalacturonic acid, while PL was not affected.
Scanning and transmission electron microscopy of three strains of Bifidobacterium
Authors: Bauer H. , Sigarlakie E. , Faure J. C.
Published: April 2010

Scanning and transmission electron microscopy was applied for a morphological study of three strains of Bifidobacterium grown on solid or liquid media. The pronounced pleomorphism of the cultures previously observed by light microscopy was confirmed. A possible sequence of the morphological events during transformation from one to another pleomorphic form is proposed for B. bifidum and B. longum. Ultrastructural differences such as the formation of extensive mesosomal complexes in B. longum and characteristic plasmalemma particles only observed in the B. bifidum mutant are described and discussed.
Infectious pancreatic necrosis (IPN) virus carriers and antibody production in a population of rainbow trout (Salmo gairdneri)
Authors: Yamamoto T.
Published: April 2010

A total of three hundred and fifty-seven 2-year-old rainbow trout from a hatchery were examined for IPN virus over a period of 5 months. The overall virus isolation rate was 23.2%. The kidneys yielded virus most frequently while the spleen and pancreas-caeca yielded virus less frequently, and the gonads and feces yielded virus infrequently.During this period there was a decline in carrier rate as well as a decline in the numbers of infectious virions in the organs. These decreases were accompanied by elevated levels of neutralizing antibody in the sera. Fish with higher antibody levels were found to lose their IPN carrier status more frequently than those with lower antibody levels.
Inhibition of oxidative metabolism in Escherichia coli by d-camphor and restoration of oxidase activity by quinones
Authors: Cardullo Maria A. , Gilroy James J.
Published: April 2010

Oxidative metabolism in whole cells of Escherichia coli strain 82/r was inhibited by d-camphor when glucose, pyruvate, or succinate was used as substrate. Inhibition was not due to lower surface tension in d-camphor-treated cell suspensions nor was it a function of cell permeability. Succinic, lactic, and NADH-oxidase activities were inhibited in alumina powder cell-free extracts (80 μg of protein/ml) by d-camphor (1100 μg/ml). NADH: and succinic: DCPIP oxidoreductase enzymes were unaffected by d-camphor. Menadione (vitamin K3) restored succinic, lactic, and NADH-oxidase activities in d-camphor-inhibited cell-free extracts. Concentrations of menadione used to restore succinic and NADH oxidase activities were not stimulatory in non-camphor-treated extracts. Succinic oxidase activity in d-camphor-inhibited cell-free extracts was also restored by ubiquinone (Q6) but not by vitamin K1. These results are interpreted to indicate that d-camphor may affect quinone function in E. coli.
The use of irradiated vaccine in immunization against experimental murine toxoplasmosis
Authors: Seah S. K. K. , Hucal G.
Published: April 2010

Trophozoites from the peritoneal cavities of mice infected with the RH strain Toxoplasma gondii were given irradiation in doses of 5, 10, 15, and 20 kiloroentgens (kr). CD-1 strain mice that received intraperitoneal inoculation of trophozoites irradiated with 5 kr all died of toxoplasmosis, but the mice that received trophozoites irradiated with the higher doses all survived. The survivors that were examined were found to be free of toxoplasmic cysts. Single doses of these irradiated vaccines provided good protection to subsequent virulent challenge. This protection was 100% in the first 3 weeks after the immunization. Survivors of the first challenge were also solidly protected against a subsequent rechallenge.
Relationship between various bacterial populations and coprostanol and cholesterol
Authors: Dutka B. J. , El-Shaarawi A.
Published: April 2010

A year-long study was conducted at three different locations in Canada to evaluate the relationship between fecal sterols and bacterial populations.A statistical model was constructed to study the following: (i) seasonal variations in the sterols and bacterial parameters; (ii) the differences between morning and afternoon samples; (iii) the relationship between the two sterols (coprostanol and cholesterol) as well as their relationship to the bacterial parameters; and (iv) the geographical differences between the three sampling sites.Application of the model to the data indicated that (i) the relationship in receiving waters between coprostanol and cholesterol was found to be highly significant; (ii) at two sampling sites the relationship between fecal sterols and fecal coliforms was positively significant at the 5% level; (iii) at one sampling site there was a positive relationship between fecal sterols and the fecal coliform – fecal streptococcus ratio; and(iv) in a.m. vs. p.m. samples significant differences were noted in coliform, fecal coliform, and fecal streptococcus densities while no significant differences were found in heterotroph densities and coprostanol and cholesterol levels.Raw and treated sewage from four sewage-treatment plants were also studied to provide baseline control data.Data support the conclusion that while no consistent relationship exists between bacterial parameters and fecal sterols, fecal sterols could be considered as unequivocal indicators of the presence of fecal material in water.
Adaptation to cycloheximide: in vitro studies with filamentous fungi
Authors: Salkin Ira F.
Published: April 2010

Adaptation of numerous strains of filamentous fungi to cycloheximide was noted upon first transfer during serial exposure to the antibiotic. The extent of this adaptation varied in part with the species and strain of the microorganism. Exposure on subsequent transfers caused no change in the growth of any of the strains used. These results suggest that nonzoopathogens may be differentiated from zoopathogens on the basis of adaptation to cycloheximide and that such adaptation might also be found in other eucaryotes.
Survival of Salmonella and other indicator microorganisms
Authors: Mitchell Daniel O. , Starzyk Marvin J.
Published: April 2010

Survival times for enteric bacteria and fecal streptococci were investigated using filter-sterilized water from a northern Illinois river and temperatures of 0°. 5°, 10°, and 20 °C. Survival of Salmonella typhimurium was essentially the same as Escherichia coli over normal seasonal temperatures. Fecal streptococci generally exhibited classic survival patterns.
Ultrastructural studies of Chlamydia psittaci 6BC in situ in yolk sac explants and L cells: a comparison with gram-negative bacteria
Authors: Costerton J. W. , Poffenroth Linda , Wilt J. C. , Kordová Nonna
Published: April 2010

Chlamydia psittaci (6BC) was grown in yolk sac explants and in L cells and fixed by perfusion in situ to provide undamaged material for comparison with gram-negative bacteria. Reticulate, intermediate, and elementary bodies were all seen to lack a well-defined periplasmic space; intermediate and elementary bodies showed condensations of the nucleoid which differ from common bacterial configurations; and the cytoplasm of highly condensed elementary bodies was much more electron dense than that of the gram-negative bacteria, while retaining its basically particulate nature.These important morphological distinctions are interpreted as reflections of a significantly different cellular level of organization in these two groups of organisms. No important morphological differences were noted in comparisons of the chlamydial particles grown in the two different host systems.
The effect of purification on the ultrastructure and infectivity of egg-attenuated Chlamydia psittaci (6BC)
Authors: Costerton J. W. , Poffenroth Linda , Wilt J. C. , Kordová Nonna
Published: April 2010

A procedure is described for the purification of mixed populations of the three different morphological forms of Chlamydia psittaci (6BC) from infected yolk sac membranes. Elementary bodies and small intermediate bodies are not perceptibly damaged during purification which involves homogenization of the host cells, differential centrifugation, sedimentation through 20% sucrose, and treatment with trypsin. The observation that elementary bodies undergo plasmolysis in 20% sucrose is interpreted as indicating that the cytoplasmic membrane of these particles is intact at that stage in the purification. Reticulate bodies and large intermediate bodies are damaged, to a degree, by the homogenization step. This damage takes the form of discontinuities of the outer envelope membrane, and results in the loss of the regular coccobacillary shape of these particles and in an increase in their size. Treatment with a combination of RNase and DNase was found to cause profound damage to all three morphological forms of the chlamydiae.
Death rates of bacterial spores: nonlinear survivor curves
Authors: Han Youn W.
Published: April 2010

Nonlinear survivor curves were obtained when spores of Bacillus cereus were heated in physiological saline solution. Curvilinear survivor curves did not appear to be caused by experimental artifacts but by the heterogeneity of spore population with regard to heat resistance.
Soil fungistasis: elevation of the exogenous carbon and nitrogen requirements for spore germination by fungistatic volatiles in soils
Authors: Griffin Gary J. , Hora T. S. , Baker Ralph
Published: April 2010

Axenic, washed conidia of Fusarium solani f. sp. phaseoli, Aspergillus flavus, and Verticillium albo-atrum were placed on washed Difco purified agar discs along with an inorganic salt solution containing various levels of carbon and nitrogen substrates. These discs were exposed to volatiles from six soils (pH 5.1–8.6). Fusarium solani macroconidial germination was inhibited mostly by volatiles from soils of pH 5.1, 6.1, 7.0, and 7.5, but high levels of glucose and NH4Cl reversed this inhibition, raising germination to that of no-soil, no-carbon or nitrogen controls. Conidial germination of A. flavus was inhibited mainly by volatiles from high pH (7.0, 7.8, and 8.6) soils, and increased levels of glucose plus an amino acid mixture nullified this inhibition. Volatiles from soils of pH 5.1, 6.1, and 7.5 stimulated A. flavus conidial germination. Assays after the removal of CO2 from the air above soil of pH 5.1 demonstrated that volatiles inhibitory to A. flavus were produced by this soil. Assays indicated that a KOH-soluble compound was a fungistatic soil volatile to F. solani macroconidial germination. The nullification by carbon and nitrogen substrates of F. solani and A. flavus inhibition caused by soil volatiles parallels that for soil fungistasis. Conidial germination of V. albo-atrum was markedly stimulated by volatiles in all soils tested, and was not affected by removal of CO2. Inhibitory soil volatiles may increase the nutritional requirements for spore germination of certain fungi.