摘要:

Biolog community-level sole-carbon-source utilization patterns are widely applied to distinguish between the microbiota of different habitats or reveal disturbances in microbial ecosystems. Our objective was to examine whether the metabolic diversity measured in the Biolog system could be related to community functioning, thus providing more information than being merely discriminative for communities. To answer this question, we compared the percentages of specific pollutant utilizers with the percentages of the degraders of distinct general (Biolog) substrates in arbitrary samples of isolates, employing in both cases the isolate sample assay (ISA). Samples for arbitrarily selected isolates were taken from in situ enclosures situated in the anaerobic lignite-carbonization effluent Lake Schwelvollert (district of Weißenfels, Saxony-Anhalt, Germany). A different aerobic-carbonization wastewater treatment was carried out in each of the in situ enclosures. It was shown that distinct arbitrarily compiled isolate samples, which displayed similar functional patterns in terms of the degradation of pollutant-related compounds, exhibited significantly different general metabolic capacities as measured using Biolog kits. The similar pollutant-degradation potentials of the arbitrary isolates indicated that the site's substrate supply plays an important role in deciding which bacteria can become indigenous, seemingly leaving room for the otherwise varying properties of the individual community members.Key words: lignite-carbonization wastewater, ISA (isolate sample assay), sole-carbon-source utilization, Biolog, community functioning

ISSN:0008-4166    

DOI:10.1139/w98-084

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Two different monoclonal antibodies (MAb) were raised against 2,4-dichlorophenol hydroxylase (DCP-hydroxylase) ofRalstonia eutrophaJMP134 (pJP4), the second enzyme in the 2,4-D-degradative pathway of this bacterium. The utility of these antibodies in detecting and characterizing 2,4-D-degrading soil bacteria was investigated. One MAb (F6) reacted with DCP-hydroxylase from 27 out of 36 strains tested, while the other (MAb C3) reacted with only 17 isolates. When used with the colony blot technique, MAb F6 was useful for detecting cross-reacting strains on plates of pure cultures or of mixtures containing nondegraders even when 2,4-D degraders were outnumbered 60 to 1. 2,4-D-degrading strains could also be detected from plates spread with enrichment cultures but not from primary isolation plates spread from soil dilutions, presumably because the ratio of degraders to nondegraders was too low. Colonies of some strains that were very distantly related genetically, but produced functionally similar DCP-hydroxlase enzymes, were detected by MAb F6. This result suggests that MAbs could be useful for detecting functionally similar proteins expressed fromtfdBanalogs, even in the absence of detectable DNA homology between the genes encoding them.Key words: monoclonal antibody, 2,4-dichlorophenol hydroxylase, 2,4-dichlorophenoxyacetic acid, 2,4-D-degrading bacteria.

ISSN:0008-4166    

DOI:10.1139/w98-090

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Previous studies in our laboratory demonstrated that the attachment ofAzospirillum brasilenseCd to maize and wheat roots was altered when the bacteria were grown under saline stress. The aim of this work was to analyze the interaction when either the plant or both components were exposed to saline conditions. We demonstrated that this stress altered the early stages of development, in this plant model, leading to an inadequate colonization. The effect of saline stress on the expression ofA. brasilenseN2fixation gene promoters was also studied. WhilenifAexpression was increased in stressed bacteria,nifHtranscription was diminished, suggesting an alteration in the NifA activation process. The induction of thenifgene transcription by root exudates was investigated, and the results suggest that they could be modulating certain bacterial processes, such as nitrogen fixation. However, stressed bacteria did not respond to the exudate's action. This could be related to the modified membrane composition resulting from changes in proteins, glucans, and capsular, exo- and lipopolysaccharides. We conclude that saline stress alters theAzospirillum brasilenseCd - maize interaction, the normal colonization, and the nitrogen fixation process.Key words:Azospirillum brasilense, saline stress,Azospirillum-root interaction, exudates,nifgenes.

ISSN:0008-4166    

DOI:10.1139/w98-078

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Membranes of young hyphae ofBotrytis cinereaandSclerotium rolfsiiin the presence or absence of monensin were isolated and their chemical content was determined. Monensin induced a reduction of protein/lipid and sterol/phospholipid ratios. These modifications show that monensin affects vesicular traffic and also both the normal biosynthesis and growth.Key words: monensin, membranes,Botrytis cinerea,Sclerotium rolfsii.

ISSN:0008-4166    

DOI:10.1139/w98-086

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The subcellular localization of the phosphatidylglycerol/phosphatidylinositol transfer protein (PG/PI-TP) ofAspergillus oryzaewas investigated using Western blot analysis of the cell protein extracts, a cellular membrane fractionation technique, and transmission electron microscopy. The PG/PI-TP, as detected by Western blot analysis with a specific immune serum, was found to be mainly cytoplasmic and partly associated with intracellular membranes. A fractionation experiment was conducted after homogenization of the filamentous fungus mycelium. The endoplasmic reticulum, Golgi-like vesicles, and the plasma membrane were separated by isopycnic ultracentrifugation on a sucrose gradient, and our data revealed that the immunodetected PG/PI-TP was only associated with the Golgi-like apparatus. All these results were documented by electron microscopy and indicate here for the first time that there exists a specific phospholipid transfer protein in a filamentous fungus that is localized in the cytoplasm and associated with Golgi-like vesicles.Key words: phospholipid transfer protein, subcellular fractionation, ultrastructural localization, filamentous fungus,Aspergillus oryzae.

ISSN:0008-4166    

DOI:10.1139/w98-092

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

A polysaccharide composed of maltotriose units was isolated from a liquid culture ofAureobasidium pullulans(De Bary) Arnaud blastospores incubated for 4 h, by precipitation with tetrahydrofuran on solvent-resistant membranes. The concentration of polysaccharide obtained from the liquid cultures after incubation of approximately 106spores/mL was estimated to be 2 &mgr;g/mL of culture filtrate. This polysaccharide seems to be pullulan, as judged by degradation with pullulanase. Newly harvested blastospores resuspended in water did not adhere to the surface of painted wood. However, suspensions of purified culture extract enhanced the adhesion of newly harvested blastospores to the surface of painted wood. It is therefore concluded that pullulan is released by blastospores and contributes to the adhesion of blastospores to surfaces.Key words: adhesion, spores, polysaccharide, pullulan, coatings, blue stain.

ISSN:0008-4166    

DOI:10.1139/w98-091

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Protoplasts ofSaccharomyces cerevisiaewere inactivated by treatment with different concentrations of antifungal compounds for various periods. Of the 14 compounds tested,N-ethylmaleimide proved to be the most efficient. The inactivation effect was fully reproducible. The inactivated protoplasts could be reactivated and still function as fusion partners. They were fused with untreated protoplasts by polyethylene glycol treatment and produced viable hybrid cells. Nuclear and extrachromosomal genetic analysis and chromosome separation of the fusion products from fusion experiments involving inactivated and non-inactivated protoplasts revealed thatN-ethylmaleimide did not affect either of the genomes and hence it was perfectly suited for the hybridization of any type yeast cells without genetic markers.Key words: yeast protoplast fusion, chemical inactivation, chromosomal polymorphism, interspecies hybrid.

ISSN:0008-4166    

DOI:10.1139/w98-093

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Three new species ofCandidaare described that were determined to be genetically isolated from all other currently accepted ascomycetous yeasts based on their sequence divergence in the species-variable D1/D2 domain of large subunit (26S) ribosomal DNA. One of the species was isolated from an ambrosia beetle, whereas the other two were from the frass of wood-boring beetle larvae. The new species and their type strains are the following:Candida ontarioensisNRRL YB-1246 (CBS 8502),Candida tammaniensisNRRL Y-8257 (CBS 8504), andCandida trypodendroniNRRL Y-6488 (CBS 8505).Key words:Candida, new yeast species, ribosomal DNA, molecular systematics.

ISSN:0008-4166    

DOI:10.1139/w98-085

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Owing to their ubiquity as compatible solutes, sucrose and trehalose and their constituent monosaccharides, glucose and fructose, may represent a significant source of carbon for the growth of other bacteria. We investigated sugar utilization by 34 strains of purple sulfur and nonsulfur bacteria isolated from coastal lagoons. Amongst the purple nonsulfur bacteria, sugar utilization was common with almost all strains utilizing the tested monosaccharides and 70 and 50% of strains utilizing sucrose and trehalose, respectively. Sugar utilization was rarer amongst the purple sulfur bacteria, with none of the strains using glucose or trehalose. Fructose, was utilized by 50% of isolates and sucrose was utilized only by strains ofThiorhodococcus. Surprisingly, although unable to use glucose directly,Thiorhodococcusstrains used both the glucose and fructose moieties of sucrose and utilized glucose slowly in the presence of fructose, indicating that these strains may be impaired in glucose transport, rather than glucose metabolism per se. Disaccharide metabolism was dependent on sugar uptake and none of the strains produced trehalases or sucrases. Efficacy of sugar utilization varied widely with specific growth yield between 0.09 and 0.78 g dry weight·g sugar-1, and was dependent upon both the sugar and the strain. Similarly, specific growth rates were highly variable with strain and the sugar present and ranged between 5.4 and 0.5 × 10-2·h-1.Overall, data indicate that in natural high salinity ecosystems, purple sulfur and particularly purple nonsulfur bacteria may be able to efficiently exploit compatible solutes released to the environment by other members of the bacterial community.Key words:Chromatiaceae,purple sulfur bacteria, purple nonsulfur bacteria, sugar utilization

ISSN:0008-4166    

DOI:10.1139/w98-095

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

To test the hypothesis that rhizobacteria naturally present in soils may interfere with the extent of root colonization and plant growth promotion by plant growth-promoting rhizobacteria (PGPR), we studied two lodgepole pine PGPR (Bacillus polymyxastrains L6 and Pw-2) when inoculated singly and when coinoculated with a non-PGPR competitor (Curtobacterium flaccumfaciensPF322).Bacillus polymyxaPw-2 andCurtobacterium flaccumfaciensPF322 were consistently found as endophytes, whileBacillus polymyxaL6 was never found within the root interior. Strains Pw-2 and L6 differed in the rate and type of growth promotion. Strain Pw-2 increased root growth (branching and elongation) and shoot biomass accumulation 6 and 9 weeks, respectively, after inoculation, while strain L6 increased primary root elongation and root biomass accumulation after 12 weeks. Seedlings coinoculated with Pw-2 and PF322 had decreased shoot biomass and primary root lengths when compared with seedlings inoculated only with Pw-2. This effect was not linked to a decrease in the population size of Pw-2 in the rhizosphere or in the root interior of coinoculated treatments. In contrast, strain L6-mediated growth promotion was not impaired by coinoculation with PF322. Strain L6 did interfere to some degree with the growth-promoting capability of strain Pw-2. These results indicate that endophytic PGPR may be less adapted to microbial competition than external root-colonizing PGPR, and that the efficacy of endophytic PGPR may be reduced by the presence of other bacteria on external or internal root tissues.Key words: PGPR, endophytes, colonization, coinoculation, competition.

ISSN:0008-4166    

DOI:10.1139/w98-097

出版商:NRC Research Press    

年代:1998

数据来源: NRC