摘要:

Measurements made from electron micrographs of serial sections and from thoroughly plasmolyzed conidia indicate that more than 50% of the volume of the conidia ofSphaerotheca macularisconsists of vacuoles in which most of the water in the conidia is stored. Electron-dense granules inside the vacuoles evidently include storage materials. Some developing vacuoles, particularly those of the germ tube, enclose membrane-bound bodies resembling lysosomes which later disappear as the vacuoles enlarge. Conspicuous multimembraned myelin-like bodies project inside the vacuolar cavity, their membranes being continuous with the vacuolar membrane. These bodies are believed to function in the synthesis of new cytoplasmic materials from the reserves in the vacuoles.The conidium, which may later produce up to four germ tubes, always retains a nucleus. The nucleus contains a peripheral granule which maintains a leading position on migrating nuclei and divides into two during the initial stages of nuclear division.Germ tubes respond positively to the stimulus of unilateral illumination and are produced on the illuminated sides of the conidia. Cytoplasmic changes which accompany germination include the increase in number and size of mitochondria, particularly in the germ tube. Their multiplication appears to be by fission. Endoplasmic reticulum is greatly increased and ribosomes are more abundant. Aggregated granules resembling glycogen particles also occur, these not being usually seen in resting conidia.

ISSN:0008-4166    

DOI:10.1139/m70-051

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

A correlation has been observed between the degree of DNA–DNA (deoxyribonucleic acid) hybridization and the frequency of interspecific genetic transformation betweenStreptococcusspecies of serological groups D and H andDiplococcus pneumoniae. The thermal denaturation (Tm) values and guanine plus cytosine (G + C) mole percent for all cultures were similar. Two mutants of the group D streptococcus, resistant to the potent antileukemic drug amethopterin, were found to be more alike than any other two organisms studied. The intraspecific genetic transfer of the thymine-requirement marker in either direction was not successfully demonstrated. The lack of transformation of amethopterin resistance to the wild type organism was partially due to the lack of homology between the mutants and the wild type.

ISSN:0008-4166    

DOI:10.1139/m70-052

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The shelf life of vacuum-packed luncheon meats during refrigerated storage was not related to "total" counts since the only organisms that multiplied in this environment were lactic acid bacteria, which formed only a small proportion of the initial population.Bacterial growth curves obtained from several Canadian products were remarkably similar, but the spoilage patterns differed. For example, wiener spoilage was a function of bacterial growth while bologna spoiled from the accumulation of bacterial end products. After 15 weeks at 5 °C, the meats contained 0.6 to 0.8% lactic acid and the pH of comminuted meats dropped below 5.0. Cooked ham contained much less carbohydrate than comminuted meats, and the pH remained above 6.0. Under these conditions, ham is susceptible to putrefaction although this was not observed during this study.It was found that cooking can eliminate all lactic acid bacteria present in the raw meats but the products become recontaminated during slicing and packaging. The cleaning and sanitizing procedure used by the Company that cooperated in this study was efficient, but it was recommended that the packaging room be cleaned more often, and that a selective medium for lactic acid bacteria be used in sanitation surveys.

ISSN:0008-4166    

DOI:10.1139/m70-053

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Evidence indicative of the presence of muramic acid in soil was demonstrated. Muramic acid values ranging from 0 to 150 μg/g dry weight of soil were obtained for 33 different soil samples. Comparisons of these values with the muramic acid contents of laboratory-grown microbial cultures revealed that the soil muramic acid levels are about 100- to 1000-fold greater than can be accounted for by a platable bacterial population in soil, but are compatible with other estimates of total bacterial soil numbers. It was suggested that a muramic acid analysis of soil might provide an estimate of its total bacterial population.

ISSN:0008-4166    

DOI:10.1139/m70-054

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Indigenous soil microorganisms on soil contact slides were stained with rhodamine-labeled lysozyme and counterstained with fluorescein-labeled gelatin. Bacteria and actinomycetes on these slide preparations were readily observed by fluorescence microscopy even if they occurred on or near soil particles. Many fungal hyphae were also stained by the fluorochrome-labeled lysozyme, and it is suggested that chitin, which is present in the cell walls of many fungi, is responsible for the fungal adsorption of lysozyme.

ISSN:0008-4166    

DOI:10.1139/m70-055

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

APseudomonasisolated from sewage was adapted to usep-toluenesulfonate as the sole source of both carbon and sulfur. Very few of over 30 aromatic compounds tested were used for growth as sole carbon sources. Significantly, sulfobenzoate, phenolsulfonates, and isomers of cresolsulfonates did not support growth. Respirometry studies with washed, resting cells showed similar results. In both studies, benzenesulfonate was always used more rapidly thanp-toluenesulfonate. The degradation ofp-toluenesulfonate was shown to be over 90% of the theoretical value required for complete mineralization to carbon dioxide, water, and sulfate. When resting cells were incubated with35S-p-toluenesulfonate, the ratio of oxygen uptake to35S-sulfate liberation remained constant during the complete degradation period. Radiochromatographic analysis showed no35S-aromatic intermediates in resting-cell supernatants at any time. Resting cells previously incubated with35S-p-toluenesulfonate liberated two35S-labeled aromatic intermediates upon disruption. Resting cells incubated with 1-14C-p-toluenesulfonate produced labeled 3-methylcatechol, labeled acetate, and unlabeled pyruvate. The labeled intermediate, 3-methylcatechol, was degraded by cell-free extracts to labeled acetate. Hydroxylation, desulfonation, ring cleavage, and subsequent fissions of the carbon chain occurred in that order; all steps but the first were catalyzed by cell-free extracts.

ISSN:0008-4166    

DOI:10.1139/m70-056

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

A strain ofMicrococcus lysodeikticus(designated dis-II) has been isolated by nutritional selection using aspartic acid as the major source of carbon, nitrogen, and energy. This organism is inhibited from dividing when grown in a defined medium in the presence ofD-serine, penicillin, mitomycincor under conditions of suboptimal magnesium concentration. All of the division-inhibiting compounds decrease growth yields and induce varying amounts of lysis.L-Lysine, when added toD-serine-containing media, allows some increase in growth yields, but division inhibition appears more pronounced. Pantoyl lactone,D- andL-alanine, and to a lesser extent Carbowax 400 (hypertonic conditions) and glycine, but not spermine, will significantly prevent but not reverse division inhibition inD-serine-lysine-containing media. Thin-slicing and electron microscopic observation of non-dividing cells shows that a relatively thick layer of porous-appearing cell wall mucopeptide is synthesized when cells are grown in the presence ofD-serine. These cells as well as those grown in the presence of penicillin or mitomycincare not lysed in distilled water. Amount of cell wall mucopeptide is greatly decreased in cells grown under conditions of suboptimal magnesium concentration; these cells undergo extensive lysis in distilled water.

ISSN:0008-4166    

DOI:10.1139/m70-057

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

A brown coloration developed in the culture filtrate whenHerellea vaginicola(Achromobacter anitratus) grew profusely in a sodium acetate and ammonium dihydrogen phosphate basal salts liquid medium. Variations of environmental and cultural conditions affected the intensity of the brown color. The conditions studied were temperature, 25° and 37°, duration of incubation, aeration of growing cultures, and various concentrations of the nitrogen and carbon source. Spectrophotometric and solubility studies suggest that the observed brown coloration was not due to a bacterial pigment. Chromatographic analyses of freeze-dried culture fluid after acid hydrolysis showed six amino acids, one amino hexose, and two hexoses. A Maillard reaction occurring among the components in the supernatant appears to be responsible for the observed brown color.

ISSN:0008-4166    

DOI:10.1139/m70-058

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The possible involvement of the following factors inClostridium perfringenstype A enteritis was investigated: cellular constituents ofC.perfringens, extracellular components, gas generated by growing cultures, and organic acid production. Lambs were used as experimental animals, and all materials were administered by the intraduodenal route.Vegetative cells (1.5 to 5 × 109) administered along with fresh medium caused diarrhea while 100 times the number of cells in spent medium or saline had no effect. Sporulating cells in saline, and their extracts, caused profuse diarrhea. Supernatant fluids from both vegetative and sporulating cultures concentrated by dialysis against polyethylene glycol had no effect, but diarrhea was produced by supernatant fluids from vegetative cultures concentrated by rotary evaporation, and by the gas generated during growth. The effect of the gas was simulated with hydrogen. The pH of the fluid in the small intestine remained constant duringC.perfringensenteritis.It was concluded (i) that the factor responsible for experimental enteritis in lambs resulting from infection of the small intestine with vegetative cells ofC.perfringensis producedin situ, and (ii) that of the various factors tested, a heat-sensitive, nondialyzable component of sporulating cells is most likely identical with the main enteropathogenic factor inC.perfringensenteritis.

ISSN:0008-4166    

DOI:10.1139/m70-059

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Concentrated supernatant fluids from vegetative cultures and cell extracts from sporulating cultures ofClostridium perfringenstype A, both of which had previously been found to cause diarrhea in lambs, were tested in ligated intestinal loops of lambs. The concentrated supernatant fluids had no detectable effect in the loops while the cell extracts caused extensive accumulation of fluid. Rabbit immune sera prepared against extracts from sporulating cells completely inhibited the activity of the cell extracts in the ligated loops.Vegetative cells, injected into ligated loops with fresh medium, sporulatedin situand caused fluid accumulation. This accumulation of fluid was not prevented by the immune sera prepared against extracts from sporulating cells.

ISSN:0008-4166    

DOI:10.1139/m70-060

出版商:NRC Research Press    

年代:1970

数据来源: NRC