bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steroid transformations by a strain of Arthrobacter oxydans incapable of steroid ring degradation
Authors: Sarmah Utpal , Roy Monoj K. , Singh H. Devendra 
Published: February 2007

AbstractArthrobacter oxydans 317 which is able to bring about the complete degradation of β‐sitosterol was treated with acridine orange to obtain a plasmid cured strain Arthrobacter 317AL, incapable of producing steroid ring degradation. The strain was neither able to form 4‐androstene‐3,17‐dione(AD) from β‐sitosterol nor to convert AD to 1,4‐androstadiene‐3,17‐dione(ADD). It was, however, able to hydroxylate AD and ADD at the C‐17 position to form testosterone and 1,4‐androstadiene‐17β‐ol‐3‐one respectively. The strain could grow on β‐sitosterol presumably utilizing the degradation products of the sterol side chain. Partial degradation of the β‐sitosterol side chain was demonstrated by the isolation of 27‐norcholest‐4‐en‐3,24‐dione, a metabolic product of the side chain degradation. The existence of metabolic blocks in a further degradation of the side chain to AD, in 1,2‐dehydrogenation and 9α‐hydroxylation of the steroid ring structure was postulated.
Altered control of chorismate mutase leads to tryptophan auxotrophy in Pichia guilliermondii
Authors: Bode R. , Koll P. , Prahl N. , Birnbaum D. 
Published: February 2007

AbstractWe isolated a tryptophan auxotrophic mutant strain, PK101, of Pichia guilliermondii. Its auxotrophy is not caused by a defect in any of the tryptophan biosynthetic enzymes, but its chorismate mutase, an enzyme of the phenylalanine‐tyrosine biosynthesis, is changed. In comparison to the wild type chorismate mutase, the enzyme of PK101 is characterized by a complete loss of sensitivity to L‐phenylalanine inhibition and to a considerable loss of sensitivity to L‐tryptophan activation. Furthermore, the chorismate mutase activity of the mutant is more than 7‐fold higher in the absence of L‐tryptophan than in the wild type. The PK 101 enzyme is also changed in the pH optimum and in some kinetic constants. We found an increased intracellular pool of both phenylalanine and tyrosine, and a reduced content of tryptophan in the mutant cells. Our genetic data indicate that the mutant phenotype is dominant over the wild type.
Isolation and structure of 26‐deoxylaidlomycin, a new polyether antibiotic from Streptoverticillium olivoreticuli
Authors: Gräfe U. , Schlegel R. , Stengel C. , Ihn W. , Radics L. 
Published: February 2007

Abstract26‐Deoxylaidlomycin (I, C37H61O11Na) was isolated together with its cometabolite laidlomycin (II) from the mycelium of Streptoverticillium olivoreticuli IMET 43782. Its structure was determined by high‐field 13C and 1H NMR, and MS spectral studies. The antibacterial activity of I against Bacillus subtilis ATCC 6633 was found to be approx. four times higher than that of laidlomycin (II).CALLING STATEMENT : magnified image.The structure of 26‐deoxylaidlomycin (I: sodium salt, R1 = Na, R2 = H): III free acid: R1, R2 = H and laidlomycin (II, sodium salt: R1 = Na; R2 = OH).
Symbiotically defective histidine mutant of Rhizobium meliloti strain L5.30
Authors: Malek Wanda 
Published: February 2007

AbstractHistidine auxotroph of Rhizobium meliloti strain L5.30 was isolated by nitrosoguanidine (NTG) mutagenesis. On alfalfa it formed ineffective nodules that contained only a few degenerating bacteroids inside large vacuoles but many starch granules. Prototrophic forms of this mutant (revertants and transductants) formed pink, effective nodules. Effective nodules were also induced by the His− mutant when histidine was supplied to the plant‐growth medium; this supported the supposition of a causal relationship between histidine auxotrophy and ineffectivity in the R. meliloti strain L5.30.The histidine mutation of the strain studied was mapped onto the chromosome of R. meliloti by transduction near earlier localized cys‐246 auxotrophic mutation (4.4% of cotransduction).
Storage temperature and viability of sporangiospores of potentially human pathogenic species of Rhizomucor from Nigerian tobacco
Authors: Ogundero V. W. , Aina J. O. 
Published: February 2007

AbstractThe effects of temperature on storage and viability of asexual spores of Rhizomucor pusillus (LINDT) SCHIPPER and Rhizomucor miehei (COONEY and EMERSON) SCHIPPER were studied. An optimal germination temperature of 35 °C was recorded for both species with good results obtained around 40 °C. On prolonged storage of the spores at various temperatures (‐19 °C, 4 °C, 30 °C, 37 °C), the best results were obtained at 4 °C and 30 °C. Very rapid losses in viability of the spores of both fungi occurred at −19°C reaching a maximum of 68% and 51%, respectively, for R. pusillus and R. miehei after 6 months of storage.Continuous exposure of the spores to 68 °C led to rapid losses of viability of up to 100% for those of R. pusillus after 40 min exposure. Sporangiospores of R. miehei showed more gradual losses on exposure to 68 °C.The potential health hazards which the presence of these fungi on tobacco products pose to man are discussed.
Einsatz der Fermenter‐Dialyse‐Kultur zur Züchtung kapseltragender Bakterien mit klinischer Bedeutung
Authors: Starke Roland , Mehl Michael , Möckel Claudia , Grunow Roland , Montag Thomas , von Baehr Rüdiger , Schmidt Gerhard 
Published: February 2007

AbstractFor mass cultivation of group B streptococci (B‐III and B‐variant streptococci), a fermenter dialysis culture technique is described and compared to conventional shaking culture and fermenter batch culture techniques.The influence of two kinds of cultivation media on the bacterial yield is demonstrated.The growth rate of the bacteria and the yield of the microbes is higher in modified POPE medium than that observed with Nährbouillon I.The type‐specific polysaccharide of B‐III‐streptococci prepared by phenol‐water extraction followed by gelchromatography can be used as a screening antigen for the production of monoclonal antibodies against B‐III‐streptococci.
A further characterization of alanine dehydrogenase from Streptomyces aureofaciens
Authors: Vančurová Ivana , Vančura Aleš , Volc Jindřich , Neužil Jiří , Běhal Vladislav 
Published: February 2007

AbstractHomogeneous alanine dehydrogenase isolated from Streptomyces aureofaciens, a producer of tetracycline, was characterized from the point of its molecular and catalytic properties. Using analytical ultracentrifugation the molecular weight of alanine dehydrogenase was found to be 198,000. The enzyme could use as cofactors apart from NAD+ also l,N6‐etheno‐NAD+, 3‐acetylpyridine‐NAD+, deamino‐NAD+ and nicotinamide guanine dinucleotide. The enzyme activity in the direction of oxidative deamination was not affected by the addition of nonsubstrate amino acids, however, it was sensitive to inhibitors of SH‐groups. Reductive amination of pyruvate was inhibited by L‐alanine, L‐serine and D‐alanine. The inhibition by L‐alanine and L‐serine was uncompetitive with respect to NADH and noncompetitive with regard to pyruvate and ammonium ions.
An efficient method for producing and purifying gramme quantities of T‐2 toxin
Authors: Lepom Peter , Baath Helga 
Published: February 2007

AbstractA simple procedure was developed for the laboratory production and purification of gramme quantities of T‐2 toxin. After growing at 22 °C on rice for two weeks, Fusarium sporotrichioides T‐21 produced average T‐2 toxin concentrations of 1309 mg/kg and as much as 1000 mg of crystalline product were recovered. The method described avoids long‐term, low temperature incubations. Crude culture extracts were rapidly purified in two steps by column chromatography on silica gel. The purity of the crystallized product was verified by thin‐layer chromatography using various spray reagents for detection.
Chemische Charakterisierung des Escherichia coli K 1 Kapselpolysaccharides
Authors: Mehl Michael , Starke Roland , Kissig Bettina , Grunow Roland , Jahn Siegbert , Schmidt Gerhard , von Baehr Ruediger 
Published: February 2007

AbstractThe exact chemical characterization of the prepared Escherichia coli K 1 capsule polysaccharide is necessary and a prerequisite for using this antigen as a screening antigen in the production of monoclonal anti‐K 1‐antibodies.The K 1‐antigen, prepared by phenol‐water‐extraction, was analyzed by protein, RNA, and neuraminic acid determination. An addition, the antigen was subjected to elementary analysis, infrared‐ and 13C‐NMR‐spectroscopy, and gelchromatography.After testing the serological specificity, the K 1‐antigen was identified as a high molecular polyneuraminic acid.
Untersuchungen über das Vorkommen von Lävansucrase und Saccharase bei Pathovarietäten von Pseudomonas syringae und eng verwandten nicht phytopathogenen Pseudomonaden
Authors: Sauerstein J. , Reuter G. 
Published: February 2007

AbstractLike P. syringae pv. phaseolicola, other pathovarieties of the Pseudomonas syringae group (P. syringae pv. glycinae, P. syringae pv. syringae, P. syringae pv. tabaci, and P. syringae pv. tomato) possess two sucrose splitting enzymes, a constitutive levansucrase found both extracellularly and cellularly, and a cellular sucrase, the synthesis of which is regulated differently. In P. fluorescens, a closely related saprophytic pseudomonad, only a levansucrase was found.
Keratinophilic fungi from the duck nails in Egypt
Authors: Abdel‐Gawad K. M. , Moharram A. M. 
Published: February 2007

AbstractThe mycoflora of one hundred and sixty of duck nail samples, collected from the duck Farm, Faculty of Agriculture, Assiut University, were examined. Using the soil plate technique and SABOURAUD'S dextrose agar, thirty six species appertaining to twenty genera of keratinophilic fungi were isolated. Chrysosporium was the genus most frequently isolated (50% of the samples). Aspergillus and Penicillium occurred in low incidences (13.1 and 12.5% of total samples). Trichophyton rubrum was found to colonize few of the duck nail samples (2.5%) as well as some other fungal species previously reported as pathogenic to man and animals (Aspergillus fumigatus, Scopulariopsis brevicaulis and Paecilomyces lilacinus).
Antifungal activity of dihydrodioscorine extracted from a wild variety of Dioscorea bulbifera L
Authors: Adeleye Adetoun , Ikotun T. 
Published: February 2007

AbstractThe bulbils and tubers of a wild variety of Dioscorea bulbifera L. contained an alkaloid, dihydrodioscorine. When crystallized in its hydrochloride form and incorporated into potato dextrose agar at a final concentration of 0.1%, it was found to slow down the rate of growth of five plant pathogenic fungi namely: Sclerotium rolfsii, Curvularia lunata, Fusarium moniliforme, Macrophomina phaseolina and Botryodiplodia theobromae. Also sclerotia formation in S. rolfsii was delayed and the number was reduced. Conidia formation in C. lunata and F. moniliforme was also delayed and reduced but pycnidia formation in M. phaseolina and B. theobromae was not affected. There was no significant difference between the rate of growth of the fungi on PDA incorporated with 0.01% final concentration of dihydrodioscorine and on control plates. Abbreviations: PDA = potato dextrose agar, D.D. = dihydrodioscorine dihydrochloride.
Biosynthesis of anthracyclinones: Biotransformation of aklaviketone
Authors: Eckardt K. , Schumann G. , Wagner C. , Stengel C. , Ihn W. , Novák J. , Tresselt D. 
Published: February 2007

AbstractIn a series of feeding experiments, aklaviketone was added to cultures of the blocked mutants Streptomyces galilaeus S 727, S. peucetius var. caesius 21/8 and S. griseus 956/2. The compound was transformed to give cinerubin A or ϵ‐rhodomycinone. The results provide further evidence for the proposed biosynthetic pathway leading from aklanonic acid via aklaviketone to aklavinone and related anthracyclinones.
Critical steps in degradation of chloroaromatics by rhodococci III. Isolation and identification of accumulating intermediates and deadend products
Authors: Ihn W. , Janke D. , Tresselt D. 
Published: February 2007

AbstractPre‐adapted resting cells of different aromatics‐utilizing Rhodococcus strains readily cometabolized various monochloroaromatic non‐growth substrates (i.e. 2‐chloroaniline, 3‐chloroaniline, 3‐chlorophenol, 4‐chloro‐phenol and/or 3‐chlorobenzoic acid). Certain intermediates (i.e. 3‐ or 4‐chlorocatechol) and/or dead‐end products (i.e. 2‐chloro‐cis,cis‐muconic acid or cis‐4‐carboxymethylene‐but‐2‐en‐4‐olide) were isolated in preparative amounts from the respective incubation media and identified by chemical and spectroscopic (UV/VIS, IR, MS, 1H‐NMR) analysis.
Biochemical characterization of a shikimic acid‐resistant mutant of Nostoc linckia
Authors: Kumar Dhruv 
Published: February 2007

AbstractThe growth of Nostoc linckia was significantly inhibited by shikimic acid concentrations greater than 4.0 μg ml−1 and was completely inhibited at 10.0μg ml−1. Shikimic acid increased the duration of the lag phase and the doubling time and hastened the onset of the retardation phase of growth. A mutant (NLshi) capable of growing in presence of 50 μg ml−1 shikimic acid, was isolated by nitrosoguanidine mutagenesis from the wild type population at a frequency of about 1 × 10−5 to 1 × 10−6. The mutant grew slower than the wild type. Both the wild type and the mutant strain grew photoheterotrophically in light, with and without 3 (3–4 dichlorophenyl) 1,1‐dimethyl urea (DCMU) and in darkness when provided with glucose. Glucose supplementation promoted ammonium uptake from the medium, when wild type and mutant were grown in an ammonium‐supplemented medium. Glucose stimulated heterocyst production and nitrogenase activity in both the strains. As compared to wild type, this mutant showed higher heterocyst frequency and nitrate reductase activity but its ammonium uptake activity was lower. No significant difference in glutamine synthetase and nitrogenase activities of the mutant were observed. The mutant was stable and retained its resistance even after several subcultures through medium free of shikimic acid.
Production of thermozymocidin (myriocin) by the pyrenomycete Melanconis flavovirens
Authors: Šašek Václav , Sailer Miroslav , Vokoun Jindřich , Musílek Vladimír 
Published: February 2007

AbstractSubmerged culture of the pyrenomycete Melanconis flavovirens produces a strongly active antifungal antibiotic. The antibiotic was isolated from the culture mash. In purified compound the physico‐chemical characteristics, including 1H NMR spectrum, were estimated. The antibiotic was found to be identical with thermozymocidin (myriocin) as confirmed by comparison with synthetically prepared thermozymocidin.
Phaseolotoxin production by Pseudomonas syringae pv. phaseolicola: The influence of temperature
Authors: Nüske Jörg , Fritsche Wolfgang 
Published: February 2007

AbstractPhaseolotoxin (N‐sulphodiaminophosphinyl‐ornithyl‐alanyl‐homoarginine) is a phytotoxic secondary metabolite produced by Pseudomonas syringae pv. phaseolicola. The production of the phytotoxin is strongly regulated by temperature. The optimal temperature for phaseolotoxin production is 18 °C. Temperatures in the range between 18 °C and 30 °C inhibit the production of phaseolotoxin in an increasing manner. By temperature shift experiments and the inhibition of protein synthesis by chloramphenicol it was demonstrated, that the synthesis of enzymes related to toxin synthesis and not the regulation of the activity of the responsible enzyme system is affected by higher temperatures.
Effect of organic soil amendments on the incidence of brown spot disease in maize caused by Physoderma maydis
Authors: Osunlaja S. O. 
Published: February 2007

AbstractSix organic materials were added to the soil in a field recently showing a high incidence of brown spot disease in maize caused by Physoderma maydis. All the amendments lowered significantly the occurrence of the disease in comparison to the unamended control. However, the ability to suppress the disease differed substantially among the amendments. Rice bran and rice straw were most effective in this respect. The suppression of the disease appeared to be related to an increased microbial activity in the soil.
Invasion of wood by basidiomycetous fungi. V. The role of fungal elicitors of plant cell necrobiosis in the expression of pathovirulence and kratovirulence
Authors: Gramss G. 
Published: February 2007

AbstractWithin the intact tree the live cell is the exclusive carrier of phytopathological defence reactions against microbial attack. In a comprehensive search for fungal virulence factors capable of weakening the living tissues in timber, 48 species of wood‐destroying basidiomycetous fungi (WBF)1) with known degree of pathosism and the corresponding degree of saprophytism were grown on liquid still cultures. Droplets of the filtered culture fluids were then applied to pin‐prick wounds in the interveinal area of leaves from several tree and one herb species. Within 48 hours of development circular spots of brown necrotic tissue expanded around the pin pricks to indicate and approximately quantify the presence of fungal elicitors of necrobiosis. The resulting necrobiosis index was, with certain exceptions, not correlated with the antimicrobial potency (kratovirulence) of the fungus, its pathosism against standing timber, and the activity of exoenzymes in white‐rot fungi. The necrobiosis index was, in part, positively correlated with the activity of those brown‐rot fungi that dispose of an effective wood‐decay capacity. Characteristic of the fungal species as well as of the fungal strain the necrobiosis index ranked from 0 to 1,421.2 mm2 necrotic net area per 300 pin pricks but there was no fungus to be unable of eliciting browning in at least a few of the leaf species. The most severe necrosis was permanently observed on leaves of several generally oversusceptible tree species rather than on the notorious host species of the test fungus. It is therefore concluded that the elicitors of plant cell necrobiosis in WBF are predominantly host‐nonspecific stress factors that may sometimes increase fungal pathovirulence. Their purification should help characterize their action as phytotoxic, necrobiotic, enzymatic, or even antimicrobial.
Biochemical mechanism of keratin degradation by the actinomycete Streptomyces fradiae and the fungus Microsporum gypseum: A comparison
Authors: Kunert Jiří 
Published: February 2007

AbstractTwo keratinolytic organisms, the procaryote Streptomyces fradiae and the fungus Microsporum gypseum, were cultured on sterile sheep's wool in a mineral solution. The loss in substrate was recorded and the degradation products in the cultivation fluid were analyzed. In M. gypseum the key reaction was the cleaving of the substrate disulfide bridges by means of sulfite excreted into the medium. Keratin denatured by „sulfitolysis’︁ was further attacked by extracellular proteases. A typical finding was the accumulation of peptides containing S‐sulfocysteine, the product of sulfitolysis of cystine. The overall excess of sulfur was removed by oxidation to sulfite and to sulfate, which was the main and final product. In S. fradiae the degradation was faster. The results did not prove that sulfite formed and the concentration of sulfate in the medium remained negligible. Neither could cysteine desulfhydration and hydrogen sulfide excretion be demonstrated. The medium was found to contain relatively high concentrations of sulfhydryl compounds, evidently cysteine‐containing peptides. Therefore, in this microorganism, keratin was most likely denatured by the direct reduction of cystine bridges. The main product of the elimination of excess sulfur was inorganic thiosulfate, which accumulated in the medium.
Purification and properties of the β‐glucosidase from a nitrile hydratase‐producing Brevibacterium sp. strain R312
Authors: Legras J. L. , Kaakeh M. R. , Arnaud A. , Galzy P. 
Published: February 2007

AbstractBesides its nitrile hydratase and wide spectrum amidase activities, the Brevibacterium sp. R312 strain also possesses a constitutive β‐glucosidase. Its optimum pH is 6. The enzyme was purified by fractionation precipitation with ammonium sulfate followed by chromatographic elutions on Q‐Sepharose Fast Flow, Sephadex G‐200 and Phenyl Superose. The resulting purification was 1960 folds for a 6% yield. The molecular weight of this enzyme was estimated at 180,000. It contains two identical sub‐units. The pI is 5.5. This enzyme has a strong affinity for aryl‐ß‐glycosides: pNPG, prunassine; it could also degrade linamarine. It is inhibited by p‐chloromercuribenzoate, δ‐gluconolactone and glucose.
Auxotrophic mutants of the yeast Trichosporon adeninovorans
Authors: Samsonova Ida A. , Böttcher Fritz , Werner Carsta , Bode Rüdiger 
Published: February 2007

AbstractWe have isolated and characterized auxotrophic mutants of Trichosporon adeninovorans, strain PAR‐4 to get genetic markers that cover the entire nuclear genome of this thermotolerant yeast of technological interest. The nitrosoguanidine mutagenesis yielded mutants at a high frequency. We detected a broad spectrum of auxotrophic phenotypes in the random mutant samples. Obviously, strain PAR‐4 is a haploid or hyper‐haploid yeast. In correspondence we determined a low DNA content per cell. In contrast to NG1, UV light was an inefficient mutagen. UV survival curves were without the typical shoulder indicating suppression of repair of UV‐induced lethal lesions. Thus, the response of PAR‐4 to UV was different from those of Saccharo‐myces cerevisiae and other yeasts.
Toxicity of sodium diethyl‐dithiocarbamate (NaDDC) on photoautotrophic growth of Anacystis nidulans IU 625
Authors: Singh D. P. , Gothalwal R. , Bisen P. S. 
Published: February 2007

AbstractThe effect of a graded concentration (0.05–0.6 mmol/1) of sodium diethyldithiocarbamate (NaDDC) on the growth rate of Anacystis nidulans was found to be concentration‐dependent. A 50% inhibition (I50) of the growth rate was observed at 0.28 mmol/1 of NaDDC. A sudden decrease in cellular absorbance at 435,625 and 675 nm on the third day, and followed by a gradual decrease up to the 6th day indicated an NaDDC‐induced bleaching of the chlorophyll α and phycocyanin pigments. Furthermore, an NaDDC‐induced increase in absorbency at 340 nm after 48 hrs of light incubation was indicative of the reduced state of the carriers. The result on the reduction of 1,6‐dichlorophenol indophenol (DCPIP), cytochrome c and NADP was an NaDDC‐induced stimulation of all the reductive processes, with saturating rates at approximately 0.4 mmol/1 of NaDDC. Furthermore, the rate of DCPIP reduction in the presence of NaDDC was inhibited by rotenone (100 μmol/l). SHAM (salicyl hydraxamic acid, 500 μmol/l) and DCMU (100 μmol/l). Similarly, the addition of 10 μmol/l of DCMU resulted in the inhibition of both cytochrome and NADP reductions. Therefore, the results suggested that NaDDC could bring about the over‐reduction of carriers by interacting with the electron transport chain on or before the DCMU sensitive site. An NaDDC‐dependent general increase in the fluorescence of chlorophyll a was further stimulated by the electron transport inhibitors. The result on oxygen evolution was a 50% inhibition (I50) of H2O2 and H2O2 supported O2 evolution at 0.12 and 0.19 mmol/1 of NaDDC, respectively. Taken together, these could suggest that the highly reduced state of carriers in the presence of NaDDC might be preventing the uphill electron flow from the light‐harvesting pigment complex, H2O and H2O2. Thus, the foregoing results inferred that the bleaching of pigments and over‐reduction of electron carriers ultimately accounted for the death of the organism.