bluuebunny/crossref_metadata_2025_split huggingface dataset:
RNA polymerase binding sites on a plasmid R6K derivative with increased copy number
Authors: Nešvera Jan , Klaus Siegfried , Štokrová Jitka , Hochmannová Jitka 
Published: February 2007

AbstractThe specific binding of Escherichia coli RNA polymerase molecules to the DNA of plasmid pNH602, a deletion derivative of R6K having an increased copy number, was detected by electron microscopy. Seven strong RNApol binding sites were found on pNH602 DNA linearized with BamHI or EcoRI restriction endonuclease. All of these specific sites occur in genetically defined regions of the pNH602 molecule. Two of them correspond with the recently reported transcription initiation sites within a region essential for plasmid R6K replication.
Proteasen in differenten Membranfraktionen von Acinetobacter calcoaceticus
Authors: Fricke B. , Jahreis G. , Sorger H. , Aurich H. 
Published: February 2007

AbstractDistinct protease activities were found in membrane fractions from Acinetobacter calcoaceticus grown on acetate‐NH+4 medium until early stationary phase. Mechanical or enzymatic cell disintegration followed by membrane fractionation through sucrose gradient revealed higher activities in the outer membrane than in the cytoplasmic membrane. Using azocasein and synthetic p‐nitranilides as substrates we found very low proteinase activities in intracytoplasmic membrane fractions. However, these fractions contained a significant aminopeptidase activity which was absent from cell envelope membranes. Peptidolytic activities in intracytoplasmic membranes of gramnegative bacteria have not been described before.
Use of salicylate to estimate the “threshold” inducer level for de novo synthesis of the phenol‐degrading enzymes in Pseudomonas putida strain H
Authors: Janke D. 
Published: February 2007

AbstractA special approach was used to elucidate the “threshold” inducer concentration for coordinative de novo synthesis of phenol hydroxylase(s), catechol 2,3‐dioxygenase and the 2‐hydroxymuconic semialdehyde‐metabolizing enzymes which initiate phenol catabolism in Pseudomonas putida strain H. It is based on cell‐precultivation with glucose (as the carbon and energy source) in the presence of different concentrations of sodium salicylate which proved to be a potent non‐metabolizable inducer in strain H of these enzymes. Subsequent estimation of the activity status of resting cell suspensions and cell‐free extracts, respectively, prepared from those strain H cultures clearly revealed failing de novo synthesis of the mentioned phenol‐degrading enzymes at salicylate concentrations lower than 0.2 mg/1.
Occurrence of phage‐like particles and growth inhibition in Streptomyces chrysomallus
Authors: Krügel H. , Solovjeva N. J. , Fiedler G. , Avraleva I. W. , Schumann G. 
Published: February 2007

AbstractFrom Streptomyces chrysomallus variant strains were isolated which inhibited their parent and were autoimmune to the action of the inhibitor (KRÜGEL and FIEDLER 1986). Phage‐like particles released by these variants as well as by strains of Streptomyces lividans and Streptomyces noursei harbouring various plasmids were analyzed by electron microscopy. We did not find any correlation between the presence of plasmids exhibiting different copy numbers or the transfer functions and the release of phage‐like particles. Also, there was no correlation between the occurrence of these particles and the inhibitory activities of the strains.
Use of batch assays to assess the toxicity of atrazine to some selected cyanobacteria. I. Influence of atrazine on the growth, pigmentation and carbohydrate contents of Aulosira fertilissima, Anabaena oryzae, Nostoc muscorum and Tolypothrix tenuis
Authors: Shabana E. F. 
Published: February 2007

AbstractThe data presented in this investigation revealed that the gain in the dry weights of all algae tested was suppressed in herbicide treatments, particularly, at higher concentrations. However, at the lowest dose of the herbicide, the growth inhibition was statistically significant for Anabaena and insignificant for the other organisms. The chlorophyll a content in Anabaena was slightly, however, insignificantly increased at lower concentrations; a phenomenon that was enhanced by increasing the herbicide dose. On the other hand, the pigment biosynthesis was suppressed in all treatments, in Tolypothrix and Aulosira, being more effective and statistically significant in the latter. The pigment accumulation in Nostoc was slightly and insignificantly promoted by all herbicide doses except at the highest concentration where a slight drop was noticed.The herbicide was most efficient at lower doses, in stimulating glucose absorption by either Nostoc and Anabaena up to 0.1 ppm. Applying higher doses, a remarkable drop was maintained. It induced significant retardation in the sugar uptake by Tolypothrix and Aulosira. This trend was confirmed by increasing the herbicide concentration. In all treatments with atrazine the total carbohydrate accumulation in all test organisms was suppressed and was more effective at the lowest concentration in Tolypothrix and Aulosira, however, of less significant effect in Anabaena and Nostoc. It may be concluded that the toxic effects of atrazine are partially due to its inhibitory effects on the synthesis of carbohydrates.
Peptidases of Lactobacillus casei and L. plantarum
Authors: Abo‐Elnaga Ibrahim G. , Plapp Roland 
Published: February 2007

AbstractFractionation of cell‐free extracts of Lactobacillus casei NCDO 151 (grown in MAN's et al. (1960) broth) by polyacrylamide disc electrophoresis showed the presence of 4 constitutive peptidases. The enzymes appear to be a tripeptidase with a narrow substrate specificity, two true dipeptidases with identical broad‐specificity, and a probable carboxypeptidase with broad‐specificity. A probable amino peptidase could also be isolated from the cell‐free extract by density gadient electrofocusing. Growth of the organism in skim milk resulted in the formation of two inducible dipeptidases.Examination of 5 other strains of L. casei for the presence of the two constitutive dipeptidases and the carboxypeptidase confirmed the results obtained for the species. Some strains, however, had one more peptidase. The peptidases of the strains differed relatively in the activity and substrate specificity from strain to strain. On polyacrylamide gel, the peptidase activity of L. plantarum appeared as one band only, probably of a carboxypeptidase.
Regulation of L‐carnitine metabolism in Escherichia coli
Authors: Jung Kirsten , Jung Heinrich , Kleber Hans‐Peter 
Published: February 2007

AbstractThe metabolization of L‐carnitine was studied using whole cells of Escherichia coli 044 K74. It showed features of an epigenetical control. L‐carnitine and crotonobetaine were able to induce the carnitine‐reducing system. Oxygen and nitrate as electron acceptors, γ‐butyrobetaine as final product of carnitine transformation in E. coli as well as glucose repress the carnitine metabolization. Other betaines and structurally related compounds did not show any effect neither as inductors nor as repressors.
Effect of nourseothricin (streptothricin) on the outer membrane of sensitive and resistant Escherichia coli strains
Authors: Seltmann Guntram , Wolter Ernst‐Jürgen 
Published: February 2007

AbstractNourseothricin (streptothricin) causes disturbances (perforations) in the outer membrane of sensitive E. coli strains allowing lysozyme and deoxycholate, but not the periplasmic alkaline phosphatase to penetrate. EDTA slightly increases, but Mg++ ions slightly decrease this effect. The cell walls of three from four nourseothricin‐resistant strains do not become permeable under these conditions, but remain sensitive against TRIS/EDTA. Nourseothricin is supposed to pass the outer membrane of sensitive bacteria via some kind of “self‐promoting” pathway. This way can (but need not) be blocked in resistant strains.
Fatty acids and production of tylosin‐like compounds in Streptomyces fradiae
Authors: Vančura Aleš , Řezanka Tomáš , Maršálek Jaroslav , Křišťan Vladimir , Basařová Gabriela 
Published: February 2007

AbstractThe composition of fatty acids and the spectrum of macrolide antibiotics produced in 7 mutant strains of Streptomyces fradiae, a tylosin producer, were investigated. The strains under investigation differed in the production level and representation of individual tylosin‐like compounds. The composition of fatty acids in the mycelium did not depend on the total production. However, the strains producing relomycin in addition to tylosin produced a significantly higher fraction of fatty acids with a higher melting point, and, on the contrary, the strains producing only tylosin or tylosin and desmycosin synthesized a significantly lower proportion of these acids. The results obtained indicate that in addition to the activity and substrate specifity of secondary metabolism enzymes, the composition of the tylosin‐like compounds produced can be influenced by the cell membrane and its function.
Nachweis einer NAD abhängigen Gluconat‐6‐phosphat‐Dehydrogenase in Pseudomonas syringae pv. phaseolicola
Authors: Sauerstein J. , Jacob J. , Reuter G. 
Published: February 2007

AbstractCrude extracts from cells of Pseudomanas syringae pv. Phaseolicola, a fluorescent pseudomonad, when grown on glucose contain a NAD‐linked 6‐phosphogluconate dehydrogenase. The reaction of the enzyme, which produces 14CO2 from 1‐14‐C‐6‐phosphogluconate, is not inhibited by NaF, a potent inhibitor of the ENTER‐DOUDOROFF (ED) pathway enzyme 6‐phosphogluconate dehydratase. In the presence of phosphate or arsenate ions the NAD‐linked glyceraldehyde‐3‐phosphate dehydrogenase reacts with glyceraldehyde‐3‐phosphate which, in the ED pathway, is produced from 6‐phosphogluconate and overlaps the 6‐phosphogluconate dehydrogenase reaction. Only a small proportion of glucose is metabolized via the 6‐phosphogluconate dehydrogenase/oxidative pentose phosphate pathway.
Oxidation of selected p‐menthane derivatives by means of Armilariella mellea (honey fungus), a parasite of woodlands
Authors: Draczyńska‐Lusiak B. 
Published: February 2007

AbstractArmillariella mellea strains were found to oxidize ‐terpineol (1), limionene (2) and 1‐p‐menthene (3). The ring double bonds were converted into respective 1,2‐trans‐diols. Furthermore, several products of allylic hydroxylation were obtained. Trans‐sobrerol (6) and 7‐hydroxy‐α‐terpineol (8) were formed from 1 and 6‐hydroxy‐carveol from 2. Phelandrene (4) and p‐cymene (5) were found resistant to the enzymatic system of Armillariella mellea.
Nucleoid segregation pattern during branching in Streptomyces granaticolor mycelia
Authors: Kretschmer Sigrid 
Published: February 2007

AbstractA survey of GIEMSA‐stained S. granaticolor mycelia grown in liquid medium revealed that branches developed only in subapical older regions of main hyphae for which large nucleoids were characteristic. The branches themselves contained only small nucleoids, as did the apical (about 30 μm long) region of the main hyphae. From the distribution pattern of the nucleoids at nascent branching areas it was concluded that during branch outgrowth one large nucleoid segregation into two small ones, both of which in most cases entered the branch.In order to determine in vivo the number of genome equivalents provided from main hyphae for a single branch, the kinetics of outgrowth of branches was measured and compared to that of germ tubes. The analysis of series of micrographs revealed that at the beginning of outgrowth, a branch received two genome equivalents from the main hypha while a germ tube got only one (from the spore). The subsequently expressed exponential elongation of branches as well as germ tubes ruled out that further nucleoids were supplied thereafter.
Utilization of various concentrations of free cystine by the fungus Microsporum gypseum
Authors: Kunert J. 
Published: February 2007

AbstractThe dermatophyte Microsporum gypseum was cultivated on two liquid media enriched with 50 to 1000 μg/ml free L‐cystine. The presence of cystine in concentrations above 250 μg/ml (gelatin medium) or 500 μg/ml (glucose‐glutamate medium) inhibited the growth. In all variants, however, cystine was utilized from the very beginning of growth and exhausted completely until stationary phase. The rate of cystine metabolization grew with its concentration to 500 μg/ml but decreased again with 1000 μg/ml. The excess sulfur was oxidized and excreted back into the medium mainly as inorganic sulfate. Moreover, sulfite was also produced which immediately reacted with the residual cystine in the medium giving rise to S‐sulfocysteine. Sulfite excretion was higher in the initial phases of growth and on the medium with poorer growth (gelatin medium). The sulfate‐to‐sulfite ratio was different on the two media used but was little influenced by cystine concentration. The excretion of strongly acidic compounds (sulfate, sulfite, and S‐sulfocysteine) reduced the usual alkalinization of the medium in the course of growth.
Phenol hydroxylase from Rhodococcus sp. P 1
Authors: Straube Gunhild 
Published: February 2007

AbstractThe enzyme phenol hydroxylase (EC 1.14. 13.7) was determined and characterized in crude extracts of Rhodococcus sp. P 1. This enzyme catalyzed the first step of phenol degradation. It was inducible, had a pH optimum of 7.9 and ad temperature optimum at 20 °C and catalyzed also the hydroxylation of some other phenolic compounds.
Effect of cultivation temperature and light intensity on fatty acid production in the red alga Prophyridium cruentum
Authors: Řezanka T. , Doucha J. , Mareš P. , Podojil M. 
Published: February 2007

AbstractThe spectrum of fatty acids was studied in a unicellular red alga Prophyridium cruentum, strain 1380‐1a, grown in a photostate at 21, 24 and 28 °C and irradianee 30 and 60 W · m−2. Basic growth characteristics were determined for the strain under these conditions.The proportion of unsaturated fatty acids (18:2, 20:4, 20:5) increaserd with decreasing cultivaration temperature, their relative proportion changing depending on irradition intensity; the proportion of 18:2 and 20:4 acids was higher at a substraturation irradiance (20 W · m−2) while at saturation irradiance (60 W · m−2) the proportion of the 20:5 acid was substantially increased. The production os atured acids (16:0) declined with decreasing temperature.
Production of interferon by peritoneal cells of several inbred mouse strains
Authors: Błach‐Olszewska Zofia 
Published: February 2007

AbstractThe ability of peritoneal cells isolated from different strains of inbred mice to spontaneous interferon production was examined. AKR, C3H, and CBA mice which are known to develop spontaneous diseases such as lymphatic leukemia, mammary tumors or hepatomas in high percentage did not produce physiological interferon. On the other hand, peritoneal cells of BALB/c, 129, DBA/2 mice showed IFN production. In the early phase of their ontogenic development NZB mice were found to produce high titers of the interferon.Differences were found in the contents of a natural IFN‐synthesis‐inhibitor between C3H and NZB mice and are considered as one of the reasons of differentiated physiological interferon synthesis. The disturbance in the regulation of the physiological IFNs synthesis in the development of neoplastic and autoimmune diseases is discussed.
Einsatz einer Mischkultur in Acetat‐Fermentationen
Authors: Mallach Cornelia , Noetzel Rainer , Meyer Manfred 
Published: February 2007

AbstractBacterial cultures were selected from the native flora of liquid manure in order to metabolize liquid manure substances. The mixed culture used in the growth experiments is characterized by low growth rates when maximum degradation of acetate occurs. The biomass concentration reached 2.2 g/l.
Mixed cultures fermentation for bioconversion of whole bagasse into microbial protein
Authors: Nigam Poonam , Pandey Ashok , Prabhu K. A. 
Published: February 2007

AbstractTwo basidiomycetes cultures, BH1 and BW1, isolated from the biomanure sample of a bio‐gas plant belonging to Polyporus sp., were used in combination with celluolytic cultures viz. Trichoderma sp. and Cellulomonas strain R2 for microbial protein production from whole bagasse. The biomass yields obtained were much higher in mixed cultures fermentation than in corresponding controls. Combination of BH1/BW1 with Cellulomonas proved to be the better in comparison with Trichoderma. Simultaneous inoculation of the bacteria along with BH1 culture resulted in higher protein production.
Electrofusion ofPenicilliumprotoplasts after dielectrophoresis
Authors: Groth I. , Jacob H.‐E. , Künkel W. , Berg H. 
Published: February 2007

AbstractThe protoplast fusion of auxotrophicPenicilliummutats after dielectrophoretic cell contact and rectangular field pulses (4,2 kV/cm, 25 μs) was microscopically observed in a microchamber consisting of two vapour‐plated chromium electrodes on a microslide (gap between the electrodes of about 150 μm). The conditions for protoplasting ofPenicilliumand for electrofusion are described. Isolation of viable fusion products was realized.
In vitro and in vivo production of pectolytic enzymes by some phytopathogenic fungi
Authors: Ikotun T. , Balogun O. 
Published: February 2007

AbstractFive fungal plant pathogens were investigated for their in vitro and in vivo ability to produce pectolytic enzymes. Only Fusarium solani did not produce any appreciable amount of enzymes in vivo and in vitro. Alternaria solani, Collectotrichum truncatum, Colletotrichum capsici and Curvularia pallescens produced pectolytic enzymes in vitro which were detected after ten‐fold concentration of the cultures by ammonium sulphate precipitation. These same four fungi produced pectolytic enzymes in vivo which were detected after twenty‐fold concentration of blended infected host tissue. The pH values of peak enzyme activity of 3.0 and 5.0 indicate that the enzymes produced were polygalacturanaes. The monogalacturonide end‐product of sodium polypectate and cell wall degradation indicate that exopolygalacturonases were produced by the pathogens. The low concentration of these enzymes in infected host plant tissues and the slow pectate‐splitting action of the exopolygalacturonases produced may account for the slow development and the dry necrotic nature of the disease these fungi cause.
Saprophytic fungi isolated from animal and bird pens in Egypt
Authors: Moharram A. M. , Bagy M. M. K. , Abdel‐Mallek A. Y. 
Published: February 2007

AbstractForty four samples collected from animal and bird pens were screened for their content of saprophytic fungi by using the dilution plate method. 76 species in addition to one variety of Aspergillus flavus belonging to 33 genera were recovered on three types of media: 20 genera and 49 species on LITTMAN‐oxgall agar, 19 genera and 41 species on cellulose‐ and 19 genera and 43 species on glucose‐Czapek's agar. The most frequent genera were Aspergillus (21 species), Scopulariopsis (4 species) and Penicillium (10 species). Among the isolated fungi A. fumigatus, A. flavus, A. terreus, A. niger, A. sydowi, A. nidulans, S. brevicaulis, S. brumptii, P. chrysogenum and P. funiculosum were the most common species.
Studies on bacterial synergism in mice infected with Bacteroides intermedius and Fusobacterium necrophorum
Authors: Price Stuart B. , McCallum Roderick E. 
Published: February 2007

AbstractThe study was undertaken to characterize the kinetics of possible bacterial synergy using a mouse model of mixed intraabdominal infection with Bacteroides intermedius and Fusobacterium necrophorum. Female CD‐1 mice were injected intraperitoneally with B. intermedius, F. necrophorum or mixtures of both organisms. Generalized septic peritonitis developed within 24 hr, with abscess formation occurring after one to two wk in survivors with the mixed infection. Involvement of the reticuloendothelial system was evidenced by dose‐dependent hepatosplenomegaly, which appeared during the first wk postinfection and progressed throughout the course of the exepriment. Indirect immunofluorescence confirmed the presence of both species of bacteria in frozen sections of liver tissue. The median lethal dose (LD50) was 2.11 × 109 for the mixture, 3.03 × 109 for B. intermedius alone, and 1.07 × 109 for F. necrophorum alone. The median abscess‐producing dose (AD50), the dose required to produce abscessess in fifty percent of the surviving mice at two wk, was approx. 1/100 of the LD50 dose. The AD50 for intrahepatic abscesses was 2.8 × 108 for the mixture, whereas the AD50 for intraabdominal abscesses occurring in any site was 5.14 × 107. Both Bacteroides and Fusobacterium persisted in tissue for at least 22 wk following mixed infection. The persistence of the Bacteroides in tissue represents a synergistic result of mixed infection with Fusobacterium and contributed to the chronicity of intraabdominal abscess formation. Bacteroides, injected alone, did not produce abscesses at any of the doses tested. However, when passaged (isolated from mixed infection hepatic abscesses) B. intermedius was used, the bacteria did induce abscesses.
Effect of oxygen concentration on denitrification in freshwater sediment
Authors: Trevors J. T. , Starodub M. E. 
Published: February 2007

AbstractThe effect of different O2concentrations on denitrification in freshwater sediment was studied using the acetylene blockage technique. Denitrification occurred over a wide range of O2concentrations ranging from 10.1 to 0.33 μmol ml−1in nitrate amended sediment. However, denitrifying activity was not observed in sediment incubated under similar conditions when NO3‐was absent. These observations suggested that an anoxic environment or low O2concentrations were not required for denitrification to occur, if NO3‐ was initially present in the sediment. Denitrification gradually decreased as the dissolved O2concentration in sediment increased to 0.25 μmol ml−1. However, between 0.25 and 0.35 μmol ml−1dissolved O2, denitrifying activity was higher than at the lower dissolved O2concentration (0.25 μmol ml−1).
Effect of NaCl on the accumulation of glycerol by three Aspergillus species
Authors: Zidan M. A. , Abdel‐Mallek A. Y. 
Published: February 2007

AbstractThe accumulation of glycerol was investigated in three Aspergillus species, A. niger, A. ochraceus and A. tamarii after being grown in media containing different NaCl concentrations. Intra‐extracellular as well as total glycerol were markedly accumulated by the three organisms in response to increased salinity. However, at salinity levels of 10–14% NaCl, extracellular glycerol was somewhat lowered. In addition, it was found that the maximum accumulation of glycerol in A. niger and A. tamarii was reached within the first 10 hours after salinization. However, after desalinization, the extracellular glycerol was continuously increased within the first 6 hours at the expense of intracellular glycerol.
Isolation and characterization of the extracellular lipase of Acinetobacter calcoaceticus 69 V
Authors: Fischer B. E. , Kleber H.‐P. 
Published: February 2007

AbstractThe extracellular lipase of Acinetobacter calcoaceticus 69 V was purified by hydrophobic interaction chromatography to homogeneity as suggested by gel electropheretic analysis.The lipase existed as a high molecular complex of about 300 kDa, with a subunit molecular weight of 30.5 kDa being obtained by SDS‐PAGE. The hydrodynamic molecular radious obtained by gel electrophoresis was 3.27 nm.The lipase had an isoelectric point of 5.5 and was stimulated by additions of deoxycholate. The activation energy for the hydrolysis of p‐nitrophenyl palmitate was 39.9 kJ mol−1. Tri‐, di‐ and monoacylglycerols were hydrolyzed. Hg2+ and p‐hydroxymercuribenzoate inhibited the enzyme activity at very low concentrations. One sulfhydryl group was found per molecule of lipase.