bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microbial transformation of isoprenoid systems by means of fungi of Zoophthora genus — Microbial transformation of compounds with α‐campholenic system by means of fungus Zoophthora (Neopandora) sp.
Authors: Zabża Andrzej , Greb‐Markiewicz Beata , Sodano Guido , De Riccardis Francesco 
Published: February 2007

AbstractUnsaturated ketones (4 and 10) and epoxides (2–3 and 8–9) were the main products of biotransformation performed by means of Zoophthora (Neopandora) phyllobii. Enantiospecificity of both reactions leading to these compounds strongly depends on the distance of reacting fragment of molecule from the chiral center at C‐1′.
Effect of medium components and metabolic inhibitors on β‐galactosidase production and secretion by Penicillium notatum 1
Authors: Fiedurek J. , Gromada A. , Jamroz J. 
Published: February 2007

AbstractFactors affecting the β‐galactosidase production by Penicillium notatum 1 were studied using fermentation media of different chemical composition. The medium containing lactose, salts, peptone and yeast extract with intitial pH 2.5 was selected as the best for enzyme production. Monobasic ammonium phosphate (0.9%) was found to be the best inorganic nitrogen source for lactase production. Various extraction media and metabolic inhibitors were examined for effective releasing of β‐galactosidase from the fungal cells. Using a simple method of mycelium extraction with 0.1 Triton X‐100, it was possible to obtain about 4‐fold higher amounts of enzyme in the cell free extracts, than those excreted into the post‐culture liquid.
Biological and molecular characterisation of potential biocontrol strains of Trichoderma
Authors: Turóczi György , Fekete Csaba , Kerényi Zoltán , Nagy Richárd , Pomázi Andrea , Hornok László 
Published: February 2007

AbstractThirty‐four strains of seven species of Trichoderma isolated from various fungal sources were compared for direct mycoparasitic activity (MPA), chitinase production and antibiotic activity (ANA) in order to choose the most appropriate partners for a strain‐breeding programme. Within species genetic differences were also assesses in T. hamatum, T. harzianum and T. viride by means of random amplification of polymorphic DNA (RAPD). Endochitinase activities of the Trichoderma strains ranged between 20.4 and 1264.5 units/g dry weight of mycelium. The correlation between MPA and chitinase activity was not unambiguous and no correlation existed between MPA and ANA. The RAPD patterns of T. viride strains were highly variable, while isolates of T. harzianum proved to be more uniform; T. hamatum revealed remarkable intraspecific divergence. All these three comprised certain pairs of strains that are promising participants of a strain‐improving programme, since their strong genetic affinities offer good changes for combining their contrasted biocontrol traits.
Bacillus subtilis α‐amylase, lichenase, β‐mannanase and xylanase: Screening for their induction by agro‐industrial byproducts and precipitation by organic solvents
Authors: El‐Helow Ehab R. , El‐Gazaerly Magda A. 
Published: February 2007

AbstractCurrent research focuses on the utilization of low value agro‐industrial byproducts for targeting B. subtilis towards different exoenyzeme lines. This includes α‐amylase, β‐mannanase, xylanase, and lichenase. As an orientation step, growth and α‐amylase activity were monitored in three different nutritional media. A medium which showed low levels of catabolite repression and spore development was selected as a basal fermentation medium. Different patterns of exoenzyme induction were obtained when beet pulp, corn cob, rice husk, wheat bran, and wheat straw were separately used to partially replace the nutrient contents of the selected medium. α‐Amylase and lichenase were maximally expressed in the presence of corn cob or beet pulp. On the other hand, considerable levels of the four polysaccharide hydrolyzing enzymes were induced by wheat bran. β‐mannanase and xylanase expression responded more significantly towards inducers than α‐amylase and lichenase. The effects of five different organic solvents as precipitative agents on these exoenzymes were also studied.
Characterization and chillproofing activity of two enzymes from Streptomyces species
Authors: Etok C. A. , Eka O. U. 
Published: February 2007

AbstractTwo enzymes, amylase and protease of Streptomyces species were purified by a combination of ion exchange chromatography and gel filtration and characterized. The amylase had an exoaction on starch yielding maltose as a major end product and was identified as β‐amylase. The purified amylase had a molecular weight of 48,000 and was maximally active at 35 °C and at pH 6.0. On the other hand, protease had a molecular weight of 21,000 and was most active at pH 10.0 and at a temperature of 30 °C. The Km or MICHAELIS constant of amylase for maize starch was 0.333 mg/ml while that of protease for casein was 2.5 mg/ml. The feasibility of using the purified protease for various industrial application especially in the chillproofing of beer is discussed.
Investigations on the cell volumes of Azotobacter vinelandii by scanning electron microscopy
Authors: Efuet Ekem T. , Pulakat Lakshmidevi , Gavini Narasaiah 
Published: February 2007

AbstractPrevious experiments by other investigators on the DNA content of Azotobacter vinelandii have demonstrated that the DNA content in these cells is several folds higher than that of E. coli. On the basis of this observation, it was hypothesized that A. vinelandii has at least 40 to 80 identical chromosomes per cell. However, the gene dosage analysis in A. vinelandii cells suggested that many genetic operations can be performed in these cells without the constraints expected in a polyploid bacterium. In an attempt to explain this apparent discrepancy, we have done systematic analysis of the relationship between the DNA content and the cell volume of this bacterium. Since a linear correlation is observed between the DNA content and the cell size in many other cell types, we hypothesized that if A. vinelandii is polyploid in nature, it should have a much larger cell volume to accommodate such a large amount of DNA. Our scanning electron microscopic analysis revealed that the cell volume of the vegetative cells of A. vinelandii is about 16 times larger than the cell volume of E. coli. This result is apparently consistent with the concept that the A. vinelandii is a polyploid bacterium. It was also reported that the encysted cells of A. vinelandii contain about 25% of the DNA content of the vegetative cells. This would mean that an encysted cell of A. vinelandii could contain about 10 copies of its chromosome. Since the estimated molecular weight of A. vinelandii chromosome is very similar to that of E. coli chromosome, the DNA content of the encysted cells also should be about 10 times higher than that of E. coli cells. If we assume that the relationship between the DNA content and the cell size is linear, then the encysted cells should have a cell volume larger than that of E. coli and smaller than that of the vegetative cells of A. vinelandii. However our scanning electron microscopic analysis showed that the cell volume of the encysted cells of A. vinelandii is in fact very similar to the cell volume of E. coli.
Properties of lysophospholipase in Mycobacterium leprae
Authors: Prabhakaran K. , Harris E. B. , Randhawa B. 
Published: February 2007

AbstractLysophospholipids are key intermediates in the metabolism of phospholipids. Cytoplasmic membranes of both eukaryotes and prokaryotes are made of phospholipid bilayers. Phospholipases are activated during phagocytosis. Lysophospholipids generated by phospholipase A2 or A1 degrade cell membranes and can cause cell lysis. An active lysophospholipase, that hydrolyzes lysophospholipids, was detected by the radioisotope technique in Mycobacterium leprae. About two‐thirds of the enzyme was particulate and one‐third cytoplasmic. Optimum activity was at 37 °C, and at pH 6.0. Temperatures above 70 °C completely inactivated the enzyme. The compound AACOCF3, a trifluromethylketone analog of arachiodonic acid, inhibited the activity; the inhibition appeared to be of the uncompetetive type. The Km of the enzyme was 2.5 × 10−4 M, suggesting a fairly strong affinity for the substrate. Lysophospholipids have been shown to be microbicidal to invading organisms. Possession of lysophospholipase by M. leprae is apparently one of the methods by which the bacilli overcome the defense mechanisms of the host.
Permeability of mycobacterial cell envelopes to sterols: Peptidoglycan as the diffusion barrier
Authors: Lisowska Katarzyna , Korycka Małgorzata , Hadław‐Klimaszewska Olga , Ziółkowski Andrzej , Sedlaczek Leon 
Published: February 2007

AbstractVancomycin, an inhibitor of peptidoglycan synthesis, depressed the growth of Mycobacterium sp. NRRL B 3805 and MB 3683, but not the β‐sitosterol side chain degradation and androstane derivatives accumulation. As a result, the specific activity (products formed/cell weight unit × h) increased threefold in the peptidoglycan‐deficient cells, indicating faster crossing of the sterol through the cell water barrier.Cell wall preparations: crude cell wall (CCW), purified cell wall (PCW), and peptidoglycan — enriched PCW — residue (PEPCW) were obtained and analysed in order to find a relationship between the vancomycin — induced chemical changes and the permeation rate of the sterol.The amounts of CCW, PCW and PEPCW, produced from 8 g lyophilised control cells were 445, 170 and 28 mg respectively. The respective figures were 176, 61, and 4.8 mg for vancomycin — treated cells. In addition to the lower content of the rigid layer, a distinct shift in the molar ratios of the peptidoglycan constituents: alanine, glutamic, diaminopimelic and muramic acids, and glucosamine was observed under the action of the murein inhibitor. The most significant change was that of muramic acid: diaminopimelic acid molar ratio, the compounds which are markers of glycan strands and tetrapeptides, respectively. In control cells it was approximately 1:1, and increased to 1.34–1.43: 1 in the compared preparation, which indicated a marked decrease in the tetrapeptide moieties crosslinking the main glycan strands. Together with the general lower content of murein, this modification may be responsible for the enhanced sterol permeation through the cell wall.
Regulation of L‐lysine biosynthesis in prototrophic revertants of Corynebacterium glutamicum
Authors: Hilliger Matthias , Hertel Waltraud 
Published: February 2007

AbstractThe regulation pattern of L‐lysine biosynthesis has been investigated in protrophic revertant derived from an initially homoserine‐auxotrophic strain of Corynebacterium glutamicum and, additionally, in antimetabolite‐resitant mutants. The influence of regulatory important amino acids of the aspartate family on growth and L‐lysine biosynthesis and especially on the activity of aspartate kinase was studied. Furthermore the activity of homoserine dehydrogenase in dependence on the growth phase was estimated.From a total number of ninety nine L‐lysine forming, homoserine‐prototrophic, and S‐(2‐aminoethyl)‐L‐cysteine‐resistant (AEC) strains the best lysine producers were selected by an emerse cultivation assay as a preselection. Strain No. 132 forming 10 g · 1−1 lysine was selected for the derivation of α‐amino‐β‐hydroxyvaleric acid (AHV)‐ and lysine‐resistant strains. From 121 double resistant mutants (hse−rev, AECr, AHVr) sixty two strains (=51.2%) were isolated producing lysine. The best producer, strain 132‐IV‐37, reached 19.8 g · 1−1 after 8 optimization steps of the growth medium in comparison to 9.2 g · 1−1 as the initial value. This higher potential for lysine synthesis in the mutant 132‐IV‐37 could be attributed to changed regulation of the homoserine dehydrogenase and aspartate kinase.As was shown by the action of threonine or threonine + lysine on the activity of aspartate kinase, a general desensibilization of this key enzyme exists in the mutant strain 132‐IV‐37, but not in the AEC‐resistant parent strain. In addition to isoleucine none of several amino acids tested showed any significant influence on the aspartate kinase. This agrees with the increased lysine formation by this strain in comparison to the parent strain 132.
Location of xylanolytic enzymes in Chaetomium globosum
Authors: Gandhi Jagruti P. , Rao K. Koteshwara 
Published: February 2007

AbstractLocalisation of endo β‐1‐4‐xylan xylanohydrolase and β‐xylosidase was studied in Chaetomium globosum when the fungus was grown on 1% (w/v) birchwood xylan. Although both enzymes are present in the soluble fraction of the cell, xylanase activity was membrane bound whereas β‐xylosidase activity was associated with the cell wall. Xylanase and β‐xylosidase acted synergistically on the xylan backbone with the appearance of xylo‐oligosaccharides, xylobiose and xylose.
Characterization of cellulase complex of Streptomyces albaduncus
Authors: Harchand R. K. , Singh S. 
Published: February 2007

AbstractExoglucanase and endoglucanase (glucanases) enzymes of S. albaduncus were found to be very stable, showing only 36% and 8% loss in activities respectively after 3 days of incubation at 50 °C. In contrast, β‐glucosidase was significantly less stable retaining only 22.30% activity after 30 min incubation at 40 °C. The glucanases manifested maximum stability in pH range of 5.5–6.0 whereas β‐glucosidase was completely stable over a broad pH range of 6.5–9.0. Both glucanases were enhanced by some cations whereas β‐glucosidase did not require any cation for activity. Km values for crude exoglucanase, endoglucanase and β‐glucosidase were 40.00 mg/ml, 92.30 mg/ml and 1.714 mM with maximum reaction velocities (Vmax) of 0.606, 33.330 and 0.109 IU/mg of protein, respectively. The enzymes were subject to end‐product inhibition, with exo‐ and endo‐glucanases decreasing by 20% and 70% respectively, in the presence of 0.3% glucose. However, β‐glucosidase showed marked resistance to glucose inhibition, retaining 59% of residual activity even in the presence of 30% glucose in the reaction mixture. This characteristic may be advantageous in the commercial exploitation of enzyme system. An activation of β‐glucosidase at lower concentrations of glucose suggests competitive inhibition.
Chemicals and heat generate different protein patterns in Acinetobacter calcoaceticus
Authors: Benndorf Dirk , Loffhagen Norbert , Babel Wolfgang 
Published: February 2007

AbstractThe effect of exposing Acinetobacter calcoaceticus 69‐V to DNP1‐stress and heat shock was examined by two‐dimensional gel electrophoresis of proteins, which were detected either by autoradiography or by silver staining. Both DNP stress and heat shock led to altered patterns of protein synthesis or concentration. About 10% of the proteins which were synthesized newly or at an increased rate and about 25% of those which were found newly or with an increased concentration after DNP treatment were identified after heat shock, too.
Production of nisin‐like bacteriocins by Lactococcus lactis strains isolated from vegetables
Authors: Franz C. M. A. P. , Du Toit M. , von Holy A. , Schillinger U. , Holzapfel W. H. 
Published: February 2007

AbstractFour bacteriocin producing lactic acid bacteria isolated from vegetables were identified as Lactococcus lactis strains on the basis of physiological and biochemical characteristics, carbohydrate fermentation patterns and analysis of total soluble protein pattern by SDS PAGE. The bacteriocins had a wide spectrum of activity as antagonism was detected not only towards a variety of lactic acid bacteria, but also to Staphylococcus aureus and Listeria monocytogenes. These bacteriocins were resistant to heating at 121 °C for 15 minutes and showed highest activity at low pH (<5.0). They were inactivated by the proteolytic enzymes α‐chymotrypsin and proteinase K, but not by lipase, α‐amylase, catalase or lysozyme. These bacteriocinogenic Lactococcus strains were all immune to the bacteriocins produced as well as to commerical nisin. Bacteriocin producer culture supernatants showed a high degree (70 or 100%) of cross‐reactivity in the nisin ELISA, suggesting similarity of the produced bacteriocins to nisin. The potential application of bacteriocin producing lactococci of vegetable origin for safety assurance of vegetable foods and controlling vegetable fermentations is discussed.
The role of pigments in the assembly of photosynthetic complexes in Rhodobacter capsulatus
Authors: Brand Matthias , Drews Gerhart 
Published: February 2007

AbstractMutants of Rhodobacter capsulatus, blocked at different steps of bacteriochlorophyll a (BChl) synthesis between protoporphyrin IX and 2‐hydroxyethyl bacteriochlorophyllide a, were induced to synthesize the photosynthetic apparatus by lowering of oxygen tension in dark cultures. The cells were pulse‐labeled with [35S]methionine and the radioactivity chased after dilution of [35S]. The specific radioactivity in the pigment‐binding proteins of light‐harvesting and reaction center proteins of the wild‐type strain was not lowered during the chase period of three hours but in the BChl‐free mutants the label disappeared within five to thirty minutes. The polypeptides were inserted into the membrane but did not remain stably incorporated. In the mutant strain NK9 the synthesis of the carotenoid spheroidenone/spheroidene was inhibited by insertion of Tn5 in the crtI gene (phytoene desaturase), which blocked completely the formation of the light‐harvesting (LH) complex II (B800–850) but not of the LHI (B870) complex. In this mutant the polypeptides of the LH complexes were synthesized in a lower amount than in the wild‐type cells and were inserted into the membrane. The LHIIα poly‐peptide disappeared after 60 min of chase while the LHIIβ was more stable. It was concluded that the pigments are not only necessary for absorption of photons and efficient transfer of excitation energy but have a structural role by stabilizing the oligomeric LH complexes. This is in accordance with the crystal structure data of LHII complexes.
Trehalases from spores and vegetative cells of yeast Saccharomyces cerevisiae
Authors: Wolska‐Mitaszko Barbara 
Published: February 2007

AbstractTrehalase (THA) activity from S. cerevisiae spores and vegetative cells could be differentiated in cell‐free extracts. THA from the vegetative cells has an optimal activity at neutral pH whereas biphase pH optimum in the spores was observed. The enzyme from the spores exhibited higher thermostability than that from the vegetative cells. The presence of magnesium ions was necessary mainly for THA activity from the vegetative cells. The effect of the other metal ions studied: Hg2+, Ag2+, Cu2+, Fe3+, Ni2+, Cd2+ etc. (Table II), on THA from both sources was almost the same, however, the spores THA was resistant to Pb2+ and especially to Zn2+. Moreover, the influence of inorganic polyphosphates and polyamines was also quite dissimilar. Polyphosphates inhibited THA from the vegetative cells and to a smaller extent from the spores. On the other hand, polyamines stimulated highly THA activity from vegetative yeast cells in contrast to spores one. The effect of these ions modulators would facilitate differentiating of THA activity in the cell‐free extracts from both sources. These data could be interpreted as phenotypic reflections of trehalase genes expression in the S. cerevisiae cells.
Thermostable, salt‐tolerant α‐amylase from Bacillus sp. MD 124
Authors: Jana M. , Pati B. 
Published: February 2007

AbstractA bacterial strain (MD 124) isolated from municipal garbage and identified as Bacillus sp. was found to be capable of producing salt tolerant and thermostable α‐amylase. Rhamnose and peptone were found to be the best carbon and nitrogen source for the production of enzyme. The pH and temperature optima for the enzyme activity were found to be at 6 and 90 °C. Seventy five per cent enzyme activity was retained in 5 M NaCl over 24 hrs.
Isolation and screening for alkaline thermostable xylanases
Authors: Subramaniyan S. , Prema P. , Ramakrishna S. V. 
Published: February 2007

AbstractScreening of xylanase producing microorganisms from soil samples and hemicellulosic materials were carried out in three stages using wheat bran extract agar medium, xylan agar medium and liquid medium with xylan. One of the isolates, identified as Bacillus SSP‐34 produced 100 times more xylanase activity than the other isolates. Maximum enzyme production by this isolate was observed after 102 hours of growth. The optimum pH for the crude xylanase preparation range from 6–8 and optimum temperature was at 50 °C. The enzyme was stable up to 20 minutes at 50 °C and at pH range 4.5–9.0 for more than 2 hours.
Arctic Oscillation and ice severity in the Bohai Sea, East Asia
Authors: Gong Dao‐Yi , Kim Seong‐Joong , Ho Chang‐Hoi 
Published: February 2007

AbstractThe Bohai Sea is the southernmost sea in the Northern Hemisphere where seasonal freezing takes place in winter. Climate and ice conditions there are very sensitive to large‐scale climatic variations. In the present study, the authors investigated the relationships of ice severity in the Bohai Sea to the planetary Arctic Oscillation (AO) during the period 1954/55–2001/02. It has been found that during low‐AO winters the regional mean temperature around the Bohai Sea is evidently lower, and the number of freezing days, freezing degree days and the length of freezing duration all change significantly. Daily temperature distribution shows a significant difference in both mean and variance between high‐AO and low‐AO phases, and the changes in the temperature means dominate over that of the variance in the context of sea ice severity. The temperature‐AO relation is well supported by the corresponding features of the large‐scale atmospheric circulation system. AO‐related changes in the Siberian High and East Asian Trough cause remarkable changes to the thermal conditions at the surface and to the dynamical conditions in the middle troposphere, consequently affecting the air temperature over the Bohai Sea and ice severity. The AO‐sea ice severity relation has been generally stationary over time during the last one hundred years. Analysis of cross‐power coherency between the AO and ice indices for the last century shows that the highest and significant covariance stands at periods of about 2.1, 3, and 7.5–14 years. The Bohai Sea ice severity has declined rapidly since the 1970s, which is unprecedented since 1880, and this feature is in agreement with the positively upward trend in the AO and the associated changes in the Siberian sea level pressure, East Asian Trough, and the regional temperature. Copyright © 2007 Royal Meteorological Society
Synoptic climatology of the Western United States in relation to climatic fluctuations during the twentieth century
Authors: Barry R. G. , Kiladis G. , Bradley R. S. 
Published: February 2007

AbstractAn objectively derived catalogue of daily pressure patterns for 1899‐1974 has been prepared for the western United States. The temperature and precipitation characteristics of the major types are described and a more detailed analysis for Colorado in extreme cold and warm months shows that the sign of the anomalies for each type is generally consistent with expectation based on the probable airflow patterns. A regression analysis of type frequencies versus temperature and precipitation anomalies for 1899‐1970 at stations east and west of the Continental Divide in the Rocky Mountain states shows that useful explanation of variance is obtained only for temperatures in the transition seasons and for precipitation west of the Divide in winter and east of the Divide in spring. Within‐type variability of the climatic characteristics is one source of the discrepancy. The results underline the problems encountered in trying to link climatic anomalies with atmospheric circulation characteristics.