bluuebunny/crossref_metadata_2025 huggingface dataset:
Amino acid composition of proteins in halophilic phototrophic bacteria of the genus Ectothiorhodospira
Authors: Imhoff Johannes F. , Kushner Donn J. , Anderson Peter J.
Published: May 2010

The amino acid composition of total proteins of eight Ectothiorhodospira strains with different salt optima and of separated membranes of selected strains have been determined. Amino acid compositions were compared with those reported for nonhalophilic phototrophic and heterotrophic bacteria and Halobacterium halobium. The membrane fractions from Ectothiorhodospira strains requiring high salt for maximum growth contained more polar and less nonpolar amino acids than strains with low salt requirements or nonhalophilic bacteria. The content of intermediate amino acids increased with the increasing halophilic properties of the Ectothiorhodospira strains. Proteins which function in high-salt environments may therefore require such compositions to maintain their structures in highly ionic solutions.
Efficacité de huit désinfectants sur trois types de surfaces contaminées par Pseudomonas aeruginosa
Authors: Gélinas P. , Goulet J.
Published: May 2010

The disinfecting capacity of eight commercial chemical products was evaluated by the use–dilution method given by the Association of Official Analytical Chemists (AOAC) on three types of surface material (steel, aluminum, and plastic). For most products tested the limit concentration was 10 times higher for disinfecting aluminum and plastic surfaces man stainless steel. As observed on the scanning electron microscope, the number of bacteria deposited on the surface and the production of extracellular material on polypropylene by Pseudomonas aeruginosa ATCC 15442 would explain the observed differences. The applicability of the AOAC method or other techniques for the evaluation of the disinfecting capacity on different surfaces is discussed.
Chlamydospore formation by Trichoderma spp. in natural substrates
Authors: Lewis J. A. , Papavizas G. C.
Published: May 2010

Various isolates of Trichoderma spp. formed chlamydospores in oat kernels placed in sterile and natural soils and in excised tissues of corn and bean inoculated with a conidial suspension. In an axenic oat – loam soil system, isolates of three species (T. viride, T. harzianum, T. hamatum) produced 1–38 × 107 chlamydospores/g of oat tissue. The soil type and its organic matter content did not affect the number of chlamydospores formed. In oat kernels retrieved from natural soils infested with Trichoderma conidia, approximately 10% were chlamydospores of indigenous Trichoderma spp. that infested and colonized the oats. Another 10% were attributed to the isolates added to soils as conidia. The remaining chlamydospores belonged to Fusarium spp., unidentified fungi, or were nongerminable on the media used. In excised corn and bean tissues infested with Trichoderma, from 19 × 106 to 61 × 106 chlamydospores/g of tissue were formed by the phyllosphere fungi. Ten percent of the chlamydospores were from the introduced isolates and the remainder from indigenous Trichoderma spp., Fusarium spp., and unidentified fungi. The results suggest the probable importance of Trichoderma chlamydospores in the survival of this genus in soil.
Pyruvate kinase from Aspergillus niger: a regulatory enzyme in glycolysis?
Authors: Meixner-Monori Bibiana , Kubicek Christian P. , Röhr Max
Published: May 2010

Pyruvate kinase from the filamentous, citric acid producing fungus Aspergillus niger was purified about 100-fold by ammonium sulfate precipitation, DEAE-cellulose chromatography, and gel filtration. The addition of fructose-1,6-diphosphate was necessary to prevent loss of activity during purification. The enzyme purified in the presence of fructose-1,6-diphosphate (FDP) exhibits hyperbolic kinetics with respect to phosphoenolpyruvate (PEP) and ADP. Monovalent cations activated the enzyme (K+, NH4+). FDP neither activated nor inhibited the enzymatic activity from extracts freshly prepared in the absence of exogenous FDP; ATP showed a weak activation. In contrast the enzyme from crude extracts which had been stored in the presence of glycerol for 3 days showed activation by FDP or a metabolite thereof and inhibition by ATP. In the absence of FDP sigmoidal kinetics were obtained with respect to PEP, which became hyperbolic kinetics after addition of FDP. ATP inhibition turned into slight ATP activation in the presence of FDP. However, it was possible to reactivate inactivated pyruvate kinase (after dialysis in the absence of FDP) by adding FDP to the enzyme assay. From these results and because of the very high affinity of pyruvate kinase for FDP (Ka < 0.1 μM), it is concluded that the enzyme probably has FDP bound to the protein in vivo. The significance of this hypothesis to the regulation of glycolysis in A. niger, with special reference to the mechanism of citric acid accumulation, is discussed.
Seroepidemiology of Q fever in Nova Scotia and Prince Edward Island
Authors: Marrie Thomas J. , Buren John Van , Faulkner Ruth S. , Haldane E. Vanora , Williams James C. , Kwan Carol
Published: May 2010

The prevalence of Coxiella burnetti infection (Q fever) was determined among Nova Scotia (N.S.) and Prince Edward Island (P.E.I.) blood donors by using the complement fixation and microimmunofluorescence (IF) test. The complement fixation and IF antibody tests measured antibody prevalence for the phase II or phase I and II antigens, respectively. Complement-fixing antibodies to phase II antigen were detected in 4.1% of 997 N.S. and 5.0% of 219 P.E.I. blood donors. Anti-phase II antibodies were detected by microimmunofluorescence in 11.8 and 14.6% of the blood donors in the two provinces, respectively. Anti-phase I antibodies were detected among 2.8% of the N.S. blood donors and 6.3% of the P.E.I. blood donors. Comparison of rates of anti-phase II IF by counties in N.S. revealed that there was at least one county where infection by C. burnetti is hyperendemic. Rates of antibody prevalence were similar in all three areas of P.E.I. examined. We conclude that "Q fever" is endemic in N.S. and P.E.I. and that the microimmunofluorescence test is more suitable than the complement fixation test for seroepidemiologic studies.
A method for assessing the root-colonizing capacity of bacteria on maize
Authors: Scher F. M. , Ziegle J. S. , Kloepper J. W.
Published: May 2010

A closed test tube assay was developed for measuring the root colonization capacity of bacteria in raw soil–sand. Bacteria were coated onto seeds at inoculum levels of 103 – 109 colony-forming units (cfu) per seed, and root-colonizing bacterial strains successfully grew along the emerging radicle. Quantification of specific bacterial populations on roots was highly reproducible between experiments with the assay. Of 54 strains tested, 24 colonized roots at populations of 104 to 106 cfu/g root. All root-colonizing strains were Gram negative. Two fluorescent pseudomonad strains that failed to colonize maize roots in raw soil did colonize in autoclaved soil. Captan seed treatment and temperature of incubation (14 and 24 °C) had no substantial effect on subsequent root colonization. Root population densities determined in the sand–soil assay were comparable with those determined with plants grown in soils under greenhouse conditions.
Effects of sulphur dioxide pollution on forest soil microorganisms
Authors: Bewley R. J. F. , Parkinson D.
Published: May 2010

Investigations were conducted to compare the forest soil microflora of three "ecologically analagous" sites, 1, 2, and 3, situated 2.8, 6.0, and 9.6 km, respectively, downwind of a sour gas plant emitting SO2. Bacteria and fungal propagules were isolated by dilution plating, and relative tolerance to the dissociation products of SO2 was tested by plating onto media also amended with Na2SO3 or NaHSO3. There were significant reductions both in total numbers of bacteria and starch-utilizing bacteria from the organic soil (F/H horizon) of site 1. A greater proportion of the bacteria from site 1 were spore formers compared with sites 2 and 3. There was no significant difference between sites in the number of fungal propagules isolated from the organic soil, but a smaller proportion of fungi recovered from site 3 were tolerant to sulphite or bisulphite compared with sites 1 and 2. No differences between sites were detected in terms of bacterial tolerance to the dissociation products of SO2. There were no major differences in the numbers of microorganisms isolated from the mineral soil or in their tolerance to bisulphite or sulphite, although in September, fewer bacteria were isolated from site 1, and a greater proportion of these were spore formers.
In vitro binding of Candida albicans yeast cells to human fibronectin
Authors: Skerl Katherine G. , Calderone Richard A. , Segal Esther , Sreevalsan T. , Scheld W. Michael
Published: May 2010

The binding of Candida albicans yeast cells to human fibronectin (Fn), a major glycoprotein of mammalian cells, was studied using an in vitro assay. Adherence was quantitated in microtiter dishes coated with Fn to which radiolabeled yeast cells were added. Under optimum conditions of the assay, i.e., 1 mM CaCl2 and 70 μg Fn protein, approximately 40% of the radiolabeled yeast cells adhered to the Fn. Adherence to Fn was greater at 30 °C than at 4 °C and was greater with viable yeast cells than with heat-killed cells. Candida albicans (two strains) and C. tropicalis adhered to Fn to a greater extent than C. pseudotropicalis, C. krusei, or Saccharomyces cerevisiae. Pretreatment of C. albicans with chymotrypsin, pronase, or papain, but not pepsin, decreased adherence to Fn. Blocking experiments using mannan, sugars, or amino sugars were carried out by preabsorbing the Fn with each of the above-mentioned compounds. Candida mannan blocked adherence of C. albicans to Fn. The mannan effect was dose dependent. However, adherence of C. albicans to Fn was not significantly reduced by mannose, glucose, or several other sugars. The role of FN as a receptor for the binding of C. albicans yeast cells to buccal and vaginal epithelial cells was investigated also using an in vitro assay. We determined, using indirect fluorescent antibody techniques, that both buccal and vaginal epithelial cells possessed Fn. In addition, yeast cells, when pretreated with Fn, showed reduced adherence with buccal and vaginal cells when compared with nontreated cells. These studies may indicate a role for Fn in the adherence of C. albicans to buccal and vaginal epithelial cells.
Death rates of obligate anaerobes exposed to oxygen and the effect of media prereduction on cell viability
Authors: Patel G. B. , Roth L. A. , Agnew B. J.
Published: May 2010

Stationary-phase cells of Methanospirillum hungatei GP1, Methanobacterium thermoautotrophicum ΔH, Methanobacterium bryantii M.o.H., Fusobacterium sp., Bacteroides fragilis, and Eubacterium limosum were aerated in medium devoid of cysteine – sodium sulfide (cysteine–Na2S) reducing agents to determine the death rates caused by exposure to oxygen. D values (time in minutes required to destroy 90% of the initially viable population) for these anaerobes were 208, 293, 543, 239, 410, and 507 min, respectively. Death was exponential throughout the treatment period for all the anaerobes, except B. fragilis and E. limosum which showed no significant death for the first 2 and 9 h of aeration, respectively. A minimum prereduction period of 6 h inside an anaerobic chamber was required for aerobically poured agar medium containing cysteine–Na2S to achieve maximum viable cell recovery of the nonmethanogens not previously exposed to air. The results also showed that agar medium containing reducing agents, poured anaerobically, and previously reduced in an anaerobic chamber for 24 h, could be plated aerobically and reintroduced into the anaerobic chamber within 60 min of inoculation without affecting viable cell recovery of the nonmethanogenic bacteria.
Production of fumigaclavine A by Aspergillus tamarii Kita.
Authors: Janardhanan K. K. , Sattar Abdul , Husain Akhtar
Published: May 2010

Aspergillus tamarii Kita. isolated from seeds of Paspalum scrobiculatum L. is found to produce ergot alkaloids in submerged culture. The cultrue filtrate and mycelium are observed to contain 0.125 mg/mL and 1.2 mg/g (dry weight) total alkaloids consisting of 86.5 and 91.3% fumigaclavine A, respectively. The identification of the compound was confirmed by high-performance liquid chromatography, ultraviolet, infrared, and mass spectrophotometry analyses. This is the first report of the production of ergot alkaloid by this fungus. The possible role of fumigaclavine A as a mycotoxin is discussed.
Ecology of aerobic hydrogen-oxidizing bacteria in two freshwater lake ecosystems
Authors: Schink Bernhard , Zeikus J. G.
Published: May 2010

Hydrogen concentration, hydrogenase activity, and numbers of aerobic hydrogen-oxidizing bacteria were measured in the water column and sediment surface of a meromictic and a holomictic lake. Low but detectable concentrations of hydrogen (0–4 μL/mL) and numbers of aerobic hydrogen-oxidizing bacteria (0–50 cells/mL) were present in the upper photic zones in both lakes. Hydrogen concentrations, numbers of aerobic hydrogen-oxidizing bacteria, and hydrogenase activity were not significant in the anoxic water column or at the chemocline. Highest levels of oxygen-dependent hydrogenase activity and of aerobic hydrogen-oxidizing bacteria occurred in the hydrogen-depleted surface sediments. The prevalent strains in both lakes were characterized and assigned as species of Pseudomonas or Aquaspirillum. The data suggest that oxygen-dependent hydrogen oxidation by aerobic chemotrophs is of minor significance to hydrogen cycling in these lake ecosystems.
Role of amino acids, peptides, and medium composition in trap formation by nematode-trapping fungi
Authors: Rosenzweig William D.
Published: May 2010

The influence of 22 amino acids and 12 peptides on trap formation by four species of nematode-trapping fungi was determined on a low-nutrient medium (LNM) and cornmeal agar (CMA). Only Arthrobotrys conoides could be induced to form traps in the presence of the amino acids or peptides, while A. flagrans, Monacrosporium eudermatum, and M. rutgeriensis were not induced by the amino acids and peptides studied. Trap formation was greater in the presence of the more nutrient rich CMA than on the LNM. On the LNM, asparagine and aspartic acid were the most active amino acids in inducing traps, while aspartic acid, valine, and phenylalanine were most active on CMA. With respect to the peptides, those containing valine, phenylalanine, and aspartic acid induced the most traps, with valine-containing peptides being especially active on both the LNM and CMA.
Methanogenesis in the absence of intracytoplasmic membranes
Authors: Sprott G. D. , Sowden L. C. , Colvin J. R. , Jarrell K. F. , Beveridge T. J.
Published: May 2010

The frequency of intracytoplasmic membranes in several methanogens grown on H2–CO2 varied with the conditions of growth and varied from one strain to another. Methanobacterium thermoautotrophicum often generated large numbers of intracytoplasmic membranes, while Methanospirillum hungatei produced these membranes only rarely. Conditions allowing for rapid growth, including optimal temperature and high agitation rates, increased the production of intracytoplasmic membranes. These membranes consisted mainly of vesicles composed of one or several membrane layers, often positioned in the central region of the cytoplasm. Several mesophilic methanogens could be grown such that intracytoplasmic membranes were rarely or never observed in thin section or in replicas of cross-fractures from frozen cells. Since high rates of methane synthesis still occurred in these cultures, it follows that the intracytoplasmic membrane system is not a necessary organelle for methane formation in these strains. Negative staining for electron microscopy is not an accurate method to visualize intracytoplasmic membranes in these bacterial cells.
The production of extracellular endo-α-mannanase by the mushroom Volvariella volvacea
Authors: Khowala Suman , Sengupta S.
Published: May 2010

Seven species of mushrooms were screened for yeast mannan hydrolysing enzyme. Low enzyme activity was identified in the culture filtrate of Volvariella volvacea, growing in starch–KNO3 medium under submerged conditions. Mannan (yeast) as a carbon source was found to stimulate enzyme production but not to support appreciable growth of the mushroom. Better enzyme production was achieved by developing a suitable fermentation medium containing mixed carbon sources (starch and mannan) and a suitable nitrogen source in proper concentrations. Some of the factors affecting liberation of reducing groups from yeast mannan by the culture filtrate enzyme were studied. Low molecular weight oligosaccharides, liberated from yeast mannan by the action of the enzyme, were isolated and identified as mannooligosaccharides. No mannose could be identified to be present in the enzymatic hydrolysate of mannan. Endo-α-mannase activity for this mushroom enzyme was suggested.
A transport-dependent energy burden imposed by growth of Enterobacter cloacae in the presence of 10% sodium dodecyl sulfate
Authors: Kramer Vance C. , Nickerson Kenneth W.
Published: May 2010

Growth of Enterobacter cloacae in a glucose asparagine salts medium in the presence of 10% sodium dodecyl sulfate entailed an energy burden in the form of a 20% decreased cell yield, a 30% faster rate of glucose utilization, and a 70% increased rate of oxygen consumption. Similar detergent-induced decreases in cell yield were observed with 10 other sugars and sugar alcohols. Only glycerol supported equivalent cell growth in the presence and absence of sodium dodecyl sulfate. A model is presented which interprets these observations in terms of an altered membrane potential which makes active transport energetically less efficient.
Characterization of the surface antigens of the marine fish pathogens Vibrio anguillarum and Vibrio ordalii
Authors: Chart Henrik , Trust Trevor J.
Published: May 2010

The technique of immunoblotting was used to identify the surface antigens of the marine vibrios pathogenic for fish, Vibrio anguillarum and Vibrio ordalii. Polyclonal antisera raised in rabbits to strains representing the two most common serotypes causing Vibriosis in fish in North America were used. The results demonstrated that antigenic specificity was conferred by the lipopolysaccharides, with three serotypes being displayed among the strains examined. The lipopolysaccharides of strains chosen as type species for V. anguillarum and V. ordalii displayed antigenic cross-reactivity. The morphological heterogeneity of the Vibrio lipopolysaccharides was also analyzed in silver-stained polyacrylamide gels and by intrinsic 32P-radiolabelling. Two distinct lipopolysaccharide morphologies were exhibited, one with 0 polysaccharide chains of heterogeneous chain length, the other having 0 polysaccharide chains of more uniform chain length but displaying microheterogeneity. These lipopolysaccharide morphologies corresponded to different serogroups. Two minor proteins of apparent molecular weights 49 000 – 51 000 present in outer membrane preparations isolated by the sarcosinate extraction procedure were also strong antigens, and common to all strains of V. anguillarum tested and to several strains of V. ordalii. The major outer membrane protein was a weak antigen common to both species.
Levels of Vibrio parahaemolyticus in Indian shrimp undergoing processing for export
Authors: Karunasagar I. , Venugopal M. N. , Karunasagar Indrani
Published: May 2010

A study of 56 samples of raw prawns, 50 samples of processed prawns, and 57 samples of frozen prawns from five prawn-processing factories around Mangalore for the levels of Vibrio parahaemolyticus revealed that most of these samples carry a load of < 10/g. None of the samples had counts > 102/g, indicating that the prawn-processing factories are able to meet the International Commission on Microbiological Specifications for Foods (ICMSF) suggested limit of 102V. parahaemolyticus per gram for frozen prawns.
Conical spinae associated with a picoplanktonic procaryote
Authors: Easterbrook K. B. , Rao D. V. Subba
Published: May 2010

A procaryote which bears conical appendages has been visualized by electron microscopy in a marine sample. These appendages appear to be nonprosthecate and constructed according to the general design of spinae. They may appropriately be considered to represent a new morphological subclass of spinae.
Directed biosynthesis of novel derivatives of echinomycin. II. Purification and structure elucidation
Authors: Gauvreau D. , Waring M. J.
Published: May 2010

New antibiotics produced by Streptomyces echinatus A8331 cultured in the presence of heterocyclic aromatic acids can be separated and purified by high-performance liquid chromatography using reversed phase columns. Natural quinoxaline antibiotics and certain quinoline derivatives can also be efficiently separated in normal phase systems. Details of purification procedures are described together with experiments to characterise the new antibiotics by field desorption mass spectrometry and proton magnetic resonance. Mono- and bis-substituted derivatives of echinomycin containing the following replacement chromophores have been isolated: 7-chloroquinoxaline-2-carbonyl, thieno[3,2-b]pyridine-5-carbonyl, and 6-methylquinoline-2-carbonyl. With a 6-methylquinoline-2-carboxylic acid precursor the analogues containing one or two replacement chromophores are each separable into two distinct components. One of the bis-substituted 6-methylquinoline products appears inactive in an antibacterial assay and behaves as a triostin analogue, presumably an immediate precursor of the corresponding echinomycin derivative.
The cytochrome complement of Haemophilus parasuis
Authors: Niven D. F.
Published: May 2010

Spectral analyses with subcellular fractions derived from Haemophilus parasuis demonstrated that this organism could synthesize membrane-bound and soluble CO- and NO-binding c-type cytochromes in addition to the membrane-bound cytochromes d, a1, b, and c; cytochromes d, a1, and o were identified as potential oxidases. The membrane-bound and soluble CO- and NO-binding cytochromes c were not spectrally variant cytochromes c, and the redox properties of the soluble cytochrome (reducible by NADH but not by succinate or ascorbate plus N,N,N′,N′-tetramethyl-p-phenylenediamine) suggested that it, at least, was a low-potential cytochrome; up to 68% of the soluble cytochrome c could be released from the organisms by osmotic-shock treatment, demonstrating its extracytoplasmic location. The cytochrome content of H. parasuis was influenced by both the composition of the growth medium and the phase of growth; it is suggested that the bacterial concentration and growth rate, and therefore the availability of oxygen, regulated cytochrome synthesis.
Suppression of nitrate utilization by ammonium and its relationship to chloramphenicol production in Streptomyces venezuelae
Authors: Shapiro S. , Vining L. C.
Published: May 2010

Cultures of Streptomyces venezuelae grown in a medium containing glucose with mixtures of ammonium and nitrate as the nitrogen source produced chloramphenicol in a distinct idiophase that followed biomass accumulation. Analysis of fermentation broths showed that ammonium and nitrate were taken up consecutively by the organism. Measurements of nitrate reductase in the mycelium established that the enzyme was constitutive and that its specific activity did not increase during the period when ammonium was exhausted from the medium and nitrate was assimilated. The enzyme was neither repressed nor inhibited by ammonium. Production of chloramphenicol was also delayed until ammonium had been consumed and remained slow until subsequent depletion of nitrate. Arylamine synthetase, the initial enzyme in the pathway of antibiotic biosynthesis, showed no marked change in specific activity during utilization of the two nitrogen sources. The result suggests that the mechanism causing preferential utilization of ammonium does not simultaneously control the onset of chloramphenicol biosynthesis.
Spontaneous induction of bacteriophage during growth of Azospirillum brasilense in complex media
Authors: Germida James J.
Published: May 2010

Spontaneous induction of bacteriophage occurred during growth of Azospirillum brasilense ATCC 29145 in complex media incubated at 27 or 30 °C under agitated and nonagitated conditions. Phage replication on strain 29145 was stimulated by divalent cations and inhibited by NaCl or temperatures greater than 37 °C. The phage morphology as revealed by electron microscopy showed an icosahedral head of 60 nm and a tail of 208 nm. The host range was limited to A. brasilense strains 29145 and 29710. Other Azospirillum strains tested did not produce phage under any of the conditions tested.
Temperature and desiccation tolerance of cowpea rhizobia
Authors: Hartel Peter G. , Alexander Martin
Published: May 2010

Strains of Rhizobium capable of nodulating cowpeas (Vigna unguiculata) were tested for their ability to tolerate desiccation and high temperature in soil. Eight strains were from a hot, dry region of Niger, and 13 strains were from cooler, wetter regions of Nigeria. All of the 21 strains tested at 30 °C grew somewhat in a moist sandy soil from Niger. Of the 21 strains tested in moist soil incubated at 37 °C, only the 8 strains from Niger did not decline in numbers. The moist soil was then allowed to dry slowly. After a 2-week period, the decline in the logarithm of cell numbers per gram of soil ranged from 0.19 to 0.41 at 30 °C and from 0.28 to 0.66 at 37 °C for the 8 strains from Niger and from 0.48 to 2.42 at 30 °C and 0.87 to 2.85 at 37 °C for the 13 strains from Nigeria. These results suggest that cowpea rhizobia from hot, dry areas are more temperature and desiccation tolerant than strains from cooler, more humid regions and that temperature and desiccation tolerance may be related to geographical origin.
Differential scanning calorimetry of membranes isolated from Bacillus megaterium spores
Authors: Vary J. C. , Skomurski J. F. , Cornell B. A.
Published: May 2010

Inner membranes isolated from Bacillus megaterium spores had a broad endothermic phase transition between 6 and 26 °C. Spores grown in isoleucine initiated germination at lower temperatures than control spores grown in glucose and their membrane endotherms were depressed about 8 °C.
The effect of aculeacin A and papulacandin B on morphology and cell wall ultrastructure in Candida albicans
Authors: Bozzola J. J. , Mehta R. J. , Nisbet L. J. , Valenta J. R.
Published: May 2010

Transmission (TEM) and scanning electron microscopy (SEM) of Candida albicans cultures treated with the cell wall active antibiotics aculeacin A and papulacandin B (10 μg/mL) revealed highly distorted, wrinkled, and collapsed cells. Dividing cells failed to separate properly and aggregates of enlarged and elongated forms were often seen. TEM sections revealed thick and layered cell walls in the treated cultures and bud cross walls failed to segregate completely. Approximately 20% of the cells demonstrated complete cell necrosis accompanied with cytoplasmic deterioration, layered and distorted walls, and improperly formed buds and scars.
Difference in the extracellular products of two strains of Aeromonas hydrophila virulent and weakly virulent for fish
Authors: Lallier R. , Bernard F. , Lalonde G.
Published: May 2010

In this study we first compared the toxigenic profile of Aeromonas hydrophila strains virulent and weakly virulent for rainbow trout. The separation of the toxic factor for fish is also described. Both strains produced hemolytic, enterotoxic, and dermonecrotic activities; the weakly virulent strain produced 20 times more hemolysin. Only the cell-free supernatant of the virulent strain produced a toxic factor for fish. After passage on Sephacryl S-200, the toxic factor for fish was separated from the hemolysin. This toxic factor is heat labile.
The parasexual cycle in the entomopathogenic fungus Paecilomyces fumoso-roseus (Wize) Brown and Smith
Authors: Riba Guy , Ravelojoana Anne M.
Published: May 2010

Auxotrophic mutants of Paecilomyces fumoso-roseus obtained by ultraviolet treatment were used to demonstrate parasexual recombination. Formation of hybrid diploids was found to be closely related to growth conditions on artificial media and on host insects. One hundred percent of prototrophic hybrids were isolated from mycosed insects, while no more than 1.5% were recovered from the complete agar medium in the Petri dishes. A few haploids (1%) were obtained from hybrid diploids exposed to haploidizing agents. Some of the haploids were segregants which could only have resulted from genetic recombination.
Immunogold electron microscopy of surface antigens of oral bacteria
Authors: Mouton C. , Lamonde L.
Published: May 2010

Colloidal gold particles 3–6 nm in diameter were prepared and stabilized with the IgG fraction of polyspecific rabbit antisera produced against four different oral bacteria. The immunogold markers were used in homologous reactions to label the bacteria in a preembedding procedure for electron microscopy. An indirect immunofluorescence procedure was concurrently used to optimize the labelling conditions before observation with the electron microscope. The immunogold markers labelled fibrillar structures extending outward 50–275 nm from the Gram-positive cell envelopes and a fuzzy 5–10 nm thick capsulelike layer on the outer aspect of Bacteroides gingivalis. The immunogold method appears to be a simple, rapid, and inexpensive procedure suitable for the study of bacterial surface antigens and can be upgraded with the use of monospecific antibodies.
Excretion of α-keto acids by strains of Streptomyces venezuelae
Authors: Ahmed Zia U. , Shapiro S. , Vining L. C.
Published: May 2010

Cultures of Streptomyces venezuelae released acidic metabolites during nitrogen-limited growth on glucose. The main products were pyruvic acid and α-ketoglutaric acid. Variation in the extent of acid production was observed; spores of the parental strain 13 s gave approximately 10% of low-producing colonies when plated on acid–base indicator medium. Examination of one low producer, strain PC 51-5, showed that differences in acid production became apparent only in low-glucose media containing manganese. In both strains PC 51-5 and 13 s, uptake of α-keto-[5-14C]glutaric acid occurred by diffusion and no marked differences in permeability to α-ketoglutarate were detected. However, differences were observed in the activity of α-ketoglutarate dehydrogenase. In cultures of strain PC 51-5, the specific activity of the enzyme increased throughout growth, whereas in the parental strain activity decreased and could not be detected in older mycelium. Loss of enzyme activity was accompanied by excretion of α-ketoglutaric acid and failure to assimilate the product after glucose exhaustion. The results suggest that accumulation of pyruvic and α-ketoglutaric acids in S. venezuelae cultures grown in glucose-containing media may be due to regulatory suppression of the dehydrogenases by this carbon source.
Nocardia in soils of southeastern Spain: abundance, distribution, and chemical characterisation
Authors: Valero-Guillén P. L. , Martín-Luengo F.
Published: May 2010

Actinomycetes belonging to the genus Nocardia were isolated from the surface horizon of 15 out of 46 soil samples examined. All the nocardiae strains isolated contained mycolic acids and saturated and unsaturated straight chain fatty acids (from 12 to 18 carbon atoms) and tuberculostearic acid and were biochemically identified as members of the Nocardia asteroides complex. Nocardiae were detected in alluvial, brown, and serosem great soil groups, but not in calcic brown, solontchack, and regosol great soil groups. Numbers of nocardiae isolated varied from 5.12 × 102 to 1.21 × 104 colony-forming units per gram of dry weight, and they were statistically correlated with the carbon content (percent C) of the soil. Soil samples were, in general, very dry.
Adaptational changes in Staphylococcus aureus MF31 grown above its maximum temperature when protected by NaCl: physiological studies
Authors: Hurst A. , Ofori Esther , El-Banna A. A. , Harwig J.
Published: May 2010

Staphylococcus aureus MF31 can grow at 46 °C, 2 °C above its normal maximum temperature of growth if 1 M NaCl is added to the medium. In the present work we show that monosodium glutamate, proline, threonine, aspartic acid, and betaine (in order of decreasing effectiveness) also enabled cells to grow at 46 °C. Cells grown at 46 °C in he presence of salt (protected or P cells) accumulated glutamate more rapidly than cells grown at 37 °C without salt (normal or N cells) and contained an increased amino acid pool. The principal constituents of this pool were dicarboxylic amino acids and proline. Turbidimetric evidence suggests that NaCl caused plasmolysis in S. aureus. The P cells, although grown in 1 M NaCl, had about the same Cl− and K+ content as the N cells grown without added NaCl. P cells had increased heat resistance but high concentrations of CaCl2 in the heating menstruum reduced their D55 value from a maximum of 214 min to < 30 s. We suggest that growth at 46 °C in 1 M NaCl can be explained, in part at least, by the increased amino acid pool internal to the cell and the external osmotic support given by Cl− anions excluded by the cell.
Morphology of Pasteurella multocida bacteriophages
Authors: Ackermann H.-W. , Karaivanov L.
Published: May 2010

Twenty-one tailed phages with icosahedral heads belong to the Myoviridae, Siphoviridae, and Podoviridae families and to four morphological types. Type AU, with 10 phages, has a contractile tail and is morphologically identical with coliphage P2. Lysates contain contracted tail sheaths assembled end-to-end and abnormal structures with long tails and multiple tail sheaths. Types C-2 and 32, with one and three phages, respectively, have long, noncontractile tails. Type 22 includes seven phages, has a short tail, and resembles coliphage T7. Our results agree with previous biological data and suggest that types AU, C-2, 32, and 22 correspond to four different phage species.
Purification and characterization of the extracellular amylases of the yeast Schwanniomyces alluvius
Authors: Simões-Mendes B.
Published: May 2010

The extracellular amylolytic system of a strain of the yeast Schwanniomyces alluvius consists of an α-amylase, a glucoamylase, and probably a debranching enzyme. Crude enzyme preparations were obtained by fractionation of the culture fluid, at the stationary phase of growth, with isopropanol. Purification was carried out by DEAE-cellulose chromatography. The glucoamylase had the following properties: molecular weight (MW), 117 000 ± 2300; optimum temperature, 50 °C; optimum pH, 4.5; range of pH stability, pH 4–6; final product of starch hydrolysis, glucose; ΔH≠ and ΔS≠ of heat inactivation, 39747 cal∙mol−1 and 274.3 cal∙deg−1∙mo−1; Km(30 °C, pH 4.5) for soluble starch, 22.22 g∙L−1. The α-amylase had the following properties: MW, 62 000 ± 500; optimum temperature, 40 °C; optimum pH, 6.3; range of pH stability, pH 4–7; final product of starch hydrolysis, maltose and glucose; ΔH≠ and ΔS≠ of heat inactivation, 36594 cal∙mol−1 and 256.9 cal∙deg−1 mol−1; Km (40 °C, pH 5.5), 2.7 g∙L−1.
Lipopolysaccharide composition of three strains of Haemophilus influenzae
Authors: Parr Jr. Thomas R. , Bryan L. E.
Published: May 2010

The lipopolysaccharides of three strains of Haemophilus influenzae with varying beta-lactam susceptibility were examined. All three strains contained galactose, glucose, galactosamine, glucosamine, heptose, phosphate, and a trace of mannose. None contained fucose, rhamnose, or mannosamine. Levels of 2-keto-3-deoxy-octulosonic acid were consistently detected in all three strains at levels similar to that of Salmonella typhimurium LT2, but only following hydrolysis with 4 N hydrochloric acid.
Improved enumeration of Trichoderma spp. on dilution plates of selective media containing a nonionic surfactant
Authors: Benson D. M.
Published: May 2010

Addition of Tergitol NP-10 (polyglycol ether), a nonionic surfactant, greatly enhanced enumeration of Trichoderma spp. colonies on three selective media. Colony diameter was restricted 11 –47% on dilution plates with Tergitol compared with media without the surfactant. Plates with the surfactant could be incubated up to 2 weeks prior to counting. Colony counts of Trichoderma spp. were not significantly different for surfactant amended or unamended plates on two of the three selective media tested. However, on RBD medium (rose bengal – chloramphenicol – pentachloronitrobenzene (PCNB) – Dexon) with surfactant, significantly fewer colonies were recovered compared with the medium without surfactant.
Mycoflora of the human dermal surfaces
Authors: Mok W. Y. , Silva M. S. Barreto da
Published: May 2010

The mycotic flora of the scalp and interdigital areas of the hand and foot of 1296 apparently healthy human inhabitants of three Amazonian communities were surveyed by means of microscopic examination of epidermal scrapings and cultural isolation on Mycosel agar. No macroscopic or microscopic evidence of fungal infection was detected in any of our study subjects. From 133 (10%) individuals, 143 fungi representing 13 genera and 39 species were recovered. Yeasts constituted 85% of the fungi. Seventy-five percent of the isolates were fungi with pathogenic potential: Aureobasidium pullulans, Candida albicans, Candida guilliermondii, Candida parapsilosis, Candida stellatoidea, Candida tropicalis, Exophiala werneckii, Geotrichum candidum, Rhodotorula rubra, Torulopsis glabrata, Trichophyton tonsurans, Trichosporon cutaneum, and Wangiella dermatitidis. The low frequency with which each species was represented resulted in a mosaic distribution of the fungi with respect to human anatomical sites and study areas. The lack of similarity in species composition beteen the human dermal mycoflora and soil mycoflora in the same study areas supports the conclusion that distinct yeast species occupy different environmental niches.
Microcycle conidiation induced by partial nitrogen deprivation in Neurospora crassa
Authors: Guignard R. , Grange F. , Turian G.
Published: May 2010

Premature macroconidiation occurs at the tips of germ tubes elongated as presumptive conidiophores from macroconidia of Neurospora crassa incubated at 37 °C in nitrogen-limited shaken cultures. The use of different nitrogen sources indicated that this differentiation process could be induced by ammonium deprivation. This microcycle conidiation was also promoted by carbon deprivation and found not to be strain specific. At 25 °C, microconidia were produced in nutrient-limited shaken cultures. The results present evidence that microcycle conidiation in N. crassa can be obtained by simple manipulation of the conditions of culture.
Septation in Zymomonas mobilis
Authors: Beveridge T. , Harris R. , Fein J. , Lawford H. , Lawford G. R.
Published: May 2010

Freeze-etching and thin sectioning have been used to demonstrate that the gram-negative rod, Zymomonas mobilis ATCC 29191, divides by septation. During this division process the plasma membrane and peptidoglycan grow symmetrically inwards into the cytoplasm at the cell centre, leaving the outer membrane behind at the cell surface. The outer membrane continues to grow causing it to bleb vesicles into the external milieu. Once the septum aperture has closed, the nascent peptidoglycan of the septum splits in two; next, the outer membrane travels inwards between the two new peptidoglycan layers separating the cells. Once this inward growth is finished, cell separation is complete.
An improved method for lysis of Frankia with acharomopeptidase allows detection of new plasmids
Authors: Simonet Pascal , Capellano Andre , Navarro Elisabeth , Bardin Rene , Moiroud Andre
Published: May 2010

An enzyme recently described for Strepiomyces sp. protoplast formation was used to digest Frankia sp. cell walls. This new enzyme, achromopeptidase, allowed the use of an in situ method to detect large plasmids. Plasmids ranging in size from 7 to 190 kilobases were detected in some Frankia strains.
A role for sulfite in inducing surface changes In Neisseria gonorrhoeae
Authors: Norrod E. Pinina
Published: May 2010

Addition of pyruvate to growth medium failed to induce the changes in Neisseria gonorrhoeae that have been reported previously. Addition of 3.8 mM sulfite or 1.3 mM sulfite plus 14 mM pyruvate restored the medium's reactivity in a test for cysteine and its ability to induce changes in N. gonorrhoeae. The induced changes that were restored were (i) increased colonial opacity and roughness, (ii) increased sensitivity to killing by normal human serum, and (iii) electrophoretic changes that may represent changes in lipopolysaccharide. Further characterization of the electrophoretic changes showed that the bands were resistant to treatment with proteinase K, that they were not affected by EDTA and urea, and that they were not dependent upon the stage of growth.
Physical factors influencing the growth of protoplasts of Entomophaga grylli
Authors: Dunphy Gary B. , Chadwick June M.
Published: May 2010

Selected physical parameters were examined to enhance the growth of protoplasts of Entomophaga grylli in Grace's tissue culture medium. The pH range of 6.2–6.7 permitted protoplast growth with pH 6.7 being optimal. The protoplasts grew well over a temperature range of 20–30 °C. The optimum temperature was 30 °C. Shaken cultures grew faster and in shorter chains than did stationary cultures. The optimum osmolality was 325–350 mosmol/kg. The osmolality of the serum of the insect host, Dissosteira Carolina, ranged from 318 to 389 mosmol/kg.
Partial purification and properties of an invertase from Pseudomonas fluorescens
Authors: Bugbee W. M.
Published: May 2010

An intracellular β-fructofuranosidase was extracted from a sugar beet root isolate of Pseudomonas fluorescens. The enzyme was partially purified using Sephacryl 200 gel and anion-exchange column chromatography. The enzyme's molecular weight was estimated at 35 400 on a calibrated column of Sephacryl 200 gel. Two protein bands with molecular weights of 19 000 and 21 000 were evident after polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The isoelectric point was pH 4.18. The Km of the enzyme was estimated at 90 mM for sucrose. The optimum pH for activity was 6.5 when measured in a phosphate buffer.
The isolation and characterisation of cytoplasmic and outer membranes from Micrococcus cryophilus
Authors: Lloyd Geoffrey M. , Russell Nicholas J.
Published: May 2010

The cytoplasmic and outer membranes of the Gram-negative bacterium, Micrococcus cryophilus, have been separated and purified. Both membrane preparations consist of a mixture of closed and apparently open vesicles, which vary in size but those of the outer membrane are on average 1.5 times the diameter of those of the cytoplasmic membrane. The membranes were characterised by their 2-keto-3-deoxyoctonate content and the activity of marker enzymes. There are gross differences in the protein and phospholipid composition of the two membranes. The outer membrane contains three major polypeptides, whereas the cytoplasmic membrane has many more. In addition the outer membrane is enriched in cardiolipin, at the expense of phosphatidylglycerol and phosphatidylethanolamine, relative to the cytoplasmic membrane. There are no significant differences in the fatty acid composition of the phospholipid classes, but all phospholipids of the outer membrane were slightly more saturated than those of the cytoplasmic membrane. Wax esters are present in both cytoplasmic and outer membranes. The significance of these findings is discussed in relation to known differences in the fluidity of the cytoplasmic and outer membranes in M. cryophilus and the specialized roles these membranes play.
Production and localization of β-glucosidase in Trichoderma harzianum and some aspects of catabolite repression
Authors: Sidhu Mohinderjit S. , Sandhu Dhanwant K.
Published: May 2010

Maximum production of aryl-β-glucosidase by Trichoderma harzianum was obtained in Vogel's medium supplemented with cellobiose as the carbon source at pH 5.0 under stationary culture conditions at 27 °C. In the exponential phase the bulk of the enzyme was almost equally distributed in the extracellular and cell debris fractions and a negligible amount was present in the cytosol. However, in the late stationary phase, extracellular β-glucosidase increased to 80% of the total enzyme. When cellulosic substrates were used, a major portion of the enzyme (90%) appeared in the extracellular fraction at all stages of growth. The repression of extracellular enzyme in the presence of exogenous glucose in the medium was apparent and the synthesis and release of enzyme were resumed after its depletion. The glucose effect in essence may be related to the adverse effect of low pH on the integrity of the enzyme.
Characterization and nutritional properties of Methanothrix concilii sp. nov., a mesophilic, aceticlastic methanogen
Authors: Patel G. B.
Published: May 2010

A nonmotile, rod-shaped, nonspore-forming, mesophilic methanogenic bacterium was isolated from sewage sludge. The cells stained Gram negative. In the presence of CO2, the isolate was able to grow and produce significant amounts of methane from acetic acid. No growth or methane formation was observed when H2, methanol, pyruvate, propionate, butyrate, formate, or trimethylamine were provided as substrates in the presence of CO2. About 0.95 mol of CH4 was produced per mole of acetic acid consumed. The optimum pH and temperature for growth were 7.1–7.5 and 35–40 °C, respectively. The mass doubling time was about 24 h under optimum growth conditions. The almost complete inhibition of methane formation by 10 μM 2-bromoethanesulfonic acid (2-BES) was reversed in the presence of 50 μM 2-mercaptoethanesulfonic acid (HS-CoM). D-Cycloserine at 0.1 mg/mL concentration caused complete inhibition of growth. Sludge fluid enhanced the rate of methane formation, whereas 0.5% (w/v) yeast extract was inhibitory. The optimum initial CO2 (added as NaHCO3) for growth on acetic acid was 1.8 mM. The DNA base composition was 61.25 ± 0.60 mol% G + C. On the basis of its characteristics, this isolate is classified as Methanothrix concilii sp. nov. and the type strain is GP6 (=NRC 2989).
Growth of yeast and mold on trypan blue agar in conjunction with the ISO-GRID system
Authors: Lin C. C. Sheree , Fung Daniel Y. C. , Entis Phyllis
Published: May 2010

Enumeration of yeast and molds on trypan blue (at 1:10 000 dilution) in potato dextrose sugar (trypan blue agar) was compared with potato dextrose agar (PDA) plus safranin flooding procedure using the hydrophobic grid-membrane filter technique (HGMF) of the ISO-GRID system. Yeast and mold grew well on trypan blue agar, producing easily recognized blue colonies on the ISO-GRID system. Results indicated that trypan blue agar is more convenient to use than the PDA plus safranin flooding procedure and as reliable (r = 0.99) for enumerating yeast and mold of cheeses, spices and dry products, and salad samples.