摘要:

The attachment of a marine pseudomonad to polystyrene was found to be dependent upon (a) culture concentration, (b) the time allowed for attachment, (c) the growth phase of the culture, and (d) temperature. The number of attached cells increased with both culture concentration and the time allowed for attachment, until the attachment surface approached saturation. The number of cells which attached and the rate of attachment was greatest with log-phase cultures, and progressively decreased with stationary and death-phase cultures. A temperature of 3 °C ± 1 noticeably decreased the proportion of stationary phase cells which attached, compared with cells at 20 °C ± 1. These results can be described by a model based on physicochemical adsorption, which suggests that non-biological processes may play a major role in the initial events of bacterial adhesion.

ISSN:0008-4166    

DOI:10.1139/m77-001

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Phospholipids ofMycobacterium phleiATCC 354 are cardiolipin, phosphatidyl ethanolamine, tri- and tetra-acylated dimannophosphoinositide and tetraacylated pentamannophosphoinositide. Contrary to a previous report (Dhariwalet al. 1975, Experientia, 31: 776–778), monomannophosphoinositide was not evident. A linear decrease in total lipid was observed with an increase in the nitrogen content of the medium. An inverse relationship was observed with the carbon supply in the medium. Cells grown on a medium with limited nitrogen contained more saturated fatty acids, whereas cells grown on a medium with limited carbon contained more unsaturated fatty acids. No significant change in phosphatidyl ethanolamine resulted from changing the carbon and nitrogen supply in the medium. Phosphatidylinositol mannosides were the major phospholipids in glycerol-grown cells, but in glucose-grown cells concentrations of phosphatidylinositol mannosides and cardiolipin were the same. Glyceride content of cells increased with an increase in carbon supply and decreased with an increase in nitrogen supply in the medium. Phosphatidylinositol mannosides were the major phospholipid component at 37 °C, whereas cardiolipin was the major phospholipid in cells grown at 27 °C. Among fatty acids, a considerable decrease in palmitic acid with a concomitant increase in palmitoleic and oleic acid was observed with a decrease in growth temperature from 37 to 27 °C. The results show that there is a preferential production of certain lipid constituents under various cultural conditions.

ISSN:0008-4166    

DOI:10.1139/m77-002

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

WhenPenicillium brevicompactumis grown on Czapek Dox medium in the surface or sub merged mode as batch or continuous-flow cultures, mycophenolic acid is produced. Unlike the classical secondary metabolic system, 6-methylsalicylic acid production byP.patulum, mycophenolic acid is formed independently of dilution rate in a flow system. Discounting the possibility that strains ofP.brevicompactumthat produce mycophenolic acid are mutants defective in the control of secondary metabolite biosynthesis, we conclude that mycophenolic acid production is not regulated as part of a non-vegetative genome. An invertase (EC 3.2.1.26) activity has been encountered in bothP.brevicompactumandP.patulum.

ISSN:0008-4166    

DOI:10.1139/m77-003

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Virus-like particles have been found in the female reproductive tracts of allApantelesspp. thus far examined. Particles generally consist of putative baculovirus-like nucleocapsids which are enveloped singly or as groups within nuclei of calyx epithelial cells. Enveloped particles are injected into host caterpillars during oviposition. Subsequently, particle nucleocapsids appear in the cytoplasm of many host cells, and appear to be uncoated at nuclear pores.

ISSN:0008-4166    

DOI:10.1139/m77-004

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Oospores ofPythium myriotylumin nonsterile soil extracts became invaded by a fungus that was isolated and identified asHyphochytrium catenoides. Sporangia ofH.catenoidesformed as spherical or ovoid lobes within thePythiumoospore and as radial catenulate swellings on agar media. In water, these sporangia formed short exit tubes through which anteriorly monoflagellated zoospores were released. Oospores ofP.myriotylumandAphanomyces euteichesplaced in suspensions of motile zoospores ofH.catenoidesbecame extensively invaded within 48 h. Oospores ofPythium aphanidermatumandP.ultimumwere also attacked, but these species were less susceptible to invasion than wasP.myriotylum. Sporangia, hyphae, and zoospores of thePythiumspp.,A.euteiches, and several other phycomycetes were not observed to be invaded. Zoospores ofH.catenoideswere formed and released in water adjusted to pH 5.0–7.0 and at temperatures of 10–35 °C, but were produced most abundantly and were most highly motile at pH 6.0–7.0 and at 20–30 °C. The roots of several crop plants did not appear to be parasitized byH.catenoides. Oospores ofP.myriotylum,P.aphanidermatum, andP.ultimumin moist soil artificially infested with these species andH.catenoideswere destructively invaded by the mycoparasite. Its presence in several soils and its ability to reproduce quickly in its parasitic stage suggest thatH.catenoidesmay play a role in the natural decline of susceptible Oomycetes in soil.

ISSN:0008-4166    

DOI:10.1139/m77-005

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Bacillus subtilis168M is lysogenic for a temperate bacteriophage called SPβ. The virus head is 76 m wide by 82 m long and the tail measures 12 by 358 m. The DNA molecular weight is 62 million. SPβ is spontaneously released at low levels in cultures ofB.subtilis168M, and can be induced at higher levels by treatment with mitomycin C orN-methyl-N′-nitro-N-nitroso-guanidine.

ISSN:0008-4166    

DOI:10.1139/m77-006

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Pathogenesis of apple by the facultative parasitePenicillium expansumwas critically dependent upon certain physiological events during the primary stages of spore germination. A comparison of two prototrophic isogenic strains of the fungus, one of which was virulent, the other avirulent, revealed that both produced an apple-macerating factor when the spores germinated in vitro. However, germination and growth of the avirulent strain in apple extract and in apple fruit was significantly lower than with the virulent strain. This contrasting behaviour was attributed to the differential sensitivity of the two strains to an inhibitory substance of host origin. Radioactive isotope studies indicated that, with the avirulent organism, the inhibitor interfered with the incorporation of14C into RNA from labelled [6-14C]orotic monohydrate during germination; under similar conditions RNA synthesis by the virulent strain was stimulated. Incorporation of14C into protein from labelled [U-14C]L-arginine monohydrochloride was not influenced by the inhibitor, nor was the differential sensitivity of the two strains attributable to differences in respiration, although apple extract greatly reduced the evolution of14CO2from [1-14C]D-glucose in both strains. The inhibitor, which was water-soluble and dialyzable, appeared to have a fundamental effect upon the metabolism of the spores in the initial stages of germination, and is postulated to be a primary determinant in the virulence ofP.expansum. The data support the hypothesis that the mechanism controlling the pathogenicity of a prototroph may be distinct from that which governs the basic nutrition of the organism.

ISSN:0008-4166    

DOI:10.1139/m77-007

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Buffered mycelial extracts were prepared from 20 isolates ofAspergillus flavusLink ex. Fries and four isolates ofAspergillus parasitionsSpeare, including aflatoxin-producing and non-producing strains within each species. The extracts were tested for activity of various enzymes after separation by polyacrylamide gel-slab electrophoresis.Aspergillusspp. were most readily distinguished by the bands of α-esterase (EC 3.1.1.2), β-esterase (EC 3.1.1.1), and peroxidase (EC 1.11.1.7). For each isolate, the relative mobilities were determined for the various multiple-molecular forms of all three enzymes. The isolates were then compared on the basis of these relative mobilities by using a simple index of similarity to construct a single-linkage dendrogram. No distinct differences in enzyme patterns were detected between aflatoxin-producing and non-producing isolates. However, patterns of similarity or groups were indicated in the dendrogram which suggested some degree of physiological relationship.

ISSN:0008-4166    

DOI:10.1139/m77-008

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Two quantitative objective methods for measuring flocculation of a yeast culture were com pared and correlated with subjective estimation by eye. One method involved counting in a haemocytometer the number of free cells (i.e., cells not found in flocs) and then the total number of cells after complete deflocculation by pronase. The number of cells in flocs was derived by subtracting the number of free cells from the total number of cells. The other method made use of the decrease in turbidity of a flocculated culture on standing. Gross flocs settled to the bottom of a tube within 5 min. The decrease in turbidity was measured by a photoelectric colorimeter. The difference in turbidity readings between 0 and 5 min was assumed to represent the turbidity component due to cells in flocs. The methods were appropriately applicable to monitoring the time course of sex-directed flocculation of the fission yeastSchizosaccharomyces pombe. A culture at maximum flocculation contained 500 gross flocs ml−1which represented up to 70% of the total number of cells. A typical primary floc occupied a volume of 1 × 10−4 ml and contained 1 × 105 cells.

ISSN:0008-4166    

DOI:10.1139/m77-009

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A fluorescence-staining method using the magnesium salt of 1-anilino-8-naphthalene sulfonic acid is described. It allows the numbers and types of viable microorganisms in soil sections to be determined by direct microscopy. About 8% of the bacteria in the soils studied were able to divide when a nutrient solution was applied. A higher percentage of the fungal propagules in these soils were viable. The effects of environmental factors, chemical compounds, and soil amendments on the ability of soil microorganisms to undergo division or mycelial extensionin situcan also be determined.

ISSN:0008-4166    

DOI:10.1139/m77-010

出版商:NRC Research Press    

年代:1977

数据来源: NRC