摘要:

Sixteen strains of group H streptococci were tested for their capacity to produce a nuclease which degraded transforming deoxyribonucleic acid (DNA), for the ability to produce the competence protein (CF), and for transformability. Six strains produced CF and were transformable upon exposure to DNA. Two strains did not synthesize CF but could be converted to transformability with CF of other strains. All transformable strains exhibited extracellular deoxyribonuclease activities of varying degrees. There was, however, no relationship between the efficiency of transformation of a particular strain and its nuclease activity. Of the eight nontransformable strains, one produced CF but no nuclease. Another strain produced some extracellular deoxyribonuclease but no CF. The remaining strains lacked both functions. The nuclease and the CF activities appeared to be expressed by different proteins.

ISSN:0008-4166    

DOI:10.1139/m72-020

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

New antibiotics have been isolated fromStaphylococcus epidermidisstrains 29297 and 36534. These agents are designated epidermidins A1, A2, B1, B2and are peptides with an average molecular weight of 1200–1400 based on three independent methods of estimation. Each fraction contained 11 amino acid residues, eight of which were shared in common. The ratio ofL- toD-amino acids was 7:4 for epidermidins A2and B1, while that for epidermidins A1and B2was 5:6.The appearance of the same amino acids at the beginning and end of many of the peptide fragments obtained by partial hydrolysis of epidermidin A1suggested that this antibiotic was a cyclic peptide. The absence of N- and C-terminal residues supported this finding. The amino acid sequence of epidermidin A1was also tentatively deduced and may be written as follows: cyclo-lys-ala-asp-glu-ser-leu-thr-gly-val-gly-arg.

ISSN:0008-4166    

DOI:10.1139/m72-021

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The ability ofMycoplasma meleagridisto metabolizeL-argininehydrochloride (HCl) and its inability to ferment dextrose can be used in identifying and differentiating this serotype from otherMycoplasmaknown to infect turkeys.Mycoplasma meleagridismay be the only species of turkey origin which lacks the ability to reduce tetrazolium chloride. A selective inhibitory effect of erythromycin and oleandomycin onM.gallisepticumcan be used to differentiate it fromM.meleagridisin in vitro tests. The metabolic inhibition test can be applied successfully to identification ofM.meleagridisand its antibody. In birds carrying a chronic type of infection,Mycoplasmamay be isolated from the vagina throughout much of their productive life. Since the infection is not readily transmitted, the maintenance of flocks free fromM.meleagridismay not be difficult once the status is achieved.

ISSN:0008-4166    

DOI:10.1139/m72-022

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Measurements of (3H) chloramphenicol production in cultures ofStreptomycesspecies 3022agrown on a medium containing (6-3H)D-glucose and (3-14C) chloramphenicol showed that chloramphenicol inhibits its own biosynthesis. Similar results were obtained in cultures supplemented with the antibacterialp-methylthio- analogue of chloramphenicol. Here synthesis of the antibiotic was completely suppressed until the concentration of analogue had been reduced by inactivating enzymes. In contrast, theL-threo- andp-methylsulfonyl- analogues did not delay growth of the organism and had little effect on chloramphenicol biosynthesis. However, like chloramphenicol and itsp-methylthio- analogue, theL-threoandp-methylsulfonyl compounds were degraded. Degradation of chloramphenicol and thep-methylsulfonyl-analogue ceased when endogenously produced antibiotic reached a concentration of 10–30 mg/liter, suggesting that changes in cell permeability are associated with the onset of chloramphenicol synthesis.

ISSN:0008-4166    

DOI:10.1139/m72-023

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Using monodispersed cell suspensions, interferon preparations were shown to have both a lethal and a growth-depression effect in the same concentration range as that required for antiviral activity. In addition, synchronized cells treated with interferon respond by delaying their normal uptake of thymidine during S phase until after a period during which new protein is synthesized. Puromycin added during this period prevents both the synthesis of this protein and the subsequent synthesis of DNA.

ISSN:0008-4166    

DOI:10.1139/m72-024

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Growth of obligate autotrophic bacteria on their specific substrate and growth of an obligate phototrophic blue green alga was sometimes enhanced by the simultaneous presence of heterotrophic organisms, either directly mixed with the culture, or in parabiotic tubes separated by a membrane. The stimulating effect of such mixed cultures seems to be highly specific.

ISSN:0008-4166    

DOI:10.1139/m72-025

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A new technique, which uses formation of double derivatives for the detection of hydroxy acids in spent cultural media by gas–liquid chromatography (g.l.c), is described. The method is practical enough for use in routine analysis. Fourteen species of the genusNeisseria, including several serogroups ofN.meningitidis, were tested. Four hydroxy acids and a keto acid which have not been previously reported inNeisseriawere tentatively identified from acidified ether extracts of spent cultural media on both polar and nonpolar columns. Different g.l.c. profiles were obtained for several serogroups ofN.meningitidis,N.gonorrhoeae,N.haemolysans,N.lactamicus,N.perflava,N.flava,N.mucosa,N.catarrhalis,N.ovis, andN.caviae. Strains ofN.meningitidis,N.subflava,N.flavescens,N.caviae, andN.catarrhaliscomprise a heterogeneous group. One strain previously identified asN.caviaegave a g.l.c. profile like that ofN.ovis. The data indicate that g.l.c. analysis of metabolic products provides information necessary for differentiating many members of the genus.

ISSN:0008-4166    

DOI:10.1139/m72-026

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Selected gram-negative, nonspore-forming, obligately anaerobic bacteria, isolated from a conventional mouse cecum by the anaerobic glove-box procedure, were characterized by standard methods. They were divided into six broad groups on the basis of cellular morphology, staining characteristics, and biochemical reactions. All organisms produced volatile and (or) nonvolatile acids from peptone and glucose. On the basis of the overall characteristics examined, these organisms were designated as the species of the generaFusobacteriumandBacteroides.

ISSN:0008-4166    

DOI:10.1139/m72-027

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The thermophilic unicellular blue-green alga,Synechococcus lividus, was studied by electron microscopy in thin sections and by the freeze-etching technique. Thin sections revealed subcellular structures like those observed by other authors in mesophilic blue-green algae. In the freeze-etched fractures similar results were obtained but, in addition, surface views of plasma and thylakoidal membranes were examined in detail. The many inclusions present in the freeze-etched preparations confirmed those displayed in thin sections and are interpreted as polyhedral, polyphosphate, and lipid bodies. Some unidentified osmiophilic granules and also phycobilisomes were seen.

ISSN:0008-4166    

DOI:10.1139/m72-028

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The acid Co2+-activated and the alkaline Mg2+-activated inorganic pyrophosphatases ofStreptococcus faeciumF24 were studied by a variety of techniques to determine whether they are activities of two distinct proteins or of a single protein. Both enzyme activities were found to be cryptic and soluble. The specific activities of both enzymes increased coordinately 1.5- to 3-fold during exponential growth at 37C, and then decreased as the cells approached stationary phase. Similar shifts in specific activity did not occur upon growth at 30C. The specific activities in extracts of cells in stationary phase varied coordinately over a 2-fold range depending on nutritional conditions. Diethylaminoethyl cellulose (DEAE-cellulose) and Sephadex G-100 column chromatography and starch–gel electrophoresis did not resolve the two activities. Slight differences in the thermal inactivation kinetics of the two activities were observed. It was concluded that the two pyrophosphatase activities are most probably those of a single protein under different assay conditions.

ISSN:0008-4166    

DOI:10.1139/m72-029

出版商:NRC Research Press    

年代:1972

数据来源: NRC