Showing papers in "Canadian Journal of Microbiology in 1994"
TL;DR: The plant growth promoting rhizobacterium Pseudomonas putida GR12-2 can utilize 1-aminocyclopropane-1-carboxylate as a sole nitrogen source because it possess the unusual enzyme ACC deaminase, which hydrolyzes ACC to ammonia and α-ketobutyrate.
Abstract: The plant growth promoting rhizobacterium Pseudomonas putida GR12-2 can utilize 1-aminocyclopropane-1-carboxylate (ACC) as a sole nitrogen source because it possess the unusual enzyme ACC deaminase...
330 citations
TL;DR: Tolerance to acid pH in R. tropici UMR1899 was not an adaptive response, nor was it plasmid mediated, correlated with the production of extracellular polysaccharide, or related to synthesis of polyamines in the cell.
Abstract: Acid pH limits the persistence of Rhizobium strains in soil, and the nodulation and nitrogen fixation of legumes. To identify acid-tolerant strains, we tested the ability of 45 Rhizobium, Azorhizob...
267 citations
TL;DR: The plant growth promoting rhizobacterium Pseudomonas putida GR12-2 was mutagenized with nitrosoguanidine and three separate mutants that were unable to utilize 1-aminocyclopropane-1-carboxylic acid as a sole nitrogen source were selected, promoting root elongation of developing canola seedlings under gnotobiotic conditions.
Abstract: The plant growth promoting rhizobacterium Pseudomonas putida GR12-2 was mutagenized with nitrosoguanidine and three separate mutants that were unable to utilize 1-aminocyclopropane-1-carboxylic aci...
243 citations
TL;DR: Respirometric measurements of microbial activity within microcosms containing oil sands tailings were used to provide further evidence that the indigenous microbial community could biodegrade naphthenic acids and components within the extracted organic acids mixture.
Abstract: Organic acids, similar in structure to naphthenic acids, have been associated with the acute toxicity of tailings produced by the oil sands industry in northeastern Alberta, Canada. Bacterial cultu...
213 citations
TL;DR: 2,4-Diacetylphloroglucinol was detected in and isolated from culture extracts of the biological control bacterium Pseudomonas fluorescens Pf-5 and its structure was identified using a combination of c...
Abstract: 2,4-Diacetylphloroglucinol was detected in and isolated from culture extracts of the biological control bacterium Pseudomonas fluorescens Pf-5. Its structure was identified using a combination of c...
190 citations
TL;DR: Key worcls: competitiveness, nitrogen fixation, rhizobial ecology, Blncl~rliizobi~~rri, and prospects for the future.
Abstract: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Documentation of the problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 13 Distribution of B,~~cly~~l i i~oDi~~rri groups in the United States . . . . . . . . . . . . . . . . . . . . . . . . . 5 13 Effects of bacterial and plant genotype . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 14 Soil properties and levels of indigenous bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 15 Other factors in the field environment that may affect survival and (or) infection . . . . . . . . . . . . . . 5 15 Approaches to controlling infection in the field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 16 Use of high inoculant doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 16 Use of bacteriocidal agents in conjunction with resistant strains . . . . . . . . . . . . . . . . . . . . . . . 5 16 Inoculant formulation or placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 16 Modification or selection of host genotype . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 16 Modification or selection of bacterial genotype . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 17 Potential problems confronting researchers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 17 Genetic diversity of rhizobial soil residents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 17 Prediction of field dominance by studies of "competitiveness" . . . . . . . . . . . . . . . . . . . . . . . . 5 17 Antibiotic-resistant ibolates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 18 Sampling of field populations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 18 Summary and prospects for the future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 18 Key worcls: competitiveness, nitrogen fixation, rhizobial ecology, Blncl~rliizobi~~rri.
152 citations
TL;DR: A Tn551 insertional pleiotropic mutant defective in the production of several exoproteins was isolated from Staphylococcus aureus 196E and characterized and a new mutation has been designated sae, suggesting that the sae locus does not involve a positive regulatory gene acting at the transcriptional level.
Abstract: A Tn551 insertional pleiotropic mutant defective in the production of several exoproteins was isolated from Staphylococcus aureus 196E and characterized. The pleiotropism of the mutant was due to a single insertion of the transposon as evidenced by Southern blot hybridization and by the transfer of its phenotype by transduction to S. aureus ISP479. The mutants showed diminished or null levels of α- and β-hemolysins, DNase, coagulase, and protein A in the supernatants of broth cultures. Production of proteases, lipase, staphylokinase, or enterotoxin A was not modified. The mutants did synthesize the cell-bound form of protein A and also the extracellular form of this protein coded by pRIT11, which lacks the COOH-terminal segment of the molecule. These observations suggest that the sae locus does not involve a positive regulatory gene acting at the transcriptional level. The phenotype of the mutant was different from that of other insertional mutants affecting exoprotein synthesis, such as agr, xpr, or sar....
127 citations
TL;DR: The requirement for exogenous carbon sources and the inability of isolated pure cultures to degrade diclofop methyl indicated that interspecies interactions are necessary for degradation, and the positive effect of sessile growth suggested that spatial organization of cells may also be important for degradation.
Abstract: A degradative microbial consortium consisting of at least nine bacterial and one algal species was isolated from soil with diclofop methyl as the sole carbon source. In continuous flow culture, the...
117 citations
TL;DR: The bacterium elaborated the enzyme organophosphorus acid anhydrase, which hydrolyzed methyl parathion to p-nitrophenol, which was further degraded to hydroquinone and 1,2,4-benzenetriol.
Abstract: Pseudomonas putida utilized methyl parathion as sole carbon and (or) phosphorus source. The bacterium elaborated the enzyme organophosphorus acid anhydrase, which hydrolyzed methyl parathion to p-n...
109 citations
TL;DR: The organization of the dual phi LC3 lysis system supports earlier suggestions that exchange of modular units is an important principle in protein evolution.
Abstract: The genes encoding the lysis proteins of Lactococcus lactis bacteriophage were cloned, sequenced, and expressed in Escherichia coli. The lysis genes, lysA and lysB, encode a membrane-disrupting protein (LysA) of 88 amino acids, and a cell wall degrading protein (LysB) of 429 amino acids, which shares significant sequence similarity with lysins from the Streptococcus pneumoniae phages Cp-1, Cp-7, and Cp-9, and Lactobacillus delbrueckii phage mv 1. Both LysA and LysB function in E. coli, as judged by lysis of the E. coli host cells and by lytic activity against lactococcal cells when the cloned lysA and lysB genes are expressed. The LysA protein possesses two putative transmembrane helices and highly charged N- and C-termini, and is structurally similar to phage holins that are known to induce lesions in the inner membrane through which phage endolysin can be released to its cell wall substrate. The C-terminal end of LysB contains two highly homologous sequence repeats of 43 amino acids. The LysB repeats sh...
106 citations
TL;DR: Two strains of the dimorphic fungus Aureobasidium pullulans were grown in liquid and on solid media varying in carbon and nitrogen content, and on leaf surfaces, and hyphae were observed in all systems but comprised a very low proportion (often below quantitative detection) of the total biomass.
Abstract: Two strains of the dimorphic fungus Aureobasidium pullulans were grown in liquid and on solid media varying in carbon and nitrogen content, and on leaf surfaces. Hyphae were observed in all systems but comprised a very low proportion (often below quantitative detection) of the total biomass. In liquid media, hyphae were found sparsely and only in the wash-zone on walls of the culture flasks. Yeast phase growth (blastospores) occurred in pH-buffered media that were nutrient balanced, or continuously carbon-limited (fed-batch culture), or carbon-exhausted (batch culture). Blastospores exposed to conditions with limited nitrogen but sufficient organic carbon, or to acidified media, converted to swollen cells and chlamydospores. The latter morphotypes accumulated carbon internally as lipid granules, and then externally as capsular and soluble extracellular polysaccharide. They were cohesive and also adhered more strongly to cellulose membranes overlying agar media or to leaves than did blastospores. Pullulana...
TL;DR: The enzyme exhibited an endo-splitting mechanism as deduced from viscosimetry experiments as well as from an HPLC study of the end products.
Abstract: Saccharomyces cerevisiae CECT1389 secreted an extracellular endopolygalacturonase (EC 3.2.1.15) when grown in shake flasks in medium containing galactose alone, or either galactose and polygalactur...
TL;DR: A significant proportion of the naturally occurring hydrocarbon-degrading populations within Alaskan sediments affected by the Exxon Valdez oil spill had both the xylE and alkB genes and could convert hexadecane and naphthalene to carbon dioxide.
Abstract: A significant proportion of the naturally occurring hydrocarbon-degrading populations within Alaskan sediments affected by the Exxon Valdez oil spill had both the xylE and alkB genes and could convert hexadecane and naphthalene to carbon dioxide; a greater proportion of the population had xylE than had alkB, reflecting the composition of the residual oil at the time of sampling; nearly equal populations with xylE alone, alkB alone, and xylE + alkB genes together were found after exposure to fresh crude oil; populations with xylE lacking alkB increased after enrichment on naphthalene. Thus, the genotypes of hydrocarbon-degrading populations reflected the composition of the hydrocarbons to which they were exposed.
TL;DR: The mtDNA variation was distributed unevenly in the populations studied as mentioned in this paper, and the mtDNAs of most of the isolates collected in Australia were of the A. tubingensis type, with an unexpectedly high degree of variation, while the rDNA of these isolates exhibited the same A. niger pattern as that of isolates from other locations.
Abstract: The mitochondrial DNAs (mtDNAs) and the ribosomal repeat unit (ribosomal DNA, rDNA) of black Aspergillus isolates collected in various parts of the world were examined. Wide-ranging mtDNA variation was observed in natural populations of the Aspergillus niger aggregate. Most isolates were classifiable as A. niger or Aspergillus tubingensis according to their rDNA and mtDNA patterns. The mtDNA variation was distributed unevenly in the populations studied. The mtDNAs of most of the isolates collected in Australia were of the A. tubingensis type, with an unexpectedly high degree of variation, while the rDNA of these isolates exhibited the same A. tubingensis pattern as that of isolates from other locations. Some other local populations displayed very little polymorphism in their mtDNA and rDNA. Hybridization experiments in which cloned A. niger and Aspergillus nidulans mtDNA fragments were used revealed that the two main mtDNA groups corresponding to A. niger and A. tubingensis are more distantly related than...
TL;DR: In addition to sequence similarity, the archael flagellins and the type IV pilin-transport superfamily share an unusual signal sequence cleavage site and may have functional parallels, which has important implications for the assembly and biogenesis of archaelFlagella.
Abstract: Ultrastructural, biochemical and genetic evidence has shown that the flagella and flagellin proteins from members of the archaea are distinct from their bacterial counterparts. The most important evidence is the sequence dissimilarity between archaeal and bacterial flagellins. We report here similarity between archaeal flagellins and members of the bacterial type IV pilin – transport superfamily. In addition to sequence similarity, the archaeal flagellins and the type IV pilin – transport superfamily share an unusual signal sequence cleavage site and may have functional parallels. This relationship has important implications for the assembly and biogenesis of archaeal flagella.Key words: flagellin, type IV pilin, homology, general secretion proteins, archaea.
TL;DR: The ruminal fungi Neocallimastix frontalis RE1, Neoc alliastix patriciarum 27, Piromyces communis 22, and Orpinomyces joyonii 19-2 were examined for their ability to digest filter paper in the presence of condensed tannins from birdsfoot trefoil.
Abstract: The ruminal fungi Neocallimastix frontalis RE1, Neocallimastix patriciarum 27, Piromyces communis 22, and Orpinomyces joyonii 19-2 were examined for their ability to digest filter paper in the pres
TL;DR: Owing to the large phylogenetic distance between the two groups of strains, the taxonomic status of chickpea-infective strains is discussed and the existence of two genetic groups on the basis of 11 phenotypic characters is confirmed.
Abstract: The diversity of 16 strains of chickpea-infective rhizobia from various geographical origins was analysed using genotypic and phenotypic approaches. Multilocus enzyme electrophoresis was performed, and restriction fragment length polymorphisms of the amplified 16S+IGS (intergenic spacer) rRNA gene, assimilation of 147 carbon sources, antibiotic resistance, and tolerance to NaCl and extreme pH values and temperatures were tested. These approaches had different discriminating powers. Esterase polymorphisms gave a unique pattern for each strain, allowing this method to be used for strain fingerprinting. Genetic distances between strains were estimated. The three approaches used in this study yielded consistent results. They evidenced high heterogeneity among the strains, and made it possible to classify the strains into two clusters. Isozyme patterns for superoxide dismutase were particularly interesting, since they delineated the same two groups. The phenotypic tests clearly confirmed the existence of two g...
TL;DR: Eleven out of 18 sterile fungal isolates and an isolate each of Penicillium sp.
Abstract: Eleven out of 18 sterile fungal isolates and an isolate each of Penicillium sp and Trichoderma sp from the zoysiagrass rhizosphere were effective in enhancing the growth of two wheat varieties in
TL;DR: Both physical and biochemical evidence showed that chloramphenicol acetyltransferase was synthesized by the electroporated C. trachomatis and expression of P7248::cat was developmentally regulated and occurred during the early stages of chlamydial reticulate body development.
Abstract: Electroporation was used to introduce DNA into the elementary bodies of the obligate parasitic bacterium Chlamydia trachomatis. The source of DNA for these experiments was the chimeric plasmid pPBW...
TL;DR: The data suggest that this protease may be a significant pathogenic determinant in infections caused by P. pseudomallei and belongs to the family of alkaline proteases sensitive to metal chelators.
Abstract: Pseudomonas pseudomallei is the causative agent of melioidosis, a glanders-like disease of humans and animals. The pathogenesis of melioidosis is not well understood, and the role of various extracellular enzymes produced by P. pseudomallei in the development of this disease is not known. The present studies were designed to purify and characterize an extracellular protease produced by P. pseudomallei isolates and to test the hypothesis that this protease may play a role in melioidosis. The protease was present in culture supernatants as an enzyme with a molecular weight of 36,000 that was optimally active at 60 degrees C and at pH 8.0. The P. pseudomallei protease was shown to be a metalloenzyme requiring iron for maximal activity, and activity was inhibited in the presence of ethylenediaminetetraacetic acid (150 mM). Antibodies directed against an alkaline protease produced by Pseudomonas aeruginosa cross-reacted with the P. pseudomallei protease. These data indicate that the P. pseudomallei protease belongs to the family of alkaline proteases sensitive to metal chelators. Purified P. pseudomallei protease was capable of digesting a variety of eucaryotic protein substrates including immunoglobulins. A P. pseudomallei strain deficient in protease production was shown to be less virulent than the parental strain in an animal model of lung infection. These data suggest that this protease may be a significant pathogenic determinant in infections caused by P. pseudomallei.
TL;DR: The occurrence of legionellae in the hot water distribution systems of 67 buildings located in different parts of Finland was studied, finding that a high organic matter content in surface waters might favor the occurrence of Legionellae and also the growth of other heterotrophic microbes.
Abstract: The occurrence of legionellae in the hot water distribution systems of 67 buildings located in different parts of Finland was studied. Most of the buildings were apartment buildings. They had diffe...
TL;DR: A mesophilic, irregular coccoid methanogen, which shows close resemblance to Methanococcus sp.
Abstract: A mesophilic, irregular coccoid methanogen, which shows close resemblance to Methanococcus sp., was isolated from a sediment sample of St. Joseph Lake located in the University of Notre Dame campus...
TL;DR: Two species of bacteria found in a phenanthrene enrichment culture of a creosote-contaminated soil are shown to be physiologically dissimilar, and their genetic relatedness is discussed.
Abstract: Two species of bacteria, identified as Pseudomonas stutzeri (P-16) and Pseudomonas saccharophila (P-15) by fatty acid methyl ester analysis, were found in a phenanthrene enrichment culture of a creosote-contaminated soil. The organisms are shown to be physiologically dissimilar, and their genetic relatedness is discussed. Phenanthrene degradation by both organisms followed Michaelis–Menten kinetics, allowing for the determination of half-saturation (Ks) and maximum activity coefficients, using nonlinear regression. Both organisms utilized kinetically similar enzymes for phenanthrene uptake and oxidation, as evidenced by similar Ks coefficients of approximately 0.2 mg/L and temperature optima of 40 °C, but levels of expression differed with different media. Each organism degraded phenanthrene via salicylic acid, but patterns of intermediate metabolism were shown to differ. P-15 excreted 1-hydroxy-2-naphthoic acid during growth on phenanthrene and demonstrated Michaelis–Menten kinetics for the oxidation of ...
TL;DR: One hundred and twenty diverse bacterial strains were screened under greenhouse conditions for their ability to protect white bean seedlings from preemergence damping-off caused by Pythium ultimum and Rhizoctonia solani and postemergences root rot by Fusarium solani f.sp.
Abstract: One hundred and twenty diverse bacterial strains were screened under greenhouse conditions for their ability to protect white bean seedlings from preemergence damping-off caused by Pythium ultimum and Rhizoctonia solani and postemergence root rot by Fusarium solani f.sp. phaseoli. Preemergence mortality or root rot increased with an increase in the inoculum concentration of fungal isolates. For further testing, 200 propagules/g soil of P. ultimum, 3 propagules/g soil of R. solani, and log 3 conidia/g vermiculite of F. solani f.sp. phaseoli were used, as these rates provided an optimal level (approximately 50%) of disease severity. Bacterial strains suspended in sterile distilled water were added to pathogen-amended soil or vermiculite at log 7 colony-forming units/g soil or vermiculite prior to seeding. Final healthy stand and root rot were recorded 4 weeks after planting. Nine bacterial strains on P. ultimum, five on R. solani, and nine on F. solani f.sp. phaseoli provided significant (P = 0.05) suppress...
TL;DR: For 24 h at pH 6.0 and 36 °C, Clostridium sp.
Abstract: For 24 h at pH 6.0 and 36 °C, Clostridium sp. No. 2, isolated from termites, converted arabinose and xylose to hydrogen with yields of 14.55 and 13.73 mmol/g of substrate consumed, respectively. Th...
TL;DR: Results showed that pap-positive isolates expressing class I or class II G adhesins were more frequent in Cases of pyelonephritis than in cases of cystitis and asymptomatic bacteriuria.
Abstract: Thirty-five Escherichia coli isolates from young children and women with pyelonephritis, cystitis, or asymptomatic bacteriuria were characterized genotypically and phenotypically. The isolates were examined genotypically by using DNA probes specific for the hemolysin gene and for the pap, sfa, and afa adhesin systems. Genes for the adhesin systems were also detected by polymerase chain reaction, using multigene amplification. The isolates were serotyped, tested for hemolysin production, and classified for their adhesion specificity by hemagglutination and by binding specificity assays. Twenty-seven of the 35 isolates were pap positive. Results showed that pap-positive isolates expressing class I or class II G adhesins were more frequent in cases of pyelonephritis than in cases of cystitis and asymptomatic bacteriuria. Expression of the class III G adhesins was more frequent in isolates from cystitis and asymptomatic bacteriuria than in isolates from pyelonephritis. Multiple adhesin systems and hemolysin w...
TL;DR: P. aeruginosa and salmonellae proliferated and survived in inoculated water for up to 100 days or longer and had a synergistic effect on the survival of salmonella, enabling them to survive for more than 140 days in double distilled water.
Abstract: Methodology used to support changes to the Regulations for bottled water in the Food and Drugs Act of Canada, which include criteria for Pseudomonas aeruginosa (0 colony-forming units/100 mL of water), was used to assess the survival of P. aeruginosa in inoculated bottled water. The effects of P. aeruginosa on the survival of Salmonella spp. in bottled water were also investigated. The methodology used in the isolation included the use of hydrophobic grid membrane filters, a resuscitation step on tryptic soy agar, and selective plating on P. aeruginosa selective agar for P. aeruginosa and on xylose lysine desoxycholate agar for salmonellae. Pseudomonas aeruginosa and salmonellae proliferated and survived in inoculated water for up to 100days or longer. Pseudomonas aeruginosa had a synergistic effect on the survival of salmonellae, enabling them to survive for more than 140 days in double distilled water.Key words: Pseudomonas aeruginosa, salmonellae, bottled water, methodology.
TL;DR: The optimal incubation conditions for the direct viable count method with nalidixic acid and 5-cyano-2,3-ditolyl tetrazolium chloride were determined and for a mixed bacterial population, the counts were always higher with the CTC method than with the nalidic acid method.
Abstract: The optimal incubation conditions for the direct viable count method with nalidixic acid were determined. They do not differ from those proposed in the literature for a laboratory strain and a mixed bacterial population isolated from drinking water. The direct viable count method with 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) was performed under in situ conditions. The bacteria were incubated with CTC at a concentration of 1 mM for 4–6 h at the temperature of the water in the pipes and without the addition of an exogenous substrate. The results obtained for a laboratory strain using the two direct count methods were similar. However, for a mixed bacterial population, the counts were always higher with the CTC method than with the nalidixic acid method.Key words: drinking water, CTC, nalidixic acid, direct viable count.
TL;DR: The isolation and characterization of four mutants of Rhizobium meliloti unable to synthesize poly-β-hydroxybutyrate (PHB) are reported, and localization studies of Tn5 insertion showed that the PHB− phenotype had, in all mutants, a transposon insertion in thesame region, although not in the same position.
Abstract: The isolation and characterization of four mutants of Rhizobium meliloti unable to synthesize poly-β-hydroxybutyrate (PHB) are reported. The mutants were independently obtained via Tn5 transposon mutagenesis and exhibited physiological and cytomorphological characteristics similar to those of the parental strain, as well as overlapping DNA profiles. These were assessed at both the plasmid and total genome level, using for the latter the sensitive technique of pulsed-field gel electrophoresis in a contour-clamped homogeneous electric field. With respect to the parental PHB+ strain, the loss of PHB-synthesizing ability in the four mutants was demonstrated by gas chromatography, transmission electron microscopy, and enzymatic tests. Localization studies of Tn5 insertion showed that the PHB− phenotype had, in all mutants, a transposon insertion in the same region, although not in the same position. The symbiotic traits (nodule-inducing ability on Medicago sativa and acetylene-reducing activity of nodules) of ...
TL;DR: The data show that CuBP-like proteins are not produced by all bacteria in response to copper stress and indicate that such proteins are common in marine Vibrio spp.
Abstract: The influence of copper on the growth of Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Bacillus subtilis, Vibrio parahaemolyticus, Vibrio alginolyticus (three strains), and an unidentified Vibrio sp. was examined in batch cultures. The effects of copper at micromolar concentrations varied from undetectable to complete growth inhibition. Each strain was able to recover from a growth lag observed after copper addition at a characteristic concentration. Copper concentrations that allowed recovery ranged from 25 to 150 μM. Extracellular proteins in the medium of cultures that had recovered from copper stress were compared with those from control cultures. Protein profiles were analyzed for the presence of proteins similar to extracellular copper-binding proteins (CuBP) previously reported in V. alginolyticus. CuBP-like proteins were found in each Vibrio sp. examined. A protein of similar molecular mass was also detected in copper-stressed cultures of P. aeruginosa and not in control cultures. Esc...