摘要:

With a view to shortening the time required for pyocine typing and reducing the proportion of untypable isolates, the effect of inducing strains ofPseudomonas aeruginosaby mitomycin C was studied. Detailed experiments with two strains showed that mitomycin C enhanced pyocine production by a typable strain and allowed formation of pyocine by an untypable strain. Maximal production of pyocine was achieved using mitomycin C in a concentration of 0.5 μg/ml.Three hundred and thirty-six isolates ofP.aeruginosawhich had been typed by Gillies and Govan's method were retyped after induction by mitomycin C. Induction and typing were performed on the same agar plate, and a 6-h incubation period at 32 °C was found sufficient for pyocine production. A similar number of typing patterns were found by both methods, but 154 isolates showed a different pattern after induction, and 23 of 38 previously untypable strains became typable. The typing patterns observed after induction were reproducible, and at least as stable epidemiologically as those obtained without induction.

ISSN:0008-4166    

DOI:10.1139/m71-134

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Germination of the ascospores of a strain ofSaccharomyces cerevisiaeHansen was stimulated by fermentable carbon sources. Nitrogen sources alone had little or no stimulating effect on germination unless glucose was present, but peptone and casein hydrolysate were exceptions. Loss of acid-fastness proved to be a useful criterion of spore germination. Evidence was obtained that germination occurs anaerobically, but is not restricted by oxygen. It is concluded that the respiratory characteristics of the three main phases of the yeast life cycle differ in that growth can occur aerobically or anaerobically, sporulation is restricted to aerobic conditions, and spore germination is anaerobic.

ISSN:0008-4166    

DOI:10.1139/m71-135

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The lysogenization ofStaphylococcus aureus, strain BSS, by staphylophageof serological group A may be accompanied by the loss of its capacity to synthesize δ haemolysin. The high multiplicity of infection ofphage changes the tinctorial affinity of BSS cell walls and lyses the same strain lysogenic for the homologous phage; this lysis is similar to that of the staphylococcin. In negative coloration by PTA, this bacteriophage shows one elongated head (750 Å × 420 Å) and a long tail (2650 Å). Electron microscopy demonstrated also the existence of structural subunits of the tail and the hexagonal end plate. By its morphology and dimensions, thephage is similar to 594nand b594nphages studied by Bradley and to staphylophages of serological group A: 3A, 3B, 3C, 6, 7, 42E, 47, 54 of the basic set of international lysotypy.

ISSN:0008-4166    

DOI:10.1139/m71-136

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Candida albicansformed germ tubes within 3 h at 37C in a glucose–salts–biotin (GSB) medium containingL-alpha-amino-n-butyric acid as the nitrogen source. Optimal germ-tube production was obtained when the inoculum was grown on Sabouraud dextrose agar. The GSB medium containingL-alpha-amino-n-butyric acid promoted germ-tube formation more effectively than GSB medium plus gamma-amino-butyric acid or Sabouraud dextrose broth.Carbon-14 incorporation studies revealed that during germ-tube formation (0–4 h) the 3 carbon of alpha-amino-n-butyric acid was incorporated intracellularly to a greater extent than the 1 carbon. However, during blastospore formation (5–16 h), this difference was less pronounced.When six otherCandidaspecies were grown in GSB plusL-alpha-amino-n-butyric acid medium, few germ tubes were observed with the exception of oneCandida stellatoideastrain. However, even this strain ofC.stellatoideaproduced far fewer germ tubes in this minimal culture medium than any strain ofC.albicanstested.

ISSN:0008-4166    

DOI:10.1139/m71-137

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

An indirect approach to the question of the role of a presumptive inhibitory factor or cell deficit to account for immunosuppression by antigenic competition was carried out in the present work.Several characteristics of antigenic competition were delineated. The response to PVP,* classed as a non-thymus dependent antigen, was capable of suppressing the response to a test antigen administered subsequently, and conversely, of being suppressed by unrelated antigens administered as initial antigens. Induction of immunological tolerance to RRBC* with cyclophosphamide did not prevent the capacity of the antigen to suppress the induction of humoral antibody formation to KLH* in a model of antigenic competition. Actinomycin-D in a dose of 0.60 mg/kg body weight abolished suppression by antigenic competition, although the drug suppressed the response to the suppressing antigen GRBC* and enhanced the response to RRBC, the test antigen, when administered to individual control groups of animals immunized with only the one antigen. Consequently, interpretation of the data in terms of antigenic competition was difficult.

ISSN:0008-4166    

DOI:10.1139/m71-138

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The fine structure ofHaemophilus vaginalis594 (ATCC 14018) was examined by electron microscopy, and the biochemical composition of its cell wall was determined. For comparison, similar studies were done with a Gram-positive bacterium,Bacillus megateriumKM, and a Gram-negative bacterium,Escherichia coliB. BothHaemophilus vaginalis594 andEscherichia coliB possessed a multiple-layered cell wall containing 11 to 14 amino acids, a low mucopeptide content, and no teichoic acid. In contrast,Bacillus megateriumKM had a thick, amorphous cell wall with five amino acids, high mucopeptide content, and detectable amounts of teichoic acid.Haemophilus vaginalis594 resembledEscherichia coli, a member of the Gram-negative group of organisms. The structural and biochemical properties ofHaemophilus vaginalis, which are described in detail, may prove useful in determining the ultimate taxonomic position of this species.

ISSN:0008-4166    

DOI:10.1139/m71-139

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Yeasts were isolated from soils from citrus orchards and citrus waste disposal areas in California and Florida. Species ofTrichosporon,Cryptococcus, andRhoclotorulawere predominant. Strains ofHansenula saturnus,Hansenula californica,Hansenula mrakii,Pichia kluyveri,Saccharomyces rosei,Saccharomyces cerevisiae, and some species ofCandidaandTorulopsiswere also found. The cultures isolated were tested for the ability to use a number of flavonoids. These compounds were used by strains ofTrichosporon cutaneum,Cryptococcus albidusand its varietydiffluens,Cryptococcus terreus,Cryptococcus lanrentii,Rhodotorula glutinis,Rhodotorula minuta,Rhodotorula rubra, andCandida humicola, but not by the ascosporogenous species or the otherCandidaspecies. Contrary to expectations, most of the cultures which used flavonoids were isolated from the orchard soils rather than from the soils of the waste disposal areas.

ISSN:0008-4166    

DOI:10.1139/m71-140

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Dielectrophoretic separation studies were undertaken to investigate the possibility of separating cells with varying physiological character. An attempt was made to define the importance of size in the determination of separability. Living cells ofSaccharomyces cerevisiaevar.ellipsoideuswere separated from the same cells killed by heating, using a batch separation. Cells cultured in wort broth were separated from cells grown in yeast nitrogen base – 1% glucose using both batch and continuous separators. Size analyses of separated fractions were performed using a Coulter transducer/multichannel pulse height analyzer. A size differential in cell separability was demonstrated, although it is clear that a complex function of both size and polarizability is instrumental in determining the separation of cell types.

ISSN:0008-4166    

DOI:10.1139/m71-141

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A soluble sulfite reductase (EC. 1.8.1.2) system is present in cell-free extracts ofClostridium pasteurianumthat reduces sulfite to sulfide in the presence of molecular hydrogen. The natural electron donor for this reductase has been found to be ferredoxin, which can be completely replaced by methyl viologen or partially by benzyl viologen. The physiological electron donors NAD, NADP, FMN, and FAD were not active in the transfer of electrons from hydrogen for sulfite reduction. The pH optimum of the sulfite reductase was found to be 7.0 using phosphate buffer, and the extracts reduced nitrite and hydroxyl-amine in addition to sulfite. The stoichiometry of the reaction in terms of hydrogen uptake to sulfide formation was 2.7, which is very close to the theoretical ratio of 3. The above properties of the system indicate that it is an assimilatory rather than a dissimilatory sulfite reductase, as outlined in the Discussion.

ISSN:0008-4166    

DOI:10.1139/m71-142

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Filamentous cultures ofStreptococcus cremorisandStreptococcus lactiswere isolated from growth which formed in orifices of medium inlet tubes of chemostats. Filamentous variants were maintained by biweekly transfer in agar stab cultures. Bacteria from parent and filamentous cultures grown in broth had the same DNA base content and the same bacteriophage susceptibility. Electron micrographs showed that filamentous streptococci had apparently normal cell walls and slightly enlarged cross walls. Filaments appeared to result from failure of daughter cells to separate after division. Filamentous cells were less readily autolyzed and were less susceptible to lysis by Iysozyme than normal cells. The results suggest that filament formation in lactic streptococci was associated with lower autolysin activity.

ISSN:0008-4166    

DOI:10.1139/m71-143

出版商:NRC Research Press    

年代:1971

数据来源: NRC