摘要:

The aerotolerance of the microaerophilic bacteriumCampylobacter fetussubsp.jejunistrain H840 (ATCC 29428) can be enhanced by addition of a combination of ferrous sulfate, sodium bisulfite, and sodium pyruvate (FBP), or of dihydroxyphenyl compounds such as nor-epinephrine (NE), to Brucella broth. Transport of55Fe3+was increased by NE, suggesting that ordinary rates of transport, while adequate for growth at 6% O2, might not permit growth at 21% O2. Growth with FBP at 21% O2did not appreciably affect levels of cytochromes or of various tricarboxylic acid cycle enzyme activities. Activities of certain iron-dependent enzymes (succinate dehydrogenase and aconitate hydratase), and also respiration rates of whole cells, were lower in cells grown at 21% O2in Brucella broth compared to 6% O2, but FBP did not cause an increase in these activities or rates. FBP caused a decrease in catalase and peroxidase activities. Total superoxide dismutase (SOD) activity increased when cells were grown at 21% O2with FBP. When grown without FBP, however, the organism possessed SOD activity as high as that inEscherichia coli, and a variant strain of H840 possessed nearly double this activity but was no more aerotolerant than the parent strain. A very oxygen-sensitive strain ofC.fetussubsp.intestinalisalso possessed high SOD activity. Consequently, total SOD activity inC.fetusdoes not appear to account for lack of aerotolerance. No evidence that FBPcauses any physiological change inC.fetusthat could satisfactorily account for enhancement of aerotolerance could be obtained. It is possible that FBP or NE might not affect some physiological process in the organisms but might instead act on the culture medium.

ISSN:0008-4166    

DOI:10.1139/m79-001

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The addition of bovine superoxide dismutase to Brucella broth or Brucellar agar greatly enhanced the oxygen tolerance ofCampylobacter fetussubsp.jejunistrain H840 (ATCC 29428). Catalase also enhanced oxygen tolerance, but to a lesser extent. These enzymes must act externally to the bacteria. All of the diverse compounds which enhance oxygen tolerance ofC.fetus, including nor-epinephrine and a combination of ferrous sulfate, sodium metabisulfite, and sodium pyruvate, share the ability to quench either superoxide anions or hydrogen peroxide. On the basis of these and other data, we propose thatC.fetusis more sensitive to exogenous superoxide anions and hydrogen peroxide than are aerotolerant bacteria, despite the occurrence of superoxide dismutase and catalase activities inC.fetus. Compounds that enhance oxygen tolerance inC.fetusappear to act by quenching superoxide anions and hydrogen peroxide which occur spontaneously in the culture medium.

ISSN:0008-4166    

DOI:10.1139/m79-002

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Sclerotia ofSclerotinia sclerotiorumin soil were invaded by a destructive fungus that was isolated and identified asSporidesmium sclerotivorum. The parasitic fungus grew slowly on an autoclaved agar medium made from comminuted sclerotia ofS.sclerotiorumand on cornmeal agar but failed to germinate or grow on many common mycological media. Macroconidia ofS.sclerotivorumgerminated adjacent to sclerotia on water agar or moist filter paper, colonized the sclerotia, and developed two distinctive asexual spore states by which it could be recognized. In moist sand, steamed soil, and natural soil the mycoparasite infected and destroyed more than 95% of the amended (1% w/w) sclerotia ofS.sclerotiorumin 10 weeks or less at 25 °C. Sclerotia killed by autoclaving were poorly colonized. Sclerotia ofSclerotium cepivorumwere attacked by the mycoparasite more slowly than those ofS.sclerotiorum. Sclerotia ofMacrophomina phaseolinaapparently were not parasitized. The mycoparasite was isolated from soils from three different areas of the northeastern United States. The prolific development of the mycoparasite in soil containing sclerotia of susceptible species and its ability to spread through soil by growth from one sclerotium to another suggest thatS.sclerotivorumis an important contributor to the natural destruction of sclerotia in.soil and that it may have high potential as an applied agent of biological control of sclerotial fungi.

ISSN:0008-4166    

DOI:10.1139/m79-003

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Spores may be reversibly activated by the application of heat, dimethyl sulfoxide, urea, or ethylene glucol. Severe changes in four environmental variables (high osmotic pressure, low oxygen tension, low or high pH, and low or high temperature) interfere with the germination process. Spores at the end of the postactivation lag phase of germination were usually deactivated if exposed to severe environmental conditions and thus did not swell; spores in the swelling and emergence stages of germination were killed if exposed to severe environmental conditions. The oxygen uptake which began during spore activation was primarily attributable to a cyanide-sensitive pathway and secondarily to a salicylhydroxamic acid (SHAM) sensitive pathway. Inhibition of the SHAM-sensitive pathway did not cause spore deactivation while the addition of cyanide resulted in rapid spore deactivation. Treatment of activated spores with azide or environmental shifts also resulted in inhibition of oxygen uptake and spore deactivation. Deactivating spores did not demonstrate the amino acid incorporation, uridine incorporation, and expression of trehalase activity which is found in the later stages of germinating control spores. Protein synthesis inhibitors did not cause spore deactivation or a decrease in oxygen uptake but they inhibited amino acid incorporation and the expression of trehalase activity in swollen spores. It is concluded that control of respiratory activity is involved in regulation of reversible activation.

ISSN:0008-4166    

DOI:10.1139/m79-004

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The composition and ultrastructure of spore walls ofAgaricus bisporusandAgaricus campestriswere compared by chemical and enzymatic assays and electron microscopy. Polymers ofN-acetylglucosamine (chitin) and glucosamine (chitosan) were the major carbohydrate wall components of both species. The chitin to chitosan ratio in the spore walls ofA.bisporuswas about 0.38, while inA.campestrisit was about 2.8. These polymers were associated with proteins, lipids (readily extractable and bound), melanin, and a low content of β-glucan. The quantity of protein, total lipid, melanin, or β-glucan was similar in spore walls of both species. With the electron microscope, the spore walls appeared as two well-defined layers which may correspond to microfibrils of chitin and chitosan in which the electron-dense melanin was located in the external layer.

ISSN:0008-4166    

DOI:10.1139/m79-005

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Grouping of beta-hemolytic streptococci was performed with the Phadebact® Streptococcus Test, a coagglutination method, and the results compared with serological grouping by the standard Lancefield precipitin method. Of 171 clinical specimens examined, 169 (98.8%) were grouped correctly by the Phadebact® Test after 24 h of continuous growth in Todd–Hewitt broth, In a parallel study, 96.9% of specimens that grew after only 4 h of incubation in broth were grouped correctly by the coagglutination method. In both studies, the accuracy of the coagglutination test was increased significantly by elimination of multiple-agglutination reactions through centrifugation of cultures and utilization of the supernatant fluid in the Phadebact® Test.

ISSN:0008-4166    

DOI:10.1139/m79-006

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Modification of the method of Tatiniet al. (1976) by addition of non-fat dry milk (NFDM) to food samples and subsequent acid precipitation at pH 3.8 enhanced the recovery of staphylococcal thermonuclease (TNase) from most of 37 foods tested. The modified TNase assay method allowed detection of 10 ng (0.002 units) of the enzyme per gram of each of the following foods: ground beef, boiled egg products, whey powder, fruit-containing yogurt, dressings and spreads, potato and egg salads, and pastas, all of which gave false-negative results without NFDM.

ISSN:0008-4166    

DOI:10.1139/m79-007

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Heavy cell suspensions ofSerratia marcescens, when grown in gelatin-containing media, produce extracellular proteases which increase in specific activity in a linear fashion for 3 to 4 h. During partial purification, a single peak of proteolytic activity was demonstrated by Sephadex G-100 chromatography. However, electrophoresis using 5% polyacrylamide gels discloses three proteolytically active bands. Evidence in favor of gelatin acting as an inducer of the 'proteolytic system' was provided by two observations. First, proteolytic activity is only present in media containing gelatin. Secondly, the addition of 10−4 Mrifampicin to cells growing in gelatin-containing medium plus an additional carbon source inhibits protease activity totally, but has no effect on growth. When glycerol is added to a growing cell suspension in gelatin-containing medium, growth increases, but protease specific activity decreases. This 'glycerol effect' is not due to an accumulation of active or inactive enzyme in association with the cell, nor to a decrease in the total number of proteases synthesized. Rather, glycerol, as other utilizable carbohydrates, exerts a repression which can be eliminated by 5 mMdibutyryl cyclic AMP.

ISSN:0008-4166    

DOI:10.1139/m79-008

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

An exocellular pyrophosphatase, active on the nucleotide precursors of peptidoglycans, has been found in the culture medium ofStreptomyces mediterraneiME/R 17. This enzyme was separated from theDD-carboxypeptidase by batchwise adsorption on DEAE cellulose. The pyrophosphatase had no strict substrate requirements, it hydrolyzed various UDP-sugar substrates: UDP-GlcNAc. UDP-MurNAc and UDP-MurNAc peptides, giving rise to the corresponding sugar phosphate and to UMP. The enzyme preparation also contained a 5′-nucleotidase activity and UMP was further split to give uridine. This nucleotidase activity was inhibited by potassium tetraborate. Both cytoplasmic and particulate preparations from cells ofS.mediterraneialso contained a pyrophosphatase activity while only the particulate fractions showed theDD-carboxypeptidase activity.The pyrophosphatase excretion was tested during the growth cycle. The activity of the enzyme showed a constant increase throughout the exponential growth and a stronger increase in the late exponential phase. Such a result could be correlated with a consumption of the nutrients in the culture medium, in fact a relatively poor culture medium had a strong positive effect upon the production of the exocellular pyrophosphatase.

ISSN:0008-4166    

DOI:10.1139/m79-009

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

When used as sole nitrogen source, certain amino acids (e.g., proline, asparagine) supported both growth and sporulation byStreptomyces clavuligerusstreaked onto solid defined medium. Ammonium supported growth but suppressed sporulation. Amino nitrogen was best for cephalosporin production in liquid defined medium, although urea was almost as useful. A comparison of amino acids showed asparagine and glutamine to be the best nitrogen sources and arginine to be almost as good. Ammonium salts supported a somewhat lower growth rate than asparagine, but antibiotic production was very poor on these inorganic nitrogen sources. Addition of ammonium to asparagine did not affect growth rate but increased mycelial mass; cephalosporin production was reduced by about 75%. Antibiotic production was more closely associated with growth in the absence of ammonium than in its presence, indicating a strong inhibitory and (or) repressive effect of NH4+on antibiotic production. Ammonium exerted its negative effect when added at 24 h or earlier, i.e. before antibiotic formation began.

ISSN:0008-4166    

DOI:10.1139/m79-010

出版商:NRC Research Press    

年代:1979

数据来源: NRC