摘要:

California (CI) and Morocco (MI) isolates ofSpiroplasma citriincubated at 4, 24, or 32 °C yielded typical mycoplasma colonies on agar at each passage. MI but not CI incubated at 37 °C yielded a few colonies at first passage only, but both isolates did not survive 42 °C for 3 days. In liquid and solid media, best growth of both isolates occurred between pH 7.0 and pH 8.5 and the optimum pH for growth in liquid medium was 7.5 (CI) and 8.5 (MI). The sensitivity of CI or MI to 21 antimicrobial substances was identical in most cases. Corn stunt spiroplasma (CSS) and CI had similar antimicrobial substance spectrum, although CSS was much more sensitive to any given substance than CI. CI fermented the following with acid production: cellobiose, dextrose, galactose, trehalose, fructose, mannitol. maltose, and sucrose. MI fermented all these in addition to arabinose, mannose. sorbitol, and raffinnose. Arginine but not urea was hydrolyzed by both isolates. CI or MI failed to reduce potassium tellurite, methylene blue, or tetrazolium chloride.

ISSN:0008-4166    

DOI:10.1139/m79-175

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The production and reduction of nitrous oxide (N2O) after the addition of N2O, nitrite (NO2−), or nitrate (NO3−) was studied in non-sterile soil, in sterilized soil inoculated withPseudomonas aeruginosa, and in washed cell suspensions of this organism. Sodium sulfide (8 μmol S2−mL−1or g−1) inhibited N2O reduction markedly in cell suspensions and also in soil, an effect which may cause sulfidic habitats to act as sources of N2O. Sodium thiosulfate (up to 64 μmol S2O32−g−1) showed no such effect. Acetylene (0.02 atm C2H2) completely inhibited the reduction of N2O by soil, but the combination of C2H2with 8 μmol S2−g−1permitted the complete reduction of 2 μmol added N2O g−1within 3 days under the most favourable conditions. Under the same conditions, 8 μmol S2O32−g−1permitted complete reduction of the N2O within 6 days. The rate of such reduction of N2O was decreased, but not inhibited completely, by raising the C2H2concentration to 0.11 atm. The data have important implications for the effectiveness of the C2H2inhibition assay of denitrification in highly anaerobic environments.

ISSN:0008-4166    

DOI:10.1139/m79-176

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Growth ofSaccharomyces cerevisiaein minimal salts – glucose – SO42−medium with varying concentrations of pantothenate (0–1000 μg/L) produced changes in the cellular lipid content and in the ratio of saturated to unsaturated fatty acids. Substantial differences in SO42−diffusion were also observed with changes in pantothenate concentration. During sulfate reduction, the δ34S value of the evolved sulfide varied with the pantothenate concentration ranging from −31‰ in the absence of pantothenate to 0‰ at 400−1000 μg/L pantothenate. The isotope selectivity is related to the effect of pantothenate concentration on cellular metabolism.

ISSN:0008-4166    

DOI:10.1139/m79-177

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Five bacteria and one yeast were grown in magnetic fields of 50–900 gauss with frequencies of 0–0.3 Hz and square, triangular, or sine waveform. Growth of these microorganisms could be stimulated or inhibited depending upon the field strength and frequency of the pulsed magnetic field. Spore germination and mutation frequency were unaffected by the magnetic fields used in this study.

ISSN:0008-4166    

DOI:10.1139/m79-178

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Myxococcus xanthusfimbriae have been purified and characterized as part of a study of the function of fimbriae in this prokaryote.Myxococcus xanthusproduced two types of fimbriae, termed flaccid (F) and rigid (R) on the basis of electron microscopy. F and R fimbriae differed slightly in their response to pH and freeze–thaw regimes but were similar in their resistance to hydrolytic enzymes, amino acid composition, molecular weight, carbohydrate content, and antigenic determinants. Although the precise relationship between F and R fimbriae is unknown, the possibility is considered that F fimbriae might represent a "contracted" form of the R type. Studies designed to determine fimbriae function inM.xanthusare described in an accompanying report.

ISSN:0008-4166    

DOI:10.1139/m79-179

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Uptake of amino acids byBacteroides ruminicolawas observed in cells grown in a complete defined medium, containing ammonia as the nitrogen source. A high rate of uptake occurred only in fresh medium, as an inhibitory substance, possibly acetate, apparently accumulated during growth. All amino acids except proline were taken up and incorporated into cold trichloroacetic acid precipitable material. Different patterns of incorporation and different responses to 2,4-dinitrophenol and potassium ferricyanide indicated multiple uptake systems were involved. Kinetic inhibition patterns suggested six distinct systems were present for amino acid uptake, with specificities related to the chemical structures of the amino acids. Thus, the failure of free amino acids to act as sole nitrogen sources for growth ofB.ruminicolais not due to the absence of transport systems for these compounds.

ISSN:0008-4166    

DOI:10.1139/m79-180

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

All species ofRhizobiumexceptR.lupinihad nitrate reductase activity. OnlyR.lupiniwas incapable of growth with nitrate as the sole source of nitrogen. However, the conditions necessary for the induction of nitrate reductase varied among species ofRhizobium.Rhizobium japonicumand someRhizobiumspecies of the cowpea strains expressed nitrate reductase activities both in the root nodules of appropriate leguminous hosts and when grown in the presence of nitrate.Rhizobium trifolii,R.phaseoli, andR.legnminosarumdid not express nitrate reductase activities in the root nodules, but they did express them when grown in the presence of nitrate. In bacteroids ofR.japonicumand some strains of cowpeaRhizobium, high N2fixation activities were accompanied by high nitrate reductase activities. In bacteroids ofR.trifolii,R.leguminosarum, andR.phaseoli, high N2fixation activities were not accompanied by high nitrate reductase activities.

ISSN:0008-4166    

DOI:10.1139/m79-181

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Pseudomonas aeruginosastrains PAO and PAK bear polar pili which are flexible filaments having a diameter of 6 nm and an average length of 2500 nm. Both types of pili are retractile and promote infection by a number of bacteriophages. The present communication describes the partial biochemical characterization of PAO pili isolated from a multipiliated nonretractile mutant of PAO. The observed properties are compared to those of PAK pili which were characterized previously. PAO pili were found to contain a single polypeptide subunit of 18 700 daltons. This is similar to PAK pili which contain a single polypeptide of 18 100 daltons. The amino acid composition of PAO pilin was also similar to that of PAK pilin. Neither protein contained phosphate or carbohydrate residues and both were found to containN-methylphenylalanine at the amino terminus. Sequencing of 20 amino acid residues at the amino terminal end of PAO pilin revealed the sequence to be identical with that of PAK pilin, while tryptic peptide analyses of PAO and PAK pilin indicated that the two proteins probably contain a number of homologous regions within the polypeptide. It was concluded that PAO and PAK pili are closely related structures.

ISSN:0008-4166    

DOI:10.1139/m79-182

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A viscous, ropy, sour milk product, called 'viili,' is produced in Finland. Capsule-forming strains ofStreptococcus cremorisare the typical starters for this product. Occasionally fermentation fails and results in a non-ropy clot. The reasons for these failures, however, are obscure. In one batch of spoiled 'viili,' a new C3-type bacteriophage, termed KSY1, was isolated. The head of the phage was about 230 nm long and about 50 nm wide and the tail was 35 nm long and carried a complex collar structure. Upon infection of a number of encapsulated cultures ofS.cremoriswith KSY1, the cocci, though not serving as a host of the phage, lost their capsules. A capsuleless strain,S.cremoris249, served as a host. The latent period was about 150 min and the average burst size 80. The buoyant density of KSY1 was 1.436 g/cm3.

ISSN:0008-4166    

DOI:10.1139/m79-183

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The proposed method for rapid testing of inositol assimilation incorporates shake cultures in an indicator-based broth containing inositol (1%). yeast nitrogen base (0.067%), bromocresol purple, and a heavy inoculum. Of 153 yeast isolates investigated, inositol assimilation was shown with the modified method, as also by the Adams–Cooper procedure, in all of the 123 isolates, representing 11 species ofCryptococcus. The results were negative by both the methods in the remaining 30 isolates belonging toCandida,Rhodotorula,Torulopsis,Pichia,Saccharomyces, andSporoholomyces. The modified method was found to be significantly more effective than the Adams–Cooper procedure; the results could be read within 36 h by the former as against 336 h by the latter method. The superiority of the modified method to the Adams–Cooper procedure is attributed to increased aeration in shake cultures, a heavier inoculum, and reduced concentration of yeast nitrogen base.

ISSN:0008-4166    

DOI:10.1139/m79-184

出版商:NRC Research Press    

年代:1979

数据来源: NRC