bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of fungi and bacteria in enhanced and nonenhanced biodegradation of carbendazim and other benzimidazole compounds in soil
Authors: Yarden O. , Salomon R. , Katan J. , Aharonson N.
Published: May 2010

The relationship between chemical structure and the enhancement of microbial degradation of three benzimidazole compounds in soil was determined. Preapplication of methyl benzimidazole-2-ylcarbamate (carbendazim or MBC), 2-aminobenzimidazole (2AB), and benzimidazole enhanced their degradation upon repeated application (self-enhanced degradation). MBC and 2AB cross-enhanced the degradation of each of these two compounds, whereas benzimidazole did not enhance the degradation of MBC. Thiabendazole (TBZ) did not enhance its own degradation or cross-enhance the degradation of MBC. No increase in the number of MBC-degrading fungi or in the capacity of soilborne fungi to degrade MBC was detected in soil exhibiting enhanced MBC degradation (MBC-history). A sharp increase in esterolytic activity in the microsomal fraction of Alternaria alternata capable of degrading MBC in culture was induced by the presence of MBC in the growth medium. 2AB was the main metabolite of MBC that accumulated in A. alternata cultures and in cell-free preparations. MBC was degraded much faster by mixed bacterial cultures that originated from MBC-history soil than in cultures from MBC-nonhistory soil. Fluctuations in the MBC degrading capacity of mixed bacterial cultures occurred during repeated subculturing of the mixed culture. Inoculation of nonhistory soil with mixed bacterial cultures resulted in enhanced MBC degradation, whereas inoculation with A. alternata did not enhance MBC degradation. It is suggested that while fungi contribute to MBC dissipation in soil, bacteria have a greater role in enhanced biodegradation of MBC in soil. Key words: accelerated degradation, fungicide, problem soils.
Immunoblot patterns of Giardia duodenalis isolates from different hosts and geographical locations
Authors: Forrest M. , Isaac-Renton J. , Bowie W.
Published: May 2010

Eighteen isolates of Giardia duodenalis from animal and human sources were studied for protein differences by polyacrylamide gel electrophoresis and for antigenic differences by immunoblot analysis. The polyacrylamide gels showed that whilst the isolates were for the most part homogeneous in their protein banding patterns, some isolates did show some differences. The immunoblot analysis yielded many bands, including prominent bands of 32 and 66 kilodaltons. Five of the six isolates that showed differences in protein banding pattern also showed differences in antigenic reactivity. Our findings suggest that differences can be seen with the use of immunoblotting and that this technique is a tool that may be useful for isolate differentiation when used in conjunction with other techniques. Key words: Giardia, giardiasis, characterization, immunoblot.
Variations annuelles et identification des Vibrions cultivant à 37 °C dans un effluent urbain, dans des moules et dans l'eau de mer en rade de Toulon (Méditerranée, France)
Authors: Martin Yvan P. , Bonnefont Jean-Luc
Published: May 2010

Annual variations of vibrios able to proliferate at 37 °C have been studied in various conditions: in urban waste water discharged in the Toulon harbour, in mussels subjected or not to those discharges, and in seawater far from the waste water effluent (for reference). Mean concentration values were nearly similar in the effluent and seawater samples, in the order of 500 bacteria/100 mL, and 400 bacteria/mL in ground mussels, with concentrations showing great variability. In all cases, seasonal abundance fluctuations occurred, with a minimum in winter. A total of 214 vibrio strains were analyzed and identified. The effluent population was the most diversified, including several species of sanitary interest such as Vibrio fluvialis (29.3%), V. cholerae (non O1) (13.4%), and V. metschnikovii (11.0%), as well as other species more typically marine, notably V. alginolyticus (11.0%). In seawater, the latter species was largely represented (48.6%), but other representatives of this genus were also present, such as V. harveyi, V. campbellii, or V. fishcheri; no strain of V. metschnikovii was isolated. The specific composition of the population associated with mussels was similar to that found in seawater. Key words: vibrios, urban sewage, mussels, seawater, annual fluctuations. [Journal translation]
Purification and characterization of a β-glucosidase from Streptomyces lividans 66
Authors: Mihoc Anca , Kluepfel Dieter
Published: May 2010

An intracellular β-1, 4-D-glucosidase (EC 3.2.1.21) was isolated from the mutant strain HP-3 of Streptomyces lividans 66 which produced about 12 times more enzyme than the wild-type strain. The purification was carried out by anion exchange column chromatography followed by high-performance liquid chromatography on DEAE and on molecular sieve columns. The enzyme is glycosylated and has an apparent Mr of 51 000 and a pI of 4.3. Its activity was optimal at pH 6.5 and at a temperature of 40 °C. The Km and the Vmax on cellobiose were 3.1 mM and 65.6 μmol min−1 mg−1 of enzyme. Key words: β-glucosidase, Streptomyces lividans, purification, characterization.
Determination of peptidyl dipeptidase activity in 24 bacterial species
Authors: Stevens Joanne , Fanburg Barry L. , Lanzillo Joseph J.
Published: May 2010

Of 24 bacterial species examined for lisinopril refractive peptidyl dipeptidase activity, only 8 contained activity. Activity in Pseudomonas maltophilia was more than fourfold higher than that of any other species. Pseudomonas maltophilia may be unique among bacteria in possessing high peptidyl dipeptidase activity that is both EDTA inhibitable and lisinopril resistant. Key words: Pseudomonas maltophilia, peptidyl dipeptidase.
An improved method for the rapid isolation of chromosomal DNA from Mycoplasma spp.
Authors: Hempstead Patricia G.
Published: May 2010

A method is described for the rapid isolation of chromosomal deoxyribonucleic acid from species of the genus Mycoplasma. The method involves incubation of washed cells at elevated temperature in the presence of an ionic detergent, chelating agents, and proteinase K prior to the removal of residual protein and ribonucleic acid with ribonuclease and chloroform. It results in a good yield of high molecular weight material that is shown to be free of endogenous nuclease and substantially free of protein or ribonucleic acid contamination without the use of phenol. The isolated DNA is shown to be an excellent substrate for restriction endonuclease digestion and ligation with T4 DNA ligase. Key words: Mycoplasma, DNA isolation, micromethod.
Taxonomy and chemistry of a new fungus from bark beetle infested Pinus contorta var. latifolia. Part 1. Arthrographis pinicola sp.nov.
Authors: Sigler Lynne , Yamaoka Yuichi , Hiratsuka Yasuyuki
Published: May 2010

Arthrographis pinicola sp.nov. (Hyphomycetes) is described; it was isolated from galleries and adult beetles of Ips latidens and from galleries of Dendroctonus ponderosae in Pinus contorta var. latifolia in western Canada. In I. latidens infested lodgepole pine, this species extensively colonizes nuptial chambers and egg galleries, characteristically forming floccose conidiomata composed of repeatedly branched hyphae which divide to form arthroconidia having schizolytic dehiscence. The fungus is antagonistic to some blue stain fungi in vitro. Arthrographis pinicola is compared with other species of Arthrographis, and with Arthropsis microsperma and the discomycete Pezizella chapmanii. Key words: Arthrographis pinicola, Hyphomycetes, bark beetle fungi, antifungal compound, arthrographol.
Taxonomy and chemistry of a new fungus from bark beetle infested Pinus contorta var. latifolia. Part 2. Arthrographol, the metabolite inhibitory to Ophiostoma clavigerum
Authors: Ayer William A. , Nozawa Koohei
Published: May 2010

The isolation and structure determination of arthrographol (1) is described. This substituted dihydrobenzofuran is the compound responsible for the antagonism shown by the newly described fungus Arthrographis pinicola Sigler and Yamaoka towards some blue stain fungi. The 1H and 13C nuclear magnetic resonance spectra, infrared and ultraviolet spectra, and the mass spectrum of arthrographol and its diacetyl derivative are reported. The inhibitory activity of arthrographol against Ophiostoma clavigerum (≡Ceratocystis clavigera) is described. Arthrographol, a new natural product, appears to be a norheptaketide related to known benzofurans of fungal origin. Key words: antifungal compound, structure of arthrographol, norheptaketide, blue stain fungus, Arthrographis pinicola.
Purification of 7α-hydroxysteroid dehydrogenase from Escherichia coli strain 080
Authors: Prabha Vijay , Gupta Meenakshi , Seiffge D. , Gupta K. G.
Published: May 2010

Purification studies of 7α-hydroxysteroid dehydrogenase (7α-HSDH) (EC 1.1.1.159) from Escherichia coli 080 showed that 1.59-fold purification could be achieved by heating (60 °C for 10 min) the ultracentrifuged enzyme preparation, and 6.46-fold purification was achieved by subsequent precipitation with ammonium sulfate. Further purification on Sephadex G-100 gel gave 10.1-fold purification. After pooling and concentrating the active fractions obtained from the Sephadex G-100 filtration, an 11.1-fold purification was achieved using DEAE-cellulose chromatography. The purified enzyme produced a single band on polyacrylamide gel electrophoresis and its molecular weight was determined to be 54 000. The enzyme was immunogenic and showed immunoprecipitation with homologus antisera. Key words: 7α-hydroxysteroid dehydrogenase, Escherichia coli.
Receptors for transferrin in pathogenic bacteria are specific for the host's protein
Authors: Schryvers Anthony B. , Gonzalez Guido C.
Published: May 2010

Transferrin receptors detected by a solid-phase binding assay were shown to be specific for the host's transferrin in the representative bacterial pathogens Neisseria meningitidis (human), Pasteurella haemolytica (bovine), and Actinobacillus pleuropneumoniae (porcine). Consistent with the receptor specificity, iron-deficient bacteria were only capable of utilizing transferrin from the host as a source of iron for growth. Key words: iron, transferrin, receptor.
Ultrastructural localization of β-1,4-glucan-containing molecules in the cell walls of some fungi: a comparative study between spore and mycelium
Authors: Benhamou Nicole , Chamberland Hélene , Noel Sylvain , Ouellette G. B.
Published: May 2010

An exoglucanase, purified from a cellulase produced by the fungus Trichoderma harzianum was complexed to colloidal gold and used for localizing β-1,4-glucan-containing molecules in the cell walls of some fungi. With the exception of Aspergillus niger, β-1,4-glucan-rich molecules were found to be associated with conidial walls of Trichoderma viride, Fusarium oxysporum f.sp. radicis-lycopersici, Verticillium albo-atrum, Penicillium thomii, and Ophiostoma ulmi. The abolition of wall labeling following previous cellulase digestion suggested that the compunds detected by the exoglucanase–gold complex were likely of cellulosic nature. Differences in cell wall composition between conidia and mycelium were reflected by the absence of β-1,4-glucan-containing molecules in the vegetative walls of most fungi tested. This raises the question as to what extent the chemical composition of spore walls should be considered as an important criterion in the taxonomy and phylogeny of fungi. The disappearance of these molecules upon conidial germination (with the exception of O. ulmi) suggests that lytic enzymes are produced to cause wall breakdown. The presence of molecules with β-1,4-linkages in conidia probably contribute to reinforcement of the wall architecture. Key words: fungi, spores, β-1,4-glucan, gold cytochemistry.
Sucrose metabolism in Zymomonas mobilis: production and localization of sucrase and levansucrase activities
Authors: Preziosi L. , Michel G. P. F. , Baratti J.
Published: May 2010

The sucrase and levansucrase activities of Zymomonas mobilis cells were characterized. The kinetics of production of sucrase activity was growth associated and the activity was constitutively expressed in cells grown on sucrose, glucose, or fructose media. Most of the sucrase activity (about 80%) was soluble and extracellular, while the cellular activity (about 20%) was demonstrated to be mostly membrane bound. The occurrence of sucrase activity in culture medium seemed to result from a secretory mechanism rather than from cell lysis. Like sucrase activity, levansucrase activity was mainly extracellular and was present in fermentations run with the above three carbon sources. These results demonstrated that both sucrase and levansucrase activities were present in cellular and extracellular extracts of cells grown on different sugars. Key words: Zymomonas mobilis, levansucrase, sucrase, localization.
Specific inhibition of iturin biosynthesis by cerulenin
Authors: Hourdou Marie-Laure , Besson Françoise , Michel Georges
Published: May 2010

Cerulenin, an inhibitor of fatty acid synthesis, inhibits the biosynthesis of iturin by Bacillus subtilis. With a cerulenin concentration of 2 μg/mL, 50% inhibition was achieved. At this concentration, cerulenin does not affect growth or total protein synthesis but does inhibit the incorporation of sodium [14C]acetate, [14C]myristic acid, and [14C]asparagine into iturin. Since cerulenin is known to block the condensation of malonyl-CoA subunits in the formation of fatty acids, the inhibition of iturin and β-amino acid syntheses by cerulenin is discussed in relation with lipid synthesis. Key words: iturin antibiotic, Bacillus subtilis, cerulenin, β-amino acid, lipid biosynthesis.
Conditions for pycnidial production and spore formation by Ampelomyces quisqualis
Authors: Sztejnberg Abraham , Galper Sergio , Lisker Norberto
Published: May 2010

On Czapek agar medium, the optimum temperature for spore germination and pycnidia formation by Ampelomyces quisqualis was 20 and 25 °C, respectively. Inoculation of Czapek agar medium with a spore concentration of 106 or 107/mL significantly increased pycnidia formation as compared with medium inoculated with 104 or 105 spores/mL. In shaken cultures, spore formation in potato dextrose broth (PDB) was higher than in the broth of bran extract and glycerol, aspargine, Czapek, Joham, and synthetic Mucor media. On PDB, pycnidia were formed in hard black aggregates. Spore production in fermentors was similar to that in shaken cultures. The omission of glucose from PDB caused a great increase in the number of spores formed. Also, PDB prepared with the broth of 100 g (instead of the usual 200 g) peeled potatoes/L was effective in spore formation and maintained spore infectivity as high as in controls. It seems that the broth of boiled potatoes is a simple, efficient, and nonexpensive medium for mass production of infective A. quisqualis spores. Key words: Ampelomyces quisqualis, pycnidial production, spore formation, biological control, powdery mildew.
Production, purification, and properties of glucose oxidase from the biocontrol fungus Talaromyces flavus
Authors: Kim Kay K. , Fravel Deborah R. , Papavizas George C.
Published: May 2010

Talaromyces flavus produces the enzyme glucose oxidase, which may be involved in biocontrol of the fungal plant pathogen, Verticillium dahliae. A strain of T. flavus was selected from the wild-type population for the production of extracellular glucose oxidase, and the enzyme was purified by a combination of acetone precipitation and high performance liquid chromatography (HPLC). Approximately 12–25 mg of pure protein was obtained from 2 L of culture, and the total recovered activity ranged from 5 to 10 × 103 μmol/min. Homogeneity of the purified enzyme was demonstrated by HPLC and by native and sodium dodecylsulfate polyacrylamide gel electrophoresis. Molecular weight of the native enzyme was 164 000 and that of the subunit was71 000, which indicated that the native enzyme is a dimer. The apparent Km value for D-glucose was 10.9 mM. The optimum pH for the enzyme activity was 5.0, but the enzyme was stable in buffer from pH 3 to 7. The enzyme was observed to be a glycoprotein, and amino acid analysis of the purified enzyme indicated a similarity to glucose oxidases from fungal sources. Isozymes of the enzyme with pI values of 4.40–4.55 were detected on analytical isoelectric focusing gels. Key words: antibiosis, biocontrol, glucose oxidase, Talaromyces flavus.
Comparison of different membranes for use in the colony-immunoblot technique
Authors: Rodrigue Lynda , Lavoie Marc C.
Published: May 2010

We compared five different supports (Whatman paper filters Nos. 1, 5, and 40, nitrocellulose, and Nylon 66) for their suitability in the colony-immunoblot (CIB) technique. Results indicate that Whatman No. 5 filter paper recovered 94–98% of the bacterial colonies tested, were more resistant to tearing than the other Whatman papers tested, and showed reduced cross-reactions as compared with nitrocellulose membranes. Whatman No. 5 filters are 20 times less expensive than the nitrocellulose membranes usually used in the CIB technique. We thus adopted the former for our ecological studies of the murine oral cavity. Key words: colony-immunoblot, filter paper, nitrocellulose membrane, microbial ecology, oral cavity.
Inability of human clinical strains of Helicobacter pylori to colonize the alimentary tract of germfree rodents
Authors: Cantorna Margherita T. , Balish Edward
Published: May 2010

Several attempts were made to colonize the alimentary tract and infect germfree BALB/c mice and germfree Sprague-Dawley rats with two human isolates of Helicobacter pylori. The alimentary tracts of mice, sacrificed at intervals between 1 day and 20 weeks after oral challenge, were culture negative for H. pylori. The alimentary tract, kidney, liver, and mesenteric lymph nodes were culture negative for H. pylori 5 h after intravenous challenge. Growth of H. pylori was inhibited by homogenates of murine stomach, small intestine, liver, and mesenteric lymph nodes. Germfree rats and mice do not appear to be readily colonized or infected by human strains of H. pylori. Key words: Helicobacter pylori, germfree mice, congenitally immunodeficient mice.
Carbon dioxide induces endotrophic germ tube formation in Candida albicans
Authors: Mock Ruth C. , Pollack Jordan H. , Hashimoto Tadayo
Published: May 2010

Candida albicans formed germ tubes when exposed to air containing 5 to 15% carbon dioxide (CO2). The CO2-mediated germ tube formation occurred optimally at 37 °C in a pH range of 5.5 to 6.5. No germ tubes were produced at 25 °C, even when the optimal concentration of CO2 (10%) was present in the environment. The requirement of CO2 for germ tube formation could be partially substituted by sodium bicarbonate but not by N2. Carbon dioxide was required to be present throughout the entire course of germ tube emergence suggesting that its role is not limited to an initial triggering of morphogenic change. We suggest that carbon dioxide may be a common effector responsible for the germ tube promoting activity of certain chemical inducers for C. albicans. Key words: Candida albican germ tubes, CO2-induced germ tube formation, endotrophic germ tube formation.
The role of hydrogenase in anaerobic biocorrosion
Authors: Bryant Richard D. , Laishley Edward J.
Published: May 2010

It is becoming clear that the activity of the hydrogenase enzyme may be involved in the anaerobic biocorrosion of metal, particularly mild steel. Since all hydrogenases appear to be active in the reversible activation of the hydrogen molecule, hydrogenase from Clostridium pasteurianum was used as a test enzyme for investigating the role of cell-free hydrogenase in anaerobic biocorrosion of mild steel. Evidence is presented which demonstrates the activity of the hydrogenase enzyme in catalyzing removal of cathodically produced hydrogen from mild steel in the presence of the appropriate electron acceptors. The results from the experiments imply that dead cells may also provide, by virtue of their biochemical makeup, all the necessary ingredients to catalyze corrosion of mild steel. Key words: hydrogenase, biocorrosion, Clostridium pasteurianum, iron phosphate complex, cathodic depolarization.
Nitrification of swine waste
Authors: Blouin M. , Bisaillon J. -G. , Beaudet R. , Ishaque M.
Published: May 2010

Complete oxidation of ammonia nitrogen (~1000 mg/L) to nitrite was observed in stabilized swine waste after 49 days in incubation at 400 rpm and 29 °C, only if 10% (v/v) activated sludge from a wastewater treatment unit and 1.5% (w/v) CaCO3, were added. Stabilized swine waste contains less than 0.09 most probable number (MPN) per millilitre of nitrosobacteria and 2.3 MPN/mL of nitrobacteria. In activated sludge, the concentrations of these bacteria were 2.4 MPN/mL for nitrosobacteria and 4.2 × 105 MPN/mL for nitrobacteria. In the swine waste where ammonia was oxidized to nitrite, the nitrosobacteria growth increased to 5.5 × 105 MPN/mL, while the nitrobacteria growth decreased to 2.3 MPN/mL. Inoculation of a freshly stabilized swine waste with 10% (v/v) of the active nitrifying waste and addition of 1.5% (w/v) CaCO3, accelerated the oxidation of ammonia nitrogen to nitrite; the reaction was completed after only 5 days of incubation. Increasing the incubation period to 10 days resulted in the complete oxidation of the accumulated nitrite to nitrate. In the stabilized swine waste, complete nitrification without accumulation of nitrite was obtained in only 5 days of incubation when the waste was inoculated with both enriched nitrifying populations (106–107 MPN/mL). Key words: nitrifying microorganisms, swine waste, nitrification, most probable number.
The immune response in a cat-related outbreak of Q fever as measured by the indirect immunofluorescence test and the enzyme-linked immunosorbent assay
Authors: Embil J. , Williams J. C. , Marrie T. J.
Published: May 2010

The isotypic immune response of 16 individuals who developed Q fever pneumonia following exposure to an infected parturient cat was studied. The enzyme-linked immunosorbent (ELISA) test was used to detect IgM, IgA, and IgG antibodies to phase I and phase II Coxiella burnetii whole-cell antigens and to the phase I lipopolysaccharide. The indirect immunofluorescent antibody (IFA) test was also used to detect antibodies to phase I and phase II whole cells. None of the 16 subjects developed antibodies to the phase I lipopoly saccharide. The ELISA was more sensitive than the IFA test. IgM antibodies to phase II antigen were detectable by ELISA in 80% of the subjects at the time of onset of symptoms and were still present in 7 of the 8 tested at 32 weeks following the onset of symptoms. In all instances (ELISA: IgG, IgM; IFA: IgG, IgM) phase II antibodies developed earlier and reached higher levels than did phase I antibodies. The absence of antibodies to phase I lipopolysaccharide in acute Q fever combined with our unpublished findings of antibodies to phase I lipopoly saccharide in chronic Q fever suggests that this test may be used to distinguish acute from chronic Q fever. Key words: Q fever, immune response, ELISA.
Starch counteracts the inhibitory action of Bacto-peptone and bile salts in media for the growth of halobacteria
Authors: Oren Aharon
Published: May 2010

It has been reported that Halobacterium sodomense requires the presence of either starch or bentonite in its growth medium. The present work shows this requirement to be attributable to Bacto-peptone as a component of the medium. When Bacto-peptone is omitted or replaced by other nutrients, no starch is required. Starch (and to a lesser extent bentonite) was shown to effectively protect Halobacterium cells from lysis by Bacto-peptone, and by bile salts, which have been identified as the lytic factor in the peptone. Key words: starch, Halobacterium, peptone, bile salts.
A colorimetric assay for immobilized chloroperoxidase
Authors: Kadima Tenshuk A. , Pickard Michael A.
Published: May 2010

A rapid and sensitive colorimetric assay was developed for the estimation of chloroperoxidase activity. N,N,N′,N′-Tetramethyl-p-phenylenediamine was chosen from four potential chromogenic substrates because the blue product resulting from chloroperoxidase conversion gave the highest molar absorption. This product exhibited two absorbance maxima, at 563 and 610 nm. Activity was monitored at 563 nm, and the product absorbance was stable for at least 1 h at 10 °C after treatment with an equal volume of a mixture (40:1) of methanol and phosphoric acid (85% w/v), pH 2. The linear range of the assay with respect to enzyme amount was determined. The assay was developed using soluble chloroperoxidase but worked well with the enzyme immobilized on glass beads. Key words: immobilized enzyme, chloroperoxidase, enzyme assay.
Distribution spatio-temporelle d'une population bactérienne allochtone (coliformes thermotolérants) dans un écosystème marin côtier (Bassin de Thau, France)
Authors: Lebaron P. , Troussellier M. , Got P. , Baleux B.
Published: May 2010

The variation in the levels of thermotolerant coliforms has been measured at various time–space observation scales in a marine coastal ecosystem (Thau pond). The spatial distribution of the bacteria was organized in the ecosystem (observation distance ≈1 km) in the form of either spots or gradients. The latter only appeared after massive drifts from the watershed. A strong local variation (< 1 km) was permanently associated with a broader observation scale. Local variation can develop from rapidly decreasing gradients in the levels of thermotolerant coliforms, starting from the drift points of the watershed. The variation with time was high whatever the observation frequency (monthly, daily, hourly). Monthly sampling usually revealed higher bacterial counts during winter compared with summer. During winter, the daily and hourly degree of variation of the bacterial levels was comparable and the populations were organized according to a linear trend. In summer time, there was a higher degree of variation in the populations and hourly variations can show cyclic trends (diurnal minima and nocturnal maxima). Our results show that privileged sampling scales occur and should be considered when evaluating the impact of environmental parameters (sun exposure, role of the watershed… ) and trying to correlate them. These results also enabled us to define a better sampling strategy for the detection of thermotolerant coliforms in such an ecosystem. Key words: thermotolerant coliforms, marine coastal ecosystem, spatial distribution, variation with time, sampling. [Journal translation]
The structure and associations of the double S layer on the cell wall of Aquaspirillum sinuosum
Authors: Smith Stephen H. , Murray Robert G. E.
Published: May 2010

Aquaspirillum sinuosum cell walls bear two paracrystalline, proteinaceous surface layers (S layers). Each shows a different symmetry: the inner layer is closely apposed to the outer membrane and is a tetragonal array (90° axes; 5-nm units; repeat frequency 8 nm); the outer layer is a hexagonal array on the external surface (14-nm units; repeat frequency 18 nm) and, although the units have a six-pointed stellate form, the linkage between units is not resolved. The outer layer consists of a major 130-kDa protein and a 180-kDa minor component; these co-extract, co-assemble, and are inseparable by hydroxylapatite chromatography or by recrystallization. The solubilizing effects of reagents suggest stabilization by hydrogen bonding and Ca2+. The two outer layer proteins are serologically related and show partial identity by peptide mapping. Periodic acid – Schiff staining of the 180-kDa band suggests that this may be a glycosylated form of the 130-kDa component. The inner layer components form a doublet of 75- and 80-kDa polypeptides with extreme resistance to extraction. Close apposition to the outer membrane, resistance to chaotropes, aqueous insolubility, and behaviour in charge-shift electrophoresis suggest hydrophobic interaction between subunits and an integral association with the outer membrane. Key words: bacterial surface, cell wall, surface layers, cell-wall proteins, cell-wall assembly.
Cartographie physique de l'ADN du cytomégalovirus humain souche AD169
Authors: Dion Michel , Hamelin Claude
Published: May 2010

The whole human cytomegalovirus strain AD169 genome was cloned into plasmid pAT153 in the form of 25 HindIII fragments. Double and triple digestions of the recombinant plasmids with restriction endonucleases BamHI, BglII, ClaI, DraI, EcoRI, EcoRV, HindIII, HpaI, KpnI, PaeR7, PstI, SphI and XbaI yielded a detailed restriction map of human cytomegalovirus DNA. Knowing the exact position of numerous restriction sites in the viral DNA molecule, we have been able to examine very closely the heterologous region between the long and the short segments of the human cytomegalovirus genome. Key words: DNA, physical map, cytomegalovirus, restriction endonucleases, HCMV.
Vegetative compatibility within Fusarium oxysporum f.sp. niveum and its relationship to virulence, aggressiveness, and race
Authors: Larkin R. P. , Hopkins D. L. , Martin F. N.
Published: May 2010

Over 250 isolates of Fusarium oxysporum collected from infected watermelon plants and soil samples from a pathogen-infested field, as well as known isolates of F. oxysporum f. sp. niveum imported from various locations around the world, were tested for pathogenicity on watermelon and used to determine vegetative compatibility groups (VCGs) within F. oxysporum f. sp. niveum. Vegetative compatibility was assessed on the basis of heterokaryon formation among nitrate-nonutilizing mutants. Race determinations were made by screening isolates on six different watermelon cultivars of varying resistance. All isolates of F. oxysporum f. sp. niveum belonged to one of three distinct VCGs, and were incompatible with isolates that were not pathogenic on watermelon. Isolates of F. oxysporum f. sp. niveum were subdivided into two races and there was a direct relationship between VCG and race. VCG 0080 consisted of race 1 isolates from five states of the United States, Taiwan, and Australia. VCG 0081 consisted solely of race 1 isolates from Florida. VCG 0082 was comprised solely of race 2 isolates, all of which were capable of causing severe wilt on all cultivars tested. Numerous Florida isolates were compatible with race 2 isolates from Texas and demonstrated comparable virulence on all cultivars, confirming the presence of race 2 in Florida. With F. oxysporum f. sp. niveum, vegetative compatibility can be utilized as an alternative or collaborative method to distinguish pathogenic from nonpathogenic strains of F. oxysporum and to differentiate subforma specialis virulence characteristics. Key words: fusarium wilt, nit mutants, watermelon.
Aggregation of Actinomyces strains by extracellular vesicles produced by Bacteroides gingivalis
Authors: Bourgeau G. , Mayrand D.
Published: May 2010

The aggregation of Actinomyces viscosus and Actinomyces naeslundii with extracellular vesicles of Bacteroides gingivalis was studied. Factors influencing the aggregation phenomenon were examined. L-Arginine was found to effectively inhibit aggregation as was an antibody preparation directed against a B. gingivalis surface hemagglutinin. Aggregation occurred over a wide pH range and did not seem to be affected by high salt concentrations or the presence of carbohydrates. Treatment of the vesicle preparation with proteases, sodium dodecyl sulphate, and high temperatures diminished or eliminated aggregation, while similar treatment of the Actinomyces had no effect on aggregation. Key words: vesicles, outer membranes, aggregation, oral bacteria.
Intracellular polyamine patterns during encystment of Physarum flavicomum
Authors: Zhu Chengming , Henney Jr. Henry R.
Published: May 2010

In Physarum flavicomum Berk., growing amoebae convert to dormant cysts under conditions of nutrient imbalance. Exogenous adenine inhibits the process and the cells produce an elevated intracellular concentration of S-adenosylmethionine. Evidence indicates that the increased level of S-adenosylmethionine is responsible for the disruption of the normal developmental process. One of the biological functions of S-adenosylmethionine is in polyamine synthesis and it is known that a well-controlled intracellular concentration of polyamines is essential for normal cell growth and differentiation. In this study, high-performance liquid chromatography was used to determine the intracellular polyamine patterns in growing cells, adenine-treated and normal encysting cells, and dormant cysts. Putrescine and spermidine were the most abundant polyamines found in the cells; growing cells had the highest level, adenine-treated cells had a 1.5 to 2.0 times higher level than normal encysting cells, while cysts had the lowest (only 3 and 12% of that of growing cells). Cadaverine and N1-acetylspermidine were found in all the cells and their levels decreased during encystment. Acetylputrescine was found in growing cells only and acetylspermine was found in all cells except cysts. Acetylcadaverine, N8-acetylspermidine, 1,3-diaminopropane, and spermine were not detected in any of the cells. Key words: polyamines, encystment, Physarum flavicomum, amoebae, cysts, growing, dormant, differentiation, development.
Promiscuous nodulation of Phaseolus vulgaris, Macroptilium atropurpureum, and Leucaena leucocephala by indigenous Rhizobium meliloti
Authors: Bromfield E. S. P. , Barran L. R.
Published: May 2010

Thirty-three isolates of indigenous Rhizobium meliloti, either possessing cryptic plasmids that hybridize to probes for symbiotic genes or lacking a 1500-kb megaplasmid band in Eckhardt gels, were tested for infectivity on 10 legume species grown under axenic conditions. A previous study had shown that all but two isolates were symbiotically effective with Medicago sativa. All indigenous isolates and two reference strains of R. meliloti induced nodules which were symbiotically ineffective on Trigonella foenum-graecum (100% plants nodulated) and Phaseolus vulgaris (40 to 100% plants nodulated). Eighteen indigenous isolates of R. meliloti elicited ineffective nodules on Macroptilium atropurpureum (2 to 25% plants nodulated) and Leucaena leucocephala (11 to 75% plants nodulated). The identity of single colony nodule isolates from each R. meliloti inoculant and host combination was verified by phage typing and analysis of plasmid profiles; tests with subsamples of these isolates showed that all were capable of nodulating M. sativa. There was no apparent relationship between the host range of indigenous R. meliloti and either the presence of cryptic plasmids that hybridize to probes for symbiotic genes or the absence of a megaplasmid band in Eckhardt gels. The data suggest that nodulation promiscuity may be a relatively common characteristic of R. meliloti. Key words: host range, Rhizobium meliloti, Leucaena, Macroptilium, Phaseolus.
Freeze-etch study of the cell envelope of cowpea rhizobia: compartmentalization of the periplasmic space in relation to polysaccharide excretion
Authors: Mody Bina , Mody Rustom , Modi Vinod
Published: May 2010

Freeze-etching electron microscopy of free-living cowpea rhizobia revealed distinctive features of the cell envelope of this bacteria. The topology of the outer and cytoplasmic membranes was comparable with that described for other Gram-negative bacteria. In cowpea Rhizobium strains JLn(c) and NC-92, the rigid cell wall almost invariably cleaved away from the outer membrane, thus exposing two distinct fracture faces in the outer membrane, which to date have been ill defined in rhizobia. Cross-fractured cells showed enlargement of the periplasmic region as a result of invagination of the cytoplasmic membrane near one end of the cell. This feature was consistent in all exponential and stationary phase cells. Ruthenium red staining of cells in various growth phases showed unipolar initiation of the capsule. A unique structure seen within the enlarged periplasm was the presence of a smooth lipidic vesicle. Key words: Rhizobium, freeze-etch, membrane, polysaccharide, vesicle.
Pattern of end growth of the fission yeast Schizosaccharomyces pombe
Authors: Miyata Hisao , Miyata Machiko , Johnson Byron F.
Published: May 2010

The patterns of end growth of individual cells of Schizosaccharomyces pombe, wild-type cells (strain 972 h−), cells exposed to 8 mM hydroxyurea, and cdc mutants (cdc11-123 and cdc2-33), were investigated by time-lapse photomicrography. It was reconfirmed that there are three patterns of end growth: cells growing at the old end, at the new end, and at both ends from the beginning of the cell cycle. Cells that initiated growth at the old (new) end increased their growth rate at the new (old) end and became constant in their growth rate at the old (new) end when cells had their growth rate higher than a critical value: 0.08, 0.09, 0.08, and 0.11 μm/min in wild-type cells, cells exposed to hydroxyurea, cdc11-123 cells, and cdc2-33 cells, respectively. The critical value is proportional to the doubling time in length. Key words: extension, growth, fission yeast.
Response of Desulfovibrio desulfuricans colonies to oxygen stress
Authors: Wall Judy D. , Rapp-Giles Barbara J. , Brown Merton F. , White Jerry A.
Published: May 2010

Oxygen tolerance of the strictly anaerobic sulfate-reducing bacteria is well documented and poorly understood. This capacity for surviving brief exposures to oxygen must be a major factor in the diversity of environmental niches observed for these bacteria. We observed that viable cells of Desulfovibrio desulfuricans (ATCC 27774) could be found in colonies on the surface of solidified medium exposed to air for periods as long as 1 month. During exposure to air, the originally black colonies became greyish white, presumably as a result of the air oxidation of the metal sulfide deposits. A black, brittle deposit formed at the bottom of the colony and, simultaneously, the colony descended into a dimple that developed into a well in the agar. Eventually the colony reached the bottom of the Petri dish. These changes did not take place when the colonies were maintained in an anaerobic chamber. The morphological changes took place with all strains tested: three strains of D. desulfuricans and one strain of Desulfovibrio gigas and Desulfovibrio multispirans. Continued sulfate reduction appeared to be essential. Cyclic sulfate (thiosulfate or sulfite) reduction to sulfide and reoxidation of sulfide by the oxygen in air are proposed to maintain the viability of the bacteria by providing substrates for energy production and by reducing oxygen tension. Scanning and transmission electron microscopy of colony and cellular changes are shown. Key words: Desulfovibrio, sulfate-reducing bacteria, oxygen tolerance, sulfate cycling, scanning electron microscopy.
Variation in epitopes of the B subunit of Vibrio cholerae non-O1 and Vibrio mimicus cholera toxins
Authors: Tamplin Mark L. , Jalali Reema , Ahmed Mohammed K. , Colwell Rita R.
Published: May 2010

Monoclonal antibodies reacting with the B subunit of Vibrio cholerae O1 strain 569B cholera toxin (CT-B) were used to identify unique and common epitopes of V. cholerae non-O1 and Vibrio mimicus CT-B. Vibrio cholerae non-O1 strains produced CT-B showing three monoclonal antibody reaction patterns (epitypes), which corresponded with epitypes described previously for V. cholerae O1 classical biotype CT-B (CT1), El Tor biotype CT-B (CT2), and a unique V. cholerae non-O1 CT-B (CT3), which lacked an epitope located in or near the GM1 ganglioside binding site of 569B CT-B. Vibrio mimicus CT-B was immunologically indistinguishable from 569B CT-B. These and previous results define six epitopes on 569B CT-B, and a fourth epitope in or near the GM1 ganglioside binding site. Key words: cholera toxin, epitopes, monoclonal antibodies.
Short exposure to Azospirillum brasilense Cd inoculation enhanced proton efflux of intact wheat roots
Authors: Bashan Yoav
Published: May 2010

Inoculation of wheat seedlings with Azospirillum brasilense Cd significantly increased the proton efflux of the roots 5 h after inoculation compared with noninoculated plants. Removal of the bacterial cells from the root surface 2, 4, or 10 h after inoculation did not affect proton extrusion, which remained similar to the proton efflux of inoculated roots with a permanent A. brasilense Cd population. Proton efflux from roots after short exposure to A. brasilense Cd was directly related to the inoculation level and to the physiological status of the bacterial cells. Active bacteria, at an optimal level for inoculation (105–107 cfu∙mL−1), produced the most proton extrusion from roots. Stressed bacteria, i.e., bacteria exposed to starvation, 45 °C, anaerobic conditions, or a high level of streptomycin before inoculation, induced smaller but not statistically significant increases in proton efflux. Inoculation with dead A. brasilense Cd cells, cell-wall fragments, or several associative nonbeneficial rhizosphere bacteria belonging to other genera did not enhance the proton efflux compared with noninoculated plants. Continuous perfusion of the nutrient solution of plants while maintaining the bacterial cells in the root vicinity eliminated the proton efflux enhancement caused by A. brasilense Cd. Bacteria, regardless of species or stress conditions, in the absence of plants produced negligible proton efflux. It is suggested that short exposures of wheat roots to live A. brasilense Cd enhanced the proton efflux of roots, probably through the release of an as yet unidentified bacterial signal. Active metabolism of the bacterium is required for this enhancement, which is of a triggering nature. Key words: Azospirillum, beneficial bacteria, plant–bacteria interaction, proton efflux, rhizosphere bacteria, Triticum aestivum, wheat.
Compact structure of cortical peptidoglycans from bacterial spores
Authors: Marquis Robert E. , Bender Gary R.
Published: May 2010

Cortical peptidoglycans isolated from Bacillus megaterium ATCC 19213 and Bacillus cereus strain terminalis by chemical extraction of decoated spores were found to have few free amino groups, indicative of a high level of peptide cross-linking, low mineral contents, indicative of low levels of net negative charge, and low dextran-impermeable volumes, indicative of compact structures. Moreover, they had little capacity to swell or shrink in response to changes in environmental pH value. Overall, the data indicated that the cortical peptidoglycan sacculus is designed to serve primarily as a restraining structure rather than as a contractile or expansive element. Key words: cortex, spores, peptidoglycan, resistance.
Effect of various biophysicochemical conditions on toxigenicity of Vibrio cholerae 01 during survival with a green alga, Rhizoclonium fontanum, in an artificial aquatic environment
Authors: Islam M. S.
Published: May 2010

Toxigenic and nontoxigenic strains of Vibrio cholerae 01 occur in the natural aquatic environment. It is not clear whether V. cholerae 01 lose toxigenicity and become nontoxigenic during survival in the aquatic environment as a result of the effect of various biophysicochemical conditions (e.g., sunlight, pH, temperature, competition with other bacteria for nutrients, etc.). Five toxigenic strains were exposed to artificial aquatic environments in the presence of a filamentous green alga, Rhizoclonium fontanum, and recovered after different time intervals (0 and 0.5 h, 3, 6, 9, and 15 days). This experimental system was exposed to sunlight and the V. cholerae 01 were in competition for nutrients with resident bacterial flora from R. fontanum. The toxigenicity of Vibrio cholerae 01 that were recovered at different time intervals was assessed by tissue culture assay using Vero cells. The toxigenicity of recovered strains was compared with that of the parent strains. The results demonstrated that toxigenic V. cholerae 01 are unlikely to lose their toxigenicity in aquatic environments as a result of the effects of various biophysicochemical conditions. These results are consistent with the hypothesis of environmental reservoirs of V. cholerae. Key words: Vibrio cholerae 01, toxigenicity, survival, environment, algae.
Development of mutants of Gliocladium virens tolerant to benomyl
Authors: Papavizas G. C. , Roberts D. P. , Kim K. K.
Published: May 2010

Aqueous suspensions of conidia of Gliocladium virens strains Gl-3 and Gl-21 were exposed to both ultraviolet radiation and ethyl methanesulfonate. Two mutants of Gl-3 and three of Gl-21 were selected for tolerance to benomyl at 10 μg∙mL−1, as indicated by growth and conidial germination on benomyl-amended potato dextrose agar. The mutants differed considerably from their respective wild-type strains in appearance, growth habit, sporulation, carbon-source utilization, and enzyme activity profiles. Of 10 carbon sources tested, cellobiose, xylose, and xylan were the best for growth, galactose and glucose were intermediate, and arabinose, ribose, and rhamnose were poor sources of carbon. The wild-type strains and the mutants did not utilize cellulose as the sole carbon source for growth. Two benomyl-tolerant mutants of Gl-3 produced less cellulase (β-1,4-glucosidase, carboxymethylcellulase, filter-paper cellulase) than Gl-3. In contrast, mutants of Gl-21 produced more cellulase than the wild-type strain. Only Gl-3 provided control of blight on snapbean caused by Sclerotium rolfsii. Wild-type strain Gl-21 and all mutants from both strains were ineffective biocontrol agents. Key words: Gliocladium, benomyl tolerance, Sclerotium, rhizosphere competence.
Induction and repair of DNA strand breaks in Bacteroides fragilis
Authors: Abratt Valerie R. , Peak Meyrick J. , Peak Jennifer G. , Santangelo Joseph D. , Woods David R.
Published: May 2010

Alkaline sucrose gradient sedimentation was used to establish whether strand breakage and repair take place in the DNA of UV-irradiated Bacteroides fragilis during the removal of pyrimidine dimers. A B. fragilis wild-type strain and two of its repair mutants, a mitomycin C sensitive mutant (MTC25) having wild-type levels of UV survival, and a UV-sensitive, mitomycin C sensitive mutant (UVS9), were investigated. Under anaerobic conditions, far-UV irradiation induced metabolically regulated strand breakage and resynthesis in the wild-type strain, but this was markedly reduced in both the MTC25 and UVS9 mutants. Approximately half of the strand breaks generated by the various strains were rejoined during further holding in buffer. Under replicating conditions, complete repair of strand breaks in the wild type was observed. Caffeine treatment under anaerobic conditions caused direct DNA strand breakage in B. fragilis cells but did not inhibit UV-induced breakage or repair. Key words: Bacteroides fragilis, DNA breakage, DNA repair, caffeine.
Purification and characterization of an extracellular proteinase from Brevibacterium linens
Authors: Juhasz Ondrej , Škárka Bohumil
Published: May 2010

The alkaline proteinase of Brevibacterium linens was partially purified through ultrafiltration and chromatography on Sephacryl S-200. The molecular weight of this enzyme was determined by gel electrophoresis in polyacrylamide to be 52 000 – 55 000. The proteinase hydrolyses natural polypeptides such as casein, haemoglobin, bovine serum albumin, and ovalbumin. An apparent Km for casein was determined to be 1.3 mg∙mL−1. The optimal pH for caseinolytic activity was between 7.0 and 8.5 at the optimal temperature of 45 °C. The isolated enzyme is thermolabile: incubation at 50 °C destroyed proteolytic activity. Substrate proteins have a stabilizing effect. Our inhibition studies revealed that the B. linens proteinase belongs to the serine proteinase class. Key words: Brevibacterium linens, proteinase, purification.