摘要:

Purification and chemical characterization of an immunosuppressive exopolysaccharide fromCapnocytophaga ochraceastrain 25 are described. This polysaccharide was extracted from spent culture medium by cold ethanol precipitation. Purification was accomplished by trichloroacetic acid and pronase treatments in combination with diethylaminoethyl-Sepharose and concanavalin A-Sepharose chromatography. Purity of the exopolysaccharide was ascertained by polyacrylamide gel electrophoresis using periodic acid – Schiff staining. The exopolysaccharide was free of protein, nucleic acid, and lipopolysaccharide, but contained large amounts of mannose with lesser quantities of glucose, galactose, glucuronic acid, and glucosamine.

ISSN:0008-4166    

DOI:10.1139/m85-001

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Crude chitin synthase extracted from young (24 h) hyphae ofChoanephora cucurbitarumandPhascolomyces articulosus, susceptible and resistant hosts, respectively, to the mycoparasite,Piptocephalis virginiana, was identified and characterized by measuring the incorporation of the substrate [14C]UDP –N-acetylglucosamine into chitin. The enzyme activity was mainly associated with the mixed membrane fraction. Properties of the enzyme preparation such as activation with proteases,N-acetylglucosamine, magnesium, inhibition with polyoxin D,Vmax, apparentKmvalue for UDP –N-acetyl-D-glucosamine (UDP-GlcNAc), and response to pH were examined. Enzyme activity from both fungi displayed basically the same features as the corresponding enzymes reported from other mucoraceous fungi. However, the two enzyme preparations (fromP.articulosusandC.cucurbitarum) differed from each other in their response to various proteases and storage at 4 °C. Enzyme preparation fromP.articulosuswas activated by all proteases, whereas theC.cucurbitarumpreparation was activated by acid protease, slightly activated by trypsin over a narrow concentration range, and was inhibited by neutral protease. Enzyme preparation fromC.cucurbitarumshowed a rapid decrease in activity within the first 5 h of storage at 4 °C and also exhibited relatively higher activity of endogenous proteases than that fromP.articulosus.

ISSN:0008-4166    

DOI:10.1139/m85-002

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

A selective inhibitor technique was used to determine the relative contributions of bacteria and fungi to total microbial respiration in pine forest soils from three "ecologically analagous" sites at intervals of 2.8 km (site 1), 6.0 km (site 2), and 9.6 km (site 3) from a "sour gas" plant emitting sulphur dioxide, SO2. The ratios of bacterial to fungal respiration given as percentages of total activity were 5:95, 14:83, and 18:82 in the F/H horizon and 31:70, 36:62, and 38:62 in the mineral soil (to 5 cm depth) at sites 1, 2, and 3, respectively. An unexplained stimulation of respiration sometimes occurred, however, in the organic soil of site 1, when streptomycin was added. There was a reduction in total microbial biomass in the organic soil of site 1 compared with sites 2 and 3, but no such differences between sites in the mineral soil. The predominant fungi isolated at all three sites wereAureobasidium pullulansfrom intact, washed pine needles andTrichoderma viridefrom washed fragments of the F/H horizon.

ISSN:0008-4166    

DOI:10.1139/m85-003

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

In the absence of food debris, Sartorius and Millipore HA filters recovered substantially fewer fecal coliforms from Ottawa River water than did Millipore HC. On addition of a small quantity of sterile blended carrot to water samples, recovery by the poorer filters equalled that on Millipore HC. Scanning electron microscopy revealed bacteria sheltered in crevices formed by carrot fibres and thus protected from the normal stresses of exposure. Addition of carrot debris (e.g., 0.03 g carrot to 100 mL of sample) thus provides a convenient and inexpensive means of reducing variations in fecal coliform recovery between brands of membrane filters.

ISSN:0008-4166    

DOI:10.1139/m85-004

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Candida guilliermondiivar.guilliermondiiwas the dominant yeast isolated from preharvest Georgia corn and comprised 3.6–47.0% of the total fungi as measured by dilution plating. The yeast was confined mainly to kernels visibly molded by filamentous fungi, primarilyFusarium moniliformeandAspergillus flavus. When grown in liquid shake culture,Cand.guilliermondiiwas unable to utilize starch. Growth of the yeast increased considerably when associated with amylolyticF.moniliformeorAsp.flavus. Utilization of starch hydrolyzates byCand.guilliermondiiin mixed cultures was reflected by a decrease in reducing sugar concentrations and a reduction in growth ofF.moniliformeandAsp.flavus. When glucose replaced starch as a carbon source,F.moniliformeandAsp.flavusdid not affect the maximum growth ofCand.guilliermondii. The association betweenCand.guilliermondiiand amylolytic filamentous fungi on preharvest corn is probably commensalistic.

ISSN:0008-4166    

DOI:10.1139/m85-005

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

A seasonal distribution of enteroviruses and adenoviruses in raw sewage effluents of Athens, Greece, was observed over a 15-month surveillance period. All 36 samples tested were positive for both virus groups. Adenovirus concentration levels ranged from 70 to 3200 cytopathic units per litre of sample, whereas the corresponding values for enteroviruses were 90–900 cytopathic units per litre. Peak values for adenoviruses were recorded during the months of April and June 1983, whereas for enteroviruses the peak was recorded in September 1983. All three types of poliovirus were present. Coxsackievirus types B-1, B-2, B-4, and B-5 and echovirus type 7 were also isolated. Adenovirus types 1, 2, 3, 5, 7, and 15 were detected as well.

ISSN:0008-4166    

DOI:10.1139/m85-006

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Media from thein vitroassociation of wheat andAzospirillum lipoferumand from wheat plants alone proved to be chemotactically active. Medium from wheat plants showed a higher attraction than medium from the association. The main attractants were sucrose, glucose, and fructose. In mineral medium without any added sugars, and in association medium with sucrose supplied, and from wheat roots alone, a sucrose excretion and an active invertase were detected. By cleaving sucrose the chemotactic potential increased. Sucrose can not be metabolized byA.lipoferum, whereas glucose and fructose are. Utilization of glucose and fructose by the bacteria may explain why medium from the association wheat–Azospirillumwas less chemotacticaly active than medium from wheat plants alone. Cleavage of sucrose has the additional effect of providing energy sources for bacterial growth and dinitrogen fixation.

ISSN:0008-4166    

DOI:10.1139/m85-007

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Tween purple agar containing 1% fructose (TFP agar) differentiatedCorynebacterium genitaliumfromC.pseudogenitalium, which respectively formed colorless and yellow colonies after 72 h incubation at 37 °C aerobically or in 5–10% CO2in air. Thus TFP agar is a differential medium. Corynebacteria-like colonies grown on nonspecific urethritis (NSU) chocolate agar from urogenital material were identified asC.genitalium,C.pseudogenitalium, or commensals when subcultured on TPF agar. TFP agar was unsuitable for their primary isolation since the commensals turned the medium yellow with 24 h incubation. Gentamicin cannot be employed as a selective agent in medium for the isolation of these corynebacteria. TFP agar containing 10 μg/mL gentamicin inhibited most strains ofC.pseudogenitaliumandC.genitaliumisolated from urogenital infections. It did not inhibit isolates of these corynebacteria from cancer patients or suppress the normal bacterial flora of the urogenital tract. Evidence that gentamicin-resistant strains are characteristic of nosocomial infections is presented.

ISSN:0008-4166    

DOI:10.1139/m85-008

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Online computer image enhancement and analysis were used to visualize and quantitate microbial growth in slide cultures. Images of a single field were collected, enhanced, and stored in random access memory at 15-min time intervals. The image obtained at time 0 was subtracted from each of the subsequent images. This produced a series of difference images showing microbial growth as a black object on a grey background and eliminating debris. Data obtained using difference imaging were compared to data obtained by computer analysis of the original images. The initial rate of growth (2.8 μm3∙field−1∙h−1) was determined within an error of 2% and continuously increased during the first 2 h of incubation. The images of seven soil fractions and of stationary phase cells were superimposed on both the initial and final images before subtraction to evaluate difference imaging as an aid in visually discriminating growing microorganisms from simulated artifacts. The coarse clay fraction (0.2–2.0 μm) was the most difficult to visually distinguish from microbial cells, but was easily eliminated in difference images. The potential for application of difference imaging in the direct measurement ofin situmetabolic activity is also discus

ISSN:0008-4166    

DOI:10.1139/m85-009

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The development of ascospores and heat resistance was determined in McClary's acetate broth in the presence of two sporulation inhibitors, ethanol and erythromycin. The inhibitors delayed sporulation without preventing development of heat resistance. The presence of ethanol in growth media caused cells to have increased heat resistance. The fatty acid and chitin contents of sporulatingHansenula anomalacells were determined. Highest triglyceride content of cells was associated with the initiation of sporulation. This phenomenon was not observed for phospholipid. As the ratio of saturated to unsaturated fatty acids in triglycerides increased, so did the heat resistance. However, the chitin content of cells was not correlated with heat resistance.

ISSN:0008-4166    

DOI:10.1139/m85-010

出版商:NRC Research Press    

年代:1985

数据来源: NRC