bluuebunny/crossref_metadata_2025 huggingface dataset:
Alterations in plant growth and in root hormone levels of lodgepole pines inoculated with rhizobacteria
Authors: Bent Elizabeth , Tuzun Sadik , Chanway Christopher P , Enebak Scott
Published: April 2011

The presence of other soil microorganisms might influence the ability of rhizobacterial inoculants to promote plant growth either by reducing contact between the inoculant and the plant root or by interfering with the mechanism(s) involved in rhizobacterially mediated growth promotion. We conducted the following experiments to determine whether reductions in the extent of growth promotion of lodgepole pine mediated by Paenibacillus polymyxa occur in the presence of a forest soil isolate (Pseudomonas fluorescens M20) and whether changes in plant growth promotion mediated by P. polymyxa (i) are related to changes in P. polymyxa density in the rhizosphere or (ii) result from alterations in root hormone levels. The extent of plant growth, P. polymyxa rhizosphere density, and root hormone concentrations were determined for lodgepole pine treated with (i) a single growth-promoting rhizobacterial strain (P. polymyxa L6 or Pw-2) or (ii) a combination of bacteria: strain L6 + strain M20 or strain Pw-2 + strain M20. There was no difference in the growth of pines inoculated with strain L6 and those inoculated with strain L6 + strain M20. However, seedlings inoculated with strain Pw-2 had more lateral roots and greater root mass at 12 weeks after inoculation than plants inoculated with strain Pw-2 + strain M20. The extent of growth promotion mediated by P. polymyxa L6 and Pw-2 in each treatment was not correlated to the average population density of each strain in the rhizosphere. Bacterial species-specific effects were observed in root hormone levels: indole-3-acetic acid concentration was elevated in roots inoculated with P. polymyxa L6 or Pw-2, while dihydrozeatin riboside concentration was elevated in roots inoculated with P. fluorescens M20.Key words: PGPR, Pinus contorta, Pseudomonas fluorescens, Paenibacillus polymyxa, auxin, cytokinin.
Characterization of major protein phosphatases from selected species ofKluyveromyces. Comparison with protein phosphatases fromYarrowia lipolytica
Authors: Jolivet Pascale , Bergeron Edith , Benyair Haguith , Meunier Jean-Claude
Published: April 2011

Casein phosphatase activities have been identified in five yeast strains grown on Pi-deficient medium. Maximal endocellular activities appeared in the exponential phase. Exocellular phosphatases were significantly produced from Yarrowia lipolytica W-29 and Kluyveromyces marxianus, in the early stationary phase. Major phosphatases from K. marxianus were one heavy acid phosphatase composed of 6467 kDa subunits, which could be secreted in the medium, and one type 2A protein phosphatase with an apparent molecular mass of 147 kDa and a 52 kDa catalytic subunit dissociated by 80% ethanol treatment. The characteristics of phosphatases purified from K. marxianus were compared with those previously purified from Y. lipolytica.Key words: yeast, type 2A protein phosphatase, acid phosphatase, [32P]casein, Pideficiency.
Comparative denaturing gradient gel electrophoresis analysis of fungal communities associated with whole plant corn silage
Authors: May Lisa A , Smiley Brenda , Schmidt Michael G
Published: April 2011

Significant portions of grain produced for livestock consumption are converted into ensiled forage. Silage producers have long recognized the positive effects of using an inoculant to insure the proper transformation of forage into a palatable and digestible feedstuff. When silage is fed from a storage structure, exposure to air stimulates the growth of epiphytic aerobes that may result in the loss of up to 50% of the dry matter. Moreover, fungi have been found to be associated with ensiled forage, but their growth is normally suppressed by the anaerobic conditions. However, the introduction of oxygen results in a fungal bloom, and the fungi and the associated metabolites may result in lost productivity in the livestock consuming the contaminated forage. In this study, we report on the diversity of the fungal community associated with whole plant corn silage during the ensiling process, and the effect of two different bacterial inoculants as compared with the uninoculated natural epiphytic fermentation on the distribution of the fungi associated with the silage. The fungal community from duplicate mini-silo packages of the same treatment was analyzed by denaturing gradient gel electrophoresis and direct sequencing of the resulting operational taxonomic units. This method proved useful in analyzing the complex microbial communities associated with the forage in that it was possible to determine that one inoculant dramatically influenced the fungal community associated with whole plant corn silage.Key words: fungi, silage, DGGE, OTU.
Acid stress upregulated outer membrane proteins in clinical isolates ofNeisseria gonorrhoeae, but not most commensalNeisseria
Authors: Pettit R K , Whelan T M , Woo K S
Published: April 2011

Human immune serum recognition of outer membrane components from commensal and pathogenic Neisseria cultured under neutral and acidic conditions was investigated. Acid stress caused no detectable alterations in lipooligosaccharide migration and (or) staining, in outer membrane protein profiles, or in immune serum recognition of outer membrane components from Neisseria mucosa or Neisseria sicca. There was also no difference in the lipoologosaccharide electrophoretic pattern of acid- and neutral-grown Neisseria lactamica, but there were differences in outer membrane protein expression. The outer membrane protein alterations induced by acid stress in N. lactamica were not the same as those seen in isolates from patients with uncomplicated gonococcal infection, pelvic inflammatory disease, and disseminated gonococcal infection. Many differences were detected in the immune serum recognition of outer membrane components from acid- and neutral-cultured N. lactamica and from the clinical isolates of Neisseria gonorrhoeae, and these should be considered in vaccine design.Key words: Neisseria gonorrhoeae, commensal Neisseria, acid stress, outer membrane proteins.
Quantifying functional gene populations: comparing gene abundance and corresponding enzymatic activity using denitrification and nitrogen fixation in pulp and paper mill effluent treatment systems
Authors: Neufeld Josh D , Driscoll Brian T , Knowles Roger , Archibald Frederick S
Published: April 2011

The relationship between the abundance of three functional genes and their corresponding biochemical reaction rates was investigated in several activated sludge and mill effluent microbial communities. Gene probes were prepared for two key denitrification genes (nirS and nirK) and for one nitrogen-fixation gene (nifH) and were validated using a variety of strains of known nir and nif genotype. ATP-based measures of viable cell numbers were used to provide total population sizes. In certain microbial communities (activated sludge enrichment cultures and multiple samples taken from the same mill primary clarifier), a strong correlation was observed between gene abundance and biochemical activity rates. However, when comparing several different nonenriched activated sludge bioreactors and separate primary clarifier microbial communities, the ratio of specific gene abundance to biochemical activity rates varied widely. These results suggest that in cases where a microbial community is not fully induced for a given biochemical activity or when very different communities are compared, quantitative gene probing can give a better measure of a community's potential to carry out the encoded function than can the relevant biochemical assay. However, the gene quantitation method employed here probably underestimated the true number of probed genes present in the microbial communities due to nirS and nifH genes in the communities having reduced DNA sequence similarity with the probes used.Key words: denitrification, nitrogen fixation, quantitative hybridization, activated sludge, primary clarifier.
Cloning and sequencing of two genes encoding chitinases A and B from Bacillus cereus CH
Authors: Mabuchi Naoto , Araki Yoshio
Published: April 2011

Two genes encoding chitinases A and B (chiA and chiB) from Bacillus cereus CH were cloned into Escherichia coli XL1-Blue MRF' by using pBluescript II SK+, and their nucleotide sequences were determined. Open reading frames of the chiA and chiB genes encoded distinct polypeptide chains consisting of 360 and 674 amino acid residues, respectively, with calculated molecular sizes of 39 470 and 74 261 Da, respectively. Comparison of the deduced amino acid sequences with those of other bacterial chitinases revealed that chitinase A consisted of a catalytic domain, while chitinase B consisted of three functional domains, a catalytic domain, a fibronectin type III-like domain, and a cellulose-binding domain. The primary structures of these two proteins were not similar to each other.Key words: Bacillus cereus, chitinase, cloning.
Mutational analysis of conserved glycines 42 and 256 in Cephalosporium acremonium isopenicillin N synthase
Authors: Loke Paxton , Sim Tiow-Suan
Published: April 2011

Isopenicillin N synthase (IPNS) is critical for the catalytic conversion of δ -(L-α-aminoadipoyl)-L-cysteinyl-D-valine to isopenicillin N in the penicillin and cephalosporin biosynthetic pathway. Two conserved glycine residues in Cephalosporium acremonium IPNS (cIPNS), namely glycine-42 and glycine-256, were identified by multiple sequence alignment and investigated by site-directed mutagenesis to study the effect of the substitution on catalysis. Our study showed that both the mutations from glycine to alanine or to serine reduced the catalytic activity of cIPNS and affected its soluble expression in a heterologous host at 37°C. Soluble expression was restored at a reduced temperature of 25°C, and thus, it is possible that these glycine residues may have a role in maintaining the local protein structure and are critical for the soluble expression of cIPNS.Key words: isopenicillin N synthase, site-directed mutagenesis, glycine, Cephalosporium acremonium.
Selective isolation and study on the global distribution of the genus Planobispora in soils
Authors: Suzuki Shin-ichi , Okuda Toru , Komatsubara Saburo
Published: April 2011

Planobispora strains, including the type strain, produced abundant sporangia on humic acid  vitamin gellan gum medium when more than 50 colonies grew on a plate. However, these strains did not produce sporangia on the aerial mycelium, a diagnostic characteristic of this genus, when fewer than 20 colonies grew on a plate. Trace salts, such as FeSO4·7H2O, MnCl2·4H2O, ZnSO4·7H2O, and NiSO4·6H2O, stimulated sporangium formation of Planobispora strains. Better sporangium formation of Planobispora strains was observed on the humic acid  trace salts gellan gum medium at pH 9.0 than at neutral pH. Moreover, an alkaline medium repressed the growth of three out of six Streptomyces strains so that this condition was effective for selective isolation of Planobispora strains. An alkaline flooding solution of skim milk, five antimicrobial agents, and dry heat treatment at 90°C for 60 min were effective for selective isolation. Using these techniques, we examined the distribution of Planobispora strains by using 1467 soil samples collected from Japan and other parts of the world. One hundred and nineteen Planobispora strains were isolated from 51 soil samples (3.5% of the samples tested) that were collected in Ecuador, Egypt, French Guiana, India, and Madagascar. Planobispora strains were recovered only in tropical and subtropical soils. To our knowledge, this is the first record that Planobispora strains have been isolated from locations other than Venezuela, Namibia, or South Africa.Key words: Planobispora, gellan gum, selective isolation, actinomycete, distribution.
Role of oxidative stress and thiol antioxidant enzymes in nickel toxicity and resistance in strains of the green alga Scenedesmus acutus f. alternans
Authors: Randhawa Varinder K , Zhou Fengzhen , Jin Xiaolei , Nalewajko Czesia , Kushner Donn J
Published: April 2011

Treatment with Ni(NO3)2 leads to the formation of reactive oxygen species (ROS) in the green alga Scenedesmus acutus f. alternans, causing lipid peroxidation. This effect was stronger in a Ni-sensitive strain, UTEX72, than in a Ni-resistant strain, B4. In the resistant strain, Ni induced an increased ratio of reduced to oxidized glutathione (GSH:GSSG), whereas it caused a lowered ratio in the sensitive strain. Enzymes involved in the control of ROS were studied in these strains as well as two others that have shown different degrees of nickel resistance. The resistant strain, B4, which grows while containing large amounts of internal Ni, had much higher levels of glutathione reductase and catalase than the other strains. The sensitive strain, UTEX72, had higher levels of glutathione peroxidase, superoxide dismutase, and glucose-6-phosphate dehydrogenase than did strain B4. The resistant strains, Ni-Tol and Cu-Tol, derived from strain UTEX72, which are partly able to exclude Ni, had enzyme profiles that resembled that of UTEX72 more closely than that of B4. Treatment with 10 and 100 µM Ni for 4 or 22 h had complex effects on enzyme levels in all four strains. Ni decreased glutathione reductase in B4, slightly increased it in Ni-Tol and Cu-Tol, and did not affect the low levels of this enzyme in UTEX72. Ni lowered glutathione peroxidase in B4 and either did not affect it or slightly raised it in the other strains. Ni lowered catalase in B4 and did not affect the other strains. Superoxide dismutase was raised in B4 and Ni-Tol and lowered in Cu-Tol and UTEX72, and glucose-6-phosphate dehydrogenase was lowered in all four strains. These results suggest that one major mechanism of Ni resistance, especially in strain B4, may be the ability to combat the formation of ROS when exposed to this metal, likely by maintaining a high GSH:GSSG ratio.Key words: Scenedesmus acutus f. alternans, glutathione reductase, glutathione peroxidase, catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, lipid peroxidation, nickel, reactive oxygen species.
Characterization of hybrid biphenyl dioxygenases obtained by recombiningBurkholderiasp. strain LB400bphAwith the homologous gene ofComamonas testosteroniB-356
Authors: Barriault D , Simard C , Chatel H , Sylvestre M
Published: April 2011

The bacterial degradation of polychlorinated biphenyls depends on the ability of the enzyme biphenyl 2,3-dioxygenase (BPDO) to catalyze their oxygenation. Analysis of hybrid BPDOs obtained using common restriction sites to exchange large DNA fragments between LB400 bphA and B-356 bphA showed that the C-terminal portion of LB400 α subunit can withstand extensive structural modifications, and that these modifications can change the catalytic properties of the enzyme. On the other hand, exchanging the C-terminal portion of B-356 BPDO α subunit with that of LB400 α subunit generated inactive chimeras. Data encourage an enzyme engineering approach, consisting of introducing extensive modifications of the C-terminal portion of LB400 bphA to extend BPDO catalytic properties toward polychlorinated biphenyls.Key words: PCB, protein engineering, BphA, BPDO, polychlorinated biphenyl.
Weeds as a source of plant growth promoting rhizobacteria in agricultural soils
Authors: Sturz A V , Matheson B G , Arsenault W , Kimpinski J , Christie B R
Published: April 2011

The influence of plant growth promoting (PGP) activity of bacterial communities recovered from each of six weed species (barnyard grass (Echinochloa crusfalli (L.) Beauv.), corn spurrey (Spergula arvensis L.), goldenrod (Sonchus sp.), Italian ryegrass (Lolium multiflorum L.), lamb's-quarters (Chenopodium album L.), and quack grass (Agropyron repens (L.) Beauv.)) was examined in relation to the effect it had on the growth of the potato cultivar Russet Burbank. Bacterial species composition and community structure were compared, species-abundance relationships were determined, and those members conferring positive benefits for potato growth and development were identified. Of the genera identified, Bacillus, Arthrobacter, Stenotrophomonas, Acinetobacter, and Pseudomonas were the most common, and Stenotrophomonas maltophilia was the most frequent species recovered across all sources. Significantly higher population densities were found in the root zones of quack grass, compared with Italian ryegrass and lamb's-quarters. There were no significant differences in species richness among the root zones; however, evenness indices (species distribution) were significantly lower in corn spurrey (P = 0.05). Significantly higher diversity indices (Hill-1 and Hill-2 numbers) (P = 0.05) were found in the root zone soil communities of potato and goldenrod, indicating a decrease in the proportional abundance of common and very abundant species, respectively, while in barnyard grass, corn spurrey, and Italian ryegrass the reverse was the case. In both years of the study, Italian ryegrass and corn spurrey were consistently better sources of PGP rhizobacteria for potatoes, significantly (P < 0.001) increasing the mean wet weight of shoots and roots in in vitro bacterization studies. Barnyard grass was a consistently poor source of such isolates. Species-abundance measures of root zone bacterial biodiversity were not found, in this instance, to be a particularly good predictor of the presence or absence of PGP rhizobacteria. We consider that the study of complementary crops and soil-conditioning treatments should not preclude the examination of weed species as possible beneficials, as alterations in rhizobacterial biodiversity and functional versatility can influence the numbers and types of PGP bacterial strains, and consequently may serve to improve soil quality.Key words: biodiversity, bioindicator, allelopathy, functional versatility, ecosystem function.
Interactions ofPseudomonas aeruginosaPA-IIL lectin with quail egg white glycoproteins
Authors: Lerrer Batia , Gilboa-Garber Nechama
Published: April 2011

Pseudomonas aeruginosa produces several lectins, including the galactophilic PA-IL and the fucose- and mannose-binding PA-IIL. The great advantage of these two lectins is their stability in purified preparations. Following observations that pigeon egg white blocks Escherichia coli P-fimbriae and PA-IL, we examined the interactions of diverse avian egg white components with PA-IIL. This lectin may represent both mannose- and fucose-specific microbial adhesins. For comparison, Con A (which also binds mannose) and Ulex europaeus lectin (UEA-I, which binds fucose) were analyzed in parallel. The lectin interactions with chicken, quail, and pigeon egg whites and several purified chicken egg white glycoproteins were examined by a hemagglutination inhibition test and Western blotting. Both analyses showed that like Con A and unlike UEA-I, which was not sensitive to any of these three egg whites, PA-IIL most strongly reacted with the quail egg white. However, in contrast with Con A, its interactions with the chicken egg white components, excluding avidin, were very poor. The results of this study might indicate the possibility that some of the egg white components that interacted with the above two mannose-binding lectins (exhibiting individual heterogeneity) might be associated with the innate immunity against mannose-specific microbial or viral adhesion during the fowl embryonic period.Key words: Pseudomonas aeruginosa, microbial lectin, PA-IIL lectin, avian egg white.
Selective isolation ofActinobisporaon gellan gum plates
Authors: Suzuki Shin-ichi , Takahashi Kohei , Okuda Toru , Komatsubara Saburo
Published: April 2011

An effective method is described for selectively isolating the actinomycete genus Actinobispora. Gellan gum plus calcium chloride significantly stimulated aerial mycelium formation of Actinobispora yunnanensis IFO 15681 so that this genus was readily recognized on the isolation plate. A new medium, HVG, containing calcium chloride and gellan gum as a solidifying agent was thus developed based on humic acid - vitamin agar. A number of Actinobispora strains were successfully isolated on this medium from 14 soil samples, which were collected in Canada, France, Japan, the United Kingdom, and the United States. To our knowledge, this is the first isolation of Actinobispora strains from locations other than China.Key words: Actinobispora, gellan gum, selective isolation, actinomycete.
Bacterial flora in the gut ofHelix aspersa(Gastropoda Pulmonata): evidence for a permanent population with a dominant homolactic intestinal bacterium,Enterococcus casseliflavus
Authors: Charrier Maryvonne , Combet-Blanc Yannick , Ollivier Bernard
Published: April 2011

We previously demonstrated the existence of bacteria degrading carboxy-methyl-cellulose in the gut of the phytophagous snail Helix aspersa and found Enterobacteriaceae predominating in the intestine of snails dissected in aerobic conditions. Here, we investigated the effects of several nutritional treatments on the snail's microflora. Food sterilization led to increased snail growth and reduced cellulase activity in the crop, suggesting a noxious effect of microbial exogenous cellulases. A second aim of this study was to look for anaerobic bacteria. No strict anaerobic cellulolytic, homoacetogenic, or methanogenic bacteria were enriched from the gut. However, a motile Gram-positive homolactic coccobacillus, grown in anaerobic conditions, dominated in the snail's intestine (1.57 x 109± 0.10 x 109cells.g-1intestine). It was identified as Enterococcus casseliflavus. Its occurrence in the intestine of H. aspersa is discussed with regard to the snail's digestive processes and the presence of a fecal mucous ribbon. A possible snail-bacterium synergistic action is suggested.Key words: snail, Helix aspersa, gut, Enterococcus casseliflavus, fermentative homolactic bacterium, antibiotics.
In vitro antifungal activity of some Mannich bases of conjugated styryl ketones
Authors: Manavathu Elias K , Vashishtha S C , Alangaden George J , Dimmock Jonathan R
Published: April 2011

Four Mannich bases of some conjugated styryl ketones IIa-IId were examined for antifungal activity. These compounds were designed as thiol-alkylators and had two centers for attack by cellular thiols. The most potent compounds IIa and IIb possessed hydrophobic, electron-attracting substituents in the aryl rings and in general had minimum inhibitory concentration (MIC) values of 0.2-25 μM against a variety of fungi. None of the four compounds inhibited the growth of a number of bacteria (MIC > 100 μM). The minimum fungicidal concentration (MFC) values for IIa and IIb were generally either similar or twofold higher than the MIC figures for fungi. Compound IIa demonstrated rapid, concentration-dependent inhibition of the growth of Candida albicans B311. The toxicity of IIa to normal human cells was much lower than the concentrations of this compound required to inhibit fungal growth. In summary, this study of four prototypic molecules has revealed that this class of compounds may have potential for further development as candidate antifungal agents.Key words: antifungal, styryl ketones, Candida albicans, Aspergillus fumigatus, susceptibility test.
Quantification of poliovirus in seawater and sewage by competitive reverse transcriptase - polymerase chain reaction
Authors: Tsai Yu-Li , Parker Stephen L
Published: April 2011

Reverse transcriptase - polymerase chain reaction (RT-PCR) has been used extensively to detect enteric viruses in environmental samples. Advantages of RT-PCR include its high detection sensitivity and rapid turn-around time. However, unlike traditional cell culture, RT-PCR has not provided quantitation and infectivity information. In this study, we have developed a quantitative RT-PCR method that can be used to determine the amount of poliovirus RNA in environmental samples. An RNA internal standard for poliovirus RT-PCR was designed and obtained through genetic engineering. Serial dilutions of RNA internal standard templates were amplified with a 5 prime -carboxyfluorescein-labeled poliovirus downstream primer and a nonlabeled poliovirus upstream primer in the RT-PCR. The fluorescent light intensity of labeled RT-PCR products was quantified using an ABI DNA sequencer with GeneScan software. The internal standard was coamplified with poliovirus in the RT-PCR, allowing for enumeration of the poliovirus RNA present in the seawater and sewage samples. This method, using a cloned internal standard and specified primers in the PCR, may be applied to quantify other microorganisms in environmental samples. Although quantitative RT-PCR has begun to be used more extensively for detecting pathogens in clinical samples, the complex nature of many environmental samples has limited the sample range of the effectiveness of quantitative RT-PCR.Key words: quantitative RT-PCR, poliovirus, sewage, seawater.
Presence of peptide synthetase gene transcripts and accumulation of ergopeptines in Claviceps purpurea and Neotyphodium coenophialum
Authors: Annis Seanna L , Panaccione Daniel G
Published: April 2011

The production of toxic ergopeptine alkaloids by the fungi Claviceps purpurea and Neotyphodium coenophialum involves the activity of one or more nonribosomal peptide synthetases. Claviceps purpurea and N. coenophialum each have several different peptide synthetase genes, fragments of which have been cloned previously. An additional Claviceps purpurea peptide synthetase gene was cloned by hybridization with one of the N. coenophialum peptide synthetase gene fragments. We detected the presence of mRNA from the peptide synthetase genes in cultures of different ages grown under conditions favorable or unfavorable for ergopeptine production. All four peptide synthetase genes from Claviceps purpurea were transcribed under at least some of the experimental conditions. Transcripts from three of the four genes were detected under conditions consistent with their potential involvement in ergopeptine biosynthesis. All three peptide synthetase genes previously identified in N. coenophialum were transcribed during symbiotic growth of this fungus with tall fescue, as well as in ergopeptine-producing cultures. The data show that all of the peptide synthetase genes are transcribed, that one of the peptide synthetase genes is dissociated from ergopeptine biosynthesis, and, as a result, prioritize the remaining genes for functional analyses by transformation-mediated gene disruption.Key words: Claviceps purpurea, endophyte, ergot, ergotamine, Neotyphodium coenophialum.
Comparative genome analysis ofBacillus sphaericusby ribotyping, M13 hybridization, and M13 polymerase chain reaction fingerprinting
Authors: Miteva Vanya , Gancheva Anna , Mitev Vladislav , Ljubenov Marin
Published: April 2011

A comparative genome analysis of 15 strains representing the five homology groups of the highly heterogenous species Bacillus sphaericus was performed by M13 hybridization fingerprinting, M13 polymerase chain reaction fingerprinting, and ribotyping with the whole rrn operon. The computer cluster analyses of the polymorphic patterns, presented in dendrograms, showed that these methods allow the differentiation of the individual strains and some homology groups. Our results confirm the close genetic relatedness of the mosquito pathogenic strains of group IIA and support the idea for differentiation of a separate species. At the same time, we present additional proof of the significant genetic heterogeneity of B. sphaericus and the necessity of reconsideration of its present classification.Key words: Bacillus sphaericus, ribotyping, polymerase chain reaction, M13 fingerprinting.
Potentiation of the virucidal activity of sterilized natural waters
Authors: Quignon F , Gantzer C , Kiéné L , Schwartzbrod L
Published: April 2011

After heat, conductivity has been described as the second most inactivating factor of viruses in surface waters. Using poliovirus-1, we showed that a highly significant linear relationship between virus inactivation rate and water conductivity can be obtained for most of the tested sterilized water samples. Using sterile saline solutions, we demonstrated that this apparent relationship is false, i.e., virus inactivation rate is not affected by water conductivity alone. With the hypothesis that salts may serve to potentiate the antiviral activities of certain microbiological substances that are supposed to be found in the tested samples, we can explain the apparent relationship observed in this study and in similar ones. As a consequence, an effective water treatment could be responsible for the removal of both viruses and some virus-inactivating factors. Alternatively, virus-inactivating capability of a given water resource could be enhanced along with its hardness or its degree of mineralization.Key words: enterovirus, inactivation, conductivity.
Azospirillum plant growth-promoting strains are nonpathogenic on tomato, pepper, cotton, and wheat
Authors: Bashan Yoav
Published: April 2011

Six strains of Azospirillum belonging to five species of plant growth-promoting bacteria (A. brasilense, A. lipoferum, A. amazonense, A. irakense, and A. halopraeference) did not cause visible disease symptoms on the roots or leaves of tomato, pepper, cotton, and wheat, failed to inhibit seed germination, and did not reduce plant dry weight when seven standard techniques for the inoculation of plant pathogens were used. Similar inoculation conditions with plant pathogens (Pseudomonas syringae pv. tomato, Xanthomonas campestris pv. vesicatoria, Xanthomonas campestris pv. translucens, and Xanthomonas campestris pv. malvacearum) induced typical disease symptoms. None of Azospirillum strains caused the hypersensitive reaction on eggplant, whereas all pathogens did. All Azospirillum strains increased phytoalexin production in all disease-resistant plant species to moderate levels, but the levels were significantly lower than those induced by the compatible pathogens. The various phytoalexins produced in plants had the capacity to inhibit growth of all Azospirillum strains. Azospirillum amazonense, A. irakense, and A. halopraeference had no apparent effect on plant growth, while A. brasilense and A. lipoferum increased the dry weight of all plant species. Under partial mist conditions, all Azospirillum strains were capable of colonizing leaf surfaces (103-107 cfu/g dry weight) regardless of the plant species. These results provide experimental evidence that Azospirillum sp. might be considered safe for the inoculation of several plant species.Key words: Azospirillum, beneficial bacteria, environmental protection, plant inoculation, plant growth-promoting bacteria.
A review of the possible bacterial determinants of clinical outcome inHelicobacter pyloriinfection
Authors: Fallone Carlo A , Barkun Alan N , Göttke Markus U , Beech Robin N
Published: April 2011

Helicobacter pylori is present in 40-60% of the population and approximately 10-20% of these infected individuals suffer from a H. pylori associated disease such as peptic ulcer disease or gastric cancer. This article reviews the potential bacterial determinants responsible for and markers predictive of both the acquisition of H. pylori infection and subsequent clinical outcome; i.e., asymptomatic infection or disease. The acquisition of H. pylori infection depends on exposure (hence the increased risk in lower socioeconomic groups and developing nations) to viable bacteria with at least a functional urease gene in a susceptible host. Once infection occurs, bacterial virulence factors, including the vacuolating cytotoxin, and genes of the cag pathogenicity island, as well as nonbacterial factors may determine disease outcome. Future research is being directed at discovering other bacterial virulence factors responsible for the different clinical outcomes of H. pylori infection. This will be greatly enhanced by the recent release of the complete genome sequence of H. pylori. The determination of the relative importance of each of these recognized and other as yet unrecognized factors responsible for disease outcome will assist in the appropriate targeting of patients in the treatment of H. pylori infection.Key words: Helicobacter pylori, genetics, virulence, bacterial.
Functional and structural successions in arbitrary samples of heterotrophic bacteria during aerobic treatments of lignite-carbonization wastewater inin situenclosures
Authors: Becker Petra M , Wand Helmut , Martius Günter GS , Weißrodt Erika , Stottmeister Ulrich
Published: April 2011

In situ mesocosm experiments were performed in Lake Schwelvollert (located in the district of Weißenfels, Saxony-Anhalt, Germany), an anaerobic lignite-carbonization effluent lake containing phenolic compounds and their autoxidation products (anthropogenic humic matter). In the aeration enclosure, the anaerobic Schwelvollert wastewater was aerated and in the flocculation enclosure, it was flocculated to precipitate the oxygen-trapping anthropogenic humic matter to enhance the input of oxygen by diffusion. To gain an insight into the metabolic state of the aerobic heterotrophic microbiota during the treatments, arbitrary samples of bacterial isolates were taken from a general agar medium and tested for their abilities to cleave predominant phenolic contaminants by a procedure called the isolate sample assay. In this way, successions of degradation potentials were observed in both mesocosms, with degradation abilities for meta- and para-alkylated phenols appearing before degradation abilities for ortho-substituted phenols as a common phenomenon. To examine the structure of samples, the respective isolates were characterized using the Biolog GN MicroPlate system, the random amplified polymorphic DNA nucleic acid (RAPD) fingerprinting technique, and amplified ribosomal DNA restriction analysis (ARDRA). Although similar functional patterns occurred in both mesocosms, the compositions and diversities of the respective bacterial communities varied significantly, even at different depths from the same enclosure, with members of the Pseudomonas RNA group I being predominant.Key words: lignite carbonization, phenols, mesocosm, isolate sample assay, Biolog, RAPD, ARDRA.
Simplified reverse transcription polymerase chain reaction procedure with detection by microplate hybridization for routine screening of hepatitis A virus
Authors: Arnal Charlotte , Ferré-Aubineau Virginie , Besse Bernard , Billaudel Sylviane
Published: April 2011

Reverse transcription polymerase chain reaction, using either nested or seminested primers, is used extensively for the detection of viruses in small quantities. However, existing methods are prone to false positive reactions. We report here an improved polymerase chain reaction technique based on the use of longer primers (39 nucleotides) with single-step amplification, applied to the detection of hepatitis A in low quantities. While the sensitivity of this technique (10 x the 50% tissue culture infective dose) is equivalent to that of existing methods, it is a simpler procedure, less time consuming, and less susceptible to contamination and therefore provides a more reliable tool for routine diagnosis. Finally, the development of a DNA enzyme immunoassay detection technique and the complete automation of the procedure allow a large number of samples to be processed in clinical laboratories.Key words: long primers, hepatitis A virus, reverse transcription polymerase chain reaction, seminested PCR, DNA enzyme immunoassay.
A novel technique for isolation ofFrankiaand generation of single-spore cultures
Authors: Sarma Gopa , Sen Arnab , Varghese Rajani , Misra Arvind K
Published: April 2011

The conventional isolation techniques for Frankia strains are likely to yield mixed cultures of genetically different strains. This makes genetic studies difficult. We report the development of a method based on calcium alginate beads for the isolation and genetic purification of Frankia strains.Key words: Frankia, alginate beads, isolation, single-spore cultures.
Aminopeptidase activities inPeptostreptococcusspp. are statistically correlated to gelatin hydrolysis
Authors: Ng James , Ng Lai-King , Mayrand Denis , Dillon Jo-Anne R
Published: April 2011

One hundred Peptostreptococcus isolates from five species were assessed for their ability to hydrolyze gelatin. Most Peptostreptococcus magnus (95.8%) and Peptostreptococcus micros isolates (79.0%) hydrolyzed gelatin in contrast to Peptostreptococcus asaccharolyticus (8.0%), Peptostreptococcus anaerobius (10.0%), and Peptostreptococcus prevotii isolates (16.7%). Gelatin hydrolysis in Peptostreptococcus magnus and Peptostreptococcus micros isolates correlated (r = 0.80; P = 0.0019) with more aminopeptidases produced than Peptostreptococcus asaccharolyticus, Peptostreptococcus anaerobius, or Peptostreptococcus prevotii. The five species were further classified into three groups using the extended Tukey test (P < 0.0001) based on the mean percentage of aminopeptidases produced by each species with Peptostreptococcus magnus and Peptostreptococcus micros belonging to group I, Peptostreptococcus asaccharolyticus and Peptostreptococcus prevotii belonging to group II, and Peptostreptococcus anaerobius forming group III. An analysis of possible proteolytic activity of four selected Peptostreptococcus magnus isolates indicated that only 5 of 11 substrates were hydrolyzed as compared to a control isolate of Porphyromonas gingivalis W83, which had a strong proteolytic profile. Therefore, gelatin hydrolysis by Peptostreptococcus spp., in particular Peptostreptococcus magnus and Peptostreptococcus micros, is probably due to a variety of aminopeptidases rather than proteinases.Key words: Peptostreptococcus, aminopeptidases, proteolytic activity.
Enhancement of verticillium wilt resistance in tomato transplants by in vitro co-culture of seedlings with a plant growth promoting rhizobacterium (Pseudomonas sp. strain PsJN)
Authors: Sharma V K , Nowak J
Published: April 2011

The potential utilization of a plant growth promoting rhizobacterium, Pseudomonas sp. strain PsJN, to enhance the resistance of tomato transplants to verticillium wilt was investigated. Plant growth and disease development were tested on the disease-susceptible cultivar Bonny Best after Verticillium dahliae infection of tissue culture plantlets bacterized in vitro (by co-culturing with the bacterium) and seedlings bacterized in vivo (after 3 weeks growth in the greenhouse). Significant differences in both disease suppression and plant growth were obtained between in vitro bacterized and nonbacterized (control) plants. The degree of protection afforded by in vitro bacterization depended on the inoculum density of V. dahliae; the best and worst protection occurred at the lowest (103 conidia ·mL-1) and highest (106 conidia ·mL-1) levels, respectively. In contrast, the in vivo bacterized tomatoes did not show plant growth promotion when compared to the nonbacterized control plants. When challenged with Verticillium, significant growth differences between in vivo bacterized plants (26.8% for shoot height) and nonbacterized controls were only seen at the 3rd week after inoculation. Compared with the in vitro inoculation, there was no delay in the verticillium wilt symptom expression, even at the lowest concentration of V. dahliae, by in vivo PsJN inoculation. These results suggest that endophytic colonization of tomato tissues is required for the Verticillium-resistance responses. Plant growth promotion preceeds the disease-resistance responses and may depend on the colonization thresholds and subsequent sensitization of hosts.Key words: Pseudomonas sp., plant growth promoting rhizobacterium, Verticillium dahliae, tomato, colonization, plant growth promotion, disease suppression.
Pichia anomalaas a biocontrol agent ofPenicillium roquefortiin high-moisture wheat, rye, barley, and oats stored under airtight conditions
Authors: Petersson Stina , Schnürer Johan
Published: April 2011

Pichia anomala inhibits growth of Penicillium roqueforti in high-moisture winter wheat, barley, and oats in cases where a malfunctioning airtight feed-storage system allows air to leak in. To imitate air leakage to such a storage system, grain was inoculated, packed in glass tubes with a restricted air supply, and incubated at 25°C. Yeast and mold colony-forming units (CFU) were counted on selective media after 14 days. Pichia anomala reached a density of about 5 x 107CFU/g on all tested cereals except in spring wheat (cv. Dragon), where a density of 109CFU/g was reached. In winter wheat (cv. Kosack), Penicillium roqueforti reached a density of 106CFU/g in grain that had not been inoculated with yeast and 105CFU/g in co-culture with 5 x 103CFU/g of Pichia anomala. At 5 x 104Pichia anomala, growth of Penicillum roqueforti was totally inhibited. Similar results were obtained with spring wheat (cv. Dragon), barley (cv. Golf), and oats (cv. Svea). However, spring wheat cv. Dragon was generally much less conducive to growth of Penicillium roqueforti. On rye (cv. Motto), Penicillium roqueforti did not grow in monoculture or when co-cultured with Pichia anomala. No differences in antagonistic activity of Pichia anomala or sensitivity of Penicillium roqueforti, respectively, were found between the three isolates tested of each species.Key words: biological control, postharvest, mold, cereal grain, storage.
Bacterial fitness and plasmid loss: the importance of culture conditions and plasmid size
Authors: Smith M Alex , Bidochka Michael J
Published: April 2011

Several pBluescript-derived plasmids of various sizes were constructed to study the effects of multicopy plasmid size on bacterial fitness and plasmid loss. Transformed and untransformed bacterial clones were grown in media with or without ampicillin. Bacterial fitness (measured by growth rate), plasmid presence or absence, and plasmid copy number were assessed during successive subculturings. In selective media (minimal medium or Luria Broth plus ampicillin), the clone transformed with the largest plasmid (pBluescript with a 9000-bp insert) had a significantly longer lag phase than all other clones. In nonselective media the rate of plasmid loss during successive subculturings was greatest in the clone with the largest insert. The clone with the largest insert displayed a lower plasmid copy number than clones with a small insert or no insert at all. Plasmid loss in the form of segregational instability and plasmid copy number reduction in nonselective environments are important to the understanding of the evolution of the bacteria-plasmid associations and the appreciation of the potential for altering the genetic properties of a clone maintained or subcultured on a standard medium.Key words: pBluescript, plasmid, stress, fitness, starvation.
HeLa cells as a model to study the invasiveness and biology ofLegionella pneumophila
Authors: Garduño Rafael A , Quinn Frederick D , Hoffman Paul S
Published: April 2011

HeLa cells were established as a model system to study the invasiveness and biology of Legionella pneumophila. In this model, invasion could be distinguished from adherence; virulent strains of L. pneumophila were adherent and invasive, whereas nonvirulent strains were adherent but poorly invasive. Invasion was rapid and did not require de novo bacterial protein synthesis, suggesting that the invasion factor is constitutively expressed by virulent strains. Entry into HeLa cells required actin polymerization and an intact microtubule cytoskeleton and was only moderately inhibited by the presence of 100 mM glucose or galactose. Intracellular replication of virulent L. pneumophila took place in ribosome-studded complex endosomes and led to the formation of free bacteria-laden vesicles presumably released from lysed HeLa cells, These free vesicles (referred to as mature vesicles) were isolated in continuous density gradients of Percoll. The bacteria contained in the isolated mature vesicles had a unique envelope structure and were highly adherent to HeLa cells, characteristics that correlated with a bright red appearance after the Giménez stain (Giménez positive). Plate-grown legionellae and replicating legionellae, harboured in complex endosomes, displayed a typical Gram-negative envelope and stained green after the Giménez stain (Giménez negative). Chronically infected cultures of HeLa cells were also established that may be a useful tool for studying long-term interactions between virulent L. pneumophila and mammalian cells. HeLa cells constitute a valuable model system that offers unique opportunities to study parasite-directed endocytosis, as well as stage specific host-parasite interactions.Key words: Legionella pneumophila, HeLa cells, invasion mechanisms, intracellular pathogens.
Evidence that a deferrioxamine B degrading enzyme is a serine protease
Authors: Zaya Ninef , Roginsky Alexandra , Williams Jamila , Castignetti Domenic
Published: April 2011

Siderophores are organic biomolecules synthesized by a wide variety of microbes. The molecules sequester ferric ion from environments where it is present at extremely low concentrations. Siderophores are of consequence with respect to microbial nutrition, pathogenicity, virulence, and microbe-plant interactions. How siderophores are degraded and returned to the carbon and nitrogen cycles is not well understood. The catalytic activity of an enzyme from a bacterium that degrades the siderophore deferrioxamine B has been examined. While the degradation of deferrioxamine B is sensitive to sulfhydryl and metal moiety inhibitors, the data presented is most consistent with the hypothesis that the enzyme uses a hydroxyl moiety (serine peptidase) to catalyze the degradation of deferrioxamine B. If sulfhydryl and metal inhibitors are simultaneously present at concentrations that when alone only partially inhibit the enzyme, the enzyme is unable to catalyze deferrioxamine B dissimilation. Analysis of the inhibitor experiments conducted led to the conclusion that the deferrioxamine B degrading enzyme is a serine-peptidase-like enzyme that needs calcium ions and sulfhydryl groups to be fully activated or stabilized. The knowledge of the catalytic moieties of the enzyme will be exploited to purify the enzyme.Key words: siderophores, deferrioxamine B, siderophore degradation.
Molecular analysis of bacterial isolates and total community DNA from kraft pulp mill effluent treatment systems
Authors: Fortin Nathalie , Fulthorpe Roberta R , Allen D Grant , Greer Charles W
Published: April 2011

Chloroaliphatics are major components of bleached kraft mill effluents. Gene probes and oligonucleotide primers were developed to monitor kraft pulp mill effluent treatment systems for the presence of key genes (dehalogenases) responsible for the dehalogenation of chloroaliphatic organics. The primers were used for polymerase chain reaction (PCR) analysis of genomic DNA extracted from dehalogenating bacterial isolates and from total community DNA extracted from water and sediments of mill effluent treatment systems. PCR amplification with oligonucleotide primers designed from dhlB, encoding the haloacid dehalogenase from Xanthobacter autotrophicus, revealed the presence of dehalogenase genes in both aerated lagoons and stabilization basins. Similarly, positive results were obtained with mmoX primers designed from the soluble methane monooxygenase gene of Methylococcus capsulatus Bath. The haloacetate dehalogenase encoding gene (dehH2) from Moraxella sp. was typically not detected in mill effluent treatment systems unless the biomass was selectively enriched. DNA sequence analysis of several PCR fragments revealed significant similarity to known dehalogenase and methane monooxygenase genes. The results indicated a broad distribution of known dehalogenation genes and bacteria with chloroorganic-degrading potential in the mill effluent treatment systems.Key words: dehalogenase, gene probes, chloroorganics, PCR, mill effluents.