ISSN:0008-4166    

DOI:10.1139/m90-014

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Arthrographis pinicolasp.nov. (Hyphomycetes) is described; it was isolated from galleries and adult beetles ofIps latidensand from galleries ofDendroctonus ponderosaeinPinus contortavar.latifoliain western Canada. InI.latidensinfested lodgepole pine, this species extensively colonizes nuptial chambers and egg galleries, characteristically forming floccose conidiomata composed of repeatedly branched hyphae which divide to form arthroconidia having schizolytic dehiscence. The fungus is antagonistic to some blue stain fungiin vitro.Arthrographis pinicolais compared with other species ofArthrographis, and withArthropsis microspermaand the discomycetePezizella chapmanii.Key words:Arthrographis pinicola, Hyphomycetes, bark beetle fungi, antifungal compound, arthrographol.

ISSN:0008-4166    

DOI:10.1139/m90-015

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The isolation and structure determination of arthrographol (1) is described. This substituted dihydrobenzofuran is the compound responsible for the antagonism shown by the newly described fungusArthrographis pinicolaSigler and Yamaoka towards some blue stain fungi. The1H and13C nuclear magnetic resonance spectra, infrared and ultraviolet spectra, and the mass spectrum of arthrographol and its diacetyl derivative are reported. The inhibitory activity of arthrographol againstOphiostoma clavigerum(≡Ceratocystis clavigera) is described. Arthrographol, a new natural product, appears to be a norheptaketide related to known benzofurans of fungal origin.Key words: antifungal compound, structure of arthrographol, norheptaketide, blue stain fungus,Arthrographis pinicola.

ISSN:0008-4166    

DOI:10.1139/m90-016

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Various solid-substrate fermentation and shake-flask liquid fermentation systems were investigated as spore production methods forPhomopsis convolvulus, a potential bioherbicide. Among them, "pot" barley grains and modified Richard's (V-8) liquid medium produced 5 × 108 conidia/g and 5 × 106 conidia/mL, respectively. Distinct pycnidia, covering the surface of pot barley grains, produced virulent conidia in a water-soluble mucilage approximately 10 days after seeding the substrate with conidia. In complex liquid media, conidia were produced in pycnidia 3 to 4 days after seeding the media with mature pycnidia or conidia. A negative relationship was demonstrated between inoculum density and yield of conidia in modified Richard's (V-8) liquid culture. Omission of V-8 juice or decrease of the carbon to nitrogen ratio in modified Richard's (V-8) medium inhibited sporulation. Conidia lost viability after 30 days when held at −10 °C in a sucrose solution, but conidia stored at −70 °C remained viable and pathogenic for at least 6 months.Key words:Phomopsis convolvulus, bioherbicide, sporulation.

ISSN:0008-4166    

DOI:10.1139/m90-017

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

In the absence of indigenous rhizobial populations, the pattern of competition between inoculum strains for nodule occupancy is found to be a stable characteristic, independent of rhizosphere population size, nitrogen application, or elevation. Soybean (Glycine max(L.) Merrill) and common bean (Phaseolus vulgarisL.), inoculated with peat-based rhizobia, were grown with three nitrogen levels at 320- and 150-m sites along an elevational transect on the island of Maui, Hawaii. Rhizosphere soil of 8-day-old plants was examined by immunofluorescence for populations of three strains each ofBradyrhizobium japonicumandRhizobium leguminosarumbv.phaseoli, which made up the inocula applied to the respective host legumes at planting. Nodules were examined for occupancy by specific strains at two sampling times. Site differences and nitrogen treatment had no significant effect on rhizosphere colonization or nodule occupancy by the three strains. The three inoculum strains colonized their respective host rhizosphere in approximately equal numbers. In soybean, strain TAL 102(USDA 110) occupied most of the nodules, while strain TAL 379 (USDA 1366) was the least competitive in nodule formation in all treatments. In common bean, TAL 182 outcompeted the other two strains in nodule formation, while TAL 1797 (CIAT 899) occupied the least number of nodules. High elevation decreased nodulation by soybean more than that by common bean. Nitrogen application reduced nodule number and mass of both legumes more at the low-elevation than the high-elevation site; the reductions in nodule mass were more pronounced in common bean. The pattern of nodule occupancy remained stable regardless of the differences in nodule number and mass between elevations, N levels, and sampling times.Key words: rhizobial ecology, rhizosphere colonization, interstrain competition, immunofluorescence, legumes.

ISSN:0008-4166    

DOI:10.1139/m90-018

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Nodulated plants ofAlnus incanassp.rugosaand ssp.incanawere grown with the roots exposed to 5, 21, and 40 kPa O2. The nodules were studied by freeze-fracture transmission electron microscopy to determine the effect of varying O2tension on the numbers of lipid laminae in theFrankiaenvelope. Lipid laminae were present in the cell envelopes of hyphae, stalks, and symbiotic vesicles. The mean number of lipid laminae in hyphal envelopes varied from five to nine. Stalks of symbiotic vesicles contained mean numbers of 35–59 lipid laminae over the range of pO2's studied. Symbiotic vesicle envelopes showed mean numbers of lipid laminae varying from 48 to 94. The numbers of lipid laminae were observed to increase significantly in the distal regions of the symbiotic vesicles in response to raised pO2while the numbers on the proximal portions remained unchanged. The increase in the numbers of lipid laminae in response to raised pO2was not sufficient to account for the expected increase in resistance to O2required at the symbiotic vesicle envelope if lipid laminae formed the exclusive diffusion barrier to O2. These results suggest that lipid laminae surrounding symbiotic vesicles may not constitute the only O2protection mechanism inAlnusnodules.Key words:Alnus incana,Frankia, nitrogen fixation, actinorhizal nodules, Actinomycetes.

ISSN:0008-4166    

DOI:10.1139/m90-019

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

As an alternative disinfectant to chlorination, electrolytically generated copper:silver (400 and 40 μg/L copper and silver, respectively) with and without free chlorine (0.3 mg/L) was evaluated over a period of 4 weeks in indoor and outdoor water systems (100 L tap water with natural body flora and urine). Numbers of total coliform, pseudomonas, and staphylococci were all less than drinking water standards in systems treated with copper:silver and free chlorine and systems treated with free chlorine alone (1.0 mg/L). No significant differences (p ≤ 0.05) in bacterial numbers were observed between systems with copper:silver and free chlorine and those with free chlorine alone. Overall, free-chlorine treatments (0.3 or 1.0 mg/L) showed significantly lower heterotrophic plate numbers than those without free chlorine. When challenged with a naturalStaphylococcussp. isolate, water with copper:silver and free chlorine had a 2.4 log10reduction in bacterial numbers within 2 min, while free chlorine alone or copper:silver alone showed 1.5 and 0.03 log10reductions, respectively. Addition of copper:silver to water systems may allow the concentration of free chlorine to be reduced while still providing comparable sanitary quality of the water.Key words: disinfection, water, copper, silver, chlorine.

ISSN:0008-4166    

DOI:10.1139/m90-020

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Purified H.8 (Lip) antigen was coupled to tresyl-activated Sepharose 4B and used in affinity columns to purify anti-Lip antibodies from convalescent patient sera and from immune rabbit sera. Affinity-purified anti-Lip antibodies isolated from two convalescent patient sera contained 1000 and 1280 ELISA units of antibody and included antibodies of IgG, IgA, and IgM isotypes. An anti-Lip mouse monoclonal ascites (2-1-CA2) had 28 400 ELISA units of antibody. Bactericidal assays were performed using three different case strains ofNeisseria meningitidisgroup B, namely 44/76, 8532, and 8047. Neither preparation of purified human anti-Lip antibodies had detectable bactericidal activity against strains 44/76 and 8532, but one of the two had a titer of 1:4 against strain 8047. Anti-Lip antibodies that were purified from immune rabbit serum and contained 1600 ELISA units of anti-Lip antibodies also failed to show detectable bactericidal activity. The rabbits were immunized with purified Lip antigen and showed specific antibody levels of 2000–2200 units by ELISA, but even the unfractionated sera had little or no bactericidal activity against the test strains. The high titer mouse monoclonal ascites had no bactericidal activity against the test strains. The poor bactericidal activity associated with monoclonal and polyclonal antibodies to the Lip antigen suggest that in spite of other attractive properties it may not be useful as a meningococcal vaccine.Key words: anti-Lip, antibodies, bactericidal,Neisseria, Lip.

ISSN:0008-4166    

DOI:10.1139/m90-021

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The various properties of the inhibitory substances produced byStreptococcus mutansstrains C67-1, Ny257-S, Ny266, and T8, and the fact that inhibitory zones produced could not be associated with lactic acid (or other organic acids), bacteriophages, or hydrogen peroxide indicate that these substances can be classified as mutacins. The substances produced by strains C67-1, Ny266, and T8 possessed similar properties. They were shown to be thermoresistant (100 °C, 30 min), low molecular weight (< 3500) substances sensitive to proteolytic enzymes (chymotrypsin, papain, pronase E, proteinase K, and trypsin) and they were active against most of the Gram-positive bacteria tested but not against most of the Gram-negative bacteria. The substance produced by strain Ny257-S differs from the other three by its narrower activity spectrum, its lower thermoresistance (80 °C, 30 min), and its higher molecular weight (8 000–14 000). The gene or the genes coding for the mutacins are probably located on the chromosome since no plasmid DNA could be detected in these four producing strains. Restriction-fragment patterns of C67-1 and T8 suggest that these strains are closely related, as supported by the strong similarity observed between the properties of their mutacins.Key words: bacteriocin, mutacin,Streptococcus mutans, inhibitory substance.

ISSN:0008-4166    

DOI:10.1139/m90-022

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Purification studies of 7α-hydroxysteroid dehydrogenase (7α-HSDH) (EC 1.1.1.159) fromEscherichia coli080 showed that 1.59-fold purification could be achieved by heating (60 °C for 10 min) the ultracentrifuged enzyme preparation, and 6.46-fold purification was achieved by subsequent precipitation with ammonium sulfate. Further purification on Sephadex G-100 gel gave 10.1-fold purification. After pooling and concentrating the active fractions obtained from the Sephadex G-100 filtration, an 11.1-fold purification was achieved using DEAE-cellulose chromatography. The purified enzyme produced a single band on polyacrylamide gel electrophoresis and its molecular weight was determined to be 54 000. The enzyme was immunogenic and showed immunoprecipitation with homologus antisera.Key words: 7α-hydroxysteroid dehydrogenase,Escherichia coli.

ISSN:0008-4166    

DOI:10.1139/m90-023

出版商:NRC Research Press    

年代:1990

数据来源: NRC