摘要:

A new autotrophic acidophilicThiobacillussp. was isolated from acidic soil adjacent to a natural gas processing plant's sulfur stockpile. This isolate metabolized S2O32−to S4O62−during growth and could not reoxidize this product; instead, the remaining S2O32−substrate was oxidized to SO42−in the stationary phase which represented a significant metabolic change as compared with other acidophilic thiobacilli. In contrast the isolate oxidized S0to H2SO4during log-phase growth with no S4O62−being formed. Ultrastructural studies revealed that the isolate's cytoplasm contained unidentified membrane-bound granules, volutin type bodies, and carboxysomes. Cleavage planes within the cell wall revealed a pattern of highly ordered subunits in the outer leaflet of the outer membrane and these ordered subunits were also discerned through the eutectic at the cell surface. This regular structure was not observed at the surface of cells of other acidophilic thiobacilli. The isolate bears a single pilus and one unusually long polar flagellum. The physiological and ultrastructural data are discussed in relation to other known thiobacilli and show this isolate to be a newThiobacillussp. namedT.kabobis.

ISSN:0008-4166    

DOI:10.1139/m81-025

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Zymomonas mobilisdemonstrated greater fermentative activity thanSaccharomyces uvarumduring the 1st day in the fermentation of two lots of aflatoxin-contaminated corn and two corresponding lots of ammonia-detoxified corn. Final ethanol yields and conversion efficiencies were generally highest inZymomonasfermentations of ammonia-detoxified corn. Aflatoxin levels in postfermentation solids from ammonia-detoxified corn all ranged below the Food and Drug Administration feedstuff guideline of <20 parts per billion, whereas the amount of aflatoxin in postfermentation solids from aflatoxin-contaminated corn was greater than in the initial corn.

ISSN:0008-4166    

DOI:10.1139/m81-026

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A radioactive method for determining the total rates of synthesis and degradation of RNA in a bacterial culture has been developed. The rates (which are expressed as moles of AMP residue transferred per unit DNA per unit time) are calculated from the amount of radioactivity accumulated in the RNA pool by taking into account (i) the increasing specific activities of a precursor triphosphate and RNA, (ii) the withdrawal of radioactivity from the RNA pool by degradation, and (iii) the increasing DNA content of the culture. The method is applicable not only to "balanced" accumulation where DNA and RNA accumulate in a constant proportion, but also to "unbalanced" accumulation. Examples illustrating the application of this method are described.

ISSN:0008-4166    

DOI:10.1139/m81-027

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Bacteriophage P1 transduction was used to study the incompatibility group H1 plasmid pRG1251, molecular weight 120 × 106, and the incompatibility group H2 plasmid pSD114, molecular weight 166 × 106. The order of resistance (R) determinants on pSD114 was deduced from transduction and segregation experiments to be chloramphenicol-tetracycline-kanamycin-streptomycin. Resistance to tellurium and to coliphages, which are properties also encoded by many H2 plasmids, were not transduced with the other markers. On pRG1251, the ampicillin and tetracycline resistance markers appear to be located together, as do the chloramphenicol, streptomycin, and sulfamethoxazole resistance markers. Frequently, blocks of R determinants were transposed to the P1 genome or to theEscherichia colichromosome. P1 DNA was isolated which carried the chloramphenicol, streptomycin, and sulfamethoxazole markers from pRG1251 and had a molecular weight of 64 × 106. Other P1 prophages carried R determinants from pSD114 and had molecular weights of 86 × 106. A plasmid of molecular weight 124 × 106was also isolated which contained incompatibility determinants from P1 (incompatibility group Y) and from the H2 group plasmid. The mechanism of formation of these unusual plasmid species is discussed.

ISSN:0008-4166    

DOI:10.1139/m81-028

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

AfricaHybridization studies based on the prototrophic selection technique, involving the use of auxotrophic mutants of strains of five accepted species of the genusSchizosaccharomyces, are reported.Intrastrain recombinants were recovered in five out of six tested parental pairs. Interstrain recombinants were recovered from crosses involving strains ofS.japonicusand strains ofS.pombe. No recombinants were recovered in 62 interspecific crosses involving all possible combinations of the six representatives of the genus.

ISSN:0008-4166    

DOI:10.1139/m81-029

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A strain ofBacillus cereus, which can grow in nutrient broth containing 50 μMHgCl2, was isolated from soil. Mercurous or mercuric ion dependent oxidation of reduced NADPH was demonstrated in crude extracts of cells grown in nutrient broth containing 10 μMHgCl2. The properties of this mercuric reductase were similar to those of the enzymes from R factor bearingEscherichia coliin substrate specificity, heat stability, requirement of sulfhydryl compounds, sensitivity to some heavy metal ions, and molelcular weight.

ISSN:0008-4166    

DOI:10.1139/m81-030

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Temporal and spatial variability of methanogenesis and the effects of environmental contamination on methanogenesis were examined in freshwater sediments. Temporal and spatial variation was found to be significant in uncontaminated freshwater reservoir sediments. The relative concentration of organic matter and temperature explained approximately 43% of the total variability. Known environmental contaminants marginally inhibited methanogenesis and only a coal conversion effluent and phenanthrene, 100 mg L−1, demonstrated statistically significant inhibition of methanogenesis under acute dosing conditions. Methyl viologen, a potent inhibitor of pure culture methanogenesis, inhibited sediment methanogenesis at high concentrations, i.e., 2570 mg L−1, indicating that the sediment environment protected the methanogenic population from the toxic effects of the environmental contaminants.

ISSN:0008-4166    

DOI:10.1139/m81-031

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The initial cause of the cessation of patulin biosynthesis in submerged cultures ofPenicillium urticaewas sought. The extrinsic limitations to patulin biosynthesis in fermentor cultures were successfully removed and kinetic profiles of the metabolites of the pathway and of three pathway enzymes were determined over a 60-h period. These profiles indicated that the first intrinsic limitation involved a decrease in the cellular content of the first enzyme of the pathway, 6-methylsalicylic acid synthetase. Other enzyme contents also decreased but on a significantly longer time scale. Thus thein vivohalf-maximal lifetimes for the synthetase and for them-hydroxybenzyl alcohol and isoepoxydon dehydrogenases were about 7, 17, and 19 h, respectively.

ISSN:0008-4166    

DOI:10.1139/m81-032

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Thirty-four strains corresponding to 16 species ofClostridiumwere examined for growth inhibition activity and production of phage and bacteriocinlike particles. Twenty-five strains were found to inhibit growth of one or more of the other strains. The widest range of activity corresponded toC.bifermentans18137 which inhibited growth of 23 strains. Cell-free filtrates of positive cultures were inactive with the exception of the one fromC.bifermentans18137. A wide variety of particles with diverse morphology was observed in lysates of cultures treated with mitomycin C (1 μg/mL).

ISSN:0008-4166    

DOI:10.1139/m81-033

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

FromSalmonella typhimuriumLT2hemA(δ-aminolevulinic acid requiring) 15 mutants were isolated which grew on the hydrophobic compound hemin. All had increased sensitivity to antibiotics such as vancomycin, bacitracin, novobiocin, erythromycin, rifampin, and oleandomycin, and were considered to be envelope mutants (Env−). Half the mutants were rough, based on altered bacteriophage sensitivity and deoxycholate sensitivity, whereas the remainder were smooth; three of the smooth mutants were studied in detail. They gave increased uptake of gentian violet but no increase in leakage of a periplasmic protein, RNase I. The total membranes and fractions from sucrose gradient centrifugations representing inner and outer membranes of the wild type and three mutants were examined by sodium dodecyl sulfate – polyacrylamide gel electrophoresis (SDS–PAGE) and isoelectric focussing – PAGE (IEF–PAGE). The major outer membrane proteins (molecular weights (MW)33 000, 34 000, 35 000, and 36 000) showed no or very little alterations in the Env−mutants. In SA1926 (env-52) one protein spot at MW 48 000, proven to be an outer membrane protein, was missing, whereas a new spot appeared nearby, and other proteins in this area of the gel were reduced. An Env+transductant selected from this strain had the wild-type protein pattern restored. The two other Env−mutants had similar but not identical changes in protein composition.

ISSN:0008-4166    

DOI:10.1139/m81-034

出版商:NRC Research Press    

年代:1981

数据来源: NRC