摘要:

The membrane-associated oxidative enzymes glucose, gluconate, and malate dehydrogenases were examined in psychrotrophicPseudomonas fluorescens. The function and activity of these enzymes was determined by measuring extracellular product formation by washed cell suspensions. Membrane dehydrogenase activities and corresponding transport activities for the substrates glucose, gluconate, and malate were compared in batch cultures grown with these substrates at 30 and 5 °C. These activities correlated with the production or lack of extracellular oxidation products. In chemostat cultures grown at 30 and 5 °C, the membrane enzymes and production of their extracellular oxidation products appeared to be regulated by the available carbon concentration. The enzymes were induced and high concentrations of extracellular oxidation products were produced under conditions of nitrogen limitation (carbon excess) but not carbon limitation. The lower affinities of the three membrane enzymes for their respective substrates, when compared with the transport systems utilizing the same substrates, correlated with the observed major function of these enzymes in carbon-excess environments. The primary role of the membrane-associated oxidative enzymes, in carbon dissimilation by this psychrotrophic microorganism at low temperatures in carbon-excess environments, was strongly implicated.

ISSN:0008-4166    

DOI:10.1139/m82-137

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Bacteriophages infecting extremely halophilic bacteria of the genusHalobacteriumhave been isolated from fermented anchovy sauce. Two distinct phages, designated Hh-1 and Hh-3, have been characterized. Both Hh-1 and Hh-3 are more tolerant of suspension in solutions of low ionic strength than their host bacteria. Both Hh-1 and Hh-3 have the ability to establish a carrier state upon infection of sensitive cells ofH.halobium. Bacterial cells infected with phage in the carrier state are viable, produce phages, are immune to superinfection with homologous phages, yet remain fully capable of supporting heterologous phages. These properties suggest that the halophages are well adapted to survival in environments in which the salinity is subject to rapid changes of considerable magnitude.

ISSN:0008-4166    

DOI:10.1139/m82-138

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The composition of the N2-fixing microflora of a rice rhizosphere was studied by a new enrichment and isolation procedure: rather than using an artificial C source, the exudates from a germinating seed ("the spermosphere model") are used. In this study, this system gave N2-fixing isolates with a frequency of 65%. Thirty-two of the many isolates obtained have been studied in detail; these wereKlebsiella oxytoca,Enterobacter cloacae,Pseudomonas paucimobilis, andAzospirillum. All these bacteria were present at densities higher than 105per gram of dry soil in the intial rice rhizosphere.

ISSN:0008-4166    

DOI:10.1139/m82-139

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

This is the first comparative study on the nature and occurrence of the outermost surface structures in chroococcacean cyanobacteria. It shows that all the structures are similar to those of other bacteria and not specific to only cyanobacteria. Twenty-two chroococcacean strains (1Microcystis, 7Synechocystis, 12Synechococcus, and 2Gloeothece) were included in the study. TwoSynechocystisstrains had a glycocalyx layer. The twoGloeothecestrains had a characteristic sheath, and the space between the sheath and the cells contained loosely packed material. On the basis of their preferential staining with ruthenium red, both the sheath and the loosely packed material most probably consist of acidic polysaccharides.Microcystis firma, threeSynechocystisstrains, and oneSynechococcusstrain were surrounded by a regularly structured surface layer consisting of hexagonally arranged subunits.Microcystis firma, all sevenSynechocystis, and threeSynechococcusstrains possessed pili. The pili of some strains occurred as bundles. None of the strains produced spinae. Additionally, some structures described in previous studies are reinterpreted according to the findings of the present study.

ISSN:0008-4166    

DOI:10.1139/m82-140

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

A yeast capable of utilizing cyclohexanecarboxylic acid as sole carbon and energy source, strain KUY-6A, was isolated from soil by enrichment cultures. Taxonomical studies indicated that strain KUY-6A wasTrichosporon cutaneum. Strain KUY-6A grew on a number of carboxylic acids. Among the cyclic compounds tested, cyclohexanecarboxylic acid was the best substrate. Cyclopentanecarboxylic acid, cycloheptanecarboxylic acid, cyclopentanone, cyclohexanone, and cyclopentanol also supported growth. In addition, the organism used the monocarboxylic acids, butyric, valeric, and caproic; the dicarboxylic acids, succinic, glutaric, adipic, pimelic, and suberic; and the aromatic acids, benzoic ando-,m-, andp-hydroxybenzoic. The yeast did not require any vitamins for growth, although thiamine gave slight stimulation. The cell dry weight yield was 0.75 g from 1 g of cyclohexanecarboxylic acid used.

ISSN:0008-4166    

DOI:10.1139/m82-141

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Whether guanosine tetraphosphate (ppGpp) has a role in the regulation of the putrescine biosynthetic enzyme, ornithine decarboxylase, inEscherichia coliis controversial. Different laboratories have reported either direct or indirect correlations between ppGpp levels and ornithine decarboxylase activity using differentin vivoconditions. In this report, using conditionsin vivoto modulate ppGpp levels, experiments are described which bear on the controversy. The rates of synthesis and biological activities of the biosynthetic ornithine and arginine decarboxylases (ODC and ADC) were measured inE.coliK-12 during experimental growth and during nutritional shift-up. There were good correlations between changes in their respective activities and the rates of synthesis of these enzymes during steady state or shift-up. ODC activity or rate of synthesis changed directly in concert with ppGpp levels, while ADC activity or rate of synthesis changed inversely with ppGpp levels. These observations support the contention that ppGpp does not inhibit ODC activity.

ISSN:0008-4166    

DOI:10.1139/m82-142

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Spores of the acellular slime moldFuligo septicagerminated and developed into motile, flagellated swarm cells using only endogenous carbon and energy sources. We observed no increase in the amount of any cell component during this time, whereas we did note a decrease in the amount of several substances. Glucose and glycogen were important reserves which were apparently catabolized via glycolysis and the tricarboxylic acid cycle. The synthesis of large amounts of ATP via a respiratory chain with oxygen as the terminal electron acceptor was essential for development. Another potential carbon and energy source was lipid which also decreased in amount during development, although the metabolism of glycerol could not be demonstrated. RNA synthesis was unnecessary for any of the morphological changes and did not occur at any time under these conditions. Protein synthesis was not essential for any step of morphogenesis but did occur. This synthesis did not result in the net accretion of protein nor in any change in the protein composition discernable by sodium dodecyl sulfate – polyacrylamide gel electrophoresis. Intracellular cyclic AMP levels increased fourfold coincident with the start of rapid glycogen depletion.

ISSN:0008-4166    

DOI:10.1139/m82-143

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Forty-eight continuous culture enrichments were performed on summer and winter water samples from two contrasting rivers. The cell output from each chemostat was dependant on the temperature and nitrogen concentration of each enrichment. The diversity of the populations from the continuous cultures, as assessed by species diversity analysis, was always greater than populations obtained on agar plates. However, the species isolated exclusively by continuous culture in these experiments were not unique to the chemostat. All of these species had been isolated at some time on plates directly. High nitrogen concentrations were found to decrease diversity. Populations sampled during the winter were influenced primarily by the concentration of nitrogen. Summer isolates were affected mainly by the temperature of the culture medium. The nutritional versatility of the population was not affected by enrichment of the continuous culture.

ISSN:0008-4166    

DOI:10.1139/m82-144

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Direct pyrolysis at 800, 900, 950, and 999 °C of bacterial samples at the entrance of the ionization source of a mass spectrometer is proposed. This technique is called multiple masses pyrospectrometry (MMPS). Its results are used for the automated rapid identification of unknown strains via computer memory and data bank facilities.

ISSN:0008-4166    

DOI:10.1139/m82-145

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Methanospirillum hungateistrains GP1 and JF1 when exposed to the adenosinetriphosphatase inhibitorN,N′-dicyclohexylcarbodiimide experienced a marked decline in growth rates, methane synthesis activities, and intracellular ATP concentrations. Although growth was inhibited, the intracellular ATP concentrations of all other methanogens tested were little affected by high concentrations of dicyclohexylcarbodiimide (500 μM). Thus, for studies of ATP synthesis, or for ATP depletion in whole cell suspensions of methanogens, the use of dicyclohexylcarbodiimide appears limited toM.hungatei.

ISSN:0008-4166    

DOI:10.1139/m82-146

出版商:NRC Research Press    

年代:1982

数据来源: NRC