摘要:

Mutant strains ofPseudomonas aeruginosa, blocked in the pathway of aromatic amino acid biosynthesis, were isolated to determine the branchpoint of pyocyanine biosynthesis. Studies of the enzyme complement of these mutants and determination of pyocyanine production indicated that chorismic acid is an intermediate in the pathway and is the branchpoint compound.

ISSN:0008-4166    

DOI:10.1139/m72-210

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A soluble antigen was isolated from the cell-membrane fraction of a transplantable adenovirus-12 tumor which had been induced and carried in inbred hamsters for more than 4 years. In this same inbred strain, an immunizing dose–response relationship was determined. As little as 60 μg of the soluble antigen, Ad-12 tumor-specific transplantation antigen (TSTA) given intraperitoneally without adjuvant led to protection of about 50% of challenged hamsters. A single intraperitoneal injection of 90 to 120 μg of Ad-12 TSTA protein, with or without adjuvant, led to protection of inbred hamsters to an inoculum of Ad-12 tumor cells which yielded tumors in 80 to 90% of nonimmunized hamsters. Immunized hamsters did not resist a challenge of 104 SV40-induced tumor cells.

ISSN:0008-4166    

DOI:10.1139/m72-211

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Staphylococcus aureusstrains from human and bovine infections were compared for mouse virulence by intraperitoneal injection and for the expression of a variety of physiological characteristics. Secretion of fibrinolysin, ability to reduce thionin, and production of delta hemolysin correlated with host origin but not mouse virulence. Production of clumping factor, pigmentation, and crystal-violet agar reaction varied from strain to strain, but correlated with neither virulence nor host origin. Beta-hemolysin production correlated with virulence in a manner dependent on host origin: human-derived, beta-positive strains were all mouse virulent; bovine-derived, beta-negative strains were all mouse avirulent. Bovine-derived, mouse-virulent strains exhibited a smaller mean cluster size and either a more rapid growth rate, or shorter lag period, than bovine-derived, mouse-avirulent strains. Bovine-derived strains were also significantly more virulent for mice than were human-derived strains. The virulence mechanisms of a givenS.aureusstrain for mice are thus in part related to its host origin. Protease-negative strains were mouse avirulent whatever their origin, pointing toward a general role in staphylococcal virulence for the protease, since it was previously shown that negative strains are also of low virulence for cattle.

ISSN:0008-4166    

DOI:10.1139/m72-212

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Numerations of total microflora, bacteria, and fungi were realized in seven ecologically defined soils of Quebec. The results show several relations between the quantity of microorganisms found and the nature of the soil as well as the composition of the vegetation.Spores of theEndogonaceaewere found in abundance only in the brunisols under maple forest whereas the sclerotia ofCenococcum graniformewere observed mainly in the podzols with fir and spruce forests.

ISSN:0008-4166    

DOI:10.1139/m72-213

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

An agar medium containing corn oil and antimicrobial compounds was developed on whichPhytophthoracolonies can be isolated and recognized macroscopically after 4 days of incubation. The presence ofPythium ultimumTrow, did not interfere with the recognition ofP.cactorumcolonies.The medium is suitable also for the isolation from soil ofPhytophthora nicotianaevar.parasitica,P.cinnamomi, andP.drechsleri, but less satisfactory for the enumeration ofP.cryptogea,P.cambivora, andP.megaspermavar.sojae.

ISSN:0008-4166    

DOI:10.1139/m72-214

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Water samples removed from two rivers and from the subtidal zone of Georgia Strait in British Columbia were treated with either 0.025 ppm of DDT, lindane, α-chlordane, or γ-chlordane, or 0.1 ppm Aroclor 1260 (PCB). The samples were incubated in the laboratory for up to 12 weeks at the temperatures of these natural waters at the time of sampling. Lindane persisted in all water samples throughout the experiment, but large proportions of the other compounds were transported into the atmosphere during incubation except when the containers were sealed. No metabolic breakdown could be demonstrated. As demonstrated with14C-γ-chlordane, uneven distribution of the pesticides occurred rapidly, but was prevented, or reversed, by addition of a surfactant to the water. Total bacterial counts were generally higher in treated than in untreated water samples.

ISSN:0008-4166    

DOI:10.1139/m72-215

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

An automatic soil-washing apparatus is described which enabled the washing of fungus spores out of large numbers of soil samples simultaneously. Tests of the apparatus indicated that superficial spores were removed from most of the soil particles. This allowed organisms growing in soil as vegetative mycelium to be isolated more readily without the serious competition commonly encountered from organisms sporulating heavily in the soil. Virtually no cross-contamination of soil samples occurred in the multichambered apparatus.

ISSN:0008-4166    

DOI:10.1139/m72-216

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Osmotic shocking of competentBacillus subtilisreduced transformability by 80–90% through depressing the uptake of radioactive DNA. The supernatant solution from competent cultures restored both transformation and DNA uptake. A factor, which was inactivated by proteolytic enzymes and which was released into the supernatant solution concomitant with the development of maximum competence, was responsible for restoration of transformability. This factor was both heat and pH labile and was produced only by competent strains. While the shock fluid did not restore transformability to shocked ceils, it increased competence 20-fold in a low-transforming strain. The supernatant solution from competent cultures also increased transformability of the low-competence strain. Thus it appears that at least two factors are involved in competence restoration.

ISSN:0008-4166    

DOI:10.1139/m72-217

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Mean cell volumes, total amount of deoxyribonucleic acid (DNA), number of nuclear bodies, and X-ray responses were determined for exponential cultures ofEscherichia coliP6, a large-cell radiation-resistant mutant strain, and forE.coli82/r, the parent strain of P6, growing in three different media at varying growth rates. Combined results comparing cultures in the same growth medium indicated that exponentially growing P6 cells are 2,5 ± 0.2 times larger, contain 3.6 ± 0.3 times more DNA, and 1.8 ± 0.1 times more nuclear bodies than comparable 82/r cells. Individual P6 nuclear bodies contained 2.01 + 0.13 times as much DNA as 82/r nuclear bodies in comparable cultures, suggesting that each P6 nuclear body may contain two complete 82/r genomes. All P6 cultures gave sigmoidal X-ray survival curves with extrapolation numbers averaging 2.0 and with limiting slopes smaller in absolute value than the slopes of the exponential survival curves obtained for 82/r cultures. P6 cells appeared to be no more efficient than 82/r cells in enzymatic dark repair of X-ray or ultraviolet damage, suggesting that the greater X-ray resistance of P6 cells may be associated with the doubled DNA content of each P6 nuclear body.

ISSN:0008-4166    

DOI:10.1139/m72-218

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

In a succession in which three bacteria having different nutritional needs were inoculated simultaneously into a medium with no added growth factors, the fastidious population developed only after an initial period of growth by bacteria with simple nutritional demands. In a model succession of soil bacteria inoculated into a glucose–salts medium, the relative abundance of cells requiring no growth factors declined with time, while bacteria needing growth factors made up an increasing percentage of the community in late stages of the succession.

ISSN:0008-4166    

DOI:10.1139/m72-219

出版商:NRC Research Press    

年代:1972

数据来源: NRC