摘要:

A highly presumptive identification ofNocardia farcinicawas made of 47 bacterial isolates. Fifteen isolates from Alberta, 9 from Ontario, and 2 each from New Brunswick, Newfoundland, and Nova Scotia were from clinical cases involved in the Canadian mastitis epizootic. Seventeen additional isolates from Alberta were recovered from farm milk bulk tanks from herds found to have cows involved in the epizootic. All isolates were shown by high-performance liquid chromatography to possess mycolic acids of a size consistent with the genusNocardia. All isolates were resistant to a concentration of 5 μg/mL of mitomycin C. Forty-five isolates grew well and 2 showed reduced growth in the presence of 50 μg/mL of kanamycin acid sulfate. Forty-six isolates were resistant to 5-fluorouracil at a concentration of 20 μg/mL. All isolates were resistant to lysozyme. Resistance to these compounds supported the placement of the isolates in the genusNocardia. Thirty-five isolates produced strong β-galactosidase reactions and 12 showed weak reactions. The demonstration of β-galactosidase activity further supports the identification of the isolates as nocardiae. Attempts to identify the bacteria to species by high-performance liquid chromatography of mycolic acid esters were frustrated, since two species ofNocardiawere found to have indistinguishable mycolic acid patterns. The physiological and growth characteristics of the isolates were consistent withNocardia farcinica.Key words:Nocardia farcinica, mastitis, mycolic acids, high-performance liquid chromatography.

ISSN:0008-4166    

DOI:10.1139/m93-092

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

An anaerobic consortium that carboxylated and dehydroxylated phenol to benzoate, and 2-cresol to 3-methylbenzoic acid, under methanogenic conditions was studied. Phenol induced this transformation activity. Addition of 4-hydroxypyridine or an increase in the concentration of proteose peptone to 0.5% (w/v) delayed the transformation. Phenol enhanced the rate of transformation of 2-cresol whereas 2-cresol delayed the transformation of phenol. Phenols withortho-substitutions (chloro-, fluoro-, bromo-, hydroxyl-, amino-, or carboxyl-) were transformed tometa-substituted benzoic acids. However,meta- andpara-substituted phenols (cresols, fluorophenols, and chlorophenols) were not transformed. Phenol was most rapidly metabolized, followed by catechol, 2-cresol, 2-fluorophenol, 2-aminophenol, 2-chlorophenol, 2-hydroxybenzoic acid, and 2-bromophenol. The consortium O-demethylated anisole to phenol and 2-methoxyphenol to catechol, and oxidized 2-hydroxybenzyl alcohol to 2-hydroxybenzoic acid. Aniline, 2-ethylphenol, 2-hydroxypyridine, 2-acetamidophenol, 2,6-dimethylphenol, 2-phenylphenol, and 1-naphthol were not metabolized.Key words: phenolic compounds, methanogenic consortium, carboxylation–dehydroxylation.

ISSN:0008-4166    

DOI:10.1139/m93-093

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Two variants of insertion sequence IS231, named IS231G and H, were isolated fromBacillus thuringiensissubsp.darmstadiensis73-E-10-2 (BTD2), an isolate toxic to dipteran insects, and characterized by DNA sequence analysis. They are encoded consecutively as direct repeats on anEcoRI fragment of 5.6 kilo base pairs. Direct tandem repeats of IS231 elements have not been previously reported. Both elements are closely related to other members of the IS231 family that have been isolated fromB.thuringiensisstrains toxic to lepidopteran as well as to dipteran insects. A close correlation exists between the evolutionary relationships of the IS231 sequences determined to date and the toxicity spectrum of the host cell. Probing of BTD2 DNA with a radiolabeled IS231G fragment demonstrated that IS231 elements are located on 55- and 34-MDa plasmids as well as on chromosomal DNA. Chromosomal DNA, but not plasmids, from BTD2 also hybridizes to another, unrelated insertion sequence, IS240, fromB.thuringiensissubsp.israelensis, an isolate toxic to dipteran insects. BTD2, therefore, contains IS elements once thought to reside exclusively in either dipteran- or lepidopteran-specific subspecies ofB.thuringiensis.Key words: IS231, IS240, mobile elements.

ISSN:0008-4166    

DOI:10.1139/m93-094

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Pseudomonas syringaesubsp.savastanoicauses tumors on olive and oleander by producing the plant growth regulators indoleacetic acid (IAA) and cytokinins following infection of the plant. The contribution of IAA production to the ability ofP.syringaesubsp.savastanoito grow and survive in oleander leaf tissue was studied. Bacterial strains differing only with respect to IAA production were characterized. Growth and survival of wild-type and two mutant strains ofP.syringaesubsp.savastanoiin oleander leaf tissue were monitored by weekly colony counts and IAA plate assays. Growth rate of the three strains in culture and in planta did not differ significantly. However, the wild-type strain reached a higher population density and maintained its maximum density at least 9 weeks longer than either mutant population. An insertion mutant containing the IAA plasmid (pIAA), but incapable of IAA production, did not maintain a higher population density than a strain cured of the IAA plasmid. The pIAA-cured strain maintained a higher population density when coinoculated with an IAA-producing strain than when inoculated alone. These results suggest that IAA production may contribute to the fitness ofP.syringaesubsp.savastanoiin oleander tissue and that theiaaoperon alone may be responsible for the competitive advantage of cells harboring pIAA.Key words: indoleacetic acid, bacterial ecology.

ISSN:0008-4166    

DOI:10.1139/m93-095

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Through the use of a single, random 15mer as a primer, between 1 and 12 DNA amplification products were obtained per strain from a selection of 84RhizobiumandBradyrhizobiumisolates. A principal-coordinate analysis was used to analyse the resulting amplified DNA profiles and it was possible to assign isolates to specific groupings. Within the speciesRhizobium leguminosarum, the biovarphaseoliformed a distinct group from the other biovars of the species,viciaeandtrifolii, which grouped together. Isolates ofRhizobium melilotiandBradyrhizobiumspecies formed their own clear, specific groups. Although it was possible to identify individual isolates on the basis of differences in their amplified DNA profiles, there was evidence that some amplified segments were conserved among individuals at the biovar and species levels.Key words:Rhizobium, DNA amplification, random primers.

ISSN:0008-4166    

DOI:10.1139/m93-096

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Proteolytic bacteria in paddy field soils under rice cultivation were characterized and enumerated using azocoll agar plates.Bacillusspp. were the proteolytic bacteria that were most frequently present, comprising 59% of the isolates. They were always the numerically dominant proteolytic bacteria isolated from three kinds of fertilizer treatments (yearly application of rice-straw compost and chemical fertilizer, yearly application of chemical fertilizer, and no fertilizer application) and at three different stages of rice development (vegetative growth stage, maximal tillering stage, and harvest stage). Of the 411 proteolytic bacteria isolated, 124 isolates had stronger proteolytic activity than others on the basis of gelatin liquefaction tests and most of them wereBacillusspp. (100% in 1989 and 92.4% in 1991).Bacillus subtilisandBacillus cereuswere the main bacteria of this group andBacillus mycoides,Bacillus licheniformis, andBacillus megateriumwere also present. We conclude that theseBacillusspp. are the primary source of soil protease in these paddy fields.Key words: soil protease, paddy field, proteolytic bacteria,Bacillusspp.

ISSN:0008-4166    

DOI:10.1139/m93-097

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Filamentous fungi from soil were screened for their ability to produce amylases in semisolid and liquid media with wheat bran. A selected strain identified asAspergillus fumigatusFresenius showed high enzymatic activity for α-amylase and glucoamylase. The maximal yield of these amylases was obtained when lignocellulosic materials were the carbon sources. The optimal pH and temperature were 6.0 and 50 °C, respectively, for both enzymes. α-Amylase activity was more thermostable than glucoamylase activity.Key words: amylolitic fungi, α-amylase, glucoamylase,Aspergillus fumigatus.

ISSN:0008-4166    

DOI:10.1139/m93-098

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Our research objectives were to (i) determine the persistence of an introduced surrogate (Cellulomonassp. NRC 2406) for a genetically engineered microorganism in sediments, growths ofCladophora glomerata(Chlorophyta), and leaf packs, (ii) test community and ecosystem structural and functional responses to the introduced bacteria, and (iii) evaluate the utility of flowing water mesocosms as tools for assessing the fates and effects of introduced bacteria in streams.Cellulomonassp. densities were determined using fluorescent antibodies; maxima were ≤ 1% of the total bacterial community in each habitat in two experiments, and ≈25% of total densities in leaf packs in a third experiment. Densities declined from postinoculation maxima faster in sediments than inC.glomeratagrowths and leaf packs.Cellulomonassp. persisted in leaf packs at densities significantly greater than background.Cellulomonassp. had no statistically significant effects on primary productivity, community respiration, assimilation ratios, photosynthesis/respiration (P/R) ratios, bacterial productivity, and leaf litter decomposition rates. Cellulase concentrations were positively correlated withCellulomonassp. densities ≥ 7 × 108 cells/g dry mass in fresh leaf litter for 2 days following exposure. Total bacterial densities, algal biomass, and total viable biomass sometimes differed between control and experimental systems, but differences were not related toCellulomonassp. introduction. Mesocosms were good tools for studying bacterial population dynamics in leaf litter and physiological aspects of litter degradation, but they were less well suited to measuring losses of litter mass and cellulose because physical abrasion during storms accelerated those processes in the field.Key words: bacterial population dynamics, mesocosms, streams, introduced bacteria,Cellulomonassp., litter decompositio

ISSN:0008-4166    

DOI:10.1139/m93-099

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

The effects of three different media on amino acid uptake and production and glucose and oxygen utilization during protoplast growth and hyphal body production by the fungusEntomophaga aulicaeunder fermentation conditions were studied. The three media consisted of a basal medium plus either (i) 2.8% fetal calf serum, (ii) 0.8% tryptic soy broth plus 0.4% bovine serum albumin, or (iii) 0.8% tryptic soy broth plus 0.4% calcium caseinate. The protoplasts grew most rapidly (initial peaks on days 2 and 3) and hyphal bodies were detected first (day 3) in the media containing albumin and caseinate. The day 9 hyphal body yields were 3.1 × 107, 7.5 × 108, and 3.1 × 109/10 L in media containing the serum, albumin, and caseinate, respectively. Growth in the albumin and caseinate media also gave the first detectable glucose utilization (days 2 and 3, respectively) and this rapidly increased to 94.9 and 90.6% utilization, respectively, on day 4. Oxygen and glucose utilization were closely related. During protoplast growth prior to hyphal body production, the only common pattern detected was the initial utilization of glutamine in serum- and caseinate-containing media. During the initial period of hyphal body production, cysteic acid, threonine, serine, asparagine, leucine, tyrosine, phenylalanine, and arginine were first utilized and glycine, alanine, and ammonia were first produced in the albumin and caseinate media. At this time (days 3–5), glutamine, proline, cystine, and tryptophan were first utilized and valine and histidine were produced in the albumin medium, and methionine was first utilized and cystathionine produced in the caseinate medium. Four main patterns of overall amino acid utilization and production were identified. The delay in major protoplast growth in the basal medium plus fetal calf serum is felt to result from inhibition by free fatty acids in the serum. Protein utilization was not detected and its main function is considered to be enhancement of protoplast stability against fermentation shear forces.Key words:Entomophaga aulicae, physiology, fermentation growth, protoplasts, hyphal bodies.

ISSN:0008-4166    

DOI:10.1139/m93-100

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Forty-sixFrankiastrains isolated from nodules of fiveCasuarina equisetifoliastands throughout Senegal and Gambia were analyzed for their enzyme electrophoretic profiles and compared with six collection strains. These strains were classified into 14 electrotypes, according to their esterase patterns. One or two electrotypes were predominant in each investigation site whereas other electrotypes corresponded to only one strain each. Esterase electrophoretic polymorphism evidenced heterogeneity of a restricted population ofFrankiastrains belonging to a single genomic species and indicated the high discriminating power of these enzymes for the study of the ecological repartition ofFrankiastrains in a tropical region.Key words:Casuarina equisetifolia,Frankia, Senegal, enzyme electrophoresis.

ISSN:0008-4166    

DOI:10.1139/m93-101

出版商:NRC Research Press    

年代:1993

数据来源: NRC