bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of the transducing phage Ml of Rhizobium meliloti
Authors: Malek Wanda 
Published: February 2007

AbstractA temperate phage Ml, infective towards some R. meliloti strains, was isolated from soil taken from local fields. Its morphology, host range, transducing ability and the locations of restriction endonuclease cleavage sites on the genomes were determined. Phage Ml was classified as belonging to B BRADLEY's group bacteriophages because of the hexagonal outlines of its head and its long, flexible and non‐contractible tail. The molecular weight of phage DNA was estimated to be 54.1 ± 1 kilobases (kb) and it corresponded to the value expected for capsid size – 70 nm. Phage Ml carries out general transduction and forms stable lysogens with the R. meliloti strain L5.30.
Isolation and characterization of an alkaloid‐blocked mutant of Claviceps paspali
Authors: Pertot Elizabeta , Gaberc‐Porekar Vladimira , Sočič Helena 
Published: February 2007

AbstractAfter UV‐irradiation an alkaloid‐blocked mutant of Claviceps paspali was isolated from an ergometrine and lysergic acid amides (1:1) producing strain. The formation of ergometrine is blocked in this particular mutant strain which accumulates only lysergic acid amides. A significant morphological differentation of colonies of mutant as well as of mycelium in submerged cultures could be observed and total alkaloid yields are rather influenced.
The occurrence of keratinophilic fungi in sewage sludge from Egypt
Authors: Abdel‐Hafez A. I. I. , El‐Sharouny H. M. M. 
Published: February 2007

AbstractThe keratinophilic fungi of 40 sewage sludge samples from Upper Egypt were studied using a goat hair‐baiting technique. 43 species representing 22 genera were isolated, 17 species of which were dermatophytes and closely related fungi:Chrysosporiumstate ofArthroderma tuberculatum, C. asperatum, C. georgii, C. indicum, C. keratinophilum, C. pseudomerdarium, C. queenslandicum, Chrysosporiumstate ofThielavia sepedonium, C. tropicum, Microsporum cookei, M. gypseum, Myceliophthoraanamorph ofCorynascus novoguineensis, M. vellereaandTrichophyton terrestre.26 species of cycloheximide resistant fungi were collected and these included members ofAcremonium, Aspergillus, Alternaria, Chaetomium, Cladosporium, Cunninghamella, Emericella, Fusarium, Geotrichum, Penicilliumand others.
Formation and regeneration of protoplasts from Gibberella fujikuroi
Authors: Brückner B. , May R. , Loeffler B. 
Published: February 2007

AbstractThe preparation and regeneration of protoplasts from Gibberella fujikuroi was examined. High yields of protoplasts were obtained by using a mixture of lyophilized enzyme preparation from the snail Helix pomatia and a laboratory prepared mycolytic enzyme system from Trichoderma harzianum. The physiological stage of the mycelium and the mycelium amount were found to be important factors in the determination of the protoplast yield. Regeneration could be achieved on the surface of culture media osmotically stabilized with NaCl, KCl, mannitol or sorbitol.
Some physiological studies on fungi isolated from poultry feedstuffs
Authors: Megalla Samuel E. , Nassar A. Y. , Moharram A. M. , Abdel‐Gawad K. M. , Mahmoud A.‐L. E. 
Published: February 2007

AbstractA total of 506 isolates of mesophilic, thermophilic and thermotolerant fungi isolated from the poultry feed ingredients included soybean meals, ground maize, cottonseed cake, wheat bran and fish meal, on glucose‐CZAPEK's agar, LITTMAN oxgall agar at 28 °C and yeast starch agar (YPSs) at 45 °C, were screened for their ability to produce hydrolytic protease enzyme on solid media. Most of the fungal isolates were able to produce such enzymes but with variable capabilities. The highest proteolytic activity was exhibited by some isolates of Penicillium chrysogenum, Aspergillus flavus, Thermoascus thermophilus and Rhizopus chizopodifarmis. Of all fungal isolates screened for proteolytic activity, Penicillium chrysogenum and Thermoascus thermophilus produced the highest amounts of proteases. These two isolates were used to study the effect of some environmental and nutritional factors on their proteolytic activity. It was found that the highest yield of protease by P. chrysogenum (12.5 units) was achieved 3 days after incubation at 30 °C, Marked reduction in protease activity was observed at 37 °C. The thermophilic fungus T. thermophillus exhibited maximum (18 units) proteolytic activity 6 days after incubation at 45 °C, The enzyme yield was reduced to 13 units at 50 °C. Among the seven carbon sources tested, sucrose was the most appropriate for maximum protease production by both P. chrysogenum and T. thermophilus (13.2 and 12.8 units, respectively). Of the sixteen nitrogen sources investigated. NaNO3 was the best inorganic additive nitrogenous salt which induced the highest proteolytic activity by P. chrysogenum and T. thermophilus, whereas DL‐tryptophan was the most preferable organic nitrogen compound for maximum protease production by the two fungi tested.
Expression and stability of a Rhizobium leguminosarum bv. trifolii Sym plasmid in R. meliloti and Agrobacterium tumefaciens and its effect on clover‐bacterium symbiosis
Authors: Miksch G. , Lentzsch P. 
Published: February 2007

AbstractThe Rhizobium leguminosarum bv. trifolii Sym plasmid pRtr5a was transferred by conjugation to R. meliloti strains deleted or mutated in the nod and fix genes, and also to a plasmid‐less strain of Agrobacterium tumefaciens. The plasmid transfer led to the elimination of the resident cryptic plasmid of the R. meliloti recipients. The Sym plasmid of the recipients was only eliminated in the case of a deletion. In some cases the transferred plasmid was instable. The nod and nif/fix genes of R. leguminosarum bv. trifolii were expressed in R. meliloti and somewhat delayed in A. tumefaciens. A high level of nitrogen fixation on clover was only found in R. meliloti containing pRtr5a. However, this occurred only if the nif/fix genes of the recipient had been deleted before. Inoculation of clover with this R. meliloti strain resulted in a higher dry matter production in comparison to clover inoculated with the donor strain.
Construction of an R‐prime plasmid carrying the hup genes of Azorhizobium caulinodans ORS571 and its transfer to and stability in Rhizobium meliloti
Authors: Miksch G. , Lentzsch P. 
Published: February 2007

AbstractAn R‐prime plasmid (pJB3JI‐18) carrying a 10 kb region of Azorhizobium caulinodans ORS571 DNA which codes for uptake hydrogenase activity was isolated from a Km8 derivative of R68.45. R‐prime plasmids were obtained by transferring R68.45 to ORS571, retransferring it to E. coli, and selecting transconjugants for hydrogenase activity by means of a colour test based on methylene blue. The R‐prime plasmid DNA was hybridized with a DNA region which contained the hup genes of Bradyrhiobium japonicum, indicating homology between the heterologous hup genes. Transfer of the R‐prime plasmid to different Hup− mutants restored the Hup+ phenotype. When it was introduced to R. meliloti strains, it maintained its molecular weight and did not affect indigenous plasmids in two of three recipients. In the third recipient cointegrate formation and incompatibility with indigenous plasmids were found.
Kinetics of hemolysin production in bovine group B streptococci
Authors: Griffiths Bertie B. 
Published: February 2007

AbstractThirteen strains of group B streptococci etiologically related to bovine infections were investigated in order to observe the effects of non‐hemoglobin iron and glucose on growth and hemolysin production; and to determine the necessity to stabilize the hemolysin with a carrier‐stabilizer agent. Ferric citrate was diluted to give final concentrations of 1–11 μg/ml, added to iron‐reduced (by CaCl2 precipitation) brain heart infusion media, inoculated and incubated at 37 °C. Parallel experiments were carried out with glucose. A variety of agents was employed to act as hemolysin stabilizers. Hemolysin production was detected by lysis of sheep erythrocytes. Both iron and glucose were crucial in concentrations 5–7 μg/ml and 0.5–1% respectively. Bovine serum albumin‐starch mixture acted as an excellent stabilizer.
Bacillus thuringiensis insecticidal delta‐endotoxin: Diversity of crystal proteins and its relatedness to the toxicity spectrum
Authors: Haider M. Z. , Mahmood S. 
Published: February 2007

AbstractBacillus thuringiensis strains produce crystal delta‐endotoxins which exhibit a diverse toxicity spectrum. In order to explore the basis of toxin specificity, a comparison of the activity of 13 strains belonging to seven serotypes was made against three insect species. The delta‐endotoxin crystals were purified and their poly‐peptide composition analyzed by SDS‐PAGE. Among the strains studied, the delta‐endotoxins consist of a variety of crystal proteins in the 60‐144 KDa size range. On the basis of molecular mass, endotoxins maybe grouped into two classes; one contained both high (125‐144 KDa, P1) and medium sized (60–66 KDa, P2) proteins and a second class consisting of only the high Mr polypeptides. Immunoblotting with B. alzawai P1 antiserum revealed antigenic cross‐reaction with one or more of the polypeptides in 125‐144 KDa range in all the strains studied. When the crystal proteins from different strains were immunoblotted with kurstaki P2 antiserum, none of the P1 protein crossreacted suggesting that the P1 and P2 proteins are not structurally related. However, the B. kurstaki P2 antiserum crossreacted with 66 KDa proteins in some other strains which underlines a structural homology in this class of the toxic polypeptides. Toxicity studies revealed that the high Mr P1 proteins of all the strains in this study were active against lepidopteran (Pieris brassicae and Diacrisia obliqua) larvae. B. thuringiensis aizawai strains exhibit a dual toxicity associated with the high Mr (130–135 KDa; P1) proteins. The P2 crystal proteins (60–66 KDa) also showed dual toxicity against the lepidopteran and dipteran larvae but were found to be structurally and immunologically distinct.
Conditioning by mitochondria and energy source of thermal death parameters in yeast
Authors: Madeira‐Lopes A. , Cabeça‐silva C. 
Published: February 2007

AbstractTwo strains of Saccharomyces cerevisiae of opposite mating type (a and α), with different resistance to thermal death, and their respective mitochondrial respiratory‐deficient mutants (petites ap and αp) were used to prepare the following diploid strains: aα, aαp and apα. Specific thermal death rates were determined at supramaximum temperatures for growth, under conditions of mitochondrial derepression (glycerol medium). Comparison of the entropies of activation of thermal death showed that diploids aα and apα behaved like the more resistant haploid α, and diploid aαp like haploid a. In glucose medium strains α and aα became even more thermoresistant. The results favour the concept that thermal death determinants are located in the mitochondrial genome, and that mitochondria repressed cells repair thermal injuries more efficiently.
Bioenergetic parameters of Acremonium chrysogenum
Authors: Telesnina G. N. , Bartoshevish Yu. E. , Krakhmaleva I. N. , Petyushenko R. M. , Sazykin Yu. O. , Navashin S. M. 
Published: February 2007

AbstractBioenergetic parameters of two isogenic strains of Acremonium chrysogenum markedly differing in their capacity for biosynthesis of cephalosporin C were studied. It was shown that in the high productive strain the system of oxidative phosphorylation played the dominant role in the cellular energy supply (the index of the substrate consumption efficiency amounted to 0.82). In both strains terminal oxidation of the reduction equivalents mainly occurred via the respiration chain with cytochrome oxidase as the terminal component. In the low productive strain an alternative cyanide resistant pathway was observed, in addition to the classic cytochrome chain.A procedure suitable for the isolation of stable protoplasts from the mycelium of A. chrysogenum was developed. It was proved to be useful in the isolation of functionally active mitochondria possessing theoretical phosphorylation efficiency and high phosphate acceptor respiration control. It was concluded that there are three oxidative phosphorylation sites in the respiration chain of the high productive strain of A. chrysogenum.
Verwertung von Sulfitablauge durch Hefen — Wachstumsparameter von Produktionsstämmen und eines Fusionsstammes
Authors: Weide H. , Bachmann Beate 
Published: February 2007

AbstractThe growth characteristics of a Candida strain (T1), a Pichia strain (T2), and of a fusion product of T2‐mutants (fp‐T2) have been examined in batch and continuous cultures with the single substrates xylose, acetate, glucose, mannose, and galactose or mixed substrates of them.Maximum specific growth rate (μmax), substrate saturation constant (Ks), substrate inhibition (Ksi), yield (Y), dilution rate (D), and the protein content of the strains have been compared. The significance of the results for the production of single cell protein is pointed out.
Selective and rapid solubilization of the microbial membrane enzyme aldehyde dehydrogenase
Authors: Hommel R. , Kleber H.‐P. 
Published: February 2007

AbstractAn improved solubilization procedure for the membrane‐bound quinoprotein aldehyde dehydrogenase from Acetobacter rancens CCM 1774 was established. After the first solubilization of membrane enzymes by Brij 35 which provided important extraction of membrane proteins other than aldehyde dehydrogenase, the application of Trition X‐100 resulted in an almost 20‐fold purification of quinoprotein aldehyde dehydrogenase. The optimal solubilization was closely connected with definite detergent/protein ratios.
Regulation of the dnaQ gene of Escherichia coli in mutants expressing the SOS regulon constitutively
Authors: Quiñones Ariel 
Published: February 2007

AbstractCurrent models for the mechanism of SOS mutagenesis in E. coli propose the involvement of a new or modified DNA polymerase III holoenzyme in error‐prone replicative bypass of bulky DNA lesions assuming an inhibited or excluded 3′ → 5′ proofreading exonuclease function of DNA polymerase. By promotor fusion to galK, gene fusion to lacZ and SI analysis the in vivo regulation of dnaQ coding the proofreading subunit of DNA polymerase III holoenzyme was analyzed under conditions of induced or constitutive SOS expression. The results presented here clearly show that, at least on the level of gene expression no regulatory event seems to contribute to the assumed decrease of proofreading activity during SOS mediated error‐prone bypassing of bulky lesions. On the contrary, an increase in dnaQ gene expression was observed following treatment with some SOS inducing agents which produces bulky DNA lesions.
Qualitative and quantitative changes in β‐1,4‐glucosidase accompanying growth of Aspergillus nidulans
Authors: Sharma S. , Bagga P. S. , Sandhu D. K. 
Published: February 2007

AbstractA comparative study of the wild type A. nidulans and a mutant strain aco‐T69 (lacking conidia and cleistothecia) revealed the better production of β‐1,4‐glucosidase in the former. The relative distribution of the enzyme levels in various morphological structures viz. somatic hyphae, spores and cleistothecia also showed a variation. Highest specific activity was found in the cleistothecial extracts. The electrophoretic analysis of the wild type strain demonstrated the presence of three isoenzymes of β‐1,4‐glucosidase i.e. β‐GLU I, β‐GLU II and β‐GLU III, the number of which varies from one to three during the growth of the organism. The parallel study of the mutant strain showed complete absence of β‐GLU II. All three forms were present in the somatic hyphae and cleistothecial extracts while spore extracts depicted the absence of β‐GLU III in the wild type.
Sporothrix schenckii — a freeze‐fracture study
Authors: Svoboda Augustin , Trujillo‐Gonzalez Amanda 
Published: February 2007

AbstractFreeze‐fracture electron microscopy of a pathogenic dimorphic fungus Sporothrix schenckii revealed planar views of cell structures corresponding to those described already on thin sections. In addition to the characteristic differences in cell wall thickness between conidia, yeast forms and filaments, variations in plasma membrane invaginations were found. In conidia the invaginations were short and abundant, while in yeast forms they were scarce and longer. The plasma membrane of the filaments was smooth without invaginations. No differences were found in the frequency of intramembrane particles among the three forms. In the region of the septal pore the particles were circularly arranged with a characteristic partitioning on the P and E fracture faces.
Lack of a correlation between the vitamin requirement and the ecological position of wood‐decay fungi
Authors: Gramss G. 
Published: February 2007

AbstractForty‐eight species of wood‐destroying basidiomycetous fungi which are represented by 74 strains were examined for their dependence on exogenous vitamin sources such as thiamine and biotin. In a series of up to 11 consecutive transfers to vitamin‐free glucose‐salt medium batches in a 4‐week rhythm it was shown that (i) the level of vitamin heterotrophy did not depend on whether the fungus was a parasite or a saprophyte, (ii) among both parasites and saprophytes vitamin‐independent and highly vitamin‐dependent isolates could be detected, (iii) almost 70% of the brown‐fungi, but only 30% of the white‐rot fungi dependend comparatively little on exogenous vitamin sources, (iv) the degree of vitamin heterotrophy varied in part dramatically among several strains of a given fungal species, (v) under permanent vitamin starvation none of the 74 fungal strains completely ceased growing, but several strains suffered an irreversible physiological collapse whose nature is still unknown. It is concluded that on natural timber resources both vitamin‐dependent and vitamin‐independent fungal strains can probably develop their normal pathovirulence and kratovirulence properties. Under conditions of vitamin starvation the equilibrium between the vitamin‐dependent decay fungus and the vitamin‐independent competitor may nevertheless become disturbed.
Steroid‐1‐dehydrogenases in nocardioform bacteria studied by electrophoresis and immuno blotting techniques
Authors: Kaufmann G. , Schumann G. , Wollweber L. , Hüller E. , Atrat P. 
Published: February 2007

AbstractFifteen nocardioform bacteria strains, capable of transforming steroid compounds were investigated with regard to their range of inducible steroid‐1‐dehydrogenase (St1DH)1 activities. The St1DHs of these bacteria were compared due to their immuno reactivity in Western blot experiments with a rabbit antiserum raised against the purified St1DH of Rhodococcus rhodochrous 7030. Four strains exhibited a strong immuno reactivity, irrespective of differences in the electrophoretic mobility of the enzymes. Fivestrains revealed significantly diminished reactivities, and in five strains with a very low St1DH content, no reactivity was found. One strain, designated as Nocardiaspec. 7151, exhibited a high, inducible St1DH activity, but no immuno reaction was found. The absence of immuno reactivity is discussed in connection with the considerably diminished electrophoretic mobility of this enzyme.
Construction of the dextrin‐degrading pof brewing yeast by protoplast fusion
Authors: Janderová Blanka , Cvrčková Fatima , Bendová Olga 
Published: February 2007

AbstractA haploid, glucoamylase‐producing strain of Saccharomyces diastaticus lacking the POF gene and thus unable to produce phenolic off‐flavour in beer was constructed by classical genetic techniques. Protoplast fusion was performed between this strain and a brewing polyploid Saccharomyces uvarum strain. Some clones derived from fusion products can produce low‐carbohydrate beer of acceptable flavour.
L‐Carnitine uptake by Escherichia coli
Authors: Jung Heinrich , Jung Kirsten , Kleber Hans‐Peter 
Published: February 2007

AbstractThe uptake of L‐carnitine by Escherichia coli044 K 74 which is able to metabolize L‐carnitine to γ‐butyrobetaine under anaerobic conditions was studied. The uptake system of E. coli was induced in the presence of L‐carnitine or crotonobetaine. The optimum influx of L‐carnitine was found to take place at 37 °C in phosphate buffer, pH 7.5. On the basis of the temperature dependence of the uptake rate an activation energy of 53.5 kJ/mol was estimated. The transport of L‐carnitine was energy dependent. The kinetics of L‐carnitine entry followed the MICHAELIS‐MENTEN relationship yielding a Km value of 5.3 · 10‐4 M and a Vmax of 154 nmol/min · mg protein. The transport system showed considerable structural specifity for trimethylamine carboxylic molecules. The results suggest that E. coli possesses an inducible, active and carrier‐mediated uptake system for L‐carnitine.
Cyclic AMP‐dependent phosphorylation of fructose‐1,6‐bisphosphatase and other proteins in the yeast Candida maltosa
Authors: Hofmann K. H. , Polnisch E. 
Published: February 2007

AbstractIn crude extracts of Candida maltosa, about 12 proteins are phosphorylated in the presence of cAMP or of a catalytic subunit of cAMP‐dependent protein kinase.A strongly labelled protein spot occurred in the position of fructose‐1,6‐bisphosphatase both after electrophoresis of crude extracts incubated with cAMP and of a partially purified fructose‐1,6‐bisphosphatase incubated with a catalytic subunit of cAMP‐dependent protein kinase. No phosphorylation of the cytoplasmic malate dehydrogenase could be detected.From these results it was concluded that cAMP‐dependent phosphorylation plays an important role in the catabolite inactivation of fructose‐1,6‐bisphosphatase in Candida maltosa, as described for Saccharomyces cerecisiae.
Instability of in vitro resistance to imipenem in Pseudomonas aeruginosa
Authors: Wolter Ernst‐Jürgen , Witte Wolfgang 
Published: February 2007

AbstractIn 3 from 19 clinical isolates of Pseudomonas aeruginosa imipenem‐resistant subpopulations could be detected in vitro. In comparison to their wild strains these imipenem‐resistant cells were lacking an outer‐membrane‐protein of 50 kD. In the subpopulation derived from Pseudomonas aeruginosa 76 resistance to imipenem was found to be instable. It could be lost within a short period of time after subcultivation in the absence of imipenem. Cells with restored sensitivity to imipenem possess the outer membrane protein of 50 kD as the wild strain does.
Isolation and primary characterization of a new bacteriophage of obligate methylotrophic bacteria
Authors: Almumin Sabah , Kadri Mustafa , Mamat Uwe , Engel Joachim 
Published: February 2007

AbstractØ KISR 1, a new bacteriophage of obligate methylotrophic bacteria, was isolated from a local pilot plant. The phage belongs to the Podoviridae family of viruses characterized by a short non‐contractile tail and double‐stranded DNA. The size of phage genome was determined on the basis of electron micrographs and restriction enzyme analysis to be about 46 kb. The host range of Ø KISR 1 is restricted to three very closely related methanol‐utilizing KISR strains belonging to the genus Methylophilus. The phage does not originate from the methylotrophic KISR strains which were tested for lysogeny.
Regulation of ammonium assimilation by Clostridium acetobutylicum
Authors: Amine J. , Marczak R. , Maazouzi N. , Masion E. 
Published: February 2007

AbstractAssimilation of ammonium by the obligate anaerobic bacterium Clostridium acetobutylicum was accomplished by the pathway: Glutamine synthetase/glutamate synthase. C. acetobutylicum also contained an asparagine synthetase, but no glutamate dehydrogenase activity was detected. The glutamine synthetase was partially repressed by addition of large amounts of ammonium chloride and/or casaminoacids to the medium, while the biosynthesis of the other enzymes was not regulated by the extracellular concentration of ammonium.