bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth ofRhodococcusS1 on anthracene
Authors: Tongpim Saowanit , Pickard Michael A.
Published: February 2010

Three slow-growing bacteria were isolated from a mixed culture enriched for growth on anthracene, using creosote-contaminated soil as the inoculum. Organisms were shown to use anthracene by the production of a clear zone around the colony after a mineral salts agar plate was sprayed with anthracene. All three bacteria were nonmotile, nonsporulating, gram-positive rods and stained acid-fast. Physiological and biochemical tests, GC content, and cell wall lipid patterns of whole cell methanolysates indicated that they belonged to the Nocardia–Mycobacterium–Rhodococcus group. On the basis of these characteristics and pyrolysis gas chromatography, they were assigned to the genus Rhodococcus. Growth of the isolates was slow on crystalline anthracene, giving a doubling time of 1.5–3 days, and they grew mainly on the crystal surface. When anthracene was supplied by precipitation from a solvent, doubling time was reduced to 1 day. All three isolates mineralized anthracene but not phenanthrene or naphthalene, nor could they grow on naphthalene, phenanthrene, fluorene, fluoranthene, acenaphthene, pyrene, chrysene, or naphthacene as sole carbon source. One isolate, Rhodococcus S1, was able to use 2-methylanthracene or 2-chloroanthracene as carbon source but not 1- or 9-substituted analogs. These results suggest that the initial enzyme attacking anthracene in these isolates has a narrow substrate specificity.Key words: Rhodococcus, anthracene, polycyclic aromatic hydrocarbon, PAH.
Characterization of an extracellular asparaginase ofRhodosporidium toruloidesCBS14 exhibiting unique physicochemical properties
Authors: Ramakrishnan M. S. , Joseph Richard
Published: February 2010

An asparaginase specific for L-asparagine was purified from Rhodosporidium toruloides CBS14 to apparent homogeneity. The enzyme was associated with L-glutaminase activity (Km, 1.43 × 10−3 M for L-asparagine and 6.45 × 10−3 M for L-glutamine). The enzyme was found to be a homodimer with a subunit molecular mass of 87 kDa. Chemical modification of tryptophan residues significantly reduced both L-asparaginase and L-glutaminase activities of the enzyme, which was prevented by the presence of either of the substrates L-asparagine or L-glutamine. The pH and temperature optima for both activities were 6.35 and 37 °C. The enzyme was serologically identical with the asparaginases of some of the other Rhodotorula and Rhodosporidium yeasts but was distinct from the asparaginase of Saccharomyces cerevisiae.Key words: asparaginase, glutaminase, Rhodosporidium toruloides.
Genetic reidentification ofSaccharomycesstrains associated with black knot disease of trees in Ontario andDrosophilaspecies in California
Authors: Naumov Gennadi I. , Naumova Elena S. , Sancho Enrique D.
Published: February 2010

Using genetic hybridization analysis, electrophoretic karyotyping, and Southern hybridization with the ADC1 promoter probe, three biological sibling species, Saccharomyces cerevisiae, Saccharomyces paradoxus, and Saccharomyces bayanus, have been identified in Ontario and California. Saccharomyces kluyveri strains were revealed by karyotyping.Key words: genetical taxonomy, sibling species, Saccharomyces complex, electrophoretic karyotyping.
Microbial metal-binding mechanisms and their relation to nuclear waste disposal
Authors: McLean Robert J. C. , Fortin Danielle , Brown D. Ann
Published: February 2010

The cell surface polymers of microorganisms readily bind a variety of metal ions, which enables the organisms to immobilize potentially toxic metal ions before they encounter the plasma membrane. Under appropriate chemical conditions, bound metal ions can form a variety of minerals that may be of major geological importance. Many studies have shown the occurrence of metal binding and biomineralization in nature, but detailed knowledge of the underlying mechanisms is lacking. The microbial influence of this binding may be indirect, such as physicochemical influences on the solution chemistry, Eh, and pH; or direct, when it is determined by the type of organisms present, their energy metabolism, and the structural and chemical characteristics of the cell surface and extracellular polymers. Metal binding by bacterial cell surfaces has several implications in nuclear waste disposal including adsorption of soluble radionuclides. A detailed knowledge of the chemical mechanisms of metal interactions with the microbial cell surface will enhance our understanding of the geochemical environment within a nuclear waste disposal vault.Key words: biomineralization, radionuclide immobilization, biofilm, bacterial cell surface.
Cellulose-binding proteins ofFibrobacter succinogenesand the possible role of a 180-kDa cellulose-binding glycoprotein in adhesion to cellulose
Authors: Gong Jianhua , Egbosimba Emmanuel E. , Forsberg Cecil W.
Published: February 2010

Fibrobacter succinogenes possesses seven cellulose-binding proteins (CBPs) of 40, 45, 50, 120, 180, 220, and 240 kDa. The 120-, 180-, 220-, and 240-kDa proteins were present in the outer membrane (OM), while the 40-, 45-, 50-, and 120-kDa proteins were either periplasmic or peripheral membrane proteins. The 120-kDa CBP, which was identified as endoglucanase 2, was a major component in both the OM and periplasm. Zymogram analysis for glucanases showed that the major membrane-associated CBPs, with the exception of endoglucanase 2, lacked endoglucanase activity. Affinity-purified antibodies against the 180-kDa CBP cross-reacted strongly with numerous cell envelope proteins of higher and lower molecular mass, including the previously characterized chloride-stimulated cellobiosidase. Treatment of the 180-kDa CBP and cell envelope proteins with periodate resulted in almost complete loss of antibody binding, suggesting that they possessed a common epitope that was carbohydrate in nature. Immunogold labelling of whole cells using antibodies against the 180-kDa CBP demonstrated that either the 180-kDa CBP or related proteins with a cross-reactive epitope were located at the cell surface. These epitopes were distributed uniformly on cells not bound to cellulose but congregated on the cell surface at sites of adhesion of cells to cellulose. Antibodies to the 180-kDa protein caused 62% inhibition of binding of F. succinogenes to crystalline cellulose, which provides evidence that either the 180-kDa CBP and (or) other related cross-reactive surface proteins have a role in adhesion to cellulose.Key words: cellulose, adhesin, adhesion, binding, Fibrobacter, succinogenes, rumen.
Anti-adhesin antibodies that recognize a receptor-binding motif (adhesintope) inhibit pilus/fimbrial-mediated adherence ofPseudomonas aeruginosaandCandida albicansto asialo-GM1receptors and human buccal epithelial cell surface receptors
Authors: Lee Kok K. , Yu Lei , Macdonald Dawn L. , Paranchych William , Hodges Robert S. , Irvin Randall T.
Published: February 2010

Pseudomonas aeruginosa and Candida albicans were reported to adhere to the glycosphingolipid asialo-GM1by means of pili and fimbriae, respectively. These diverse adhesins have been previously reported to have an immunologically conserved antigenic epitope and the role of this cross-reactive epitope in adherence to asialo-GM1 was investigated in this study. Both the unbiotinylated PAK pilus and fimbrial adhesins inhibited biotinylated pili from P. aeruginosa PAK and biotinylated C. albicans fimbriae binding to asialo-GM1and receptors present on human buccal epithelial cells (BECs), which suggested that the same receptor sites were recognized by the two adhesins. Monoclonal antibodies PK99H and Fm16 raised against the P. aeruginosa PAK pili and C. albicans fimbriae, respectively, recognized a conserved epitope present on the two adhesins. Both Fm16 and PK99H blocked fimbriae binding to asialo-GM1and BEC receptors and also inhibited P. aeruginosa and C. albicans whole cell binding to BECs. These data suggested that the conserved epitope confers receptor-binding properties to the adhesins, demonstrated that (i) asialo-GM1-like receptors present on epithelial cell surfaces are utilized by the pilus and fimbrial adhesins and (ii) the binding to these glycoreceptors is mediated by a conserved epitope that has receptor-binding properties.Key words: adhesins, pilus, fimbria, receptors.
Lysis and biological control ofAspergillus nigerbyBacillus subtilisAF 1
Authors: Podile A. R. , Prakash A. P.
Published: February 2010

A biocontrol rhizobacterial strain of Bacillus subtilis AF 1 grown for 6 h was coinoculated with Aspergillus niger at different time intervals and microscopic observations revealed adherence of bacterial cells to the fungal mycelium. Bacterial cells multiplied in situ and colonized the mycelial surface. Growth of AF 1 resulted in damage to the cell wall, followed by lysis. AF 1 inoculation into media containing A. niger at 0, 6, and 12 h suppressed >90% fungal growth, while in 18- and 24-h cultures fungal growth inhibition was 70 and 56%, respectively, in terms of dry weight. In dual culture the fungal growth was not accompanied by formation of spores. The mycelial preparation of A. niger as principal carbon source supported the growth of B. subtilis, as much as chitin. Extracellular protein precipitate from B. subtilis culture filtrate had a significant growth-retarding effect on A. niger. Groundnut seeds bacterized with B. subtilis showed a reduced incidence of crown rot in A. niger infested soil, suggesting a possible role of B. subtilis in biological control of A. niger.Key words: mycolytic bacteria, Bacillus subtilis, Aspergillus niger, biological control.
Flocculation onset, growth phase, and genealogical age in Saccharomyces cerevisiae
Authors: Soares Eduardo V. , Mota Manuel
Published: February 2010

Flocculation onset, the time during the fermentative cycle at which the strains of Saccharomyces cerevisiae become flocculent, is an important factor in the brewing industry. The flocculation ability of Flo1 phenotype (strain NCYC 869) remained practically unchanged throughout the growth and seems to be insensitive to the presence of nutrients of the culture medium. On the contrary, the flocculation of NewFlo phenotype (strain NCYC 1195) exhibited a cyclic behaviour. It was found that the loss of flocculation in the early growth was the result of two combined effects: the dismantling of the flocculation mechanism of the cells coming from the inoculum and the nonflocculent state of the new cells produced after growth has started. The onset of flocculation of strain NCYC 1195 in the cultural conditions used in this work coincided with the end of the exponential growth, when the minimum glucose level in the culture medium was attained. It was demonstrated that it is possible to manipulate the flocculation onset by changing the initial glucose concentration in the culture medium.Key words: yeast, flocculation inhibition, glucose limitation, flocculation onset, genealogical age.
Surface composition, surface properties, and adhesiveness ofAzospirillum brasilense—variation during growth
Authors: Dufrêne Yves F. , Rouxhet Paul G.
Published: February 2010

The surface chemical composition, the physicochemical properties, and the adhesiveness of Azospirillum brasilense have been investigated during growth in Luria–Bertani* rich medium. The surface elemental composition obtained by X-ray photoelectron spectroscopy was converted into a molecular composition in terms of model constituents: proteins, polysaccharides, and hydrocarbon-like compounds. The protein content increased during growth, from 30 (exponential phase cells) to 50% (stationary phase cells), concomitantly with a decrease in the polysaccharide content, from 60 to 35%. These modifications were related to a change in cell surface hydrophobicity, i.e., to an increase of the water contact angle from 20 to 60°. No difference of electrophoretic mobility was detected between cells harvested in the exponential phase and cells harvested in the stationary phase. The increase of both cell surface protein concentration and cell surface hydrophobicity during growth was correlated with an increase of cell adhesiveness to model supports. This points to the involvement of cell surface proteins and cell surface hydrophobicity in the adhesion process.Key words: Azospirillum brasilense, surface composition, hydrophobicity, adhesiveness, X-ray photoelectron spectroscopy.
Heat-shock response of the entomopathogenic fungusBeauveria brongniartii
Authors: Xavier Ilungo J. , Khachatourians George G.
Published: February 2010

The heat-shock response of five strains of the entomopathogenic fungus Beauveria brongniartii was studied using two-dimensional (2D) gel electrophoresis. The fungal cells were heat shocked at 45 °C for 1 h and the total cellular protein was subjected to 2D gel electrophoresis. Proteins were separated in the first dimension using isoelectric focusing (pH range of 3.0–10) and in the second dimension by sodium dodecyl sulphate – polyacrylamide gel electrophoresis. More than 150 polypeptides for each strain were visualized by silver staining and have been assigned individual numbers as polypeptide coordinates. Analysis of the polypeptide map obtained by 2D gels indicated three patterns; several unique heat-shock proteins (HSPs) were (i) induced, (ii) enhanced, or (iii) repressed. Some of the HSPs induced by 45 °C were unique for each of the strains tested. Identification of heat-inducible protein synthesis or repression has ramifications for field survival and performance of entomopathogenic fungi. As well, the HSPs can be used as "signature proteins" for identification pruposes and this raises the possibility of using HSPs as a diagnostic tool applicable to other pest control fungi.Key words: heat-shock proteins, heat-shock response, two-dimensional electrophoresis, entomopathogenic fungi, Beauveria brongniartii.
Expression of theEscherichia colichromosomalarsoperon
Authors: Cai Jie , DuBow Michael S.
Published: February 2010

A chromosomally located operon (ars) of Escherichia coli has been previously shown to be functional in arsenic detoxification. DNA sequencing revealed three open reading frames homologous to the arsR, arsB, and arsC open reading frames of plasmid-based arsenic resistance operons isolated from both E. coli and staphylococcal species. To examine the outline of transcriptional regulation of the chromosomal ars operon, several transcriptional fusions, using the luciferase-encoding luxAB genes of Vibrio harveyi, were constructed. Measurement of the expression of these gene fusions demonstrated that the operon was rapidly induced by sodium arsenite and negatively regulated by the trans-acting arsR gene product. Northern blotting and primer extension analyses revealed that the chromosomal ars operon is most likely transcribed as a single mRNA of approximately 2100 nucleotides in length and processed into two smaller mRNA products in a manner similar to that found in the E. coli R773 plasmid-borne ars operon. However, transcription was found to initiate at a position that is relatively further upstream of the initiation codon of the arsR coding sequence than that determined for the E. coli R773 plasmid's ars operon.Key words: arsenic resistance, Escherichia coli, transcription, gene fusions.
Polymorphism in morels: isozyme electrophoretic analysis
Authors: Wipf Daniel , Bedell Jean-Philippe , Botton Bernard , Munch Jean Charles , Buscot François
Published: February 2010

The aim of this study was to assess whether isozyme polymorphism in different members of the Morchellaceae could be used to improve the systematics in this fungal group and to characterize intraspecific crossings between monosporal strains in Morchella esculenta. For this purpose, isozyme electrophoretic analysis of the following enzymes was performed: glutamine synthetase, NAD–glutamate dehydrogenase, NADP–glutamate dehydrogenase, aspartate aminotransferase, malate dehydrogenase, NAD–glyceraldehyde phosphate dehydrogenase, glucose phosphate isomerase, and superoxide dismutase. The analyses allowed discrimination at the inter- or intra-specific levels and could help to establish a method of identification for strains in the Morchellaceae. To a certain extent they appeared to be suitable to analyze interactions of monosporal strains of Morchella esculenta in pairing experiments. The polymorphism shown in this study was consistent with the phylogenetic relationships between the investigated strains only at the genus level.Key words: isozyme analysis, electrophoresis, Morchella sp., polymorphism.
Preference in the nodulation ofPhaseolus vulgariscv. RAB39. II. Effect of delayed inoculation or low cell representation in the inoculant on nodule occupancy byRhizobium tropiciUMR1899
Authors: Montealegre Constanza , Graham Peter H.
Published: February 2010

Common bean (Phaseolus vulgaris L.) is a traditional crop in much of Latin America, where it is often planted into soils containing numerous, sometimes ineffective, indigenous rhizobia. The presence of these indigenous organisms can limit response to inoculation. Because of this, we have sought bean cultivars that will nodulate preferentially with the inoculant strain, and have previously reported on the preference between the bean cultivar RAB39 and strains of Rhizobium tropici. We have detailed this interaction using the inoculant-quality strain UMR1899. In the present study the root tip marking (RTM) technique was used to demonstrate that this preference in nodulation was evident, even when inoculation with UMR1899 was delayed up to 8 relative to that with Rhizobium etli UMR1632. In contrast to studies with other legumes, roots of RAB39 were not predisposed to nodulate with UMR1632, even though preexposed to this strain for considerable periods of time. The presence of UMR1899 actually reduced nodulation by UMR1632 substantially, even when inoculation with UMR1899 was significantly delayed. When UMR1899 and UMR1632 were applied to separate halves of a split-root system, the number of nodules on the side receiving UMR1632 was less than for the half root inoculated with UMR1899, but the differences were not significant. This suggests that the preference response is not systemic but requires proximity between the strains involved. UMR1899 produced more than 50% of the nodules even when the ratio of UMR1632:UMR1899 in the inoculant was 10:1. The results are further evidence of a stable and marked preference of RAB39 for UMR1899, which warrants a more detailed study at the field level.Key words: Phaseolus vulgaris L., common bean, delayed inoculation, strain preference, cell proportions.
Microbial transformation of 3,4-methylenedioxy-N-methylamphetamine and 3,4-methylenedioxyamphetamine
Authors: Foster B. C. , Wilson D. L. , Marwood T. , Ethier J. C. , Zamecnik J.
Published: February 2010

The biotransformation of 3,4-methylenedioxy-N-methylarnphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) was examined in the fungus Cunninghamella echinulata. In addition to the reported mammalian metabolites (MDA, 3,4-methylenedioxybenzyl methyl ketoxime, 3,4-methylenedioxybenzyl methyl ketone) and the parent substrate, there were six novel metabolites detected. N-Acetyl-3,4-methylenedioxyamphetamine (NAcMDA) was unequivocally identified and three unidentified metabolites related to NAcMDA were also detected. N-Acetyl-3,4-methylenedioxy-1-phenyl-1-hydroxy-2-aminopropane was tentatively identified as a metabolite of MDMA. The only metabolite of MDA identified was NAcMDA. Two metabolites related to MDA remain unidentified.Key words: Cunninghamella, amphetamine, biotransformation, 3,4-methylenedioxy-N-methylamphetamine, 3,4-methylenedioxyamphetamine.
Analysis by flow cytometry of surface-exposed epitopes of outer membrane protein F ofPseudomonas aeruginosa
Authors: Hughes Eileen E. , Gilleland Jr. H. E. , Matthews-Greer Janice M.
Published: February 2010

Antisera were produced in mice immunized with 18 synthetic peptide conjugates representing various regions throughout the length of the outer membrane protein F molecule of Pseudomonas aeruginosa and analysed by flow cytometry to identify those antisera capable of binding to the surface of whole cells of P. aeruginosa. Antibodies to peptides 9, 18, 10, and 4 were significantly cell-surface reactive. The maximum median percentage of antibody-binding cells in this assay was 36.6%. Over six different determinations, peptide 9 antisera binding to the cells ranged from 16.9 to 57.0% of the cell population. We propose that the surface accessibility of protein F epitopes varies during the cell cycle.Key words: surface-exposed epitopes, outer membrane protein F, Pseudomonas aeruginosa, flow cytometry.
Influence of indoleacetic-acid-producing Bacillus isolates on the nodulation of Phaseolus vulgaris by Rhizobium etli under gnotobiotic conditions
Authors: Srinivasan M. , Holl F. B. , Petersen D. J.
Published: February 2010

Twenty-two Bacillus spp. isolates from the rhizosphere of Phaseolus vulgaris 'Contender' were identified using Biolog™, gas chromatographic fatty acid methyl ester, and 23S rDNA analyses. Some of the Bacillus isolates produced significant amounts of the phytohormone indoleacetic acid (IAA) when grown in a liquid culture medium supplemented with 100 μg L-tryptophan/L; less IAA was produced in culture medium not supplemented with L-tryptophan. Thin-layer chromatography, high-performance liquid chromatography, gas chromatography – mass spectrometry, and the avena coleoptile bioassay were used to identify and quantify IAA produced by Bacillus isolates. Significant differences were observed in the amounts of IAA produced by different strains of Bacillus, with amounts varying from 0.40 to 4.88 μg/mL. α-Methyltryptophan-resistant mutants of Bacillus exhibited altered IAA production and excreted tryptophan into the growing medium. The IAA-producing Bacillus isolates promoted root growth and (or) nodulation when coinoculated with Rhizobium etli (TAL 182) on Phaseolus vulgaris 'Contender' under gnotobiotic conditions in growth chambers. Coinoculation resulted in increased nodule number, nodule fresh weight, nitrogenase activity, leghemoglobin content, and total soluble protein content in the root nodules of Phaseolus vulgaris. In contrast, coinoculation with α-methyltryptophan mutants resulted in decreased nodulation, indicating that Bacillus isolates have a direct effect on either the Rhizobium or the plant and the effect may not be singularly attributed to their ability to produce IAA in vitro.Key words: Bacillus, indoleacetic acid production, nodulation enhancement.
Staphylococcus aureusstrains differ in their in vitro responsiveness to human urokinase: evidence that methicillin-resistant strains are predominately nonresponsive to the growth-enhancing effects of urokinase
Authors: Hart David A. , Reno Carol , Louie Thomas , Krulicki Wallace
Published: February 2010

Clinical isolates of Staphylococcus aureus were found to exhibit strain-specific heterogeneity to the growth-enhancing effects of human urokinase (UK), a proteinase with plasminogen activator activity. Nine out of fourteen (64%) methicillin-sensitive strains of S. aureus were responsive to UK in "in vitro" cultures. In contrast, 3/29 (10%) methicillin-resistant strains were responsive to the proteinase. When only strains isolated from western Canada were considered, 6/11 methicillin-sensitive strains and 1/26 methicillin-resistant strains were responsive to UK. The single western Canadian methicillin-resistant strain (strain 456) responsive to UK was one of two isolated from the same patient, indicating that the two strains were phenotypically different. Strain 456, resistant to 32 μg mefhicillin/mL, was responsive to as little as 50 U UK/mL and enhancement of growth was evident by 9 h of incubation at 37 °C. This growth enhancement was specific to UK and not duplicated by equivalent concentrations of other proteins (bovine serum albumin, trypsin, plasminogen). The results presented indicate differences in the frequency of the UK-responsive phenotype between methicillin-sensitive and -resistant S. aureus. These findings indicate that the UK phenotype of S. aureus may have utility in both phenotyping clinical isolates, as well as providing insights into the regulation of growth in this clinically important organism.Key words: Staphylococcus aureus, growth, urokinase, methicillin resistance.
Differential sensitivity of 16S rRNA targeted oligonucleotide probes used for fluorescence in situ hybridization is a result of ribosomal higher order structure
Authors: Frischer Marc E. , Floriani Peter J. , Nierzwicki-Bauer Sandra A.
Published: February 2010

The use of 16S rRNA targeted gene probes for the direct analysis of microbial communities has revolutionized the field of microbial ecology, yet a comprehensive approach for the design of such probes does not exist. The development of 16S rRNA targeted oligonucleotide probes for use with fluorescence in situ hybridization (FISH) procedures has been especially difficult as a result of the complex nature of the rRNA target molecule. In this study a systematic comparison of 16S rRNA targeted oligonucleotide gene probes was conducted to determine if target location influences the hybridization efficiency of oligonucleotide probes when used with in situ hybridization protocols for the detection of whole microbial cells. Five unique universal 12-mer oligonucleotide sequences, located at different regions of the 16S rRNA molecule, were identified by a computer-aided sequence analysis of over 1000 partial and complete 16S rRNA sequences. The complements of these oligomeric sequences were chemically synthesized for use as probes and end labeled with either [γ-32P] ATP or the fluorescent molecule tetramethylrhodamine-5/-6. Hybridization sensitivity for each of the probes was determined by hybridization to heat-denatured RNA immobilized on blots or to formaldehyde fixed whole cells. All of the probes hybridized with equal efficiency to denatured RNA. However, the probes exhibited a wide range of sensitivity (from none to very strong) when hybridized with whole cells using a previously developed FISH procedure. Differential hybridization efficiencies against whole cells could not be attributed to cell wall type, since the relative probe efficiency was preserved when either Gram-negative or -positive cells were used. These studies represent one of the first attempts to systematically define criteria for 16S rRNA targeted probe design for use against whole cells and establish target site location as a critical parameter in probe design.Key words: 16S rRNA, oligonucleotide probes, in situ hybridization.
Movement of Pseudomonas aureofaciens from the rhizosphere to aerial plant tissue
Authors: Lamb Thomas G. , Tonkyn David W. , Kluepfel Daniel A.
Published: February 2010

Following inoculation onto seeds, the rhizobacterium Pseudomonas aureofaciens Ps3732RNL11 (L11), which contains the constituitively expressed lacZ and lacY genes from Escherichia coli, was recovered from the interior of aerial tissues of all 16 monocot and dicot plants tested, and the exterior of aerial surfaces of 15. In more detailed studies with corn, wheat, and broccoli, both Ps3732RNL11 and its nonengineered parent strain PS3732RN (RN) rapidly established large populations on all root systems and smaller densities within the aerial tissues, all of which persisted at stable levels throughout 12- to 23-day test periods. There were no differences in the behavior of L11 and RN on any of the three plant species. L11 invaded the aeriel tissues of corn in at least two distinct ways. First, it moved into the interior of leaves following inoculation of guttation drops, suggesting that the bacteria may contaminate the developing shoot prior to its emergence from the soil and then invade through natural openings. However, when this route was blocked by inoculating the roots after shoot emergence in either soil or hydroponic systems, the bacteria still invaded the aerial tissues within 24 h, suggesting direct vascular transport from the roots. Such bacterial movement is an important consideration in future field releases of both native and genetically modified rhizobacteria.Key words: rhizosphere, genetically engineered microorganism, Pseudomonas aureofaciens.
Genetic diversity amongBradyrhizobiumisolates that effectively nodulate peanut (Arachis hypogaea)
Authors: Urtz Bruce E. , Elkan Gerald H.
Published: February 2010

Symbiotic gene diversity and other measures of genetic diversity were examined in Bradyrhizobium isolates that form an effective symbiosis with peanut (Arachis hypogaea). Initially, restriction fragment length polymorphism (RFLP) analysis using a nitrogenase (nif) gene probe was performed on 33 isolates along with one Bradyrhizobium elkanii and two Bradyrhizobium japonicum strains. Considerable diversity was observed among the RFLP patterns of many of the isolates, especially those from South America. Some isolates, however, were found to have similar nif and subsequent nod (nodulation) gene RFLP patterns, indicating symbiotic gene relatedness. With some noted exceptions, symbiotic gene relatedness correlated with relatedness based on total DNA homology and ribotyping analyses. Symbiotic gene relatedness also correlated with symbiotic effectiveness. The RFLP and DNA homology analyses indicate that bradyrhizobia effective with peanut are genetically diverse and consist of at least three different species. This diversity, however, was not particularly evident with partial 16S rRNA gene sequencing. Sequences obtained from the isolates were very similar to each other as well as to sequences previously reported for other Bradyrhizobium strains.Key words: Bradyrhizobium, nif, peanut, restriction fragment length polymorphism, 16S rRNA.
Organization and interactions of cell envelope proteins of the extreme thermoacidophileSulfolobus acidocaldarius
Authors: Grogan Dennis W.
Published: February 2010

To address basic questions concerning proteins of the Sulfolobus acidocaldarius cell envelope, cell ghosts (empty cells consisting of cytoplasmic membrane complexed with the glycoprotein S-layer) were isolated and analyzed by standard biochemical methods. The constituent proteins included the two dissimilar subunits also found in the baglike structures (sacculi) of S-layer (purified from whole cells by detergent extraction), plus approximately 30 additional protein species. When S-layer-dissociating conditions were applied to intact cell ghosts, the large sacculus subunit was released, whereas the small subunit remained bound to the cytoplasmic membrane. These results provided evidence that the small subunit may anchor the S-layer to the S. acidocaldarius cell membrane. The S. acidocaldarius S-layer was highly resistant to proteolysis in its native state but not when dissociated into subunits. Virtually all other membrane-associated proteins were readily digested by pronase treatment of cell ghosts. Pronase treatment of whole cells, in contrast, removed only a defined subset of the membrane-associated proteins, suggesting that this subset represents a few proteins normally exposed to the external medium. Several putative membrane glycoproteins were detected in cell ghosts that were not demonstrably associated with the S-layer.Key words: Archaea, geothermal environments, cell envelope, denaturing conditions, membrane proteins, S-layer.
Evidence for independent binding domains within a group A streptococcal type IIo IgG-binding protein
Authors: Tsivitse Maryanne , Boyle Michael D. P.
Published: February 2010

The gene for a type IIo IgG-binding protein has previously been cloned and sequenced. The ~60 000 Mrrecombinant gene product binds all four human IgG subclasses and fibrinogen. Treatment of this recombinant protein with CNBr results in generation of a series of fragments. One fragment, an ~32 000 Mrpolypeptide, binds IgG1, IgG2, and IgG4but neither IgG3nor fibrinogen. N-terminal amino sequencing of this fragment indicated that this was an internal fragment of the protein starting at amino acid 186 of the mature protein. These findings provide evidence for two distinct domains for binding IgG1, IgG2, and IgG4and binding IgG3within a single bacterial IgG-binding protein.Key words: IgG-binding protein, protein H, Streptococcus pyogenes.
Metabolism of pyrene by basidiomycetous fungi of the generaCrinipellis,Marasmius, andMarasmiellus
Authors: Lange Bettina , Kremer Stefan , Anke Heidrun , Sterner Olov
Published: February 2010

The ability of different species and strains of the genus Crinipellis and the related genera Marasmius and Marasmiellus to metabolize pyrene was investigated. The metabolism of pyrene and the nature of metabolites formed were strain specific and depended on the culture medium. The following metabolites of pyrene were detected in the cultures: 1-hydroxypyrene, 1-pyrenylsulfate, 1,6- and 1,8-dihydroxypyrene and the corresponding quinones, trans-4,5-dihydro-4,5-dihydroxypyrene, and two transformation products which have never before been detected, 6-hydroxypyrene-1-sulfate and pyrene-1,6-disulfate. In addition, several not yet identified pyrene metabolites were produced by some strains.Key words: polycyclic aromatic hydrocarbons, pyrene, basidiomycetes, metabolism, transformation products.
Segregation of yeast polymorphic STA genes in meiotic recombinants and analysis of glucoamylase production
Authors: Balogh István , Maráz Anna
Published: February 2010

Hybrid yeast strains were constructed using haploid Saccharomyces cerevisiae and Saccharomyces cerevisiae var. diastaticus strains to get haploid meiotic recombinants having more than one copy of STA1, STA2, and STA3 genes. STA genes were localized on the chromosomes by pulsed field gel electrophoresis. Working gene dosage effects were found among STA genes in liquid starch medium, indicating low levels of glucose repression. Growth of strains, however, was not influenced by their STA copy number.Key words: yeast, STA genes, gene dosage, karyotyping.
ASaccharomyces cerevisiaephleomycin-sensitive mutant, phl40, is defective in theRAD6DNA repair gene
Authors: He Chuan Hua , Masson Jean-Yves , Ramotar Dindial
Published: February 2010

The antibiotic bleomycin is used as an anticancer agent for treating a variety of tumours. The antitumour effect of bleomycin is related to its ability to produce lesions such as apurinic/apyrimidinic sites and single- and double-strand breaks in the cellular DNA. Phleomycin is a structurally related form of bleomycin, but it is not used as an anticancer agent. While phleomycin can also damage DNA, neither the exact nature of these DNA lesions nor the cellular process that repairs phleomycin-induced DNA lesions is known. As a first step to understand how eukaryotic cells provide resistance to phleomycin, we used the yeast Saccharomyces cerevisiae as a model system. Several phleomycin-sensitive mutants were generated following γ-radiation treatment and among these mutants, phl40 was found to be the most sensitive to phleomycin. Molecular analysis revealed that the mutant phl40 harbored a mutation in the DNA repair gene RAD6. Moreover, a functional copy of the RAD6 gene restored full phleomycin resistance to strain phl40. Our findings indicate that the RAD6 protein is essential for yeast cellular resistance to phleomycin.Key words: yeast, phleomycin, DNA repair, RAD6.
Tn5431 arose by transposition of Tn3 into Tn 1721
Authors: Žgur-Bertok Darja , Ambrožič Jerneja , Grabnar Miklavž
Published: February 2010

To further characterize Tn5431, which is composed of Tn3 and Tn1721, DNA sequencing was carried out. It was demonstrated that Tn5431 arose by transposition of Tn3 into Tn1721. Multiple mutations in the Tn3 tnpA gene have occurred, rendering the Tn3 portion of Tn5431 transposition defective and ensuring the simultaneous transposition of the antibiotic resistance determinants on Tn3 and Tn1721.Key words: transposon Tn5431, assembly, Tn3 transposition.
Dynamics of growth and death within aSalmonella typhimuriumpopulation during infection of macrophages
Authors: Buchmeier Nancy A. , Libby Stephen J.
Published: February 2010

Survival of Salmonella typhimurium within macrophages is associated with virulence. Most data on the fate of Salmonella during infection of macrophages are derived from viable counts of intracellular bacteria. These counts are a result of a combination of bacterial death and growth within the intracellular population but may not reflect the true levels of either macrophage killing of Salmonella or bacterial growth inside cells. In this study, two independent methods have been used to obtain a more accurate measurement of absolute levels of both death and growth of Salmonella inside macrophages. A purine auxotroph (purD) was used to measure Salmonella death in the absence of bacterial growth and then bacterial growth was measured by supplementing the purD cultures with adenosine. Numbers of dead and live Salmonella were also quantitated using the BacLight staining system, which distinguishes dead from live bacteria. Both methods demonstrate that killing of Salmonella by macrophages is considerably greater than detected using traditional cell counts and that bacterial inactivation occurs throughout the infection period. Salmonella was inactivated at a similar rate in both J774 macrophages (most permissive macrophages) and peritoneal exuadate macrophages (least permissive macrophages), suggesting that the major difference between these cells is the ability to limit bacterial growth. These studies also demonstrate that growth of Salmonella within murine macrophages occurs simultaneously with significant amounts of bacterial death. Identifying the factors responsible for shifting the interaction between macrophages and bacteria toward conditions that favor bacterial growth will be critical to understanding Salmonella virulence.Key words: Salmonella, macrophage, purD, purine auxotroph.
The use of methyl β-D-xyloside as a substrate for xylanase production byAspergillus tamarii
Authors: Simāo R. C. G. , Souza C. G. M. , Peralta R. M.
Published: February 2010

Aspergillus tamarii was able to produce biomass in media containing β-methyl D-xyloside, a synthetic analogue of xylobiose, as the only carbon source. β-Methyl D-xyloside was a more effective inducer than xylan at the same concentration for xylanase and β-xylosidase activities. The delayed consumption of β-methyl D-xyloside by A. tamarii cells suggests the requirement of a specific inducible transport system and a slow metabolic process. The synthesis of this transport system was probably repressed by the presence of easily metabolizable sugars. β-Methyl D-xyloside was hydrolyzed to xylose by an intracellular β-xylosidase.Key words: xyanolytic microorganisms, xylanase, β-xylosidase, Aspergillus tamarii.
Cloning and molecular analysis of promoter-like sequences isolated from the chromosomal DNA ofLactobacillus acidophilusATCC 4356
Authors: Djordjevic G. , Bojovic B. , Miladinov N. , Topisirovic L.
Published: February 2010

Promoter-like sequences from the chromosomal DNA of thermophilic strain Lactobacillus acidophilus ATCC 4356 were cloned. Analysis of the three DNA fragments showing promoter activity, designated P3, P6, and P15, were performed in Lactobacillus reuteri, Lactococcus lactis, and E. coli. The reporter cat-86 gene was expressed in all three bacterial species under control of the fragments P3 and P6. Fragment P15 showed promoter activity only in Lactobacillus reuteri and E. coli but not in Lactococcus lactis. The three host-specific transcriptional start points (TSPs) were used when transcription of the cat-86 gene was controlled by fragment P3 in Lactobacillus reuteri, E. coli, and Lactococcus lactis. Similarly, fragment P15 initiated transcription of the cat-86 gene at two distinctive sites in Lactobacillus reuteri and E. coli. Only within fragment P6, a common TSP was used in Lactobacillus reuteri and E. coli, but different from that used in Lactococcus lactis. Each TSP was preceded by the putative −35 and −10 hexamers. Computer analysis of the fragment P3 sequence revealed the existence of divergent promoterlike sequence (P3rev) located on the complementary DNA strand. Fragments P6 and P15 were also functional in Lactobacillus acidophilus ATCC 4356 from which chromosomal DNA they were originally cloned.Key words: Lactobacillus acidophilus, promoter-like sequences, regulation.
Distribution of ectomycorrhizal fungi in pure stands of different age groups ofPinus kesiya
Authors: Rao C. S. , Sharma G. D. , Shukla A. K.
Published: February 2010

A study on ectomycorrhizae and mycorrhizal fungi of Pinus kesiya (Royle ex Gordon) in 2-, 4-, 11-, and 17-year-old pine plantations was carried out. Thirteen mycorrhizal fungi forming ectomycorrhiza with khasi pine were observed. Diversity index of mycorrhizal fungi was directly proportional to the age of the pine stand. The maximum number of fungal species was observed in the oldest stand. Evenness of the sheathing mycorrhizal fungi was also increased with the increase in age of pine. The sporocarps of Boletus luteus, Scleroderma aurantium, Tricholoma saponaceum, and Hygrophorus limacinus were observed as an early colonizing fungi with Pinus kesiya. However, in older plantations Russula lepida and Amanita phalloides were observed as late stage fungi. Boletus luteus and Scleroderma aurantium were dominant species in all the pine stands. Sporocarps of mycorrhizal fungi were maximum during the rainy season and minimum during the winter months. A positive correlation was observed between the number of ectomycorrhizae and mycorrhizal infection with soil moisture, soil pH, total nitrogen, available phosphorus, exchangeable potassium, and organic matter of the soil. The number of sporocarps exhibited a positive significant correlation with soil moisture content in all the plantations.Key words: ectomycorrhiza, fungi, physicochemical characters, Pinus kesiya.
Azospirillum– plant relationships: environmental and physiological advances (1990–1996)
Authors: Bashan Yoav , Holguin Gina
Published: February 2010

This review presents a critical and comprehensive analysis of the developments in environmental and physiological studies related to Azospirillum interactions with plants based on information published between 1990 and 1996. It was designed as an update of a previous review with a similar scope. Apart from an update, this review emphasizes the central issues of Azospirillum research today, such as coinoculation with other microorganisms and hormonal studies, shows the less researched areas, and proposes possible avenues for the exploitation of this bacterium in areas other than agriculture.Key words: Azospirillum, bacterial inoculation, plant–bacteria interaction, plant growth promoting rhizobacteria, rhizosphere bacteria.
Characterization of a lipopeptide-resistant strain ofCandida albicans
Authors: Frost David J. , Knapp Melinda , Brandt Kim , Shadron Amber , Goldman Robert C.
Published: February 2010

Lipopeptides are antifungal agents that inhibit cell wall β-(1, 3)-glucan biosynthesis in fungal organisms. A mutant resistant to lipopeptides was generated by UV mutagenesis and characterized. The Candida albicans mutant (LP3-1) was stable and showed resistance specificity to a broad range of lipopeptides and certain glycolipid inhibitors. Other antifungal agents with diverse modes of action had a normal minimum inhibitory concentration profile for LP3-1 compared with the wild-type strain (CCH 442). In the in vitro β-(1, 3)-glucan synthase assay, both the lipopeptides and papulacandin-related agents had considerably higher 50% inhibitory concentration values in the LP3-1 strain than in the wild-type strain. In reconstitution assays, the resistance factor was associated with the integral membrane pellet rather than the peripheral GTP-binding protein. The LP3-1 strain had a membrane lipid profile similar to that of the parent strain and was virulent in a murine model of systemic candidiasis. Taken together, these results indicate that the resistance factor is associated with the integral membrane component of β-(1, 3)-glucan synthase. Lipopeptides are common antifungal agents encountered during screening of natural products. The LP3-1 strain was resistant to natural product extracts known to contain various lipopeptides. Thus, LP3-1 can be used in a dereplication assay.Key words: Candida albicans, β-(1, 3)-glucan synthase, lipopeptides, drug resistance.
Rapid procedure for acid adaptation of oral lactic-acid bacteria and further characterization of the response
Authors: Ma Yousheng , Curran Timothy M. , Marquis Robert E.
Published: February 2010

Acid-adaptive responses could be induced readily in oral lactic-acid bacteria by growing them in batch cultures with excess sugar or more conveniently and rapidly by transferring cells to acidified growth media for the time required for biomass doubling. The response of Streptococcus mutans GS-5 was induced in a progressive rather than all-or-nothing way, and the extent of acid tolerance was inversely related to the pH of the inducing medium over a range from 8.5 to 5. The weak acids fluoride, acetate, or lactate did not measurably enhance acid adaptation, and so the response did not appear to depend primarily on changes in ΔpH or the proton motive force across the cell membrane. Transcription and translation to form new proteins did appear to be necessary, as indicated by inhibition of adaptation by rifampin or chloramphenicol and by lack of adaptation by cells suspended in phosphate buffer at pH 5. Streptococcus salivarius and Lactobacillus casei were acid adapted by the rapid method, and the method appeared to be generally useful for oral lactic-acid bacteria. The rapid induction of the response in multiple oral lactic-acid bacteria suggests that it is of general importance for maintaining a diversity of organisms in the oral microbiota, which is regularly subjected to acid stresses.Key words: acid adaptation, oral lactic-acid bacteria, Streptococcus mutans.
A specific oligonucleotide primer for the rapid detection of Lactobacillus lindneri by polymerase chain reaction
Authors: Yasui Tetsuji , Taguchi Hiroshi , Okamoto Tomoyuki
Published: February 2010

A polymerase chain reaction (PCR) method was developed for the rapid detection of the beer-spoilage heterofermentative lactic acid bacterium Lactobacillus lindneri. Three strains, the Chinese brewery isolate DA1, the Japanese commercial beer isolate BG2, and the Japanese brewery isolate SE3, which were serologically classified as belonging to L. lindneri, were used in this study. After sequencing the 16S rDNA of the isolates DA1 and BG2 and the typical beer-spoilage heterofermentative Lactobacillus brevis L63, these sequences were compared with published data. A L. lindneri specific PCR primer, DA-40, was then constructed based on the V1 variable region of 16S rDNA. The specificity of PCR using the L. lindneri specific primer DA-40 and the universal primer 907r was examined using five L. lindneri strains: the three isolates described above and two strains from culture collection, DSM 20690 and DSM 20692. A variety of beer-spoilage lactic acid bacteria, including 71 Lactobacillus strains and 13 Pediococcus strains, were also included in this examination. No PCR product was obtained from any DNA with the exception of the five L. lindneri strains, indicating that the L. lindneri specific primer DA-40 was highly specific. The detection limit for L. lindneri in beer was 63 CFU/100 mL of beer.Key words: Lactobacillus lindneri, oligonucleotide probe, sequence analysis, 16S rDNA.