bluuebunny/crossref_metadata_2025 huggingface dataset:
The temperature profiles of growth, thermal death and ethanol tolerance of the xylose‐fermenting yeast Candida shehatae
Authors: Lucas Candida , Van Uden N.
Published: February 2007

The temperature profile of growth and thermal death of the xylose‐fermenting yeast Candida shehatae was dissociative. The Arrhenius plot of growth lacked a descending supraoptimal branch and the specific growth rate at the maximum temperature for growth (around 31°C) was not significantly different from its values at the other temperatures studied (down to 20°C). Ethanol enhanced thermal death by increasing its entropy of activation (entropy coefficient 16.1 entropy units mol−1)−1). The temperature profile of ethanol tolerance with respect to growth displayed a temperature plateau (10–17.5°C) of maximum ethanol tolerance (limit 6% v/v of ethanol) while the toxic effects of ethanol increased on either side of the plateau depressing the maximum temperature for growth from 31 to 17.5°C and increasing the minimum temperature for growth from 2.5 to 10°C.
pH‐linked control of energy charge in Acetobacter methanolicus sp. MB 70
Authors: Loffhagen N. , Babel W.
Published: February 2007

The influence of the extracellular pH on the adenylate system of the acidophilic Acetobacter methanolicus sp. MB 70 was investigated.

The ATP level was maintained over a pH range from 3.0 to 6.0. An increased endogenous respiration was observed after a raise of the pH from 4.0 upwards.

Above pH 6.0 the level of ATP decreased and the level of ADP and even more that of AMP increased. This resulted in a drop of the energy charge from 0.78 to values below 0.2. At pH 4.0 the level of ATP and AMP decreased only after prolonged incubation without an external energy source but the energy charge remained constant at about 0.7. In the range of external pH values where the energy charge is maintained the intracellular pH value is expected to be stable. The investigation of the reasons for the displacement of this range to low extracellular pH values may help to more profoundly understand the phenomenon of acidophily.
Katabole Repression bei aerobem und O2‐limitiertem Wachstum — energetische und stoffliche Bilanz des Kohlenhydratmetabolismus bei Hefen
Authors: Röber B.
Published: February 2007

Radiorespirometry during aerobic and O2‐limited growth with Candida maltosa H and mutants oxidizing glucose specifically labelled with 14C in carbon atoms 1–4, 6 or universally labelled demonstrated the simultaneous operation of the pentosephosphate pathway, tricarboxylic cycle and pyruvate decarboxylation (Röber and Reuter 1984a). Therefore, material and energy balances are developed for product formation and biomass production by Candida maltosa H and mutant strains using 14C‐glucose, 14C‐fructose, 14C‐mannose as sole source of carbon and energy or glucose/mannose as a mixed substrate.

Measured values of 14C‐incorporation into 14CO2, 14C‐biomass and 14C‐product are used to obtain estimates of biomass energetic yield, of the fraction of substrate energy evolved as heat, of Y0, of the P/O‐quotient and of the ATP synthesis. Aerobic growth on glucose resulted in repression of the tricarboxylic cycle (strain H, mutant H3). An increased efficiency of the utilization of the substrate energy was found during O2‐limited growth of the mutant strains based on the increased hexose catabolism via tricarboxylic cycle and increased P/O quotients. Mutant strains showed no or less product formation with fructose or mannose as the sole source of carbon and energy under aerobic growth conditions.
Lysine biosynthesis in the yeast Candida maltosa: properties of some enzymes and regulation of the biosynthetic pathway
Authors: Schmidt H. , Bode R. , Lindner M. , Birnbaum D.
Published: February 2007

Four enzymes of the lysine biosynthetic pathway of Candida maltosa were investigated and the regulatory pattern was established. α‐Aminodipate reductase (Mr 160,000), saccharopine reductase (Mr 90,000) and saccharopine dehydrogenase (Mr 45,000) were separated from each other. Homocitrate synthase was sensitive to the separation methods used. The formation of saccharopine reductase was constitutive, whereas the synthesis of homocitrate synthase, α‐aminoadipate reductase and saccharopine dehydrogenase were regulated by the general control of amino acid biosynthesis. l‐Lysine (Ki = 5.0 mm), l‐thialysine (Ki = 15 mm) and dl‐α‐aminoadipate (Ki = 5.1 mm) inhibited homocitrate synthase, the first enzyme of the pathway. The inhibition was competitive with respect to 2‐oxoglutarate. The Km‐values of the enzyme were estimated to be 0.033 mm for acetyl‐CoA and 0.025 mm for 2‐oxoglutarate. The Michaelis constants of the α‐aminoadipate reductase were calculated to be 0.20 mm for α‐aminoadipate, 0.50 mm for ATP, 0.10 mm for NADPH and 3.8 mm for MgCl2. The Km‐values of the saccharopine reductase were 0.55 mm for saccharopine and 0.13 mm for NADP+, respectively. The values of the saccharopine dehydrogenase were estimated to be 1.6 mm for l‐lysine, 0.66 mm for 2‐oxoglutarate and 0.23 mm for NADH. Furthermore, a number of amino acids were found to be effectors of the enzyme reactions.
Enrichment of mutants of Rhodosporidium toruloides by the use of inositol starvation
Authors: Tully M.
Published: February 2007

Inositol‐requiring mutants of strains of Rhodosporidium toruloides were isolated and the frequency of isolation of auxotrophic and catabolic mutants from them was measured after starvation for inositol. Mutants can be isolated at frequencies up to 31 times greater than those of mutagenized cultures without enrichment.
Rapid isolation of bacterial proteinases by column chromatography on sawdust
Authors: Šafařík I.
Published: February 2007

Proteolytic enzymes produced by some strains of Bacillus sp. were isolated by column chromatography on sawdust. Ballast proteins were eluted with water while the adsorbed proteinases were eluted with 1 m sodium chloride solution. The specific activities of proteinases increased 54‐ to 70‐fold after chromatography.
Effects of mercuric chloride on akinete germination and sporulation in Pithophora oedogonia (Mont.) Wittrock (Cladophorales, Chlorophyceae)
Authors: Chaudhary B. R. , Singh H. V.
Published: February 2007

The effect of mercuric chloride on akinete germination and sporulation with respect to time lapse and extent was studied in Pithophora oedogonia (Mont.) Wittrock (Cladophorales, Chlorophyceae). At HgCl2 concentrations from 1.25 to 45 mg/l akinetes showed progressive delay in the initiation and reduction in the extent of germination. HgCl2 concentrations of 60 mg/l and above proved to be completely lethal to the spores as they failed to germinate. The time necessary for the initiation of akinete formation and the percentage sporulation also decreased with an increase in the concentration of HgCl2 from 1.25 to 45 mg/l where spore germination was encountered. Inactivation of enzymes and metabolic inhibition seemed to be the cause of spore lethality.
Transductional analysis of the cysII region of Pseudomonas aeruginosa
Authors: Schelenz H.‐J. , Günther E. , Herrmann H. , Schatte L.
Published: February 2007

The close linkage between hisI and mutations of the cysII group in Pseudomonas aeruginosa was confirmed by mapping experiments with new mutants. All mutants of the cysII group were blocked in the cysteine biosynthesis before sulfite (this include the mutant cys‐5605 which had previously been mapped by Mee and Lee, 1969). Most of the sulfite requiring cys mutants belonged to this group.

The farthest distance between two mutations of the cysII group was calculated by the Wu formula to be approximately 2.5 kbp. We, therefore, suggest that more than one gene of the cysteine pathway may be located within this region.
Isolation and properties of mutants of Streptomyces noursei resistant to benzyl alcohol
Authors: Gräfe U. , Reinhardt G. , Friedrich W. , Bormann E. J.
Published: February 2007

Stable mutants resitant to benzyl alcohol (= Balr) were selected from natural colony populations of several strains of S. noursei JA 3890 b. Irrespective of the absence of aerial mycelium formation the majority of the Balr mutants produced the same amount of nourseothricin as their parental strains. The Balr derivative 2/8 showed a higher production of biomass and lipids than its ancestor BF32 under standard conditions of growth. In the presence of increasing concentrations of benzyl alcohol in the medium (0–0.2%), growth of this Balr strain was more resistant to the toxic agent, and the lipid content dropped more slowly concomitant with aberrant alterations of the composition of fatty acids. The results suggest that Balr strains represent regulatory mutants whose occurrence in natural populations has been caused either by changes at the level of pleiotropic gene functions or by several, independent genetic alterations.
Temporal relationship of diploidization and haploidization in the yeast Yarrowia lipolytica
Authors: Kurischko Cornelia , Weber H.
Published: February 2007

By means of special selective conditions we analyzed the temporal relationship of diploidization and haploidization in the yeast Yarrowia lipolytica. These processes could be divided into several steps. Twelve hours after mixing parental strains dissociation products of unstable heterokaryons are selectable. Four hours later karyogamy takes place as shown by isolation of mitotic recombinants. At this time spontaneous haploidization starts which leads to an enrichment of haploid and aneuploid segregants in the cell population. A high portion of chimeric clones which represents the dynamics of segregation were selected at time intervals 16, 23 and 29 hours.

We concluded that an unstable heterokaryon should be a connecting link between sexual and parasexual processes in Y. lipolytica.
Butylmaduramycin, a new antibiotic from Actinomadura rubra
Authors: Strauss D. G. , Baum M. , Fleck W. F.
Published: February 2007

Butylmaduramycin, a new derivative of maduramycin was isolated from the culture medium of a mutant strain of Actinomadura rubra. This communication describes some biological and physicochemical characteristics of the new antibiotic.
Emulsifier formation with Acinetobacter: Search for an excretion‐reduced mutant of Acinetobacter calcoaceticus 69‐V
Authors: Müller R. H. , Babel W.
Published: February 2007

After 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

The 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

A 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

Analogs 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

There 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

A 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

Increasing 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

Three 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

Using 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

A 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

A 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

From 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

At 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

Anaerobic 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

Atrazine 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

Thirty 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

Pyrimidine 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

For 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

The 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

The 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

Extracellularly 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

Four 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

A 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.
Molecular cloning of a gene coding for thermostable beta‐glucanase from Bacillus macerans
Authors: Borriss Rainer , Manteuffel Renate , Hofemeister Jürgen
Published: February 2007

The bg/M gene DNA coding for a thermostable beta‐1.3,1.4‐glucanase of Bacillus macerans E138 was isolated by direct shot‐gun cloning into Escherichia coli using plasmid pBR322 as a vector. By deletion analysis the bg/M coding region was located within a 1.0 kb region of the cloned Bacillus DNA fragment. In E. coli, plasmid pBGLM12/2 containing the B. macerans bg/M gene gave rise to a beta‐glucanase expression 40 times higher than that of the B. macerans gene donor. The molecular weight of beta‐glucanase, isolated either from E. coli cells or from the culture filtrate of B. macerans, was in the range of 24 kD. The enzymes purified from E. coli or from the culture filtrate of B. macerans, had a halflife of about 40 min at 65 °C. This indicated an increased temperature stability of the B. macerans enzyme in comparison to other Bacillus‐beta‐glucanases.
Dihydrotentoxin: A precursor of tentoxin or its degradation product?
Authors: Liebermann B. , Ihn W.
Published: February 2007

Besides tentoxin, dihydrotentoxin is produced by Alternaria alternata in similar quantities. Both peptides are excreted mainly into the culture medium, with a low content (20–55 μg/g) being found in the mycelium already of an early stage of fermentation. Tentoxin is not degraded during cultivation, therefore, dihydrotentoxin cannot be a decomposition product of the phytotoxin. During the isolation procedure, some tentoxin (10 to 15%) and even more dihydrotentoxin (30–40%) is lost. Incorporation of labelled dihydrotentoxin (14C, 15N) into tentoxin during fermentation allows the conclusion that the nonoxidized peptide is the precusor of tentoxin.
Microsomal oxygenases involved in ergoline alkaloid biosynthesis of various Claviceps strains
Authors: Maier Walter , Schumann Brigitte , Gröger Detlef
Published: February 2007

The conversions of agroclavine to elymoclavine and elymoclavine to paspalic acid/lysergic acid are catalyzed by microsomal preparations from various Claviceps strains. The enzymes designated as agroclavine 17‐monooxygenase and elymoclavine 17‐monooxygenase respectively are dependent on NADPH and molecular oxygen. NADH enhances enzyme activity observed in the presence of NADPH. Transhydrogenase activity in the presence of NADH and NADP+ which is dependent on ATP was found. Carbon monoxide, as it was shown by KIM et al. (1981, 1983) and cytochrome c inhibit hydroxylation, whereas NACN did not affect the reactions. This and other properties suggest that both clavine specific enzymes are cytochrome P‐450 dependent monooxygenases. Lysergol was not converted by elymoclavine 17‐hydroxylase. Feedback inhibition of agroclavine 17‐monooxygenase by elymoclavine was demonstrated under in vitro conditions.
Cloning and preliminary characterization of the streptothricin resistance determinants of the transposons Tn1825 and Tn1826
Authors: Tietze E. , Brevet J. , Tschäpe H. , Voigt W.
Published: February 2007

Streptothricin resistance determinants have been cloned from the transposons Tn1825 and Tn1826 to the vector plasmid pUC8. The recombinant plasmids were characterized with respect to their physical structure. The resistance properties of their hosts were characterized with respect to the minimal inhibitory concentration of streptothricin and the activity of the streptothricin acetyltransferase. The proteins encoded by the cloned resistance determinants were analysed in a maxicell system. The results of our investigations suggest that the resistance to streptothricin is mediated by the activity of a streptothricin acetyltransferase with both, Tn1825 and Tn1826. However, the resistance determinant of Tn1825 is more complex than Tn1826 and additional functions involved in realizing the resistance phenotype must be recognized.
Genetic engineering in Yarrowia lipolytica
Authors: Gaillardin C. , Heslot H.
Published: February 2007

The development of a highly efficient integrative transformation system for the yeast Yarrowia lipolytica has permitted gene cloning by direct complementation. The main features of this system will be presented, as well as the results so far obtained on gene structure. Recent developments of these techniques now concern heterologeous gene expression and protein secretion and will be reviewed.
Genetic control of methanol utilization in yeasts
Authors: Sibirny A. A. , Titorenko V. I. , Gonchar M. V. , Ubiyvovk V. M. , Ksheminskaya G. P. , Vitvitskaya O. P.
Published: February 2007

Considered are our own data and those found in literature on the properties of yeast mutants impaired in their ability to utilize methanol as sole carbon and energy source; hypotheses about the role of alcohol oxidase and citrate synthase in biogenesis of peroxisomes are proposed. It has been proved that formaldehyde reductase participates in the control of the formaldehyde level in the cell. Properties of mutants defective in the catabolite repression and inactivation of enzymes of methanol metabolism are described. The existence of several autonomous mechanisms of the catabolite repression of alcohol oxidase has been shown. It has been found, that the induction of glyoxysomal enzymes of C2‐metabolism is repressed by methanol in the ecr1 mutant of Pichia pinus with the affected repression of alcohol oxidase by ethanol. Data are presented on the regulatory properties of the recently discovered acidification system of the medium induced by methanol. Such acidification occurs due to symport extrusion of protons and formate anions from the cells.
Construction of promoter‐probe vectors for Candida maltosa, a n‐alkane‐assimilating yeast, using the LEU2 gene of Saccharomyces cerevisiae
Authors: Takagi Masamichi , Uchino Shigeo , Sugimoto Masakazu , Kawai Shinya , Hikiji Takeshi , Yano Keiji
Published: February 2007

For the purpose of isolation of promoter regions which are regulated by a carbon source in the medium in an n‐alkane‐assimilating yeast, Candida maltosa, two promoter‐probe vectors were constructed. Each of them consists of the LEU2 gene of Saccharomyces cerevisiae whose 5′‐non‐coding region was trimmed with BAL31, an autonomously replicating sequence isolated from C. maltosa genome (the TRA region) which we have previously isolated, and the pBR322 sequence. One of them, pPLC2, having the TATA box, lacks the regulatory sequence (“sequence L”) of the LEU2 gene, and the other, pPLC1, lacks both the TATA box and sequence L. Using pPLC1 as a shot‐gun cloning vector in C. maltosa, many promoter regions which were active when glucose was present in the medium as a carbon source were obtained from the genome of C. maltosa. The sizes of the inserted fragments of two of them were determined. (In this paper, a promoter region refers to a promoter which includes a TATA box, plus a regulatory sequence such as an UAS (upstream activating sequence)‐like sequence).
Transformation of methylotrophic yeast Hansenula polymorpha: Cloning and expression of genes
Authors: Tikhomirova L. P. , Ikonomova R. N. , Kuznetsova E. N. , Fodor I. I. , Bystrykh L. V. , Aminova L. R. , Trotsenko Yu. A.
Published: February 2007

We developed a host‐vector system for transformation and gene cloning experiments using the methylotrophic yeast Hansenula polymorpha. Regeneration of protoplasts in a medium containing polyethylene glycol before plating made transformation more efficient and reproducible (2 to 3 · 104 μg DNA). The frequency of transformation was significantly lower when dominant resistance marker Cup1r was used for transformant selection. The transformation system developed was used to clone the DNA fragment which complements functionally the defect in the dihydroxyacetone kinase (DHAK

Abbreviations: DHA, dihydroxyacetone; DHAK, dihydroxyacetone kinase; DHAS, dihydroxyacetone synthase; PEG, polyethylene glycol.

activity of a H. polymorpha mutant strain. The DNA insert isolated was shown to increase by up to ten times the activity of DHAK in transformants carrying recombinant plasmids. When recombinant plasmids were introduced into S. cerevisiae, the transformants obtained acquired the ability to grow on the medium with dihydroxyacetone as a sole carbon source and the activity of DHAK was observed.
Influence of cytochrome c‐deficiency on the energy conservation of whole cells of Acetobacter methanolicus sp. MB 58
Authors: Loffhagen N. , Babel W.
Published: February 2007

The ability of A. methanolicus sp. MB 58 and of a cytochrome c‐deficient mutant (A. methanolicus sp. MB 58105) to synthesize ATP by the oxidation of methanol, ethanol, glucose, formate and formaldehyde was investigated. It was found out that cells of the wild type were energized and that cells of the mutant were not energized by the oxidation of ethanol.

The energization of cells by the oxidation of glucose, formate and formaldehyde is obviously not influenced by the cytochrome c defect. The results point to a coupling of the alcohol dehydrogenase at cytochrome c, as already postulated in a previous paper for the alcohol and the methanol dehydrogenases of A. methanolicus sp. MB 70.

The dehydrogenases responsible for the oxidation of glucose and formate should be coupled to other cytochromes of the respiratory chain. Evidence for the coupling of the formaldehyde dehydrogenase could not be obtained, because it was not possible to differentiate between cytochrome‐dependent oxidation of formaldehyde and the NAD+‐dependent oxidations after fixation of formaldehyde.
Changes of protein pattern of Streptomyces griseus strains that characterize differentiation of mycelia in submerged culture
Authors: Vitális S. , Valu G. , Békési I. , Szeszák F. , Szabó G.
Published: February 2007

S100 fractions were isolated from submerged cultures of well conidiating (No. 45H), nonconidiating (No. 52‐1) and factor C treated No. 52‐1 Streptomyces griseus strains and analyzed by one‐dimensional SDS‐PAGE. The quantity and synthesis of soluble proteins were examined on densitograms and fluorograms. The evaluation was carried out by a computer aided method. Specific radioactivities of the protein bands were also calculated.

Some groups of protein bands were found to be characteristic of the two strains during development. On the other hand densitograms of the two strains could be in part superimposed showing similarities in the position and relative intensity of bands.

Most of the soluble proteins were synthesized all over the life‐cycle of both strains, although characteristic individual bands appeared or disappeared during differentiation or when the two strains were compared.

The protein pattern of S100 fraction from factor C treated No. 52‐1 cultures became similar although not identical, with that of strain No. 45H. Fluorograms showed closer similarities than densitograms. At 40 h there were certain peaks of specific radioactivity in the factor C treated mycelium which were missing from strain No. 45H of that age, but were expressed later in the 64 h old mycelium.

Although the bands obtained by one‐dimensional SDS‐PAGE did not represent individual proteins, the results shown demonstrate that our method is suitable for the characterization of the process of biochemical differentiation. The quantitative changes of some bands detected by densiometry, fluorography and specific radioactivity may reflect important events of differentiation (Table 1).
Nitrogen regulation of avermectins biosynthesis in Streptomyces avermitilis in a chemically defined medium
Authors: Cimburková E. , Zima J. , Novák J. , Vanék Z.
Published: February 2007

The biosynthesis of avermectins was significantly affected by the nitrogen source used. The maximum yield of AVMs1) was achieved in a chemically defined medium with ammonium sulfate as the sole nitrogen source. Higher concentrations of ammonia inhibited the production of AVMs without the inhibition of the growth. AVMs of the group B were prevailing in the complex until 15 mM ammonium sulfate. At higher concentrations, AVMs of the group A predominated. Of various amino acids tested, lysine and asparagine were found to be the best for the biosynthesis of AVMs. The concentration of most amino acids higher than 0.2% inhibited the production, while the mycelium was still growing. The biosynthesis of AVMs was completely suppressed by 15.2 mM isoleucine, however, this inhibition was reversed by adding alanine at the beginning of cultivation.
Critical steps in degradation of chloroaromatics by rhodococci II. Whole‐cell turnover of different monochloroaromatic non‐growth substrates by Rhodococcus sp. An 117 and An 213 in the absence/presence of glucose
Authors: Janke D. , Al‐Mofarji T. , Schukat B.
Published: February 2007

Kinetic experiments were performed to examine the effect of glucose and some related compounds on the removal of different monochloroaromatic non‐growth substrates (i.e. monochloroisomers of aniline, phenol and benzoate, respectively) by resting pre‐adapted cells of either Rhodococcus sp. An 117 or Rhodococcus sp. An 213. With both strains, the use of glucose as the additional carbon substrate allowed to differentiate between “cometabolizable” monochloroaromatics (i.e. 2‐chloroaniline, 3‐chloroaniline, 3‐chlorophenol, 4‐chlorophenol whose turnover appeared to be primarily limited by the availability of reducing power and/or energy to the cells) and those which were weakly removed “under any condition” due to narrow substrate specificity of the enzymes initiating the transformation process.

In a second line of investigation, the reduction of ferricyanide by resting An 117 or An 213 cells was shown to exhibit a pattern of cosubstrate‐dependence analogous to that found for turnover of the “cometabolizable” monochloroaromatics. As demonstrated with different cell preparations of strain An 117, whole‐cell ferricyanide reduction strongly interferred with the cometabolic turnover of various monochloroaromatic non‐growth substrates. The results obtained are those to be expected if the former (NAD(P)H‐dependent) type of process, in preference to the second one, would consume the reducing equivalents which become available from the metabolism of glucose. They point out the opportunity to make use of the carbon substrate‐dependent whole‐cell reduction of ferricyanide (or of other external electron acceptors) as a rapid and inexpensive assay of pre‐screening for carbon compounds which would function as energy‐replenishing cosubstrates in the (cometabolic) turnover of xenobiotic non‐growth substrates by rhodococci.