bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of a cell cycle model of slowly growing Eschericha coli cells
Authors: Knorre W. A. , Müller H. , Simon Z. 
Published: July 2010

AbstractA threshold concentration model for bacterial cells corresponding to the slow growth conditions studied by Kubitschek et al. (1967) was simulated on an analog computer. The stability of the model and the range of parameter values which reproduce the slow growth characteristics were studied. A characteristic of our model is the great oscillation of the DNA‐precursor pool whose synthesis is assumed to be subject to self‐inhibition. This periodic process is the basis of cell division in our model. Some modifications to rapid growth are also discussed.
Interferenzmikroskopische Trockenmassebestimmungen an primären Strumazellen in Gewebekultur. III. Effekt der Infektion mit Adeno‐Virus Typ 5
Authors: Seeber Christine , Beyer H. , Körting H. J. 
Published: July 2010

AbstractDie Zellparameter Trockenmasse, Volumen und relative Trockenmasse von Plasma, Kern und Nucleolus wurden bei Adeno‐Virus Typ 5 infizierten (n = 76) und nicht infizierten (n = 33) Strumazellen bestimmt. Bei Virusreplikation ließ sich eine signifikante Abnahme der Trockenmasse (Kern und Nucleolus), eine Volumenverminderung (Plasma, Kern und Nucleolus) und ein Anstieg der relativen Trockenmasse registrieren. 24 Stunden nach In‐fektion waren Trockenmasse (Kern und Nucleolus), Volumen (Kern und Plasma) und relative Trockenmasse (Kern und Plasma) gegenüber Kontrollzellen signifikant verändert. Signifikante Korrelationen bestanden zwischen den Wertepaaren Trockenmasse/Volumen (Plasma. Kern und Nucleolus) sowie bei den relativen Trockenmassen von Kern/Plasma und außerdem von Kern/Nucleolus bei Virus infizierten und Kontrollzellen. Der Kern als Ort der Virusreplikation wies signifikante Korrelationen von Trockenmasse/Volumen auf, wenn die Korrelationskoeffizienten verschiedener Zeitpunkte p.i. (den Zeitraum von 24 bis 97 Std. p.i. umfassend) miteinander verglichen wurden. Diese Veränderung der Korrelationskoeffizienten lokalisierte den Kern als dynamisches Zentrum während der Replikation.Die Anwendung der Interferenzmikroskopie für die Virusschnell‐Diagnostik wurde diskutiert.
Physicochemical investigations on DNA isolated from bacteria after photodynamic inactivation
Authors: Jacob H.‐E. , Sarfert Eva , Triebel H. 
Published: July 2010

AbstractSpectrophotometric and sedimentation measurements have been used to investigate the influence of photodynamic in vivo action on the DNA from Proteus mirabilis. After photodynamic treatment of bacteria using thiopyronine as sensitizer the DNA was isolated under equal conditions both from the illuminated suspension and the corresponding control and dark suspension. The results obtained with various control samples show the high reproducibility of the DNA preparation technique used.The photodynamic effect leads to a deterioration of cell lysis and to a considerable lowering of DNA yield. Photodynamic inactivation of bacteria results in several changes in the UV‐spectrum of DNA which indicate a loss of guanine bases.From the sedimentation experiments performed on native and alkaline denatured DNA molecular weight distributions, number average molecular weights, and average numbers of single‐ and double‐strand breaks have been evaluated. The results show that DNA from photodynamically treated bacteria exhibitsa strong degradation of the single polynucleotide chains which considerably increases with light dose. On the basis of our result it cannot be decided whether the single‐strand scissions observed represent primary lesions of photo‐dynamic action or secondary lesions induced by alkaline treatment. Further studies at neutral pH conditions are necessary to answer this question.–As a byproduct, evidence is given for the existence of single‐strand interruptions in the control DNA from untreated bacteria.
Sporenbildung in wachsenden Bacillus subtilis‐Kulturen und ihre Korrelation zur Kompetenz für genetische Transformation
Authors: Kretschmer S. 
Published: July 2010

Using shift‐experiments it was shown that there are two kinds of spores in Bacillus subtilis 168 differing in their genesis. Spores, which develop to a small extent in nonlimitated cultures are called NL‐spores, while the other ones, whose formation is initiated by growth‐limitation, are called L‐spores. The development of NL‐spores took 2.5 hrs. more than that of L‐spores. This prolongation was due to a presporulation stage, during which cells do not divide, and apparently no sporulation‐specific metabolism is expressed, Addition of glutamic acid to the glucose‐salt‐medium did not influence the frequency of cells passing from growth to the presporulation stage. But its presence prevented these resting cells from entering the sporulation stage, which they did in the glutamic acid‐free medium after having passed through the 2.5 hrs. lasting presporulation stage.Cells developing competence for genetic transformation resemble to some extent sporulating cells. But as they do not appear under growth‐limiting conditions, it seems likely that competence may be connected only with the NL‐sporulation. Comparison of the kinetics as well as the frequency of transformation and NL‐sporogenesis do favour this hypothesis. Competence than would correspond to the last 50 min of the presporulation stage of the NL‐sporogenesis. But additional factors are involved in the expression of competence in cells being at that stage.
Protein production by local yeast strains with special emphasis on Geotrichum candidum
Authors: Osman H. G. , Chenouda M. S. , El‐Masry H. G. 
Published: July 2010

AbstractThe efficiency of yeasts isolated from decaying fruits was investigated. The strains studied were Torulopsis westerdijkii, Paratorulopsis ingeniosa, P. maris, Geotrichum novakii, and four different strains of G. candidum. G. candidum was the most promising new protein producing strain. The effects of molasses, corn steep liquor, and different carbon and nitrogen sources on yeast and protein production by G. candidum have been studied. A newly formulated synthetic medium supporting growth and protein yield of G. candidum has been adopted.
Metabolic activities and dynamic aspects of growth in Geotrichum candidum
Authors: Osman H. G. , Chenouda M. S. , El‐Masry H. G. 
Published: July 2010

AbstractThe metabolic activity of Geotrichum candidum was investigated. The chromatographic analysis of the cell pool and of the acid hydrolysate revealed the presence of almost all the amino acids previously detected in other yeasts. The pool pattern was not greatly different from the acid hydrolysate pattern, but it varied in certain stages of growth.
Morphology and cytology of Ravenelia emblicae Sydow
Authors: Singh U. P. 
Published: July 2010

AbstractThe morphology of spore‐forms in Ravenelia emblicae Sydow is described in detail. Only pycnial, uredial, and telial stages occur in its life cycle. Observations on nuclear behaviour in teliospore, basidium, and basidiospore are presented here. The haploid chromosome complement at the metaphase of meiotic nuclear division indicated 5 morphologically distinct chromosomes (n = 5).
Hippurate hydrolysis as a taxonomic criterion in the genus Streptomyces (order Actinomycetales)
Authors: Ziegler P. , Kutzner H. J. 
Published: July 2010

AbstractAbout 300 strains of Streptomyces have been tested for their ability to hydrolyze hippurate to benzoic acid and glycine. Four different methods were employed to demonstrate this physiological activity: Formation of an alcaline reaction on hippurate agar and determination of benzoic acid by precipitation with sulfuric acid or by thin layer‐and gas liquid‐chromatography.The results obtained in this study show that “hippuricase‐activity” is widespread among streptomycetes. Strong activity can be demonstrated with the sulfuric acid test whereas only partial hydrolysis of the substrate can be detected by chromatographic methods. Some species of which several strains were a vailable showed uniformity in regard to this property. This result indicates that the hydrolysis of hippurate is a useful taxonomic criterion in the genus Streptomyces.
Action of some metal ions, EDTA, and heated milk on the milk‐clotting process of Penicillium citrinum rennin‐like enzyme
Authors: Abdel‐Fattah A. F. , El‐Hawwary N. M. 
Published: July 2010

AbstractThe influence of some metal ions was investigated on the milk‐clotting activity of the pure rennin‐like enzyme of Penicillium citrinum 805. Barium and calcium enhanced the clotting activity while copper, nickel, and sodium ions showed slight inhibitory effects. Above a certain concentration limit, EDTA played a role by which its complexing action with calcium ions was compensated and the milk became readily coagulable by the enzyme. This phenomenon was more significant when EDTA was added to the milk instead of the enzyme. It was suggested that treatment of milk with EDTA led to homogenization and aggrregation of the phosphocaseinate particles whereby the clottability of milk was increased. The heating of milk rendered it more coagulable by the rennin‐like enzyme. This was attributed to different factors including the increase in the degree of aggregation of casein micelles and the release of NPN‐bound NANA by heat.
Aerobic inhibition of nitrate assimilation in Escherichia coli
Authors: Kobayashi Miya , Ishimoto M. 
Published: July 2010

AbstractGrowth of Escherichia coli, strain K‐10, in synthetic medium with nitrate as a sole source of nitrogen was not found under aerobic conditions, but found in the medium under anaerobic conditions as well as in synthetic medium with ammonium or nitrite under both aerobic and anaerobic conditions. The presence of nitrate reductase activity in cells indicates that the growth inhibition is due to the inhibition of the enzyme by oxygen and not due to its absence. Conditions of preculture, inoculation size, pH, and composition of the nitratesynthetic medium did not affect the inhibition. All the 37 strains of E. coli tested were grown in the nitrate medium only anaerobically, while 18 strains of Klebsiella‐Aerobacter among 22 strains tested were grown in the nitrate medium both aerobically and anaerobically.
Apparent effect of pentachloronitrobenzene on the hyphal wall polysaccharides of two strains of Neurospora crassa
Authors: Georgopoulos S. G. 
Published: July 2010

AbstractA pentachloronitrobenzene (PCNB) resistant mutant of Neurospora crassa and its respective wild type were grown in liquid medium with and without PCNB. Physically isolated hyphal walls were subjected to acid hydrolysis and analyzed for glucose and glucosamine. In the wild type strain PCNB reduced the amount of glucosamine by about 49% and increased the amount of glucose by 15%. The total glucose + glucosamine was significantly higher in the hydrolysates from the PCNB grown walls. These changes were accompanied by striking alterations in the hyphal morphology of the wild type strain but the chemical did not prevent the formation of cell wall around wall‐free protoplasts obtained from this strain. The morphology of the resistant mutant was not affected by PCNB but in the wall hydrolyzates there was a significant reduction of the amound of glucosamine. The findings are discussed in relation to other studies correlating morphology with cell wall composition in N. crassa.
Untersuchungen zur Antigenstruktur von Shigellen. IX. Struktur der O‐spezifischen Seitenketten der Lipopolysaccharide eines Shigella flexneri‐Serotyp 4b‐Stammes
Authors: Seltmann G. , Beer W. 
Published: July 2010

AbstractDurch Partialhydrolyse des O‐spezifischen Polysaccharids von Sh. flexneri Stamm 38/64 (Serotyp 4b, Antigenstruktur IV:6…) und Charakterisierung der gebildeten Oligosaccharide, sowie durch Permethylierungsanalyse wurde die Struktur der “repeating units” dieses Polysaccharids ermittelt: magnified image
Repression des Malatenzyms durch n‐Alkane in Acinetobacter calco‐aceticus
Authors: Kleber H.‐P. 
Published: July 2010

AbstractAcinetobacter calco‐aceticus oxydiert Succinat besser, wenn die Zellen auf Succinat gewachsen sind, als wenn sie auf Acetat oder n‐Alkanen kultiviert wurden. Das wird auf eine Repression des Malatenzyms durch Verbindungen zurückgeführt, die Acetat oder Acetyl‐CoA bilden. Die spezifische Aktivität des Malatenzyms ist auch nach Wachstum auf Succinat hoch, nach Wachstum auf Acetat oder n‐Alkanen dagegen sehr niedrig. Succinatadaptierte Zellen mit hoher Aktivität an Malatenzym verlieren im Acetat‐ bzw. n‐Alkan‐Medium signifikant an Aktivität.Acetat und n‐Alkane wirken analog auf das Malatenzym, weil offenbar beim n‐Alkan‐Abbau intermediär Fettsäuren entstehen, die im Verlauf der β‐Oxydation Acetat bzw. Acetyl‐CoA liefern. Acetat scheint in A. calco‐aceticus durch die Repression des Malat‐enzyms eine Art „Grobkontrolle”︁ auszuüben, da eine Neuproduktion von Acetyl‐CoA aus Malat über Pyruvat unnötig geworden ist.
Ermittlung reaktionskinetischer Daten der Dampfinaktivierung von endotroph mit bivalenten Kationen beeinflußten Bacillus stearothermophilus‐Sporen
Authors: Musieslki H. 
Published: July 2010

AbstractVon endotroph in Tris‐Puffer mit Calcium‐, Magnesium‐ und Manganionen beeinflußten Bacillus stearothermophilus‐Sporen wurden für eine reine Dampferhitzung bei 121 °C die Überlebensdaten aufgenommen. Unter vergleichbaren Bedingungen erfolgte nach der Halvorson‐ und Ziegler‐Gleichung beim Einsatz von 24 Cellulosescheiben mit angetrockneten Sporen der letztmögliche Überlebensnachweis für Ca‐Sporen nach 9 min bei D121 = 1,6 min, für Mg‐Sporen nach 7,2 min bei D121 = 1,3 min und für Mn‐ und Tris‐Sporen nach 5,5 min bei D121 = 1,0 min. Aus 9 verschiedenen Überlebenskurven konnte von angetrockneten Ca‐Sporen eine Absterbekurve in dem Temperaturbereich 115–135°C mit einen z‐Wert von 10 °C ermittelt werden.
Optimierung der Kulturbedingungen für Candida gulliermondii, Stamm H17
Authors: Schröder K. D. , Weide H. 
Published: July 2010

AbstractDurch quantitative Optimierung von sieben für das Wachstum von Candida guilliermondii, stamm H17, wesentlichen Faktoren wurde die Teilungsrate von 0,61 h−1 erreicht. Dazu waren drei Serien von je 64 Kulturversuchen erforderlich. Die optimale Versuchsplanung erfolgte nach der Methode von Box‐Wilson in Kombination mit 2n‐Faktorenplänen. Dieses Verfahren führte nicht zu minimalen Größen für die Variablen, deren Kombination die maximale Meßgröße ergibt. Deshalb sollten die Ausgangswerte zur mathematischen Optimierung von Prozessen der mikrobiellen Biomasse‐ und Produktgewinnung generell aus suboptimalen Bereichen vorher aufgestellter Optimumskurven gewählt werden.
Anaerobiosis and oxygen consumption of some strains of Propionibacterium and a modified method for comparing the oxygen sensitivity of various anaerobes
Authors: Schwartz A. C. 
Published: July 2010

AbstractA method is described that permits to compare the oxygen senstivity of different anaerobes independent of the respective cultural conditions, when a certain procedure of standardization outlined in detail is observed. If the corrected inhibition zones (1) obtained in deep agar cultures under 2 atm of O2 are plotted against the logrithms of the decimal dilutions (D) used for inocula, a straight line results which is described by the equation I = A log D + B. It is sugggested to call the slope A „modification factor”︁, and B “constant of oxygen sensitivity”. As proved for Propionibacterium a high value of A indicates a respiration, or a similar oxygen‐consuming process, which is responsible for the oxygen tolerance of the organism concerned. Growth inhibition becomes effective in Propionibacterium, only when the amount of oxygen present exceeds the oxygen‐consuming activity of the cells, and thus cannot be removed by them. The existence of several oxygensensitive sites in P. shermanii and P. pentosaceum is demonstrated by the inactivation of lactate, glycerol, and propionate oxidation in aerated cell suspensions.
A model on the induction by UV irradiation of Escherichia coli bacteria lysogenic with the bacteriophage Lambda
Authors: Noack D. , Rontó Gy. 
Published: July 2010

AbstractThe induction of Lambda prophages in lysogenic Escherichia coli cells is started after inactivation of repressor molecules coded for by the prophage genome itself. All agents known to inhibit bacterial DNA synthesis are able to initiate a set of processes resulting in the inactivation of these repressors. In the case of UV light as an inducing agent it is suggested that the UV mediated damages within the bacterial DNA diminish the replication velocity leading through a set of intermediate processes to the inactivation of phage repressors by accumulation of repressor inactivating precursors of DNA synthesis. The analytical function for the dose effect curve is obtained from the product of the probability PI of cells containing I UV damages multiplied by the number I of UV damages after summing up all possible numbers of I. The probability of PI is calculated on the basis of the radiation kinetic model of RONTÓ et al. (1972). The theoretical dose effect curve, obtained shows a shoulder with an extrapolation number of 1.2 and a linear part at high irradiation doses in semilogarithmic plot. The experimental data obtained with UV induction of E. coli K12 (λ) are consistent with the model and show that only a few UV damages smaller than 10 per bacterial chromosome are sufficient for induction.
Geomikrobiologische Untersuchungen. XII. Verhalten von Mikroorganismen auf uranhaltigen Gesteinen
Authors: Ebner H. G. , Schwartz W. 
Published: July 2010

AbstractUranhaltige Gesteine führen an ihrer Oberfläche Verwitterungs‐Biozönosen von Pilzen und Bakterien, wie sie auch bei anderen Gesteinen vorhanden sind. Pilze und heterotrophe Bakterien lösen geringe Mengen von Uran. Ihr Keimgehalt je g Gestein nimmt ab, wenn das Verwitterungswasser mehr als 200 mg Uran pro Liter enthält. Wesentlich höher kann die Urantoleranz bei Stämmen von Thiobacillus ferrooxidans und besonders von Th. thiooxidans sein. Die bis jetzt nach Adaptation erreichten Höchstwerte liegen für Th. thiooxidans bei 12,5 g U/l, für Th. ferrooxidans bei 1 g U/l als (UO2)SO4. Sind Kupfersulfat und Uranylsulfat in der Lösung vorhanden, so wirken beide Schwermetalle unabhängig voneinander. Die maximalen für jedes Schwermetall getrennt ermittelten Toleranzwerte bleiben unverändert; eine kombinierte Giftwirkung läßt sich nicht nachweisen.
Studies of septation and separation in a mutant of Salmonella typhimurium
Authors: Ahmed N. , Rowbury R. J. 
Published: July 2010

AbstractSalmonella typhimurium strain 4a is a temperature‐sensitive division mutant. At 39° or 42° in several media a septation lesion occurs since non‐septate filaments form at these temperatures. At lower temperatures in some media separation is aberrant since long chains of cells are formed. Since these division abnormalities are corrected either by revertion to ts+ or phenotypically by growth with sucrose, it is likely that both are the result of one lesion and that the component (S) which is temperature‐sensitive in strain 4a is involved in both septation and separation. At 42° S is irreversibly inactivated but at 39° inactivation appears to be reversible since division restarts rapidly when 39° filaments are returned to 25° and protein synthesis is not required for such division. Comparison of recovery times for 39° and 42° filaments suggests that the synthesis of enough S for division takes about 20 min at 25° while the septation and separation stages of division take only about 10 min at this temperature. Since these latter processes occur so quickly it seems likely that events other than septation and separation take up a substantial fraction of the D period.
Modes of multiplication in an unstable spheroplast type L‐form of Escherichia coli K12(λ)
Authors: Gumpert J. , Taubeneck U. 
Published: July 2010

AbstractThe multiplication of an unstable spheroplast type L‐form of E. coli K12(λ) inst I was investigated by light microscopic and electron microscopic methods. The L‐form cells were grown under the influence of penicillin in broth and on agar media. They show wall defects of different degrees. 5 types of multiplication could be differentiated morphologically: Multiplication by single site constriction, multiplication by multiple site constriction, multiplication by cell formation at the top of an outgrowth of cell wall and cytoplasmic membrane, multiplication by intracellular fragmentation as a result of asymmetric invagination of the cytoplasmic membrane, and multiplication as a consequence of fragmentation by formation of intracellular membranes. In larger cells different modes of multiplication can occur simultaneously. The results show that the mode of multiplication in unstable spheroplast type L‐form cells of E. coli K12 (λ) inst I does not only depend on some physical factors of the environment but also on the extent of disturbance in the cell envelope system. Obviously, the cytoplasmic membrane and intracellular membranes play an important role in the multiplication processes.
pH‐induzierte Wachstumsinhibition in Turbidostatenkulturen von Escherichia coli 2000
Authors: Müller P. J. , Bergter F. , Günther H. H. , Knorre W. A. 
Published: July 2010

AbstractGrowth of Escherichia coli 2000 in a turbidostate is inhibited for several hours after a transient decrease of the pH. This inhibition is not due to a damage of the bacteria by the acidity, but is due to product inhibition by secreted L‐valine. This result contributes to the interpretation of pH‐induced oscillations of growth in continuous cultures.
Temperature and hydrostatic pressure effects on gelatinase activity of a Vibrio sp. and partially purified gelatinase
Authors: Weimer Mary S. , Morita R. Y. 
Published: July 2010

AbstractThe production of gelatinase by psychrophilic Vibrio sp. and its subsequent activity were shown to be maximal at 24°C (the highest growth temperature for the organism) and pH 8.8. Hydrostatic pressure caused a decrease in cells' gelatinase production and activity.Gelatinase, partially purified by ammonium sulfate fractionation and column chromatography, demonstrated optimal activity at 40°C and pH 9.3. In the absence of NaCl, no activity was observed while optimal activity occurred at 4.0% NaCl concentration. A greater decrease in activity was caused by hydrostatic pressure at 25°C than at 40°C.
Hemmung des Malatenzyms aus Acinetobacter calcoaceticus durch Acetyl‐CoA
Authors: Kleber H.‐P. 
Published: July 2010

AbstractDas aus Acinetobacter calcoaceticus angereicherte Malatenzym wird durch Acetyl‐CoA gehemmt. Während in Abwesenheit des Inhibitors der Kurvenverlauf sowohl in der Primär‐ als auch in der Sekundärdarstellung für L‐Malat (KM‐Wert = 2,5 × 10−4 M) und NADP+ (M‐Wert = 5,3 × 10−5 M) linear ist, bedingt Anwesenheit von Acetyl‐CoA einen nichtlinearen Kurvenverlauf.Gegen L‐Malat hemmt Acetyl‐CoA kompetitiv nichtlinear, gegen NADP+ nichtkompetitiv nicht‐linear. Die durch Acetyl‐CoA bedingte Hemmung ist abhängig vom pH‐Wert. Während bei pH 7,2 das Maximum der Hemmung liegt, ist die Hemmwirkung des Acetyl‐CoA bei pH 8,75 völlig auf‐gehoben.