摘要:

Details are given of the conditions which allow vacuolar structures ofFusarium culmorumto be released after osmotic bursting of mycelial protoplasts. Steps in the release of vacuoles are shown. The composition of the suspending medium affects the formation, size, and number of the vacuoles seen in the protoplasts. Fusion of vacuoles in regenerating protoplasts has been observed, indicating a self-sealing property of the tonoplast. Preparations of vacuolar structures, rather free from cytoplasmic debris, have been obtained.

ISSN:0008-4166    

DOI:10.1139/m67-058

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

An attempt was made, using the soil-washing box technique, to obtain detailed information about the initiation of the rhizosphere mycoflora of dwarf bean seedlings.Tabulated information of the fungi isolated from washed non-rhizosphere soil and washed rhizosphere soil from plants during the first 20 days after seed germination is presented together with data of the fungi isolated from the waters in which these soil samples were washed. These data are discussed in relation to previous observations of fungi isolated from rhizospheres by other methods.The results obtained revealed that in the early days after seed germination the rhizosphere mycoflora was qualitatively similar to that of the non-rhizosphere soil. However, a number of distinct differences were discernible between the rhizosphere and non-rhizosphere populations even at these early stages of plant growth, namely thatCylindrocarpon radicicola,Humicola grisea, and a sterile sclerotial form (W1) were isolated with increased frequency from the rhizosphere, whereasTrichoderma viridewas consistently isolated less frequently from the rhizosphere than from non-rhizosphere soil.

ISSN:0008-4166    

DOI:10.1139/m67-059

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Neurosporamycelia were grown in Vogel's medium N. The mycelia were harvested and vacuum filtered to yield moist, mycelial mats 2 to 3 mm thick. The mycelial mats were placed in Petri dishes and incubated at 25°. On or about the third hour of incubation conidiophores appeared over the mycelial surface. The conidiophores differentiated into conidia on or about the eighth hour of incubation. The production of conidia continued for approximately 8 hours.The addition of 0.05 Mmalonate to the growth medium synchronized the appearance of the conidiophores on harvested moist mats of mycelia. The conidiophores so produced also approached synchrony in their differentiation into conidia. The uniformity of conidiophore production and the differentiation of conidiophores into large numbers of conidia were also influenced by both the length of aeration of the submerged mycelia and by treatment of the harvested mycelial mat with different buffers.There appeared to be a difference in the rate of germination for conidia harvested at different times from conidiophores of harvested mycelial mats. However, there was little difference in the germination rate for conidia produced from conidiophores of harvested mycelial mats and similar aged conidia grown on solidified medium N. The conidia, regardless of age or culture technique, retained a random capacity to germinate.

ISSN:0008-4166    

DOI:10.1139/m67-060

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The requirements for a continuous culture system for extended studies of the growth physiology of functional rumen bacteria are outlined and the choice of Dawson's (1963) cyclone column culture vessel as the basis for further development is explained. The modifications required for establishment and maintenance of anaerobiosis, for pH control and for increasing the reliability and utility of this system are described. The general performance of the modified system is discussed and illustrated by results obtained during extended runs with a strain ofRuminococcus albusand aButyrivibriospecies.

ISSN:0008-4166    

DOI:10.1139/m67-061

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Soil is regarded as consisting of a number of microbial habitats or ecological niches. Each niche is made up of three factors: substrate, environment, and time. A model system was used to simulate a niche reasoned to occur in field soils and to be occupied by heterotrophic bacteria. The system comprised a particulate substrate (dried yeast) mixed in a porous environment (sand) maintained over periods of up to 1 year. Yeast and sand were placed in special culture tubes which were inoculated with known numbers of bacteria suspended in mineral salt solution. This was distributed evenly through the sand by a suction method. The fate of single and mixed populations of three species of soil bacteria was followed by plate counts and microscopical observations. The bacteria wereArthrobacter globiformis, a second soil diphtheroid, andAzotobacter chroococcum. Both diphtheroids grew and persisted well either in single or mixed culture. Populations of azotobacter grown singly initially maintained their numbers, but then declined progressively; they declined more rapidly in association with the second soil diphtheroid, and abruptly to zero withA.globiformis.

ISSN:0008-4166    

DOI:10.1139/m67-062

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Spheroplasts ofMycobacterium tuberculosiswere formed by culture of the organism in a nutritionally complete medium to which lysozyme and an extract obtained from rabbit peritoneal monocytes were added. The potentiating effect of the factor, or factors, present in the monocyte extract was lost upon prolonged storage at −20 °C or heat at 90 °C for 5 minutes, but was unaffected by dialysis. It was inactive in the presence of fluoride or oxalate. Enzymatic analysis of the monocyte extract showed the presence of lysozyme, acid phosphatase, phospholipase, and trypsin. When acid phosphatase or phospholipase were substituted for the monocyte extract in the lysozyme test system, spheroplast formation was obtained.

ISSN:0008-4166    

DOI:10.1139/m67-063

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Intact spores ofBacillus subtilisare susceptible to subtilopeptidase attack and this enzymatic reaction induces changes in the spore similar to those that take place during "physiological" germination. Germination occurred between pH 5.5 and 10.0 showing a pH optimum of 9.0 and between 25 °C and 45 °C with an optimum of 37–40°. Subtilopeptidase-induced germination took place in completely anaerobic conditions. Sublethal heating of spore suspensions increased the rate of subtilopeptidase-induced germination. Germination with subtilopeptidase was almost completely inhibited by an excess of diisopropyl fluorophosphate.L-Alanine-induced germination was not affected by diisopropyl fluorophosphate. Participation of the spore metabolism in subtilopeptidase-induced germination seemed likely. These results suggest that subtilopeptidases initiate spore germination by releasing germination agents from the spore.No significant loss of viability was noted until after exposure to the proteolytic enzyme for at least 60 minutes. Prolonged exposure ofB.subtilisspores to subtilopeptidase results in death of the exposed spores.Subtilopeptidase-induced germination was also observed in several spores of other members of the genusBacillus.

ISSN:0008-4166    

DOI:10.1139/m67-064

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

A third species has been added to the typhus group of rickettsiae. This new rickettsia was isolated fromHaemaphysalis leporispaluslristicks removed from indicator rabbits in the vicinity of Richmond, Ontario. Inoculation of tick suspensions into embryonated hens' eggs was the method of culture. Results of complement fixation tests with guinea pig, hamster, and rabbit antisera showed that it is a member of the typhus group while results with antiserum prepared in mice suggested that it is different from the two known species,Rickettsia typhiandRickettsia prowazeki, in the group. Results of toxin neutralization tests furnished the final proof that this is a new species of rickettsia. The nameRickettsia canadais proposed for it.

ISSN:0008-4166    

DOI:10.1139/m67-065

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Three mycobacterial strains isolated from fish were tested for their ability to metabolize various amines, supplied individually as sources of carbon. A series of six aliphatic and two cyclic amines was used. Growth occurred only with putrescine. The ability to oxidize putrescine was enhanced by growing the cells in the presence of the compound. Putrescine did not appear to influence the rate of endogenous respiration and therefore O2uptake values were corrected for endogenous O2uptake. During the oxidation of putrescine by washed cells, O2uptake curves "broke" at a point corresponding to 41–44% of the maximum level of oxidation. Thereafter, very small increases in O2uptake occurred so that on the completion of experiments, the level of oxidation corresponded to 45–47%. At this point, 69–76% of the amino nitrogen of putrescine was released as ammonia, the rest being assimilated. Using putrescine-1,4-14C under CO2-free conditions, approximately 75% of the terminal carbons were evolved as14CO2. Since the data suggested that carbons 2 and 3 were assimilated, CO2production accounted for a loss of 37.5% of putrescine carbon. When washed cells oxidized putrescine-1,4-14C, cell fractions containing lipid, nucleic acid, and protein were rapidly labelled.

ISSN:0008-4166    

DOI:10.1139/m67-066

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Three mycobacterial strains isolated from fish degraded putrescine by a pathway in which γ-aminobutyraldehyde (Δ′-pyrroline), γ-aminobutyric acid, succinic semialdehyde, and succinic acid were intermediates. These results agree substantially with those of other workers using different microorganisms. Intact cells utilized γ-aminobutyric acid in a transaminase reaction with endogenously supplied α-ketoglutarate to produce succinic semialdehyde and glutamate. Studies with arsenite-poisoned cells showed that a significant proportion of putrescine was metabolized via pyruvate and alanine. When putrescine-1,4-14C was substrate, HCl extracts of cells contained radioactive aspartate and glutamate in addition to alanine. The further metabolism of succinate therefore proceeded in two directions: one yielding oxalacetate and α-ketoglutarate by way of the tricarboxylic acid cycle, and the other branching off the cycle to yield pyruvate. Studies with cell-free extracts suggested that putrescine nitrogen was assimilated via glutamate, which served as the amino-group donor to yield alanine and aspartate.

ISSN:0008-4166    

DOI:10.1139/m67-067

出版商:NRC Research Press    

年代:1967

数据来源: NRC