bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Gramoxone and paraquat on growth and respiration of Azotobacter vinelandii
Authors: Gadkari Dilip 
Published: February 2007

AbstractThe influence of the herbicide Gramoxone and its active ingredient paraquat on growth and respiratory activity of Azotobacter vinelandii was studied. The experiments were performed in nitrogen‐free medium and in medium with combined nitrogen. Addition of Gramoxone (50 ppm) or paraquat (15 ppm) to the cultures during lag phase caused a total inhibition of growth. However, even after 24 h of incubation in the presence of herbicides the number of viable counts did not decrease. When herbicides were added to exponentially growing cultures, the growth response of the cultures was different. After addition of herbicides only a transient short inhibition period was noted and the length of the inhibition period was dependent on the time of herbicide addition. Neither Gramoxone (50 ppm) nor paraquat (15 ppm) enhanced catalase production. The respiratory activity of paraquat‐treated cells in the presence of 1 mM KCN was distinctly reduced (75%), while that of untreated cells did not change.
Development of a plasmid‐cloning system for Streptomyces viridochromogenes Tü494
Authors: Strauch E. , Wohlleben W. , Pühler A. 
Published: February 2007

AbstractA plasmid‐cloning system was developed for Streptomyces viridochromogenes Tü494, a producer of the tripeptide antibiotic phosphinothricyl‐alanyl‐alanine (PTT). Parameters affecting protoplast formation and transformability of S. viridochromogenes were investigated in detail. A procedure giving rise to transformation efficiencies of 104–105 transformants per μg DNA was worked out. Several Streptomyces plasmid vectors such as pIJ350, pIJ61, pEB2, pGM4 and pSW2 were tested in S. viridochromogenes. Some of these vectors (pGM4, pEB2) showed a high copy number, whereas the copy number of others (pIJ350, pIJ61 and pSW2) was markedly lower. Under non‐selective conditions some of the vectors (pIJ350, pEB2) were not stably maintained, in contrast to the vectors pGM4 and pSW2 which did not require any selection pressure for stable meintanance. Therefore, the plasmid vectors pGM4 and pSW2 derived from endogenous replicons of Streptomyces ghanaensis strains represent appropriate plasmid vehicles for cloning experiments in S. viridochromogenes.
Effect of growth temperature on the externalization and localization of α‐amylase in Bacillus stearothermophilus
Authors: Bezbaruah R. L. , Pillai K. R. , Gogoi B. K. , Singh H. D. , Baruah J. N. 
Published: February 2007

AbstractThe synthesis and localization of α‐amylase were studied in Bacillus stearothermophilus AN002 at 40, 45, 50 and 55 °C and also during early exponential, late exponential and stationary phases of growth. The extracellular α‐amylase synthesis was highes at 50 °C and at stationary growth phase. Accumulation of intracellular α‐amylase was observed in cells grown at 40 °C and was distributed in all the cell fractions. At 50 and 55 °C the cell did not have α‐amylase in the protoplasm or protoplamic membrane. The synthesis and externalization of extracellular enzyme are two processes and the externalization is controlled by growth temperature and cell age.
The ability of Aphanocladium album and Rhodotorula mucilaginosa to transform some compounds of juvenoid type
Authors: Dmochowska‐Gładysz J. , Kołek T. , Siewiński A. , Derdziński K. , Zabza A. , Galera E. , Walkowiak U. 
Published: February 2007

AbstractThe strains of Aphanocladium album (isolated from insects Tenebrio molitor) and Rhodotorula mucilaginosa reduce α,β‐unsaturated ketone groupings in (±)5‐(2′,2′,3′‐trimethy1‐3′‐cyclopenten‐1′‐y1)‐3‐penten‐2‐one, pseudoionone or in its (±) γ,δ‐dihydro‐derivative to respective saturated alcohols.The strains reduce the same carbony1 group to both alcohols in two enantiomeric 3,4‐dihydroderivatives of the first substrate as well as in () hexahydro‐analogue of pseudoionone. For all these substrates, the transformations were found to be enantiospecific.
Selektion und biotechnische Herstellung von Kulturlösungen mikrobieller Antagonisten zur Unterdrückung phytopathogener Bodenpilze
Authors: Huber Johann , Bochow Helmut , Junge Helmut 
Published: February 2007

AbstractTwo strains of bacteria,Bacillus subtilisT 99 andStreptomycessp. G43, antagonistic to phytopathogenic soil fungi, were isolated from natural substrates.In vitrotests indicated activities against differentFusariumspecies including formae speciales ofFusarium oxysporum, Stromatinia gladioli, Botrytis cinerea, Thanatephorus cucumeris, and other fungi. For both of the antagonists, biotechnical procedures were developed yielding culture broth for large‐scale application. After dilution of these media antagonists were tested successfullyin vivoby soil drenching treatments in a greenhouse carnation production facility. The application forms of the fermentation media developed were capable of suppressing wilt disease ofDianthus.
Temperature and aflatoxin production by Aspergillus flavus and A. parasiticus strains from Nigerian groundnuts
Authors: Ogundero Vincent W. 
Published: February 2007

AbstractThe ability of four strains of Aspergillus parasiticus (IMI 301 001) and two strains of Aspergillus flavus (IMI 300 998) to produce aflatoxins on Nigerian groundnuts under varying conditions of temperature was studied. While all the A. parasiticus strains produced the four major aflatoxins (B1, B2, G1, G2), only aflatoxin B1, and B2 were produced by the A. flavus strains used. The optimum temperature for aflatoxin production by both the fungal species was 30 °C with no toxin production at 10 °C.
Partial purification and characterization of anhydrotetracycline oxygenase of Streptomyces aureofaciens
Authors: Vančurová Ivana , Flieger Miroslav , Volc Jindřich , Beneš Milan J. , Novotná Jana , Neužil Jiří , Běhal Vladislav 
Published: February 2007

AbstractAnhydrotetracycline oxygenase was purified both by affinity chromatography and by hydrophobic interaction chromatography. Molecular weight of anhydrotetracycline oxygenase was determined to be 115,000 by Sephadex G‐200 gel filtration. Using preparative isoelectric focusing the isoelectric point of the enzyme was estimated to be 5.3. The enzyme showed a sensitivity to thiol‐specific inhibitors. During the hydrophobic interaction purification step, the activity dropped considerably. Reactivation occurred when a heat treated crude extract was added to the reaction mixture.
Ultrastructural studies on the cyanobacteriumNodularia spumigenaand its epiphytic bacteria of the genusSeliberia
Authors: Gumpert J. , Šmarda J. , Hübel M. , Hübel H. 
Published: February 2007

AbstractA 400–900 nm thick slime sheath showing 2–3 layers of different thickness and fibril orientation as well as large amounts of densely packed gas vesicles are characteristic for vegetative cells ofNodularia spumigena, a cyanobacterium, forming extended water blooms in the Baltic Sea. Comparative SEM and TEM investigations revealed typical screw‐like shaped epiphytic bacterial cells anchored in the slime sheath ofNodulariatrichomes. Their unique helically sculptured surface is characteristic for the genusSeliberia.Two types ofSeliberiacells can be distinguished, regarding cell morphology, formation of apical spherical bodies and their occurrence on host organisms. The main ultrastructural peculiarities concern a helically sculptured membraneous cell wall, a 100–250 nm large, heavily stained inclusion granulum in the cytoplasm of the anchored polar region, and a pad‐structure with associated hold‐fast material surrounding the polar cap, which is attached to the slime sheath. A permanent subcultivation of pure cultures ofSeliberiaepiphytes could not be obtained. In samples from natural water blooms,Nodulariacells were found to contain single or numerous gram‐negative rod‐shaped bacteria, and to show a more or less advanced destructio of the intracellular organization.
Leucine aminopeptidase in intracytoplasmic membranes of Acinetobacter calcoaceticus
Authors: Ludewig M. , Fricke B. , Aurich H. 
Published: February 2007

AbstractCells of Acinetobacter calcoaceticus strain 69‐V contain an aminopeptidase that cleaves L‐leucine amide, leucylglycine or lecine hydrazide with high efficiency. Leucine 4‐nitroanilide and alanine hydrazide are hydrolyzed to less than 0.1% and 1%, resp. of leucine amide.Grown on acetate‐NH+4 medium the activity of the enzyme in the cytoplasm is increased 5‐fold compared with cells grown on a casamino acid medium or on yeast extract. In these cases the specific activity of the unpurified enzyme is about 5 nkat/mg for the cytoplasmic and membrane‐bound enzyme species as well.Up to 30% of the aminopeptidase activity were found mainly in intracytoplasmic membranes, less in cytoplasmic membranes and only traces in outer membranes, presumably as contaminations. It is solubilized by detergents but not by high salt concentrations. An addition of antipain or Z‐Ala2‐Phe‐CH3 before cell rupture did not change the distribution of the enzyme. A mixture of EDTA and 1.10‐phenanthroline diminished the membrane‐bound enzyme from 11.4% to 4.3% and leupeptin or E‐64 increased it to 20%. The enzyme is regarded as leucine aminopeptidase (LAP) bound to intracytoplasmic membranes.
Netropsin increases formation of mRNA coding for a neutral metalloproteinase in Bacillus megaterium
Authors: Chaloupka J. , Kučerová H. 
Published: February 2007

AbstractThe anticancer drug netropsin increases the synthesis of an exocellular metalloproteinase during exponential growth as well as in the stationary phase of a sporulating strain of Bacillus megaterium. Its effect is due to a stimulation of the synthesis of the mRNA coding for the proteinase, determined as a residual synthesis of the enzyme in the presence of actinomycin D. The half‐life of the proteinase mRNA (5–6 min at 35 °C) is not affected by netropsin. Netropsin relieves partially the repression of the proteinase mRNA caused by amino acids, whereas the repression brought about by an increased temperature is almost unaffected by the drug.
NADP+‐dependent aldehyde dehydrogenase from ‘Acetobacter rancens’ CCM 1774: Purification and properties
Authors: Hommel Rolf , Kurth Jochen , Kleber Hans‐Peter 
Published: February 2007

AbstractNADP+‐dependent aldehyde dehydrogenase from the cytosolic fraction of the alkane‐degradating ‘Acetobacter rancens’ CCM 1774 was purified 112‐fold (specific activity of 112 nkat mg−1 protein). After polyacrylamide gel electrophoresis of the purified enzyme only one band was visible. The relative molecular weight was estimated to be 82,000 by both gel filtration and disc gel electrophoresis. The substrate specifity of the purified enzyme within the straight chain aliphatic aldehyde series is confined to acetaldehyde and propionaldehyde. Butyraldehyde and formaldehyde are considerably less converted. NADP+ alone served as electron acceptor. Mg2+ stimulated the reaction velocity in a strong manner by ‘non‐competitive’ activation. The estimation of kinetic parameters and inhibition experiments of the irreversible oxidation of ethanal indicate a random kinetic mechanism at optimal aldehyde concentrations and saturating NADP+ concentrations at optimal pH 8.5 which, however, trends to become ordered with decreasing pH values. Properties described exclude the participation of the enzyme in degradation of n‐alkanes. One physiological function of this constitutive aldehyde dehydrogenase may be the intracellular detoxification of short chain aldehydes by conversion to corresponding fatty acids.
Stepwise increase of elongation rate in individual hyphae of Streptomyces granaticolor during outgrowth
Authors: Kretschmer S. 
Published: February 2007

AbstractStarting with germinating spores of Streptomyces granaticolor, the kinetics of elongation of 3 types of outgrowing hyphae was determined. The 3 hyphal types were: first germ tube, second germ tube (which appeared from the same spores about 3 hours later) and branches arising from the first germ tubes. Taking photographs every fifth minute, with all hyphae a linear multiphasic elongation behaviour was found. Alternatively, periods with constant elongation rate (α) changed with steps at which α increased abruptly. Several successive shifts were observed until finally at a hyphal length of about 25 μm a constant maximum α of about 22 μm h−1 was attained.The length of the periods during which α remained constant did not depend on either the hyphal type or the order of the period. On an average, a single period lasted 46.8 minutes.The lengths of the hyphae, at the time when α increased, corresponded for the first germ tubes to successively about 2,4,8 and 16 unit cells. With branches and second germ tubes these lengths corresponded to 4 and 10 unit cells.Concerning increase of α during each step the quotients were in the range between 1.3 and 2.0. Branches and second germ tubes started with twice the rate observed with first germ tubes and thus reached the maximum α after a reduced number of steps. Calculations indicated, that on principle α of each linear period was determined by the number of unit cells (nucleoids) present at its beginning.
A simple method of distinguishing the bacterial viruses T3 and T7, and a critical reevaluation of their heterologous and homologous exclusion
Authors: Krüger D. H. , Mann W. , Hansen S. , Bläsing G. , Bläsing M. , Schroeder C. 
Published: February 2007

AbstractA method is presented allowing a clear distinction between bacterial viruses T3 and T7 by plating on selectively permissive host cells. The indicator strains are Escherichia coli cells containing either cloned pif genes (exclusively permissive for T3) or the EcoRV DNA restriction system (permissive only for T7): The efficiencies of plating of the two phages on these hosts differ by more than 8 orders of magnitude. This method was applied to reinvestigate the controversial question of mutual exclusion between T3 and T7. Under single‐burst conditions, about 50% of coinfected cells (permissive for both viruses) produced T3 and T7 progeny while about 25% reproduced only T3 and about 25% only T7. The burst size of co‐infected cells was slightly reduced, compared to controls infected with only one virus type. Homologous exclusion among T3 phages was also not seen; rather, there was a gene dosage effect: T3‐encoded RNA polymerase activity as well as T3‐specific RNA synthesis increased proportionally to the multiplicity of infection (2.5–20 plaque‐forming units/cell).
Energy conservation in whole cells of the acidophilic methylo‐trophic bacterium Acetobacter methanolicus sp. MB 70
Authors: Loffhagen N. , Babel W. 
Published: February 2007

AbstractHitherto, lower growth yields were found with acidophilic methylotrophic bacteria, than those found with neutrophilic methylotrophic ones. Since differences with respect to the oxidative phosphorylation might be responsible for this phenomenon, P/0 quotients were determined for the oxidation by Acetobacter methanolicus sp. MB 70 of endogenous substrates, methanol and other substrates. P/0 quotients for endogenous substrates were calculated from the formation of “energy‐rich” phosphate bonds and the concomitant oxygen uptake on transition of the cells from anaerobiosis to aerobiosis in the range between 0.07 to 0.17 nmol P/nmol 0. P/0 quotients for methanol between 0.1 to 0.25 were determined under aerobic conditions by intracellular energization. For this purpose, the energy charge was decreased to values lower than 0.5 by changing the extracellular pH from 4.0 to 7.0, and increased again to values from 0.7 to nearly 1.0, by adding methanol. The addition of FCCP and DCCD2) totally prevented the increase of the ATP concentration. The energization of the same cell preparation produced similar P/0 quotients for methanol, ethanol and glucose. But in a certain cell preparation, the P/0 quotient for glucose (0.01) was considerably lower than that for methanol (0.18); this was the only quotient reduced from 0.12 to 0.05 by aerating the former cell preparation for 4 h. The results are discussed in terms of the coupling of dehydrogenase reactions, for endogenous and exogenous substrates, to the cytochromes of the respiratory chain. Its composition and structure before cytochrome c appears to be responsible for the fact that the growth yields of these bacteria are smaller than expected for such a type of methylotrophs.
Purification and analysis of DNA‐binding proteins from Streptomyces hygroscopicus
Authors: Sarfert Eva , Zimmer Christoph , Gumpert Johannes , Störl Joachim 
Published: February 2007

AbstractPurification by DNA‐cellulose chromatography of acid‐soluble DNA‐binding proteins (ASB) from Streptomyces hygroscopicus is described. Two main fractions, ASBII and ASBIII, containing different major protein components were isolated. The dominating protein of ASBIII (19 kd) could be enriched on Streptomyces DNA‐cellulose.DNA‐binding properties of ASBIII were studied by using a filter retention assay, thermal melting, and by following the DNA template activity in the RNA polymerase system of E. coli. Binding to supercoiled and linear pBR322 DNA occurred effectively at 0.05 M NaCl while increasing salt concentrations up to 0.15 M and 0.2 M NaCl caused dissociation of the complexes. Single‐stranded DNA showed a slightly lower affinity for the ASBIII protein. ASBIII blocked the DNA template activity of the RNA polymerase reaction in vitro. The binding properties and role of ASB‐proteins are discussed with respect to their possible influence on the chromosomal state of the DNA.
The molecular genetics of copper resistance in Saccharomyces cerevisiae — a paradigm for non‐conventional yeasts
Authors: Fogel Seymour , Welch Juliet W. , Maloney Daniel H. 
Published: February 2007

AbstractAfter a short introduction on the historical background of the development of Saccharomyces cerevisiae as a model eukaryote, a review is given on the present state of genetics and molecular biology of copper resistance in S. cerevisiae. The gene CUP1 encodes a protein (copper metallothionein) of a molecular weight of 6570 dalton. The synthesis of this copper chelatin is induced by copper and is regulated at the level of transcription.Copper resistance (CUPr) is correlated with amplification of CUP1 and resulted in a higher copy number of this gene on chromosome VIII. Spontaneous meiotic alterations of the gene copy number have been studied.
Towards diacetyl‐less brewers' yeast. Influence of ilv2 and ilv5 mutations
Authors: Gjermansen Claes , Nilsson‐Tillgren Torsten , Petersen Jens G. Litske , Kielland‐Brandt Morten C. , Sigsgaard Poul , Holmberg Steen 
Published: February 2007

AbstractDuring alcoholic fermentations, the off‐flavour compound diacetyl is formed non‐enzymatically from acetolactate leaking out from the cells. Acetolactate is an intermediate in the biosynthesis of valine. In beer fermentation, the amount of diacetyl is reduced to acceptable levels during maturation. A reduction of the time needed for maturation may be achieved by the use of a brewing yeast that produces less diacetyl.Saccharomyces cerevisiae laboratory strains with an inactive ilv2 gene can not form acetolactate, while ilv5 strains, blocked in the subsequent step, leak acetolactate in high amounts.Induction of recessive mutations in production strains of Saccharomyces carlsbergensis has not yet been achieved, as the yeast is polyploid and possibly a hybrid between S. cerevisiae and another Saccharomyces species. Thus, all chromosomes investigated so far are present in at least two genetically different versions. Genetic and molecular analysis has shown that the brewing yeast is structurally heterozygous for ILV2 and ILV5.Genetic modification of brewers' yeast to reduce diacetyl formation is being carried out by mutation of ILV2. Deletion mutations in both ILV2 alleles have been constructed in vitro to be used for gene replacement in the brewing strain. In addition, partial inactivation of the ILV2 function is carried out by selecting spontaneous dominant mutations resistant to the herbicide sulfometuron methyl. Among these mutants some produce only half the amount of diacetyl compared to the parental strain.An alternative way to reduce diacetyl production might be to increase the activity of the ILV5 gene product. Model experiments in S. cerevisiae show that the presence of the ILV5 gene on a 2‐micron based multi‐copy vector can reduce the diacetyl production by half.
Mating in the alkane‐utilizing yeast Yarrowia lipolytica
Authors: Weber H. , Kurischko Cornelia , Barth G. 
Published: February 2007

AbstractMating in Yarrowia lipolytica can be induced by mixing cells of both complementary mating types (A and B) in yeast extract‐malt‐medium. By means of an inbreeding programme, strains with significantly improved mating frequencies were selected. The main events of the mating process, that have been detected so far, by means of cytological methods, are: formation of mating tubes, cell contact, cell fusion and karyogamy. During the process of conjugation, mating tubes of different lengths as and shapes are formed between haploid parental cells. Under special conditions the preformation of mating tubes was observed. Mating in the dimorphic yeast Y. lipolytica has been shown to be a distant mating and to occur between cells of a different shape and size. Cells involved in conjugation are no changed morphologically, except for the formation of special copulation structures. Several events of mating and the morphology of zygotes are different than those in the case of baker's yeasts. It is supposed that there is in this yeast also an action of diffusible factors that trigger mating.
OFAGE banding patterns of different yeast genera and of intergeneric hybrids
Authors: Zimmermann M. , Hoffmann‐Hintz M. , Kolvenbach M. , Emeis C. C. 
Published: February 2007

AbstractElectrophoretic karyotypes of yeasts belonging to the species Saccharomyces cerevisiae, Kluyveromyces marxianus and Candida macedoniensis were established by means of OFAGE. Hybrids between S. cerevisiae and K. marxianus as well as between K. marxianus and C. macedoniensis were analyzed by comparing their OFAGE‐banding‐pattern with the parental banding‐patterns. Thus, evidence for exchanges of intact chromosomes and for chromosomal rearrangements could be gained on a molecular level.
Purification and properties of a glycoprotein acid phosphatase from the yeast form of Yarrowia lipolytica
Authors: López M. Carmen , Domínguez Angel 
Published: February 2007

AbstractAn acid phosphatase from derepressed cells of the yeast form of Yarrowia lipolytica was purified 176‐fold by ammonium sulfate precipitation, chromatography on DEAE‐Sephacel and gel filtration in Biogel A 5‐M. The enzyme is a glycoprotein with a sugar content of 60%. The MICHAELIS constant of the enzyme is 5.5 × 10−4 M for p‐nitrophenyl phosphate as substrate; the isoelectric point estimated by electrofocusing is around 4.6 and the optimum pH is 6.2. Phosphatase activity was destroyed by exposure of the enzyme to 40 °C for 30 min or at pH 3 for 30 min. The purified enzyme shows size heterogeneity within a linear concentration gradient of polyacrylamide (4–20%) which indicates an apparent molecular weight in the range of 90,000–200,000 in the presence of sodium dodecyl sulfate. The heterogeneity of the enzyme is due to its carbohydrate content, as can be demonstrated by gel filtration and by treatment with endoglycosidase H. The carbohydrate‐depleted protein has a molecular weight of 60,000. Aminoacid analysis revealed a high content of aspartic acid, serine, threonine, glycine and alanine. Antibodies against the protein moiety show cross reactivity with the acid phosphatase of Saccharomyces cerevisiae.