摘要:

Bioremediation of polluted temperate and cold temperature environments may require the activity of psychrotrophic bacteria, because their low temperature growth range parallels the ambient temperatures encountered in these environments. In the present study, 135 psychrotrophic microorganisms isolated from a variety of ecosystems in Canada were examined for their ability to mineralize14C-labelled toluene, naphthalene, dodecane, hexadecane, 2-chlorobiphenyl, and pentachlorophenol. A number of the psychrotrophic strains mineralized toluene, naphthalene, dodecane, and hexadecane. None of the psychrotrophs were capable of mineralizing 2-chlorobiphenyl or pentachlorophenol. Those strains demonstrating mineralization activity were subsequently screened by the polymerase chain reaction (PCR) and Southern hybridization of PCR products for the presence of catabolic genes (alkB,ndoB,todC1, andxylE) involved in known bacterial biodegradative pathways for these compounds. Some of the psychrotrophs able to mineralize toluene and naphthalene possessed catabolic genes that hybridized toxylEortodC1, andndoB, respectively. ThealkBPCR fragments obtained from the strains that mineralized dodecane and hexadecane did not hybridize to analkBgene probe derived fromPseudomonas oleovorans. Psychrotrophic strain Q15, identified as aRhodococcussp., also mineralized the C28n-paraffin octacosane. A gene probe constructed from the "alkB" PCR fragment from strain Q15 did hybridize with thealkBPCR fragments from most of the psychrotrophic alkane biodegraders, indicating that thealkBprimers may be amplifying another gene(s), perhaps with low homology toP.oleovorans alkB, which may be involved in the biodegradation of both short chain (dodecane) and longer chain alkanes (hexadecane, octacosane). All of the psychrotrophic biodegradative isolates examined were capable of mineralization activity at both 23 and 5 °C, indicating their potential for low temperature bioremediation of petroleum hydrocarbon contaminated sites.Key words: psychrotrophic microorganisms, biodegradation, catabolic gene probes, organic pollutants.

ISSN:0008-4166    

DOI:10.1139/m96-016

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Polyamines of 97 strains (60 species) belonging to 18 genera of the familyEnterobacteriaceaewere determined by high performance liquid chromatographic analysis. In addition to putrescine and cadavarine, diaminopropane was widely distributed inEnterobacteriaceaeand almost ubiquitously withinEnterobacter,Pantoea,Erwinia,Leminorella,Proteus,Leclercia,Morganella,Klebsiella,Hafnia,Rahnella,Serratia, andTatumellaspecies and sporadically withinCitrobacter,Escherichia,Moellerella,Providencia,Yokenella, andYersiniaspecies. Histamine was detected in some cultures ofProteusandMorganella. Agmatine was sporadically spread. Heterogeneity in the occurrence of spermidine was observed within the 18 genera. Acetylated spermidine was found concomitantly in the spermidine-containing cultures. Distribution profiles of diaminopropane, spermidine, and acetylspermidine inEnterobacteriaceaecan serve as a chemotaxonomic marker to distinguish this family from other taxa of the gamma subclass of the classProteobacteria.Key words: polyamine, diaminopropane, acetylspermidine,Enterobacteriaceae.

ISSN:0008-4166    

DOI:10.1139/m96-017

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Chloride (≥ 0.1 mM) was essential for asexual and sexual reproduction, but not mycelial growth, byPythium ultimumin synthetic culture media. Bromide partially substituted for chloride in support of oogonia formation. The production of gemmae (sporangia or hyphal swellings) increased in proportion to concentrations of KCl in culture media between 0.2 and about 0.5 mM but leveled off between 0.5 and 4 mM. Chloride contents of mycelia after 3 days incubation were proportional to the number of gemmae produced when the fungus was grown in low concentrations of KCl. Under the culture conditions of this study, production of oogonia and gemmae commenced in about 70 and 95 h, respectively, in complete media. When 0.2 mM KCl was added to cultures 95 h or older that were grown in chloride deficient media, oogonium or gemma production was initiated in 20–25 or 10–17 h, respectively. Germination of gemmae, mycelial growth (gain in dry matter), and culture pH were not influenced significantly by the chloride deficiences that prevented sexual and asexual reproduction.Key words: chloride requirement, soilborne plant pathogen, reproduction of fungi, sporangia, hyphal swellings.

ISSN:0008-4166    

DOI:10.1139/m96-018

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Asae::Tn551 agr::tetMdouble mutant was constructed and characterized. The production of several exoproteins (e.g., β-hemolysin, DNase, and proteases) by this mutant was determined and found to be lower than the already diminished production of either isogenic single mutantsae−oragr−. The double mutant also showed, like theagr−mutant, null production of α- and δ-hemolysins and diminished levels of lipase. The reduced levels of many exoproteins in the double mutant as compared with their already diminished levels in either single mutant suggest that there is an additive or synergistic interaction between the two mutations involved,sae−andagr−. However, inactivation of both loci,saeandagr, had a different effect on the two exoproteins that are up regulated in theagr−mutant; thus, coagulase dropped to levels close to the null levels of thesae−parental strain, while extracellular protein A displayed the high levels characteristic of theagr−single mutant. The virulence of thesae−agr−double mutant, determined by intraperitoneal injection in mice, was found to be significantly diminished as compared with that of thesae+agr+parental strain or thesae−agr+single mutant.Key words:Staphylococcus aureus, exoprotein expression,sae−mutant,agr−mutant.

ISSN:0008-4166    

DOI:10.1139/m96-019

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Four lines ofSpiroplasma citristrain BR3, derived from different maintenance conditions over several years and differing in their ability to be transmitted by the beet leafhopperCirculifer tenelluswere characterized. The lines included BR3-T (transmissible), maintained in turnip by leafhopper transmission; BR3-G (now nontransmissible), maintained in plants by periodic graft transmission; BR3-P (now rarely transmissible), subcultured in artificial medium over 130 times; and BR3-M (transmissible), subcultured 43 times. Although all four lines had similar overall protein profiles, the two transmissible lines each contained two proteins missing in the non- or rarely transmitted lines. In addition, one protein was unique to BR3-M and another was unique to BR3-P. Spiralin, a majorS.citrimembrane protein, had dual mobility in line BR3-G only. Patterns of extrachromosomal DNA and restricted total DNA also were similar, although differences occurred among the four lines. The genome of line BR3-G was larger than those of the other lines and unique restriction bands occurred in this line. Protein and DNA profiles of six to eight individual clones of each line also were compared. Protein patterns within each clone were indistinguishable except for a difference in the migration rate of spiralin in clones of BR3-G. Restricted total DNA showed differential patterns among clones of each line, possibly reflecting differences in extrachromosomal DNA. Molecular differences among the spiroplasma lines may reflect the selection pressures of the different environments in which they were maintained and suggest genes and proteins that may be involved in the biological phenotypes of these lines.Key words: spiroplasma, Mollicutes, insect transmission.

ISSN:0008-4166    

DOI:10.1139/m96-020

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

The urease from the ascomycetous fission yeastSchizosaccharomyces pombewas purified about 4000-fold (34% yield) to homogeneity by acetone precipitation, ammonium sulfate precipitation, DEAE-Sepharose ion-exchange column chromatography, and if required, Mono-Q ion-exchange fast protein liquid chromatography. The enzyme was intracellular and only one species of urease was detected by nondenaturing polyacrylamide gel electrophoresis (PAGE). The native enzyme had aMrof 212 kDa (Sepharose CL6B-200 gel filtration) and a single subunit was detected with aMrof 102 kDa (PAGE with sodium dodecyl sulfate). The subunit stoichiometry was not specifically determined, but the molecular mass estimations indicate that the undissociated enzyme may be a dimer of identical subunits. The specific activity was 700–800 μmol urea∙min−1∙mg protein−1, the optimum pH for activity was 8.0, and theKmfor urea was 1.03 mM. The sequence of the amino terminus was Met-Gln-Pro-Arg-Glu-Leu-His-Lys-Leu-Thr-Leu-His-Gln-Leu-Gly-Ser-Leu-Ala and the sequence of two tryptic peptides of the enzyme were Phe-Ile-Glu-Thr-Asn-Glu-Lys and Leu-Tyr-Ala-Pro-Glu-Asn-Ser-Pro-Gly-Phe-Val-Glu-Val-Leu-Glu-Gly-Glu-Ile-Glu-Leu-Leu-Pro-Asn-Leu-Pro. TheN-terminal sequence and physical and kinetic properties indicated thatS.pombeurease was more like the plant enzymes than the bacterial ureases.Key words: urease,Schizosaccharomyces pombe, fission yeast, ascomycetous ye

ISSN:0008-4166    

DOI:10.1139/m96-021

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Culture filtrates and mycelial extracts of two mycoparasiticTrichodermaspecies were tested for the presence of lectins, by haemagglutination with human and marsupial erythrocytes. InTrichoderma viride, haemagglutinating activity was present in both mycelial extracts and culture filtrate. While secreted lectins were only detected after 6 days of growth, the presence of mycelium-associated lectins was first noted in 3-day-old cultures. Agglutinating activity was also demonstrated in the mycelium of 6-, 9- and 13-day-old cultures ofTrichoderma harzianum. In this species, however, lectins were not secreted. In all instances, haemagglutination was inhibited byN-acetylgalactosamine and related sugars. This is the first report on the occurrence of lectins inTrichodermaspp.Key words:Trichoderma, lectins, mycoparasitism.

ISSN:0008-4166    

DOI:10.1139/m96-022

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Goodenough Lake is a small (ca. 1 by 0.6 km) saline-alkaline lake on the Caribou Plateau in British Columbia, Canada, which has a mean depth of < 1 m, allowing the growth of substantial prokaryote-dominated benthic microbial mats over the entire lake bottom. Microbial mats were investigated on both a detailed ultrastructural level and at a macroscopic level to determine, on a lakewide scale, the seasonally influenced changes that occurred over the course of a spring to fall growth season. The acceleration of phototrophic activity with warming of the lake water in spring could be followed by increases in dissolved oxygen levels, which quickly reached supersaturation early in the summer. The grazing activity of brine fly larvae (Ephydra hians) was found to have a significant influence on mat growth and development patterns. On an ultrastructural level, several types of filamentous cyanobacteria were the main phototrophic organisms present, even in anaerobic parts of the mats, where they were accompanied by purple bacteria. The dominant cyanobacterium present was a large oscillatoriacean form which, in certain parts of the lake, formed unusual columnar structures that had a very low diversity of microbial species in comparison to mats from other regions of the lake. The microbial community also differed in areas of the lake where less saline groundwater springs emerged from the lake bed.Key words: microbial mats, saline-alkaline lakes, cyanobacteria, ultrastructure.

ISSN:0008-4166    

DOI:10.1139/m96-023

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Nitrifiers (bacteria,n = 160) were enriched and isolated from samples of hydrothermal waters, sediments, invertebrate tissues, and chimney rocks collected from two East Pacific deep-sea hydrothermal vents (2000 m): the 13°N site and the Guaymas Basin. They were nitrite producers and seemed be widely and uniformly distributed in various parts of hydrothermal ecosystem. These bacteria grew and nitrified better heterotrophically than autotrophically and they possessed characteristics of heterotrophic nitrifiers. All were aerobic, mesophilic gram-negative rods with a unfermentative metabolism and 88% were nitrate reducers or denitrifiers. They were characterized by a high physiological and nutritional diversity, and because of their ability to ammonify, nitrify, and reduce nitrate, they could largely contribute to the nitrogen cycle in hydrothermal sites.Key words: hydrothermal vents, heterotrophic bacteria, nitrifying activity.

ISSN:0008-4166    

DOI:10.1139/m96-024

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

The conditions for improved yields of the α hormones ofPhytophthora parasiticacompared with those of the original technique established by Ko are described. Both hormones al and α2 were adsorbed on the Millipore filter by exposing both sides of the filter directly to freshly inoculated 40% V-8 agar blocks for 4 days. Usage of polycarbonate membrane in the original method to maintain sterility of the filter was replaced by sterilization of the filter with ethanol. Among five organic solvents tested, 95% ethanol was the most effective in extracting both α hormones from the Millipore filter. A 1-min shaking of the hormone-loaded filter with 95% ethanol was sufficient to extract ca. 95% of hormones α1 and α2. Results on the solubility properties suggest that the α hormones ofPhytophthora parasiticaare lipid-like natural products and that hormone α2 is more polar than hormone α1.Key words: sex hormone, hormone production, sexual reproduction,Phytophthora parasitica.

ISSN:0008-4166    

DOI:10.1139/m96-025

出版商:NRC Research Press    

年代:1996

数据来源: NRC