Cytologische Untersuchungen an Azotobacter chroococcum Beij

Ohne Zusammenfassung     

Beziehungen zwischen der Streptomycin-und Strahlenresistenz bei Azotobacter chroococcum Beij

Zusammenfassung Nach Röntgenbestrahlung von vier Azotobacter chroococcum-Stämmen wurden Mutanten ausgelesen, die sich hinsichtlich ihrer Koloniegröße,-form und-farbe von den Ausgangsstämmen unterscheiden. Von diesen zeigten 60% erblich fixierte Veränderungen in der Streptomycinresistenz. Bestrahlungsversuche mit unterschiedlich streptomycinanfälligen Mutanten ergaben, daß zwischen der Streptomycin- und der Strahlenresistenz dieser Stämme enge Beziehungen bestehen. Mit steigender Antibioticumresistenz ist die Strahlenresistenz erhöht.     

Wirkung des Sauerstoff-Partialdrucks auf Wachstum und Stickstoffbindung von Azotobacter chroococcum Beij

Ohne Zusammenfassung     

Kontinuierliche Atmungsmessungen an Azotobacter chroococcum Beij. in Montmorillonit unter chronischer Röntgenbestrahlung

Zusammenfassung An zwei Stämmen Azotobacter chroococcum Beij. wurden in Montmorillonit als Bodenmodell Atmungsmessungen unter Röntgenbestrahlung durchgeführt. Durch die Bestrahlung wurde bei beiden Stämmen die Atmungsintensität erniedrigt. Aus dem Beginn der Atmungsdepression nach Einsetzen der Bestrahlung lassen sich Rückschlüsse auf die Strahlenresistenz der verschiedenen Stämme ziehen. Die Strahlenresistenz der beiden untersuchten Bakterien-Stämme war im Montmorillonit im Vergleich zu Suspensionen wesentlich erhöht.     

Sodium-Dependent Growth of Azotobacter chroococcum

Selected ion-monitoring gas chromatography-mass spectrometry was used for detection of beta-hydroxy fatty acids as an independent assay for the presence or absence of endotoxin in materials claimed to induce nonspecific activation of Limulus amoebocyte lysate. To this end, suspensions of gram-negative and -positive bacteria, one fungal species, cerebrospinal fluid, and hollow-fiber hemodialyzer rinses were assayed for endotoxin by gas chromatography-mass spectrometry and the Limulus amoebocyte lysate assay. Good qualitative agreement was shown for both methods when suspensions of test organisms were assayed. Two false-negative results were obtained by gas chromatography-mass spectrometry assays of cerebrospinal fluid and were shown to be a result of insufficient endotoxin in the cerebrospinal fluid specimens for detection by gas chromatography-mass spectrometry. Hemodialyzer rinses were Limulus assay positive; however, no beta-hydroxy fatty acids were detected by gas chromatography-mass spectrometry. These data were compared with data obtained from USP rabbit pyrogen tests of the rinse materials (nonpyrogenic) and chemical characterization of the Limulus assay-reactive rinses, which showed the rinses to be cellulosic in nature. It is suggested that beta-hydroxy fatty acids, as assayed by selected ion-monitoring gas chromatography-mass spectrometry, be used as chemical marker molecules for the presence or absence of endotoxin in materials reported to cause nonspecific activation of Limulus amoebocyte lysate.     

Sodium-Dependent Growth of Azotobacter chroococcum

Selected ion-monitoring gas chromatography-mass spectrometry was used for detection of beta-hydroxy fatty acids as an independent assay for the presence or absence of endotoxin in materials claimed to induce nonspecific activation of Limulus amoebocyte lysate. To this end, suspensions of gram-negative and -positive bacteria, one fungal species, cerebrospinal fluid, and hollow-fiber hemodialyzer rinses were assayed for endotoxin by gas chromatography-mass spectrometry and the Limulus amoebocyte lysate assay. Good qualitative agreement was shown for both methods when suspensions of test organisms were assayed. Two false-negative results were obtained by gas chromatography-mass spectrometry assays of cerebrospinal fluid and were shown to be a result of insufficient endotoxin in the cerebrospinal fluid specimens for detection by gas chromatography-mass spectrometry. Hemodialyzer rinses were Limulus assay positive; however, no beta-hydroxy fatty acids were detected by gas chromatography-mass spectrometry. These data were compared with data obtained from USP rabbit pyrogen tests of the rinse materials (nonpyrogenic) and chemical characterization of the Limulus assay-reactive rinses, which showed the rinses to be cellulosic in nature. It is suggested that beta-hydroxy fatty acids, as assayed by selected ion-monitoring gas chromatography-mass spectrometry, be used as chemical marker molecules for the presence or absence of endotoxin in materials reported to cause nonspecific activation of Limulus amoebocyte lysate.     

Regulation of Azotobacter chroococcum invertase

Synthesis of the Azotobacter chroococcum invertase was found to be dependent on sucrose or raffinose in the growth medium. The activity of this invertase was slightly inhibited by glucose. Fructose, which by itself did not affect the enzyme activity, protected invertase from glucose inhibition. Per cent residual activity plotted against glucose concentration, and Hill plot indicated that this monosaccharide binds to one interacting site of the enzyme. The results show that regulation of this prokaryotic enzyme clearly differs from that of eukaryotic orgnisms.     

Nitrite uptake in Azotobacter chroococcum

Nitrite uptake is made up of two components in Azotobacter chroococcum, a passive diffusion, presumably of nitrous acid, and an active transport of nitrite which uses the nitrate transport system. Only the active component is under regulatory control.     

Nitrate permease from Azotobacter chroococcum

Active transport systems in bacteria can be divided into two groups: those that are osmotic shock-resistant with one single membrane protein, and those that are shock-sensitive and have a membrane-bound protein complex plus a soluble periplasmic protein. Whether the bacterial assimilatory nitrate transport falls into the one or the other of these two groups has not been studied before. We report that nitrate uptake by the strictly aerobic, N₂-fixing heterotrophic bacterium Azotobacter chroococcum is sensitive to osmotic shock. The polypeptide composition of cytoplasmic membranes changes in response to the nitrogen source available to the cells. Incorporation of [³⁵S]-methionine into proteins as well as use of the A. chroococcum TRI mutant, which is defective in nitrate transport, and the A. choococcum MCD1 strain, a mutant unable to use nitrate as a nitrogen source, suggest that nitrate transport into A. chroococcum cells is mediated by a multicomponent system tightly bound to the cytoplasmic membrane.     

Untersuchungen zur Stoffproduktion bei Futterkohl

Zusammenfassung An 5 Idiotypen verschiedener Convarietäten und Varietäten vonBrassica oleracea L. wurde der Verlauf des Trockenmassen-, Rohfaser-, Rohprotein- und Reinproteingehaltes sowie der löslichen N-Fraktion während der Vegetationszeit ermittelt. Im Trockenmassen-und Rohfasergehalt treten zwischen den geprüften Formen beachtliche, bei den Proteinfraktionen geringfügige Unterschiede auf. Die Organe Stamm, Blattspreite und Blattstiel unterscheiden sich in den Gehalten beachtlich. Der Verlauf während der Vegetationszeit bei der Gesamtpflanze ist dem Trend nach für den Trockenmassengehalt steigend, Rohfasergehalt fallend, Rohproteingehalt zunächst fallend, dann steigend und Reinproteinanteil gleichbleibend. Die Sorten und Organe zeigen in einigen Fällen ein abweichendes Verhalten.Während die Gesamttrockenmasse nach Ende Oktober nicht mehr zunimmt, steigt die Rohproteinmasse weiter an. Die relative Trocken- und Rohproteinmassenbildung wird durch Bildung des rel. Proteinfaktors verglichen. Bei Wachstumsbeginn läuft die Rohproteinbildung der Trockenmassenbildung voraus. Der Umschlagspunkt liegt bei den Organen und Sorten zeitlich verschieden und fällt mit dem Beginn des Wachstumsabschnittes 3 (Stoffumlagerung) zusammen. Das Modell der Massenzunahme für die Rohproteinmasse stimmt mit dem der Trockenmasse weitgehend überein.Die Selektion trockenmassenreicher Typen (Winterfestigkeit) ist erfolgversprechend und scheint die Futterqualität kaum zu beeinflussen. Die geringe Variabilität der Proteingehalte eröffnet keine wesentlichen züchterischen Möglichkeiten zu ihrer Erhöhung. Die Ergebnisse werden diskutiert und mögliche Zusammenhänge angedeutet.

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Experiments on the production of bulk in cabbageII. Quantitative changes in some quality determining contents during the course of development

Summary In five different varieties and subvarieties ofBrassica oleracea L. dry matter, crude fibre, crude and pure protein contents as well as soluble nitrogenous fractions have been ascertained during the vegetation period. Among the various forms under study, considerable differences with respect to dry matter and crude fibre and small differences with respect to protein content were noticed. Stem, leaf blade and leaf stalk differ considerably in composition. In the course of the vegetation period dry matter content increases while crude fibre content decreases later on. Its pure protein fraction remains the same, though in some cases the varieties and organs show deviating results.While total dry matter no longer increases after October, the crude protein fraction increases continuously. The relative synthesis of dry matter and crude protein becomes equalized by the formation of the respective protein factor. At the onset of growth crude protein formation exceeds the production of dry matter. The time of change differs with the organ and varieties, and coincides with the start of the 3rd growth period. The model for mass increase of crude protein agrees with that of dry matter.Selection of types rich in dry matter (winter hardiness) promises success; it seems to have hardly any influence on fodder quality. The low variability in protein content does not lead to possibilities for improvement. The results are discussed.

     

Untersuchungen zur Stoffproduktion bei Futterkohl

Ohne ZusammenfassungMit 12 Abbildungen