bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emulsifier formation with Acinetobacter: Search for an excretion‐reduced mutant of Acinetobacter calcoaceticus 69‐V
Authors: Müller R. H. , Babel W. 
Published: February 2007

AbstractAfter growth on acetate three groups of Acinetobacter strains could be indentified with respect to the excretion of a bioemulsifier. Mutants of A. calcoaceticus 69‐V were selected which produced reduced amounts of emulsifier.
Effects of different factors on the akinete germination of Pithophora oedogonia (Mont.) Wittrock
Authors: Agrawal S. C. 
Published: February 2007

AbstractThe present study focuses on the effects of different kinds of visible light, the intensities of white light, temperature and pH on akinete germination in the green alga Pithophora oedogonia (Mont.) Wittrock. In addition, it was studied how different kinds of visible light applied during akinete formation influenced the subsequent germination in white light. Akinetes initiated to germinate 3 days earlier in blue and green light than in yellow, red and white light. The green light was most favourable to akinete germination, while red light had a poor effect. No photoreversible effect of red and green light was observed. Akinetes formed under green, blue and yellow light germinated quickly and showed a higher percentage of germination than those formed under red light. Germination of akinetes was initiated even when kept in total darkness. Germination of akinetes was favoured in white light at intensities between 0.50 and 1.5 Klux. Maximum germination of akinetes occurred at 25 °C, while progressively higher and lower temperature suppressed germination of akinetes at different levels. Initiation of akinete germination was delayed at a pH of 7 and 8. No germination of akinetes was observed at a pH of 9 and 10.
Directed selection of differentiation mutants of Streptomyces noursei using chemostat cultivation
Authors: Noack D. 
Published: February 2007

AbstractA nourscothricin‐producing Streptomyces noursei strain was continuously cultivated in a chemostat equipped with a stirrer for mechanical fractionation of the mycelium. Different cultivation conditions allowed the selection of six types of differentiation mutants after the culture had reached a population genetically stationary state. The mutants showed an altered control pattern of sporulation as well as altered antibiotic biosynthesis and antibiotic resistance. In addition, the stability of the recombinant plasmid pIJ385 in several differentiation type mutants as host strains was tested. The results suggest that there exists a strong correlation between the cultivation conditions employed and the type of differentiation mutants selected.
Wirkung von 2‐Ethyl‐2‐en‐l‐al und verwandter Verbindungen auf Wachstum und Ultrastruktur von Pilzen
Authors: Casperson G. , Banasiak L. , Lyr H. , Sunkel M. 
Published: February 2007

AbstractAnalogs of the natural substance (E)‐hex‐2‐en‐l‐al which occurs naturally in green plants and is known to have microbiocidal properties were synthesized and studied with respect to their antifungal properties. Saturated and unsaturated aldehydes, alcohols, carbon acids and enolacetate were tested against various fungi by applying these compounds either over the gaseous phase or in suspension. The following ranking was observed on the basis of fungicidal activity: enolacetate of 2‐ethylhex‐2‐en‐l‐al > 2‐ethylhex‐2‐enoic acid > 2‐ethylhex‐2‐en‐l‐al > 2‐ethylhex‐2‐en‐l‐ol. Saturated analogs showed the same order of activity as the unsaturated ones, however, they were less efficient.The effects on the ultrastructural changes were analyzed in Mucor mucedo exposed to concentrations of the analogs that inhibited growth. Main effects were observed on mitochondrial and nuclear membranes. The kind of destruction caused by enolacetate of 2‐ethylhex‐2‐en‐l‐al differed from the other substances tested. Aspects of the mode of action are discussed.
Synthesis of poly(A)+ ‐containing RNA during growth in Escherichia coli relA+ and relA− strains
Authors: Hanschke R. , Hecker M. 
Published: February 2007

AbstractThere are very different results on the synthesis of poly(A)+‐containing RNA in bacteria. We, therefore, studied the influence of growth and amino acid starvation on the synthesis of poly(A)+‐RNA in a relA+ and relA− strains of E. coli. Only the relA+ strains is able to respond to an amino acid limitation by production of ppGpp which causes a strong reduction of stable RNA transcription.During growth we observed significant alterations of the percentage of [3H]‐uridine labelled total RNA which bound to poly(U)‐sepharose (% poly(A)‐RNA). It was mainly influenced by drastic changes of the synthesis of non‐polyadenylated stable RNA (rRNA, tRNA) during growth and, therefore, it did not reflect the actual synthesis of polyadenylated mRNA. An amino acid starvation induced in the relA+ strain a stronger and more rapid reduction of the transcription of non‐polyadenylated RNA as well as of poly(A)+‐RNA than in the relA− strain which did not produce ppGpp under these conditions. Therefore, we conclude that ppGpp inhibited not only the synthesis of the non‐polyadenylated stable RNA but also that of poly(A)+‐containing mRNA, although the latter was apparently less affected.
Alcohol oxidation by Acinetobacter calcoaceticus EB 104 — a n‐alkane‐utilizing and cytochrome P‐450‐producing strain
Authors: Jirausch M. , Asperger O. , Kleber H.‐P. 
Published: February 2007

AbstractA soluble, NADP+ ‐dependent alcohol dehydrogenase (ADH) with a pH optimum at 8.7 was found in A. calcoaceticus EB 104 after growth on different carbon sources. n‐Alkanols with short and medium chain length were employed as test substrates. The Kmvalues decreased with increasing chain length. The Vmax values remained nerly unchanged. The activities determined were independent of the carbon source.Furthermore, a n‐alkanol‐dependent reduction of DCPIP was measured in membrane fractions of cells grown on different carbon sources. The optimum pH for this reaction was at 7.5. Further proof for the presence of a pyridine nucleotide‐independent ADH was derived from the oxidation of 14C‐decanol in the absence of NADP+ or NAD+.
Thermal regulation of phospholipid fluidity in Corynebacterium glutamicum
Authors: Hänel F. , Brezesinski G. , Hilliger M. , Gräfe U. , Dörfler H.‐D. 
Published: February 2007

AbstractIncreasing temperatures of cultivation caused the cellular phospholipid content of C. glutamicum to decrease significantly. Simultaneously, the melting point of phospholipid fractions, i. e. the temperature of the ordered‐disordered phase transition, increased. A hypothetical connection between the cellular phospholipid composition and the temperature‐depended lysine efflux is discussed.
Isolation and characterization of some chemoautotrophic Chromatiaceae
Authors: Kämpf Charlotte , Pfennig N. 
Published: February 2007

AbstractThree strains of facultatively chemoautotrophic Chromatiaceae were isolated from natural habitats under chemotrophic conditions and identified as Chromatium gracile (strains 23‐3 and 25‐1) and Thiocapsa roseopersicina (strain Laboe). The strains utilized hydrogen and reduced sulfur compounds for photo‐ and chemolithoautotrophic growth. Ammonium or dinitrogen were utilized as nitrogen sources for photo‐ and chemotrophic growth. With most of the organic carbon compounds examined chemoheterotrophic growth was dependend on the presence of a reduced sulfur compound. The newly isolated strains grew chemoorganotrophically with fumarate, fructose as well as with some short‐chain fatty acids and aliphatic alcohols. The determination of the respiratory activity of Chromatium gracile 25‐1 revealed that the utilization of butyrate for chemotrophic growth was not constitutive. The maximal respiratory activity of phototrophically grown Chromatium gracile 25‐1 was 2 times higher than that of other facultative chemotrophic Chromatiaceae. The respiratory activity of the obligately phototrophic Thiocapsa pfennigii was similar to that of phototrophically grown facultatively chemotrophic Chromatiaceae.
Optimierung von Fermentationsprozessen unter Berücksichtigung struktureller Zusammenhänge im Modell
Authors: Reimann B. 
Published: February 2007

AbstractUsing simulation programs for batch secondary metabolite fermentations, I developed a “hybrid” process optimization approach characterized by considering pragmatic aspects related to the theoretical concept as well as methodical aspects regarding experimental experience.Influences and mutual relationships of starting parameters amenable to change are discussed with the aim of defining an efficient strategy of optimization, using a classification scheme for the model parameters employed.Due to mutual and stochastic influences of these parameters, there remain only a few experiments to be carried out, and their number depends on the sensitivity of the gain function to the respective parameter.Some requirements any simulation program must fulfil in order to help optimize fermentation processes are pointed out.
Characteristics of a thermotolerant strain of Candida krusei
Authors: Kar Rita , Viswanathan L. 
Published: February 2007

AbstractA novel thermotolerant strain of Candida krusei was distinguished on the basis of its typical enzymatic, growth and respiratory properties. Unlike other thermotolerant Candida species and other strains of the same species, this strain exhibited diauxy on glucose. The strain also exhibited prolonged lag during growth on citrate and very low levels of NAD‐linked isocitrate dehydrogenase in comparison to the NADP linked enzyme. The capability of the strain to grow over a wide temperature range, relatively high exponential growth rate and short lag period indicate the potential of the organism for industrial applications.
Aklanonic acid‐producing mutants of Streptomyces galilaeus and Streptomyces peucetius var. caesius
Authors: Schlegel B. , Stengel C. , Schumann G. , Prauser H. , Eckardt K. 
Published: February 2007

AbstractA number of blocked mutants was investigated which were obtained from taxonomically identified Streptomyces strains producing anthracyclines. Two of these mutants, NTG 061 derived from S. galilaeus F 198 and mutant 135 derived from S. peucetius var. caesius 601 F.I.1), accumulated an anthraquinone derivative which was identified as aklanonic acid. The results supplied further evidence that this compound was an intermediate of the biosynthetic pathway leading to different types of anthracyclines. It occurred before ring closure to the final tetracyclic anthracyclinone skeleton.
Morphology and general characteristics of phages active against Rhizobium
Authors: Staniewski Ryszard 
Published: February 2007

AbstractFrom a collection of 28 virulent phages peviously used for the typing of Rhizobium strains, four were selected for detailed characterization: 3C for R. trifolii, 3H for R. leguminosarum, 1A and 2A for R. meliloti, respctively. On the basis of their morphology phages 3H and 1A were included into group B and phage 3C into group C according to the classification of BRADLEY (1967). Rceptors for phage 3H were thermosensitive in contrast to those for phages 3C and 2A. Phage 3H kept in phosphate buffer (0.01 M), Na‐citrate or EDTA, lost its activity. Ca++ and Mg++ protected the infectivity of phages 3H and 3C maintained in phosphate buffer.
Chitin synthase activity and the rate of chitin formation in cell‐division cycle mutant Saccharomyces cerevisiae cdc 24
Authors: Daňková Renáta , Farkaš Vladimir 
Published: February 2007

AbstractAt the nonpermissive temperature (37 °C) the cells of the temperature‐sensitive mutant Saccharomyces cerevisiae cdc 24 accumulated chitin 10 times faster than at 22 °C. In situ determinations of the activity of chitin synthase reveasled that in the cells grown at 37 °C more than 37% of the total chitin syntheses were in the active state whereas in cells grown at 22 °C only 7% of the potential enzyme activity were expressed. When the enzyme activity was calculated per cell number unit, there was 10 times more of the active chitin synthase per cell in the cells grown at 37 °C than in the cells grown at 22 °C, a value which correlated well with the observed difference in the rates of chitin accumulation at different temperatures.
Ergänzende Methoden zur Bestimmung der Gramzugehörigkeit anaerober Erreger
Authors: Höhne Claus , Sandow Dieter 
Published: February 2007

AbstractAnaerobic microorganisms (364 gram‐negatives and 154 gram‐positives) were investigated with respect to their behaviour against aqueous solutions of potassium hydroxide as well as their sensitivity to polymyxin and vancomycin by means of a disk diffusion test. Whereas the gram‐negative anaerobes showed a good correlation (97.5%) with a positive KOH test, only 88.3% of the gram‐positive microorganisms exhibited a negative KOH reaction. Therefore, in cases of ambiguous gram‐negative staining results, the KOH test alone cannot give sufficient informations about the exact gram reaction. It was shown, however, that together with the determination of resistance to polymyxin and vancomycin, this uncertainty remains only for microorganisms showing a positive KOH reaction, polymyxin resistance, and vancomycin sensitivity. Therefore, in combination with the polymyxin and vancomycin disk diffusion test, the KOH test is recommended as an additional means to determine the gram reaction of anaerobes.
Use of batch assays to assess the toxicity of atrazine to some selected cyanobacteria. II. Effect of atrazine on heterocyst frequency, nitrogen and phosphorus metabolism of four heterocystous cyanobacteria
Authors: Shabana E. F. 
Published: February 2007

AbstractAtrazine added in different doses to the culture media, augmented with glucose, of Aulosira fertilissima, Tolypothrix tenuis, Anabaena oryzae and Nostoc muscorum enhanced heterocyst frequency and efficiency of nitrogen fixation. Variations in the amounts of fixed nitrogen between the four test organisms may be attributed to differences in the levels of the high energy substance ATP, and also to various effects on the permeability barrier of cells. Although atrazine is a metabolic inhibitor, it enhanced particularly the nitrogen and phosphorus metabolism, leading to more amino‐N and protein‐N accumulation, yielding active synthesis of organic phosphorus, total soluble and insoluble phosphorus contents.
Invasion of wood by basidiomycetous fungi. IV. Microbiological approach to the role of kratovirulence in the expression of pathovirulence
Authors: Gramss G. 
Published: February 2007

AbstractThirty one members of a phytophatologicaly relevant choice of wood‐destorying basidiomycetous fungi WBF) that range from early pathogens to late saprophytes were exposed to each other in dual culture tests in nearly all possible combinations. Patogens in general dispose of the patho‐virulence (PV) capacity to grow in standing host wood in spite of the tre's live defence responses. Their lackin kratovirulence (KV, competitive saprophytic ability), however, excludes them from colonizing downed host wood as they fail to repress and kill its heavily antagonistic microflora. In contrast, saprophytes can control the antagonistic mixed population in dead wood. Their lack poor microbial antagonism. In recent understory‐tree inoculations one group of pathogens colonized stem wood through drill holes which were pre‐infected with antagonistic competitors while another group died back under the pressure of tree defense responses and/or microbial angagonism. The dual culture tests between model organisms such as WBF do not help decide whether this dieback is actually caused by microbial antagonoms. A final decision can only be drived. With a certain probability, from dual cultures between WBF and the original competitor microroganims of standing timber, for it is shown that the competive ability of a WBF against individuals of groups of deputy microbia is extremely seleective (SCA, selective competitive ability). This ability of one organism to overgrow others was expressed in a competition figure. Top competition figures against other WBF are found among pathogens that normally fail to control mixed microbial populations. Minimum competition figures are surprisingly found in the late saprophytes which excellently compete with mixed microbial populations.Among the 14 WBF with low competition figure only 21% cause severe symptom expression in artifically inoculated standing timber, while among the 17 WBF with high competition figure, 59% induce considerable stem deecay. This comparison strongly suggests that the expression of pathovirulence in living wood is at least in part supported by a minimum level of kratovirulence.
Pyrimidine base and nucleoside metabolism in Pseudomonas cepacia
Authors: West Thomas P. , Chu Chien‐Peng 
Published: February 2007

AbstractPyrimidine base and nucleoside metabolismin Pseudomonas cepacia was investigated. It was found that this pseudominad utilized uracila, cytosine or cytidine as a sole nitrogen source while prymidine bases and nucelosides supported little bacterial growth as sole carbon sources. Low nuceloside hydrolase and cytosine deminase activitiers were detected in P. cepacia. Synthesis of both enzymes appeared to be subject to repression by ammonium ions but repression of cytosine deaminase synthesis was more severe. Synthesis of nuceloside hydrolase or cytosine deminase was induced if the cells were grown on the substrate cytidine or cytosine, respectively, as a sole nitrogen source.
Einstaz der Fermenter‐Dialyse‐Kultur zur Züchtung kapseltragender Bakterien mit klinischer Bedeutung I. Escherichia coli K1
Authors: Starke Roland , Mehl Michael , Buddenberg Sebastian , Presber Wolfgang , Jacobi Hans‐Dieter 
Published: February 2007

AbstractFor mass culture of Escherichia coli K1 a fermenter dialysis culture technique based on an artificial hollowfiber kidney and substrate feeding is described and compared with conventional shaking culture and fermenter batch culture techniques.Important growth parameters as bacterial dry weight, optical density and live cell counts demonstrate the advantage of this new method. On the basis of bacterial yields, effectivity had increased about 100 fold. The synthesis of K1 capsular polysaccharides, which is influenced by a number of factors, proved to be good. Thus it was possible to obtain the quantities of native capsular substances necessary for bed‐side diagnostics and the investigation of this virulence marker.
Ultrastructural characteristics of a submerged active Claviceps paspali strain
Authors: Pertot Elizabeta , Jezernik Kristijan , Didek‐Brumec Matjana , Sočič Helena 
Published: February 2007

AbstractThe fine structure changes of a high producing Claviceps paspali strain during submerged cultivation were followed by means of different electron microscopy techniques. Considerable changes in ultrastructure have been found between the vegetative and the production mycelium particularly in the 4‐day‐old production mycelium. In this state freeze‐fracturing micrographs reveal a number of “section” vesicles and vacuoles mediating communication between the growing and producing cells and the external milieu. Abundant signs of secretory activity on the plasma membbrane are possible sites of alkaloid secretion.
Sporocidal activity of local anaesthetics and their binary combinations with preservatives
Authors: Abdelaziz A. A. , El‐Nakeeb M. A. 
Published: February 2007

AbstractThe sporocidal activity of 1% solutions of five local anaesthetics and five preservatives (cetrimide, chlorocresol, chlorhexidine, phenoxyethanol and phenylmercuric nitrate) at their pharmacopeial concentrations, alone and in binary combinations was determined against Bacillus subtilis and Aspergillus niger spores at different temperature levels by the surface viable count technique. The sporicidal activity of all tested systems were temperature dependent. A. niger spores were much more sensitive to the tested systems than B. subtilis spores. The temperature at which 99% of all spores were killed after 30 min exposure time of the anaesthetics were calculated. In case of the local anaesthetics alone against spores of A. niger the recorded temperatures were 30 °C for amethocaine, 45 °C for both amylocaine and cincochaine, 48 °C and 50 °C for lignocaine and procaine, respectively, in contrast to 58 °C in a control with saline solution. Much higher temperatures were calculated against B. subtilis spores. Cincochaine was the most effective local anaesthetic with a recorded temperature of 60 °C, where 99% killed occurred. Amylocaine and amethocaine showed temperatures of 84 °C and 90 °C, respectively. Procaine, lignocaine as well saline solution as a control caused a 99% killing effect at temperatures higher than 100 °C.Among the 25 tested binary combinations of local anaesthetics and preservatives, the highest incidence of potentiation of the sporocidal activity was recorded with chlorocresol combinations, while other combinations of the four remaining preservatives showed different types of interactions at different percentages.
Hydrolytic enzymes detected in the exudates of Ceratocystis paradoxa infected pineapple fruit
Authors: Adisa V. A. 
Published: February 2007

AbstractExtracellularly expressed exudates from pineapple fruit infected by Ceratocystis paradoxa were partially purified and the exudate‐filtrate preparations were assayed for the presence of three hydrolytic enzymes. The preparations were found to contain cellulolytic and proteolytic enzymes when inoculated on carboxymethylcellulose and casein as substrates, respectively, while pectin‐methylesterases and polygalacturonases were detected in the exudate‐filtrate when apple pectin and sodium pectate were used as substrates, respectively. The activities and stabilities of these groups of enzymes were found to be optimal at pH 7.0 and at 30 °C. The exudates also exhibited macerating action when potato discs showed complete loss of coherence and maceration after a 24 hr incubation. More total reducing sugars were detected in exudates of infected fruit than those obtained from healthy fruit.
Inhibition of growth of some plant pathogens by antagonistic microorganisms
Authors: Omoifo C. , Ikotun T. 
Published: February 2007

AbstractFour known antagonistic microorganisms, namely, Bacillus cereus, Bacillus subtilis, Aspergillus ochraceus and Penicillium cyclopium were paired against four pathogens of maize, namely, Curvularia pallescens, Drechslera maydis, Fusarium moniliforme and Macrophomina phaseoli and a pathogen of cassava, Colletotrichum gloeosporioides f. sp. manihotis on potato dextrose agar. The main aim was to test the ability of the antagonists to inhibit the growth of the pathogens. Whereas B. cereus and B. subtilis inhibited the growth of C. pallescens, D. maydis, M. phaseoli and C. gloeosporioides f. sp. manihotis, they did not inhibit the growth of F. moniliforme. A. ochraceus and P. cyclopium were effective only against M. phaseoli. Inhibitory activity on the target organisms are thought to be due to some toxic substances produced by the antagonists.
Lysine degradation in Pichia guilliermondii: Characterization of a novel enzyme, L‐lysine:pyruvate aminotransferase
Authors: Schmidt H. , Bode R. , Birnbaum D. 
Published: February 2007

AbstractA novel aminotransferase catalyzing the oxidative transmination of the ‐group of L‐lysine was found in the yeast Pichia guilliermondii. The enzyme, L‐lysine: pyruvate aminotransferase, is strongly induced in cells grown on L‐lysine as sole nitrogen source. The enzyme is highly specific for both L‐lysine and pyruvate. The Km‐values are 12 mM for L‐lysine, 0.55 mM for pyruvate, und 40 μM for pyridoxal‐5‐phosphate. An apparent relative molecular weight of 90,000 was estimated by gel filtration. The enzyme has a maximum activity at pH 9.0 and a temperature optimum of 32 °C.