Showing papers in "Canadian Journal of Microbiology in 1996"
TL;DR: The role of bacterial IAA in the stimulation of plant growth and phytopathogenesis is considered and several different IAA biosynthesis pathways are considered.
Abstract: Production of the phytohormone indole-3-acetic acid (IAA) is widespread among bacteria that inhabit the rhizosphere of plants. Several different IAA biosynthesis pathways are used by these bacteria, with a single bacterial strain sometimes containing more than one pathway. The level of expression of IAA depends on the biosynthesis pathway; the location of the genes involved, either on chromosomal or plasmid DNA, and their regulatory sequences; and the presence of enzymes that can convert active, free IAA into an inactive, conjugated form. The role of bacterial IAA in the stimulation of plant growth and phytopathogenesis is considered.
1,158 citations
TL;DR: A numerical study of the fatty acid patterns of 263 reference strains belonging to the genera Arthrobacter, Aureobacterium, Brevibacterium and Cellulomonas found that strains of the species Corynebacterium glutamicum, CoryneBacterium ammoniagenes, and Erysipelothrix rhusiopathiae could be found in distinct clusters, based on quantitative differ...
Abstract: A numerical study of the fatty acid patterns of 263 reference strains belonging to the genera Arthrobacter, Aureobacterium, Brevibacterium, Cellulomonas, Clavibacter, Corynebacterium, Curtobacteriu...
1,041 citations
TL;DR: The role of oxalic acid in pathogenesis is through acidification of host tissues and sequestration of calcium from host cell walls, thereby allowing polygalacturonase to effect degradation more rapidly in a synergistic response.
Abstract: Oxalate secretion by fungi provides many advantages for their growth and colonization of substrates. The role of oxalic acid in pathogenesis is through acidification of host tissues and sequestrati...
625 citations
TL;DR: A most-probable-number (MPN) procedure was developed to separately enumerate aliphatic and aromatic hydrocarbon degrading bacteria, because most of the currently available methods are unable to distinguish between these two groups.
Abstract: A most-probable-number (MPN) procedure was developed to separately enumerate aliphatic and aromatic hydrocarbon degrading bacteria, because most of the currently available methods are unable to dis...
381 citations
TL;DR: Early seedling root growth of the nonlegumes canola and lettuce was significantly promoted by inoculation of seeds with certain strains of Rhizobium leguminosarum, including nitrogen- and nonnitrogen-fixing derivatives under gnotobiotic conditions.
Abstract: Early seedling root growth of the nonlegumes canola (Brassica campestris cv. Tobin, Brassica napus cv. Westar) and lettuce (Lactuca saliva cv. Grand Rapids) was significantly promoted by inoculatio...
246 citations
TL;DR: Analysis of heavy metal impacted soil microbial communities found that, in general, although lead adversely affected biomass, metabolic activity, and diversity, autochthonous lead- and cadmium-resistant isolates were found.
Abstract: Heavy metal pollution is a principle source of environmental contamination We analyzed heavy metal impacted soil microbial communities and found that, in general, although lead adversely affected biomass, metabolic activity, and diversity, autochthonous lead- and cadmium-resistant isolates were found In several metal-stressed soils, the microbial community consisted of two populations, either resistant or sensitive to lead Additionally, a lead-resistant isolate was isolated from a control soil with no known previous exposure to lead, suggesting widespread lead resistance Lead-resistant genera isolated included Pseudomonas, Bacillus, Corynebacterium, and Enterobacter species Plasmids, ranging from 5 to 260 kb, were not detected through standard purifications from lead-resistant isolates Positive correlations existed between antibiotic resistance and isolation habitat for lead-resistant strains, microbial metabolic activity and soil type, soluble lead concentration and microbial diversity, and arsenic concentration and total or viable cell concentrations
213 citations
TL;DR: An initial rapid decline in extractable toxin concentration in the first 14 days, followed by a slower decline, was observed in four of the five experiments, and at the end of the experiments, Btk toxin from transgenic plant tissue was undetectable (less than 0.1% of starting concentration).
Abstract: Transgenic plants that produce pesticidal proteins will release these proteins into the soil when these plants are incorporated into the soil by tillage or as leaf litter. Little is known about the...
159 citations
TL;DR: All of the psychrotrophic biodegradative isolates examined were capable of mineralization activity at both 23 and 5 degrees C, indicating their potential for low temperature bioremediation of petroleum hydrocarbon contaminated sites.
Abstract: Bioremediation of polluted temperate and cold temperature environments may require the activity of psychrotrophic bacteria, because their low temperature growth range parallels the ambient temperatures encountered in these environments. In the present study, 135 psychrotrophic microorganisms isolated from a variety of ecosystems in Canada were examined for their ability to mineralize 14C-labelled toluene, naphthalene, dodecane, hexadecane, 2-chlorobiphenyl, and pentachlorophenol. A number of the psychrotrophic strains mineralized toluene, naphthalene, dodecane, and hexadecane. None of the psychrotrophs were capable of mineralizing 2-chlorobiphenyl or pentachlorophenol. Those strains demonstrating mineralization activity were subsequently screened by the polymerase chain reaction (PCR) and Southern hybridization of PCR products for the presence of catabolic genes (alkB, ndoB, todC1, and xylE) involved in known bacterial biodegradative pathways for these compounds. Some of the psychrotrophs able to minerali...
154 citations
TL;DR: Following inoculation onto seeds, the rhizobacterium Pseudomonas aureofaciens Ps3732RNL11 (L11), which contains the constituitively expressed lacZ and lacY genes from Escherichia coli, 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.
Abstract: Following inoculation onto seeds, the rhizobacterium Pseudomonas aureofaciens Ps3732RNL11 (L11), which contains the constituitively expressed lacZ and lacY genes from Escherichia coli, was recovere...
124 citations
TL;DR: Results indicate that SC can be a very useful tool to reduce lactate accumulation in vitro during fermentation of soluble sugars, the same trend being observed when maltose or soluble starch were used as carbon and energy source.
Abstract: The effect of Levucell SC, a strain of Saccharomyces cerevisiae marked as a feed additive for ruminants, was investigated in vitro on lactate metabolism by the ruminal bacteria Streptococcus bovis and Megasphaera elsdenii. The coculture between 10(7) live cells x mL(-1) of SC and a Streptococcus bovis strain in the presence of glucose reduced lactate production by the bacterial strain. Live yeast cells were able to compete with Streptococcus bovis for glucose utilization in strictly anaerobic conditions, so less glucose was available for the bacterium. SC also stimulated L-lactate utilization by a strain of M. elsdenii. The effect depended on the concentration of yeast cells added. Bacterial growth and fermentation end-product concentrations were also increased in the presence of SC. Some amino acids and vitamins, but not dicarboxylic acids, stimulated the bacterial specific activity of L-lactate uptake. SC was able to provide amino acids to M. elsdenii. In a coculture of Streptococcus bovis and M. elsdenii on glucose, the reduction of lactate concentration was improved by SC, the same trend being observed when maltose or soluble starch were used as carbon and energy source. These results indicate that SC can be a very useful tool to reduce lactate accumulation in vitro during fermentation of soluble sugars.
118 citations
TL;DR: Twenty-two Bacillus spp.
Abstract: 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 t
TL;DR: 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.
Abstract: 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 bac...
TL;DR: Enterobacter asburiae colonizes different plant species and establishes endophytic populations in various tissues and showed an intensive gold label in drop preparations of bacterial suspensions in phosphate buffer, plant sap, and ultrathin sections of plant tissue.
Abstract: Immunological methods were used to study the colonization of internal tissues of different plant species by the endophytic bacterium Enterobacter asburiae JM22. Polyclonal and monoclonal antibodies applied in enzyme-linked immunosorbent assay (ELISA), dot blot assay, tissue printing, or immunogold labeling were sensitive and specific enough to detect JM22 in plant tissues. Detection limits were 1.0 x 103 colony-forming units (CFUs)/mL for tissue printing, 1.0 x lo4 CFUs/mL for ELISA and 1.0 x lo5 CFUs/mL for dot blot assay. Polyclonal and monoclonal antibodies showed a positive immunological reaction with nearly all tested Enterobacter spp. In contrast with polyclonal antibodies, the monoclonal antibodies differentiated Enterobacter spp. and closely related genera like Pantoea or Serratia. Other bacterial genera, plant sap from nontreated field-grown crops, and soil solutions did not react with the antisera. When applied as a seed treatment, JM22 colonized roots, stems, and cotyledons of bean, cucumber, and cotton plants. Fourteen days after inoculation of cotton cotyledons or leaves, JM22 was detected inside the inoculated plant tissue and the bacteria moved to the roots. JM22 reached concentrations up to 1.0 x lo5 CFUs/g in roots, 1.0 x lo4 CFUs/g in stems, and 1.0 x lo3 CFUs/g in cotyledons or leaves. Population densities of JM22 varied between the different plant species, being highest in bean and lowest in cotton. JM22 was detected with ELISA in different plant growth media. While sand, ground clay, and loamy sand showed high and comparable ELISA readings, the extinctions of sandy loam and Promix were significantly lower than the ones of the other three growth media, indicating a strong influence of soil mixes on immunological reactions. JM22 showed an intensive gold label in drop preparations of bacterial suspensions in phosphate buffer, plant sap, and ultrathin sections of plant tissue. After seed treatment, the bacteria were located on the root surface, concentrated in grooves between epidermal cells, below collapsed epidermal cells, within epidermal cells, and inside intercellular spaces in the root cortex close to conducting elements. Inoculation of leaves or cotyledons resulted in the occurrence of many gold labeled cells of JM22 on the petiole surfaces. Enterobacter asburiae colonizes different plant species and establishes endophytic populations in various tissues.
TL;DR: The effects of water activity (aW, 0.994-0.85 = 0.4-21.0 (-)MPa water potential), temperature, and their interactions on microconidial germination of three isolates each of Fusarium moniliforme and FUSarium proliferatum were determined in vitro on a maize meal extract medium.
Abstract: The effects of water activity (aw, 0.994–0.85 = 0.4–21.0 (−)MPa water potential), temperature (5–42 °C), and their interactions on microconidial germination of three isolates each of Fusarium moniliforme and Fusarium proliferatum were determined in vitro on a maize meal extract medium. Temporal germination rates of microconidia of isolates of both species were significantly influenced by both aw and temperature. Germination was very rapid at >0.94 aw with an almost linear increase with time. Germination rates of microconidia of F. moniliforme were slower than those of F. proliferatum isolates at marginal aw levels and 5–25 °C, while at higher temperature (30–37 °C), the former germinated more rapidly than the latter. The aw minima for germination of isolates of both species was 0.88, with none occurring at 0.85 aw over a 40-day incubation period. At 37 °C, isolates of F. moniliforme had slightly lower aw minima than those of F. proliferatum. The narrowest range of aw for germination was at 5 °C, and none ...
TL;DR: Twenty-two strains showed more antibiotic activity against virulent Streptomyces scabies RB3II than the standard pathogen-suppressive strains PonR and PonSSII, and were non-pathogenic on leaf-bud tubers in the greenhouse.
Abstract: Ninety-three strains of Streptomyces were isolated from lenticels of potato tubers grown in naturally disease-suppressive and disease-conducive soils. Twenty-two strains showed more antibiotic acti...
TL;DR: Stems of susceptible and resistant cassava plants have been cytologically investigated for their defense reactions to an aggressive strain of Xanthomonas campestris pv.
Abstract: Stems of susceptible and resistant cassava plants have been cytologically investigated for their defense reactions to an aggressive strain of Xanthomonas campestris pv. manihotis. Histochemistry, i...
TL;DR: 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.
Abstract: 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. U...
TL;DR: The diversity and distribution of bacteria in underground environments have been found to be extensive and to depend on the prevailing environmental conditions as discussed by the authors, and they are found to adapt to the prevailing conditions.
Abstract: The diversity and distribution of bacteria in subterranean environments have been found to be extensive and to depend on the prevailing environmental conditions. In 1987, microbiology became a part...
TL;DR: Cluster analysis of the combined data set showed good resolution of two groups of small-spored Alternaria: the Alternaria infectoria group and theAlternaria alternata group.
Abstract: Some small-spored species belonging to the genus Alternaria Nees have been studied according to their chemical, morphological, and cultural characteristics. A data matrix was constructed based on a...
TL;DR: Transcriptional analysis of creA indicates that the transcript is autoregulated and analysis using 5' rapid amplification of cDNA ends indicates that transcriptional start points exist in clusters over a region of 200 bp located up to 595 bp 5' of the translational start point, leading to the creA transcript being most abundant in carbon catabolite nonrepressing conditions.
Abstract: The molecular nature of a number of creA mutant alleles has been determined. Three alleles analysed are missense mutations in the DNA binding domain and predicted to reduce but not abolish binding....
TL;DR: The occurrence and metabolic capacities of sulfate-reducing bacteria (SRB) were studied in 23 water samples taken from producing wells at 14 different sites and several strains of SRB were isolated and characterized metabolically.
Abstract: The occurrence and metabolic capacities of sulfate-reducing bacteria (SRB) were studied in 23 water samples taken from producing wells at 14 different sites. Oil fields in France, the North Sea, an...
TL;DR: The RFLP and DNA homology analyses indicate that bradyrhizobia effective with peanut are genetically diverse and consist of at least three different species.
Abstract: 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 fra...
TL;DR: 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.
Abstract: 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 [gamma-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.
TL;DR: In this article, the effects of microbiology on nuclear waste disposal, carried out in a number of countries, is summarized, and a concept for the perma-molecular approach is presented.
Abstract: Current research on the effects of microbiology on nuclear waste disposal, carried out in a number of countries, is summarized. Atomic Energy of Canada Limited has developed a concept for the perma...
TL;DR: 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, which points to the involvement of cell surface proteins and cell surfaces hydrophobia in the adhesion process.
Abstract: 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, poly saccharides, 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 degrees. 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.
TL;DR: A review of the current literature on transport of bacteria through geologic media is presented in this article, where the authors address the major controls on bacterial transport, such as the nature of the geology, the distribution of the bacteria, and the type of the environment.
Abstract: A review of the current literature on transport of bacteria through geologic media is presented. The review addresses the major controls on bacterial transport. These controls include the nature of...
TL;DR: The thermophilic fungus Humicola grisea var.
Abstract: The thermophilic fungus Humicola grisea var. thermoidea produced beta-glucosidase activity when grown in a solid-state culture on wheat bran as carbon source. A beta-glucosidase was purified to apparent homogeneity by ultrafiltration, gel filtration chromatography on Sephacryl S-100, and ion-exchange chromatography on S-Sepharose, as judged by sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE) on a 12.5% (w/v) slab gel. The enzyme had a molecular mass of 82 and 156 kDa, as estimated by SDS-PAGE and gel filtration on a high performance liquid chromatographic column, respectively, suggesting that the native enzyme may consist of two identical subunits. The purified enzyme was thermostable at 60 degrees C for 1 h with a half-life of 15 min at 65 degrees C, and displayed optimum activity at 60 degrees C and a pH range. of 4.0-4.5. The Km and Vmax values for p-nitrophenyl beta-D-glucopyranoside were determined to be 0.316 mM and 0.459 IU.mL-1, respectively. D-Glucose, D-gluconic acid lactone, Hg2+, Cu2+, and Mn2+ inhibited beta-glucosidase activity. The enzyme activity was competitively inhibited by D-glucose (ki = 0.6 mM). The purified enzyme was very active against cellobiose and p-nitrophenyl beta-D-glucopyranoside.
TL;DR: A rapid and sensitive method for the detection of low levels of bacteria in potable water was developed, which can detect 1-10 bacterial cells/50 mL water sample within 6-8 h, in contrast to traditional culturing or Southern hybridization methods which require 2-3 days for results.
Abstract: A rapid and sensitive method for the detection of low levels of bacteria in potable water was developed. The fecal indicator bacterium Escherichia coli was used as the test organism in a filtration...
TL;DR: The N-terminal sequence and physical and kinetic properties indicated that S. pombe urease was more like the plant enzymes than the bacterial ureases.
Abstract: The urease from the ascomycetous fission yeast Schizosaccharomyces pombe was purified about 4000-fold (34% yield) to homogeneity by acetone precipitation, ammonium sulfate precipitation, DEAE-Sepha...
TL;DR: In this article, an endo-β-1,3-glucanase from the culture filtrate of T. harzianum was purified by gel filtration on Sephacryl S-200, followed by hydrophobic interaction chromatography on phenyl-Sepharose.
Abstract: β-1,3-Glucanases are produced by Trichoderma harzianum when it is grown in the presence of chitin or isolated cell wall from fungi. An endo-β-1,3-glucanase from the culture filtrate of T. harzianum was purified by gel filtration on Sephacryl S-200, followed by hydrophobic interaction chromatography on phenyl-Sepharose. A typical procedure provided 134-fold purification with a 3.6% yield. The molecular mass of the purified endo-β-1,3-glucanase was found to be approximately 36 kDa, as estimated by sodium dodecyl sulfate – polyacrylamide gel electrophoresis on a 10% w/v slab gel. The enzyme was active toward glucans containing β-1,3-linkages and hydrolysed laminarin to form oligosaccharides. The Km and Vmax values for β-1,3-ghicanases, using laminarin as substrate, was 1.18 mg∙mL−1 and 1.26 U∙mL−1, respectively. The pH optimum for the enzyme was pH 4.4 and maximum activity was obtained at 45–50 °C. Enzyme activity was strongly inhibited in the presence of HgCl2 and stimulated by cations such as Zn2+ and Ca2+...