摘要:

In this minireview the expression microbial "footprints", the term used, to date, for adhesive polymers of microorganisms, is discussed. In addition, recent findings on the potential of microorganisms to label interfaces are considered. In conclusion a suggestion is made to distinguish between adsorption footprints and desorption footprints.Key words: adhesion, interfaces, "footprints," labeling, polymers.

ISSN:0008-4166    

DOI:10.1139/m92-165

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The use of single random primers, selected in the absence of target sequence information, has been shown to be effective in producing DNA amplifications that provide fingerprints which are unique to individual organisms. DNA amplification by random priming was applied to the DNA from isolates ofRhizobium leguminosarumbiovartrifolii. Amplification products were produced using a number of primers, and the resulting fingerprints allowed strain differentiation. However, the effectiveness of primers was dependent upon length and GC content. It was also possible to amplify DNA directly from cells in culture and in nodule tissue. Lysis of these cells was achieved simply through heat applied in the initial DNA denaturation stage of the thermal reaction. The ability to produce varied amplification patterns from differentRhizobiumisolates, especially directly from nodules, gives this method potential for use in examining genetic structures and relationships inRhizobiumpopulations.Key words:Rhizobium, DNA amplification, random primers.

ISSN:0008-4166    

DOI:10.1139/m92-166

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The growth rate ofBorrelia burgdorferiandBorrelia hermsiiin BSK II medium prepared with cysteine-free or cysteine-containing (0.185–5.92 mM) CMRL 1066 medium was studied. In media with cysteine-free CMRL 1066, growth of borreliae was detectable, although it was reduced by approximately 80%. Bacterial growth was maximal when the concentration of cysteine in CMRL 1066 reached 1.48 mM, which represents the standard cysteine concentrations of the medium; higher concentrations inhibited the growth of borreliae. Cysteine incorporation, measured by the uptake of radiolabeled cysteine, showed that cysteine entersB.burgdorferiandB.hermsiicells by passive diffusion. Labeling studies of borreliae with [35S]cysteine indicated thatB.burgdorferihas several cysteine-containing proteins, including ones at 22, 30 (OspA), and 34 kDa (OspB), whereasB.hermsiishowed only two [35S]cysteine-incorporating proteins, at 22 and 24 kDa, which were exposed onto the outer cell surface. In addition, most of the cysteine-incorporating proteins could be biosynthetically radiolabeled when bacterial cells were grownin vitrowith [3H]palmitate, and the differences in cysteine incorporation observed betweenB.burgdorferiandB.hermsiiwere found to be correlated with differences in lipoproteins.Key words:Borrelia burgdorferi,Borrelia hermsii, cysteine, cysteine uptake, lipoproteins, outer surface proteins.

ISSN:0008-4166    

DOI:10.1139/m92-167

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Eleven actinomycetes, isolated from the gut of worker termites (Macrotermes, Armitermes, Microcerotermes, Odontotermes), were identified asStreptomyces chromofuscus,S.chromogenus,S.diastaticus, andS.rochei. Their ability to grow on natural lignocellulosic substrates was tested in solid state fermentation experiments using wheat straw (C/N = 49.8) as a sole carbon source. Weight loss was 4.7–20.9% of the initial substrate, after 5 weeks at 30 °C; lignin and cellulose content decreased 2.0–16.1 and 3.5–32.9%, respectively. When the 11Streptomyceswere grown on wheat straw pretreated with (NH4)HCO3(C/N = 28.2), weight loss was 9.3–29.9% of the initial substrate, indicating an overall enhancement of lignocellulose degradation. Weight, lignin, and cellulose losses were enhanced whenS.chromofuscus(strain A2 and A11) andS.rocheiA4 were grown on pretreated wheat straw instead of the untreated substrate. WithS.rocheiA10 the weight loss and lignin degradation were enhanced, while cellulolysis was slightly depressed. Weight loss and cellulose degradation were both enhanced when the remaining strains were grown on pretreated wheat straw. In this case, lignin degradation was depressed (S.chromofuscusA6 and A8,S.diastaticusA12,S.rocheiA14) or remained essentially the same (S.diastaticusA3 andS.chromogenusA7).Key words:Streptomyces, wheat straw, degradation, lignin, cellulose.

ISSN:0008-4166    

DOI:10.1139/m92-168

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Pseudomonas putida, a saprophytic root-colonizing bacterium, produces multiple forms of catalase. Catalase A, which increases in specific activity during growth phase and after treatment with H2O2, is located in the cytoplasm and is inhibited by 3-amino-1,2,4-triazole, EDTA, and cyanide, but not by chloroform–methanol treatment. Catalase B, which is induced by external H2O2or during stationary phase of growth, is membrane associated and is inhibited by chloroform–methanol, EDTA, and cyanide, but not by aminotriazole. Catalase A has a broad pH optimum, from pH 6.0 to 11.0, with two peaks, at pH 8.0 and 11.0. Catalase B is most active at pH 5.0–11.0. Mutant J-1, generated by ethyl methanesulfonate mutagenesis, lacked catalase A activity in extracts of cells harvested throughout lag to early stationary growth phase in liquid medium. Catalase B was produced by J-1 in stationary phase. Exposure of J-1 to H2O2caused the production of both catalase A and catalase B. Mutant J-1 was more susceptible to cell death than the wild type upon direct exposure to 2.5 mM H2O2but survived this treatment after exposure to lower (0.3 mM), nonlethal doses of H2O2. The ability to adapt to H2O2may be related to the behaviour of J-1 on roots where active oxygen species are produced by root surface enzymes. J-1 colonized root surfaces at wild-type levels and produced catalases A and B after exposure to root surfaces for 12 h.Key words:Pseudomonas putida, catalase, root colonization.

ISSN:0008-4166    

DOI:10.1139/m92-169

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Serratia marcescensis an important pathogen with noteworthy hydrophobicity characteristics as assessed by microbial adhesion to hydrocarbons. However, the present knowledge on the surface characteristics ofS.marcescensstrains does not include physicochemical properties relevant for adhesion such as surface free energy and zeta potential. Also, little attention has been paid hitherto to the structural features and chemical composition of the cell surface. Therefore, as a primary aim of this paper, we characterizedS.marcescensstrains by means of contact angle and zeta potential measurements, X-ray photoelectron spectroscopy, and infrared spectroscopy. In addition, transmission electron microscopy on negatively stained (methylamine tungstate) and ruthenium red stained cells was employed to study structural features on the cell surface. Furthermore, as a secondary aim of this paper, the power of the various techniques to discriminate between strains was evaluated. Negative staining showed thatS.marcescensRZ almost completely lost its surface fibrils upon increasing the growth temperature from 30 to 37 °C. This loss of surface fibrils was accompanied by a decrease in hydrophobicity, as measured by water contact angles on bacterial lawns. No significant differences in hexadecane contact angles were observed. Zeta potentials were only different forS.marcescens3164, showing a considerably higher isoelectric point (IEP = 3.9) than the other strains involved (IEP about 2.5). X-ray photoelectron spectroscopy yielded differences in O/C, N/C, and P/C surface concentration ratios, which related with the IEPs of the strains, despite the fact that X-ray photoelectron spectroscopy is done on fully dehydrated cells, whereas zeta potentials are measured on cells in their physiological state. Infrared spectroscopy was not sufficiently surface sensitive to discriminate between these strains. N/C surface concentration ratios by X-ray photoelectron spectroscopy, which probes approximately 5 nm deep from the surface, were slightly higher for the pigmented, prodigiosin-containing strains RZ30 and 3164, although the presence of prodigiosin did not influence the cell surface hydrophobicity. Thus the prodigiosin is probably confined in deeper layers than probed by contact angles (approximately 0.3–0.5 nm).Key words:Serratia marcescens, fibrils, surface properties, hydrophobicity, zeta potential.

ISSN:0008-4166    

DOI:10.1139/m92-170

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Nondenaturating disc gel electrophoresis revealed that99Mo was incorporated into the nitrate reductase ofAzospirillum brasilensegrown in the absence but not in the presence of tungstate. Under denitrifying conditions,A.brasilensegrown in tungsten-free medium steadily accumulated99Mo for 12 h. In contrast,Paracoccus denitrificansgrown under the same conditions ceased uptake after 1 h. However, both bacteria were incapable of accumulating significant amounts of99Mo in media containing 10 mM tungstate, even though nitrate was reduced byA.brasilense. Aerobically grownA.brasilensecells transported99Mo more efficiently than anaerobically grown cells.Key words:Azospirillum brasilense, tungsten, molybdenum incorporation, nitrate reduction.

ISSN:0008-4166    

DOI:10.1139/m92-171

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The abundance of the fish pathogenic bacteriumAeromonas salmonicidain different parts of the marine environment was determined in a fish farm stocked with Atlantic salmon (Salmo salar) suffering from furunculosis. By application of highly specific monoclonal antibodies and immunofluorescence techniques, the bacterium was found in high abundances (4.3 × 103cells/mL) at the air-water interface.Aeromonas salmonicidawas also registered in high numbers in the sediments beneath the farm, and in moderate to low numbers in the water column. When samples were collected in the environment outside the fish farm, the number ofA.salmonicidawas below the detection limit in surface samples, but the bacterium could be detected in the water column in samples collected downstream to the farm. The high number ofA.salmonicidafound in the lipid-rich air-water interface is discussed, taking into consideration the high hydrophobicity of the cell surface of the bacterium and the physical and ecological conditions in this specific habitat.Key words: immunofluorescence, total bacterial counts, surface microlayer, furunculosis.

ISSN:0008-4166    

DOI:10.1139/m92-172

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Measures of fungal growth with potential for use on wood-chip media were developed. These included (i) visual inspection, (ii) substrate dry weight loss, (iii) rate of fluorescein diacetate hydrolysis, (iv) extractable protein content, and (v) chitin content of the colonized substrate. The responses of the various assays to different growing conditions were assessed by using them on measured weights of mycelium, collected at intervals from liquid media with various composition. Growth of various species on either nutrient supplemented or unsupplemented wood chips was then measured. Each assay measured a different aspect of growth. The relationship between these changed in a distinctive way for each species during growth. Chitin gave the best measure of biomass, whereas fluorescein diacetate hydrolysis was a measure of growth-related metabolic activity. The protein and substrate dry weight loss data gave information about fungal protein and carbohydrate metabolism of the species, respectively. Addition of nutrient supplement to the wood increased both biomass and growth-related metabolic activity. It also increased the amount of wood used to produce a given amount of biomass by about 500% with some species. Some species showed a strong capacity to lower their cellular protein concentration during growth, which is probably of advantage for growth on a low-N substrate such as wood. Used together, the assays gave insight into different strategies fungi use to grow on wood.Key words: fungi, growth, chitin, fluorescein diacetate.

ISSN:0008-4166    

DOI:10.1139/m92-173

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Antibiotic-resistant bacteria were isolated from sediment samples collected beneath two fish farms west of Bergen (Norway). The samples were collected just after the fish had been treated with oxytetracycline. Eighty-four bacterial isolates were tested for susceptibility to antibacterial agents. Most of the isolates were resistant to oxytetracycline, kanamycin, and sulfamethoxazole. Transferable plasmid-related resistance was shown by direct cell transfer and agarose gel electrophoresis. Among 34 multiple-resistant isolates, 7 isolates were able to transfer resistance toEscherichia coliHB101. Phenotypical characterization indicated that these seven isolates belonged to the generaVibrioandPseudomonas. The results indicate that sediments beneath fish farms may serve as a reservoir for transferable antimicrobial resistance genes.Key words: drug resistance, gene transfer, marine sediment bacteria.

ISSN:0008-4166    

DOI:10.1139/m92-174

出版商:NRC Research Press    

年代:1992

数据来源: NRC