摘要:

Four nuclear and two cytoplasmic chloramphenicol-resistance markers were selected inS.cerevisiae. The effect of the suppressive factor (abnormal mitochondria deoxyribonucleic acid) on the inheritance of these markers was studied. Nuclear markers were shown to be unaffected by the suppressive factor, in contrast to the loss of cytoplasmically inherited chloramphenicol resistance upon the generation of the suppressive factor.

ISSN:0008-4166    

DOI:10.1139/m72-001

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Salmonella typhimuriumincreased in virulence during growth in an acid environment whereas in a near neutral environment, the reverse was true. The lipopolysaccharide content of acid- and alkaline-grown cells remained relatively constant during growth, but that in neutral-grown cells decreased. The crude endotoxin extracted from acid-grown cells was slightly more toxic than that extracted from either neutral- or alkaline-grown cells. Based on these results, any attempt, therefore, to correlate a hazard to public health with the numbers ofSalmonellapresent in a food would at this time be impossible.

ISSN:0008-4166    

DOI:10.1139/m72-002

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Facultative anaerobic asymbiotic N2-fixing bacteria have been identified consistently on the surfaces of roots and nodules of soybean plants cultured under laboratory and greenhouse conditions. An examination of a limited number of samples of alfalfa and clover plants from natural soils also has revealed similar types of bacteria. Most of the isolates investigated were members of theKlebsiella–Aerobactergroup. Serological tests of 11 isolates indicated different degrees of relationship toKlebsiella pneumoniae. Rates of growth and N2fixation in anaerobic cultures were markedly stimulated by a sterile extract of soybean nodules. Bacteria of the type identified on root surfaces of legumes were found often as contaminants of legume seeds and in most cases were not removed by surface sterilization treatments.

ISSN:0008-4166    

DOI:10.1139/m72-003

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The effects of respiratory deficiency on the level of NAD-dependent alcohol dehydrogenase activity were studied. Respiratory-deficient mutants produced by acriflavine, and wild-type cells grown on glucose in the presence of chloramphenicol had elevated alcohol dehydrogenase activities compared with the wild-type cells grown on glucose. The increased activity was a result of an increase in ADH-I. The respiratory-deficient mutants appeared unable to produce ADH-II or isocitrate lyase even after incubation of the cells in ethanol medium. However, this transfer to ethanol medium increased the level of ADH-I activity. The presence of chloramphenicol in the ethanol medium further increased the alcohol dehydrogenase activity of these mutants. The effect of chloramphenicol in the wild-type cultures depended on the time of its addition to the culture. If chloramphenicol was present during both the period of growth on glucose and in the ethanol medium, ADH-II activity did not appear. If the cultures were grown on glucose in the absence of chloramphenicol, allowing respiration to develop, the subsequent presence of chloramphenicol in fresh ethanol medium did not prevent the appearance of either ADH-II or isocitrate lyase activity. The respiratory-deficient mutants also contained alcohol dehydrogenase activity which resembles ADH-III in respect to electrophoretic mobility, heat stability, and relative activity with various alcohols as substrates.

ISSN:0008-4166    

DOI:10.1139/m72-004

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

An asporogenic mutant ofClostridium botulinumtype E, ATCC 9564, was recovered on liver veal agar, which had been supplemented with MnSO4(0.13 mM) and mercaptoacetate (0.2%). Growth in TPG measured by optical density increased exponentially for the two strains during the first 11 h. But subsequently, the optical density of the wild type rapidly declined while the sp−mutant showed a more gradual decrease. The pH decreased significantly during growth but remained unaltered at pH 5–6 during sporulation. The DPA synthesis in the sp+strain paralleled the appearance of refractile spores, while the sp−strain showed no measurable amounts of DPA. Protease and antibiotic activities were detected late in the log growth phase of the wild type. Gas–solid chromatography showed that during growth and sporulation the mercaptoethanol and CO2content declined significantly in the wild type, but remained unchanged in the sp−mutant, whereas N2O was evolved concurrently with sporulation. This study has provided us with an effective method for the isolation of asporogenic mutants ofC.botulinum, as well as a basis for the analysis of the events which occur during the stages of sporulation.

ISSN:0008-4166    

DOI:10.1139/m72-005

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Saccharomyces fragilis, a yeast capable of fermentation, grows poorly on ethanol as the carbon source. The respiratory quotient for glucose of aerobically grown cultures approaches 1 and glucose does not repress the formation of mitochondria. The effect of ethanol on the oxygen consumption and the NAD (nicotinamide adenine dinucleotide)-dependent alcohol dehydrogenase activity of this yeast has been studied. The electrophoretic pattern of alcohol dehydrogenase activity on polyacrylamide gels is complex. Six bands of activity can be identified in homogenates from cultures grown on glucose. Three of these appear associated with the particulate fraction. Differences in the relative amounts of the three particulate bands of activity under different growth conditions indicate that the particulate fraction may contain more than one isozyme. The particulate fraction also exhibits alcohol oxidase activity. While ethanol and acetate stimulate the oxygen consumption of the glucose-grown cultures, theQo2for these substrates is much less than that for glucose. If the glucose-grown cultures are transferred to fresh ethanol medium, theQo2for ethanol and acetate increases to values higher than that seen for glucose. This increase does not depend on an increase in the terminal respiratory capacity of the cells. On transfer to ethanol medium there is also a marked increase in the total alcohol dehydrogenase activity, and on electrophoresis a new band of activity appears. Acetate cannot replace ethanol in producing these effects.S.fragilisalso produces an NAD-dependent alcohol dehydrogenase which reacts with cinnamyl alcohol as substrate but not with ethanol.

ISSN:0008-4166    

DOI:10.1139/m72-006

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The formation of pentachloroanisole by methylation from pentachlorophenol byTrichoderma virgatumin liquid cultures was detected using gas chromatography and confirmed by melting point determination and infrared (i.r.) spectroscopy. The formation of pentachloroanisole, however, did not account for the total loss of pentachlorophenol in the medium, suggesting that this reaction is only the first step in the metabolism of this compound or a parallel reaction to degradation. Pentachloroanisole was much less toxic than pentachlorophenol toTrichoderma virgatum,Cephaloascus fragrans, andPenicilliumsp., as well as to fish in laboratory toxicity tests.

ISSN:0008-4166    

DOI:10.1139/m72-007

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

While probing or feeding on leaves,Myzus persicaeproduced wounds that resulted in lesions when virus was applied later. Lesions were also produced on leaves covered with tobacco mosaic virus (TMV), tobacco mosaic virus ribonucleic acid (TMV-RNA), brome mosaic virus (BMV), or hybrid BMV (BMV-protein/TMV-RNA) when these leaves were subsequently exposed to aphids. With TMV the number of lesions increased with increasing virus concentration. Keeping plants in the dark reduced the number of lesions produced by aphids, but increased those produced by mechanical inoculation.Nicotiana glutinosawas more susceptible to inoculation of TMV by aphids than wasN.tabacumvar. Xanthi nc. It is concluded that infectible sites produced by mechanical means differ from those produced by aphids.Aphids could not transmit TMV-RNA, BMV, BMV-RNA, or hybrid BMV from a virus-covered leaf to a healthy leaf. However, BMV and TMV could be recovered from the mouthparts of aphids which had fed or probed on virus-covered leaves.

ISSN:0008-4166    

DOI:10.1139/m72-008

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Antisera specific forSpirillumthermolabile antigens (TLA) of 29Spirillumstrains were obtained by adsorption of antisera prepared against unheated cells with homologous heat-treated cells. Each antiserum was tested against all of theSpirillumstrains by cross-agglutination. Cross-agglutinations occurring at serum dilutions of 1:160 and above were considered indicative of a sufficient degree of antigenic relationship to permit serological grouping, and the antigenic relationships within such groups were supported by adsorption tests. The TLA antisera were used successfully to identify unknownSpirillumisolates. The high specificity ofSpirillumTLA antisera allowed serological distinction of most of the species ofSpirillumfrom one another and from members of related genera.

ISSN:0008-4166    

DOI:10.1139/m72-009

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

An examination of the odorous constituents produced byPhellinuswas carried out using gas chromatography and infrared spectrometry. The predominant compound in all three species was methyl benzoate although significant amounts of methyl salicylate and benzyl alcohol were also found.

ISSN:0008-4166    

DOI:10.1139/m72-010

出版商:NRC Research Press    

年代:1972

数据来源: NRC