摘要:

The mode of formation of conidia by a strain ofStreptomyces viridochromogeneswas followed by the observation of ultrathin sections of aerial hyphae at various stages of sporulation. Before sporulation the aerial hyphae contain a long central strand of nuclear material. The laminated hyphal wall is covered with a fibrous non-spiny layer. At equal intervals, and apparently simultaneously, the hyphal wall becomes involuted while the outer fibrous sheath becomes spiny. The nuclear material constricts, adjacent to the points of involution of the wall. As the involution of the cell wall continues, only a thin isthmus of cytoplasm connects two adjacent future spores. The nuclear material breaks into spheroid structures. The spiny fibrous layer breaks into spore size segments that envelop each spore. An amorphous electron dense material accumulates between adjacent spores during maturation and eventually participates in the formation of interspore pads. Spores in a chain are held together only by the fusion between adjacent interspore pads. As the spores in a chain become fully mature, an area of weakness can be seen between spore pads that are still held together. Although studied in less detail, the mechanism of spore formation is believed to be similar in a strain ofS.violaceus.

ISSN:0008-4166    

DOI:10.1139/m64-042

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Optimal conditions for non-lethal assimilation of radioactive phosphorus bySerratia marcescenshave been studied. Ten microcuries or less of P32per 300 ml of medium has no significant lethal effect on the test organism. The presence of 1% w/v glucose in the culture medium stimulates phosphorus assimilation causing an increase of approximately 34%. Phosphorus assimilation over a 24 hour period increases by approximately 50% when cultures are incubated at 30 °C rather than 37 °C.The concentration of P32in the various cellular constituents has been determined at various intervals during 24 hour incubation. Incorporation of P32in the acid-soluble and lipid fractions of the cell begins almost immediately whereas there is a slight delay prior to incorporation into the R.N.A. and longer delay before incorporation into D.N.A. Sixty to 65% of the P32assimilated by the bacterial cell is incorporated into the nucleic acids. Although R.N.A. has the highest specific activity of the cell fractions studied, the phospholipid fraction also has high specific activity.

ISSN:0008-4166    

DOI:10.1139/m64-043

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Antibiotic activity chromatographically resembling that produced in vitro byCenococcum graniformehas been demonstrated in extracts fromC.graniformemycorrhizae and from roots and needles of three species of conifers. In trembling aspen (Populus tremuloidesMichx.), activity was observed only in mycorrhizal roots and not in leaves. Seedlings of conifers, presumably devoid ofC.graniformemycorrhizae, also contained antibiotic resembling that ofC.graniforme. However, the surrounding soil, which containedC.graniformesclerotia, also exhibited the antibiotic on extraction with acetone but not on extraction with saline.

ISSN:0008-4166    

DOI:10.1139/m64-044

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

When pH was controlled during the growth ofC.perfringenstype C there was an increase in toxin but not in cells. The increases in toxin over that obtained at uncontrolled pH were 3-, 20-, 70-, and 4-fold, for alpha, beta, delta, and theta toxins respectively. pH control did not increase the yield of kappa toxin. Optimum pH was 6.7 for alpha, 7.5 for beta and theta, and 7.5–8.0 for delta. The maximum yields of toxins at optimum pH were 90 MLD of alpha, 100,000 MLD of beta, 2000 hemolytic units of delta, and 4000 hemolytic units of theta. Mu and nu toxins were not produced by the strain of type C used.

ISSN:0008-4166    

DOI:10.1139/m64-045

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Certain non-proliferating bacteria, suspended in saline, are inhibited by folic acid as judged by the ability of the cells to form visible colonies on a nutrient agar subsequent to exposure to folic acid. On the other hand, some yeasts (three strains) are insensitive to folic acid. InEscherichia coliATCC 9637, folic acid toxicity can be prevented by a variety of metabolites. Although a purine-requiring strain ofE.coliis resistant to folic acid, and purines prevent folic acid toxicity in another strain ofE.coli, experiments with C14-formate failed to demonstrate an unequivocal effect of folic acid onde novopurine biosynthesis.

ISSN:0008-4166    

DOI:10.1139/m64-046

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The fatty acid compositions of the oils of several spore forms of seven species ofGymnosporangiumwere determined by gas–liquid chromatography. No simple relationships were found between the host plants and the compositions of the spore oils.cis-9, 10-Epoxyoctadecanoic acid was found in the teliospore oil of five of the species. The oil of basidiospores closely resembled that of teliospores but there was considerable variation in the oil of aeciospores. In one species the aeciospore and teliospore oils were very similar to each other, in another species there was partial resemblance, and in a third species they were different. The fats from four "axenic" cultures ofGymnosporangium juniperi-virginianaeSchw. were analyzed, and were quite different from those of any of the rust species but resembled those frequently obtained from the vegetative stages of many species of fungi.

ISSN:0008-4166    

DOI:10.1139/m64-047

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The oils from one or more spore forms of three species ofPuccinia, four species ofUromyces, and two species ofCronartiumhave been analyzed,cis-9, 10-Epoxyoctadecanoic acid was the major component for bothCronartiumspecies, and was also found in two species ofUromycesand in one ofPuccinia. The oils of uredospores and teliospores of the same rust were always quite similar to each other, but the oils of uredospores and aeciospores of the same rust were sometimes different from each other. An epoxide-hydrolyzing enzyme appeared to be present in the spores of theCronartiumspecies.

ISSN:0008-4166    

DOI:10.1139/m64-048

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

An antibiotic active against representatives of the bacteria, yeasts, and actinomycetes has been extracted from the mycelium, produced in vitro, of several strains of the mycorrhizal fungus,Cenococcum graniforme. No activity was observed in culture fluids of this organism. The antibiotic differed from that found inBoletus luteusmycelium by its microbial inhibition and ultraviolet absorption spectra.

ISSN:0008-4166    

DOI:10.1139/m64-049

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Measurement of the urease activity of fractions of strained rumen fluid from a urea-fed sheep showed that intracellular bacterial urease was responsible for ureolysis by rumen contents. Subjection of the rumen microflora to differential centrifugation showed that 65% of its total urease activity was associated with a group of larger organisms which sedimented at 1200 × g. An average of 35% of the total viable bacteria in rumen fluid was found by a dilution count technique to manifest urease activity. Mixed cultures of rumen bacteria, in which the urease activity per unit concentration of cells was enriched fourfold over that in rumen-fluid, were obtained by serial transfer in a medium containing 80% rumen supernatant liquor (clarified rumen fluid) supplemented with glucose, phytone, and urea. A facultatively anaerobic bacterium with a low urease activity was isolated from rumen fluid, but attempts to isolate obligately anaerobic urease-producing species from enrichment cultures of rumen bacteria were unsuccessful.

ISSN:0008-4166    

DOI:10.1139/m64-050

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The urease activity of whole cell preparations of the mixed rumen microflora was reduced when the cells were washed with maleate buffer. Resuspension of the washed cells in rumen supernatant liquor (RSL) enhanced their urease activity owing to the presence of an inorganic urease-stimulating factor in RSL. When the whole cells were washed in buffer there was a progressive reduction in the urease activity of the cells as the number of washings increased. This effect was attributed to progressive removal from the cells of the urease-stimulating factor. The urease activity of preparations of whole cells washed three times in buffer was stimulated in the presence of Mn2+, Mg2+, Ca2+, Sr2+, and Ba2+, and inhibited in the presence of Na+, K+, and Co2+. These ions brought about similar effects on the urease activity of acetone-dried powders and cell-free extracts of washed rumen microorganisms. The activity of jack-bean urease was reduced in the presence of the ions which stimulated rumen urease.When inorganic ions were added individually to suspensions of washed rumen microorganisms there were time lags before the ions exerted their stimulating or inhibiting effects on urea hydrolysis. Once the stimulation or inhibition of activity by an ion had begun, however, the reaction proceeded at a constant rate which was characteristic of the ion tested. Modification of the permeability properties of washed cells of rumen microorganisms by acetone treatment modified but did not eliminate the time lags. When a cell-free extract of washed cells was tested, Mn2+, Mg2+, Ca2+, Co2+, and K+all influenced urease activity immediately upon addition to the extract, whereas Sr2+, Ba2+, and Na+were active only after a lag period.The urease produced by rumen bacteria is considered to be a metal-activated, intracellular enzyme. The urease-stimulating factor present in the cells was not bound to any appreciable extent intracellularly. The time lags observed with the whole cells were attributable in most cases to the time taken for the ions to penetrate the cells; with Sr2+, Ba2+, and Na+they were apparently due, at least in part, to a delay in the formation of an active complex between ion and enzyme.

ISSN:0008-4166    

DOI:10.1139/m64-051

出版商:NRC Research Press    

年代:1964

数据来源: NRC