摘要:

Cells of several copper-protein denitrifiers that produce nitrite reductase reduced nitrate to gaseous products but were completely or strongly inhibited by the copper chelator diethyldithiocarbamate (DDC), which did not comparably inhibit cells of cytochromeed1nitrite reductase producers. Both types of true denitrifiers released NO while reducing nitrite anaerobically in the presence of the uncoupler 3-chlorophenylhydrazonepropanedinitrile (CCCP), as seen previously only inParacoccus denitrificons. In contrast, the pseudodenitrifierRhizobium"hedysari" HCNT1, which grows as neither adenitrifier nor a fermenter, failed to reduce nitrate or nitrite or to nitrify ammonia when grown aerobically but reduced nitrite to N2O after growth at low oxygen tension even without any nitrogen oxide in the culture medium. Such oxygen-limited cells also formed N2O when incubated anaerobically with NO and hydroxylamine, and with nitrite and hydroxylamine as well, but not when anaerobic nitrite reduction (i.e., apparent production of NO) was inhibited by DDC.Rhizobium"hedysari" HCNT1 cells released no NO while reducing nitrite even in the presence of CCCP. The use of CCCP may permit differentiation of respiratory from nitrite-detoxifying denitrifying bacteria. Under aeration, but not anoxia, NO and hydroxylamine reacted to form N2O even in the absence of cells, providing a possible indicator of NO production assayable by gas chromatography.Key words: nitrite, nitric oxide, diethyldithiocarbamate (DDC), hydroxylamine, 3-chlorophenylhydrazonepropanedinitrile (CCCP).

ISSN:0008-4166    

DOI:10.1139/m94-001

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Two strains of the dimorphic fungusAureobasidium pullulanswere 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. Pullulanase treatment diminished the capsules, cohesion, and adhesion. Addition of soluble extracellular polysaccharide to blastospores enhanced their adhesion to leaves. We conclude that extracellular polysaccharide can play a role in adhesion ofA.pullulans.Key words: phylloplane, leaf surface, epiphytic growth, extracellular polysaccharide, cell attachment.

ISSN:0008-4166    

DOI:10.1139/m94-002

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Production of extracellular β-1, 3-glucanase activity by a monokaryoticSchizophyllum communestrain was monitored and results indicated that the β-glucanase activity consisted of an endo- β-1, 3-glucanase activity, besides a negligible amount of β-1, 6-glucanase and β-glucosidase activity. Unlike the β-1, 3-glucanase production of the dikaryotic parent strainS.communeATCC 38548, the β-1, 3-glucanase formation of the monokaryon was not regulated by catabolite repression. The endo- β-1, 3-glucanase of the monokaryon was purified from the culture filtrate by lyophilization, anion exchange chromatography on Mono Q, and gel filtration on Sephacryl S-100. It appeared homogeneous on SDS-PAGE with a molecular mass of 35.5 kDa and the isoelectric point was 3.95. The enzyme was only active toward glucans containing β-1, 3-linkages, including lichenan, a β-1, 3-1, 4-D-glucan. It attacked laminarin in an endo-like fashion to form laminaribiose, laminaritriose, and high oligosaccharides. While the extracellular β-glucanases from the dikaryoticS.communeATCC 38548 degraded significant amounts of schizophyllan, the endo- β-1, 3-glucanase from the monokaryon showed greatly reduced activity toward this high molecular mass β-1, 3-/β-1, 6-glucan. TheKmof the endoglucanase, using laminarin as substrate, was 0.28 mg/mL. Optimal pH and temperature were 5.5 and 50 °C, respectively. The enzyme was stable between pH 5.5 and 7.0 and at temperatures below 50 °C. The enzyme was completely inhibited by 1 mM Hg2+. Growth of the monokaryoticS.communestrain was not affected by its constitutive endo- β-1, 3-glucanase formation.Key words: endo- β-1, 3-glucanase,Schizophyllum commune, monokaryon, constitutive endo- β-1, 3-glucanase formation.

ISSN:0008-4166    

DOI:10.1139/m94-003

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Hyphae and hyphal extracts from fungi isolated from inside healthy black spruce needles were assayed for their effect on spruce budworm (Choristoneura fumiferanaClem.) cell cultures and larvae. Isolates were from needles of four age-classes (current –3 years old) collected throughout a 4-month sampling period. Hyphal extracts from 21 of the 100 isolates tested were toxic to spruce budworm cell cultures and isolates from older needles (2 and 3 years old) negatively affected cells more frequently (p < 0.05) than isolates from younger needles (current and 1 year old). Hyphae from five isolates and hyphal extracts from seven increased mortality (p < 0.05) when fed to second instar larvae in a laboratory bioassay. Development was delayed and larval dry mass reduced when budworm were fed hyphae fromCryptocline abietinaPetrak (isolate number 69). Larval dry mass was reduced when budworm were fed the extract fromAureobasidium pullulons(de Bary) Am. (isolate 87) but increased when fedCryptocline abietina(isolates 40 and 80), a coelomycete (isolate 12), andHormonema dematioides(isolates 28, 63, and 96).Key words: endophytic fungi, budworm,Choristoneura fumiferana,Picea mariana, toxicity.

ISSN:0008-4166    

DOI:10.1139/m94-004

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The diffusible brown pigment produced by some strains ofXanthomonas campestrispv.phaseoliwas found to be due to the secretion and subsequent oxidation of homogentisic acid (2, 5-dihydroxyphenylacetic acid) rather than tyrosinase activity as previously reported. Homogentisic acid is an intermediate in tyrosine catabolism for a number of bacteria. Brown-pigmented strains appeared to be disrupted in tyrosine catabolism and could not use tyrosine as a nutrient. Nonpigmented strains, however, could utilize tyrosine as a nutrient, and although they secreted homogentisic acid, the levels were approximately 1/100th that of brown-pigmented strains. Production of brown pigment was stimulated by tyrosine and repressed by glucose. Growth in glucose resulted in a drop in the pH of the media, and the greatest pigment formation was associated with a shift to alkaline conditions in the culture media. By buffering the media near pH 7.0, brown pigment formation was repressed, even though unoxidized homogentisic acid accumulated in the culture media. The disruption of tyrosine catabolism corresponds to other reports describing differences between brown-pigmented and nonpigmented strains, and provides further support for the retention of a special taxonomic status for the brown-pigmented strains.Key words: homogentisic acid, pigments,Xanthomonas,fuscans.

ISSN:0008-4166    

DOI:10.1139/m94-005

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

A sensitive immunological tool has been developed to detect the sapstaining fungusOphiostoma piceae3871, which plagues the wood industry. Monoclonal antibodies (1F3(1), 4G3(14), 4G2(4), and 2B6(24)) produced against cell wall protein extracts of this fungus were specific. Specificity was estimated by enzyme linked immunosorbent assay, western blotting, and light and electron microscopy using the immunogold technique. Electron microscopy revealed gold particles localized on the outer surface of the cell wall. When screened against 24 biological control fungi the antibodies showed pratically no cross-reactivity (< 4%). When tested against 19 other staining fungi, the antibodies recognized three strains ofOphiostoma piceae, 1F3(1) recognizedPhialophora botulispora, and the antibodies showed less than 5% reactivity with the other fungi. Chemical and enzymatic modification of the antigen revealed that the epitopes recognized by the monoclonal antibodies were glycospecific. Although the antibodies were produced against the cell wall protein extracts of the fungus grown in liquid culture, they also recognized the fungus growing in wood and therefore can be employed to investigate wood colonization by this fungus.Key words:Ophiostoma piceae, monoclonal antibodies, glycoprotein.

ISSN:0008-4166    

DOI:10.1139/m94-006

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Flagella of the haloalkalophilic archaebacteriumNatronobacterium magadiiwere purified and characterized. The diameter of the flagella was 10 nm. It was shown that the flagella consist of four major proteins with molecular weights of 105 000, 60 000, 59 000, and 45 000. With decreasing NaCl concentration, the flagella dissociated into protofilaments. The structure of dissociated flagella and individual flagellins was studied by limited proteolysis. It was found that proteolytic cleavage of flagellins in dissociated flagella into high molecular weight fragments (about 40 000) did not lead to protofilament degradation. It was shown that the most stable fragment is formed from the 60 000 molecular weight flagellin. Cleavage of this fragment led to complete disappearance of protofilaments. On the basis of the data obtained, possible principles of archaebacterial flagellar construction are discussed.Key words: flagellin, archaebacteria, protofilaments,Natronobacterium magadii.

ISSN:0008-4166    

DOI:10.1139/m94-007

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The physiological characteristics and fatty acid composition of 40 strains ofYarrowia lipolyticaisolated from irradiated poultry meat, commercial chilled foods, the superficial water of lagoons of an Italian river delta, and commercial light butter were compared. Discriminant analysis of the results permitted the 40 strains to be classified into four groups according to their isolation source. The lag phase length at 3, 5, and 7 °C, the proteolytic and lipolytic activities, and the growth on sorbitol, gluconate, andN-acetylglucosamine, as well as the relative percentages of C12:0, C15:0, C17:1, C18:1, C18:2, the unsaturation level, and the percentage of total odd chain fatty acids were the characteristics exhibiting the highest discriminatory power. These results indicate that the isolates are well adapted and significant biochemical characteristics may account for the success of individual strains in their original habitat.Key words:Yarrowia lipolytica, fatty acid composition, discriminant analysis.

ISSN:0008-4166    

DOI:10.1139/m94-008

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Iron-oxidizing autotrophs (mainlyThiobacillus ferrooxidans) and acidophilic heterotrophs were recovered and quantified at an incubation temperature of 18 °C, in four tailings-effluent samples obtained from the environment of a uranium mine in Ontario, Canada. The samples were collected during winter when the temperatures of the effluents were in the range 0.5–5.0 °C. Iron-oxidizing autotrophs were recovered in the four samples and their numbers ranged from 3 ± 2 to 185 ± 18 colony-forming units/mL; acidophilic heterotrophs were recovered in three of the four samples and their numbers ranged from 13 ± 3 to 2517 ± 859 colony-forming units/mL. Forty-six of the iron-oxidizer isolates and 63 of the acidophilic heterotrophic isolates were examined for their ability to grow at temperatures of 4, 18, 21, and 37 °C. None of the isolates was psychrophilic, although 96% of the iron oxidizers and 54% of the acidophilic heterotrophs were psychrotrophs; less that 5% of the isolates for both nutritional types were capable of growth at 37 °C. In addition, the isolates were categorized as 'broader temperature range psychrotrophs,' 'narrower temperature range psychrotrophs,' 'intermediates,' or mesophiles, and the narrower temperature range psychrotrophs were found to be numerically predominant.Key words: psychrotrophs, psychrophiles,Thiobacillus ferrooxidans, acidophilic heterotrophic bacteria.

ISSN:0008-4166    

DOI:10.1139/m94-009

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Phage PID produces particles of essentially uniform head size and differs from P1 in its range and tail length. The dimensions of phage P1 are reassessed. The P1 phage group shows signs of morphological evolution.Key words: bacteriophage P1, evolution, morphology.

ISSN:0008-4166    

DOI:10.1139/m94-010

出版商:NRC Research Press    

年代:1994

数据来源: NRC