摘要:

A thermophilic fungus, isolated from the city wastes and identified asMyceliophthora thermophilaD-14, produces cellulase and β-glucosidase. The optimum pH, temperature, and incubation period for extracellular enzymes acting on different types of cellulosic substrates were determined. The apparentKmvalues of these enzymes were ascertained by using culture filtrates. Partial purification of the enzymes was carried out by (NH4)2SO4precipitation and gel filtration. Electrophoresis of the fractions obtained from gel filtration revealed at least eight components in the enzymes. The involvement of all the components for degradation of native cellulosic wastes, especially cotton, was determined and synergestic effects were indicated.

ISSN:0008-4166    

DOI:10.1139/m82-040

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Bacteriocinlike activity was sought among 58 streptococcal strains using a deferred antagonism technique and 50 indicator strains. Antagonist production was generally increased by glucose supplementation of brain heart infusion agar and reduced by addition of calcium carbonate. Activity due to complete bacteriophage was excluded, as was toxic buildup of lactate, acetate, or ethanol. Hydrogen peroxide activity was responsible for all, or part, of antagonist activity inStreptococcus mitiorand in three strains ofStreptococcus milleri. Bacteriocinlike activity was confirmed in the strain ofStreptococcus mutanstested and in nine strains ofS.milleri. Virtually all isolates ofS.milleritested were sensitive to the bacteriocinlike activity ofS.mutansNCTC 10832.

ISSN:0008-4166    

DOI:10.1139/m82-041

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Lipid composition of threeArthrobacterstrains (mesophilic, psychrotrophic, and psychrophilic strains) grown at their optimum growth temperature was studied. Great differences appeared only in the nature of their fatty acids: the psychrophilic strain synthesized less linear acids, C17acids, and moreisoisomers than the other two strains.Incubation of the three strains at temperatures below their optimum resulted in variations only in proportion of the different fatty acids: increase of the ratio of unsaturated, of branched, and of short-chain fatty acids.The relation between lipid composition and ability to grow at temperatures around 0 °C is discussed.

ISSN:0008-4166    

DOI:10.1139/m82-042

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Freshly prepared cell suspensions of Clostridia (Clostridium bifermentans,C.botulinumproteolytic type A,C.difficile,C.sordellii, andC.sporogenes) andPeptostreptococcus anaerobiusconverted leucine to isovaleric (iV) and isocaproic (iC) acids in the absence of other amino acids. The optimal pH for conversion was between 8 and 9 at 37 °C. The stoichiometry of reaction was compatible with that expected for the Stickland reaction, as the ratio of iV to iC was 1:2, the amount of CO2produced was equivalent to that of iV, and ammonium ion concentrations were equal to the total C5and C6acids formed. The presence of alanine and valine (proton donors in the Stickland reaction) in incubations effectively increased the concentration of iC at the expense of iV production, implying that leucine acted here primarily as a proton acceptor. Glycine and proline (proton acceptors) stimulated both iV and iC production from leucine, but increases in iV concentrations were proportionately greater than for iC, so that leucine was primarily a proton donor in the presence of proton acceptors. Glucose stimulated the conversion of leucine to volatile fatty acids but favoured iC production. Production of iC from leucine was inhibited by surface active compounds (cetyltrimethylammonium bromide and desoxycholate) as well as arsenite and iodoacetate. The redox dyes methyl viologen and phenosafranine inhibited iC production more severely than iV production, as did the nitroimidazole antimicrobial agent, metronidazole.

ISSN:0008-4166    

DOI:10.1139/m82-043

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Neisseria gonorrhoeaeexist in transparent (Tr) and opaque (Op) colony forms. Op forms are recovered from patients early in the menstrual cycle; Tr colonies predominate late in the cycle. The mechanism for this colonial variation was examined by determining the influence of gonodal hormones on growth inhibition of Op and Tr isogenic variants of gonococci. The estrogens, estrone and estradiol, enhanced growth whereas 19-nortestosterone, testosterone, and progesterone significantly inhibited gonococcal growth. Testosterone and progesterone inhibited growth of the Op variants to a greater degree than the Tr variants. Mixtures of Tr and Op colonies grown in the presence of progesterone became predominantly Tr, as occurs in the luteal phase of the menstrual cycle. This study supports the hypothesis of hormonal influence on colonial variation but employed artificialin vitroconditions and high hormone levels.

ISSN:0008-4166    

DOI:10.1139/m82-044

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The assimilation of selenite byEscherichia coliinvolves a transport process specific for this anion. Cystine, a repressor of sulfate and selenate uptake, when added to the growth medium, had no effect on selenite uptake; nor did sulfite inhibit assimilation of selenite. Cells grown aerobically in a basic salts medium transported selenite at an initial rate of 0.14 μmol∙g−1∙min−1and aVmaxof 393.0 μmol∙g−1∙min−1. In contrast, cells grown in a medium that contained the trace elements necessary for synthesis of the selenoenzyme formate dehydrogenase took up selenite at a significantly faster rate (initial rate = 0.27 μmol∙g−1∙min−1,Vmax = 658.2 μmol∙g−1∙min−1).Kmvalues for the transport process in the two media, however, were found to be similar. The results suggest the existence of a metabolic pathway, specific for selenite, responsible for the incorporation of selenium into format

ISSN:0008-4166    

DOI:10.1139/m82-045

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Chloramphenicol production was studied in cultures ofStreptomyces venezuelaegrowing in a simple buffered medium with ammonia as the nitrogen source and glucose, lactose, or a glucose–lactose mixture as the sole source of carbon. With each carbon source the antibiotic was formed during growth. In the glucose–lactose medium, the production pattern was biphasic; a marked decrease in the rate of synthesis was associated with depletion of glucose from the medium and a corresponding diauxie pause in growth. Cells ofS.venezuelaecontained an inducible β-galactosidase. Induction by lactose was suppressed by glucose. Measurement of the concentration of intracellular adenonsine 3′,5′-cyclic monophosphate during growth of cultures with glucose or a glucose–lactose mixture as the source of carbon showed no appreciable changes coinciding with depletion of glucose or the onset of chloramphenicol biosynthesis. It is concluded that the cyclic nucleotide does not mediate selective nutrient utilization or control antibiotic biosynthesis in this organism.

ISSN:0008-4166    

DOI:10.1139/m82-046

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Twenty-three marine and two terrestrial gram-negative bacteria were examined for the effect on the outer membrane of the cells of washing the organisms successively in 0.5 MNaCl and 0.5 Msucrose, a procedure which brings about the loss of the outer membrane fromAlteromonas haloplanktis214. Six organisms lost their outer membrane completely, three lost it partially, and six retained it but in a form which indicated that the membrane had been affected extensively. The remaining 10 organisms including the two terrestrial species,Escherichia coliandPseudomonas aeruginosa, showed no changes detectable in thin section by electron microscopy. None of the 16 organisms which retained their outer membrane after washing were converted from rod forms to spheres by lysozyme before washing but 12, includingPseudomonas aeruginosa, formed spheres in the presence of the enzyme after the wash treatment. For many of the latter organisms, treatment with lysozyme caused large segments of the outer membrane of the cells to be removed. Losses in cell viability following washing and treatment with lysozyme paralleled the extent of damage to the outer membrane perceived by electron microscopy.

ISSN:0008-4166    

DOI:10.1139/m82-047

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The addition of 1 mMSeO42−significantly affected the physiology and metabolism ofClostridium pasteurianumgrowing on SO42−in the following ways: (1) the generation time was increased, essentially producing a biphasic growth curve, (2) cells became elongated and chains formed, (3) no H2S was liberated during the stationary phase, (4) assimilatory SO32−reductase activity was decreased, (5) ferredoxin levels decreased by a factor of 4. The effects of 1 mMSeO42−onClostridium pasteurianumgrowing on SO32−were comparatively minor.H2S evolution in the stationary phase decreased by a factor of 2 and the δ34S maximum in the inverse isotope effect pattern occurred at a slightly lower percent H2S evolution. The deleterious effects of SeO42−addition were less pronounced than those associated with SeO32−addition. SeO32−but not SeO42−was reduced to elemental selenium by both whole cells and crude extracts.

ISSN:0008-4166    

DOI:10.1139/m82-048

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Acetylene (C2H2) strongly inhibited (Ki0.25 μMor 0.66 Pa) the oxidation of ammonia (NH4+) to nitrite (NO2−) byNitrosomonas europaeabut did not affect the oxidation of hydroxylamine (NH2OH) to NO2−by this organism. We suggest that the C2H2-sensitive step is associated with the ammonia oxygenase. Oxidation of NH4+was inhibited only approximately 50% by 0.4 mM(10 kPa) ethylene and by 2.1 mM(10 kPa) nitrous oxide and was unaffected by 0.1 mM(10 kPa) methane. The oxidation of NO2−to nitrate (NO3−) byNitrobacter winogradskyiand of NH4+to NH2OH and NO3−by the heterotrophic nitrifier,Arthrobactersp., was not affected by 3.83 mM(10 kPa) C2H2.

ISSN:0008-4166    

DOI:10.1139/m82-049

出版商:NRC Research Press    

年代:1982

数据来源: NRC