bluuebunny/crossref_metadata_2025 huggingface dataset:
The fungal flora of post‐harvest grains of Sorghum guineense Stapf and their importance in pathogenicity
Authors: Ogundero V. W.
Published: February 2007

The mycoflora of air‐dried grains of Sorghum guineense and their importance in pathogenicity were studied. Nine species of both phytopathogens and saprophytic storage fungi were consistently obtained. The pathogenic fungi included Cladosporium vignae Gardner, Macrophomina phaseolina (Tassi) Goid and Helminthosporium turcicum Pass., While the saprophytes were mostly species of Aspergillus particularly A. flavus Link, A. fumigatus Fres. and A. niger van Thieghen. Pathogenicity tests showed C. vignae, M. phaseolina and H. turcicum to be seed‐borne pathogens of Sorghum guineense and gave symptoms ranging from leafblight to brown spot diseases of the leaves. The ability of the pathogens to produce cell wall‐degrading enzymes in vitro was studied while the fungi were shown to grow well at a wide temperature range of 20°–30 °C.
Saprophytic fungi and the deterioration of malting grains of Sorghum guineense Stapf
Authors: Ogundero V. W.
Published: February 2007

The ability of Humicola insolens Cooney & Emerson and Aspergillus fumigatus Fres. to cause biochemical changes in the components of milled Sorghum guineense grains and the factors necessary for these activities were studied. Significant losses (at p = <0.01) in the cellulose, hemicellulose, diastase and ethanol soluble fractions of the malted grains were recorded on inoculation with asexual spores of A. fumigatus and H. insolens and 21 days of incubation at 35 °C and 45 °C, respectively. This was accompanied by a corresponding rise in the total nitrogen components of the medium with period of incubation. None of the microbes was able to degrade the lignin components of the malted grains. While A. fumigatus was most active on the grains at 35 °C and pH 6.2, H. insolens grew best at 45 °C and pH 5.4.

When both fungi were grown on varying sources of carbon and nitrogen good results were obtained on most of them with optimal growth recorded on starch and dextrin and the organic nitrogen sources l‐asparagine, l‐glutamic acid and l‐alanine. Both fungi also produced extracelluearly amylase, cellulases, pectate lyase, xylanase, protease, lipase, DNase and RNase. The potential health risks which the presence of these fungi on malted Sorghum grains pose to the consumers of the end products are discussed.
Effect of methyl viologen and oxygen concentration on thermophilic bacteria
Authors: Allgood G. S. , Perry J. J.
Published: February 2007

The level of superoxide dismutase, catalase, and peroxidase was determined in obligately thermophilic bacteria after growth either in the presence of methyl viologen (paraquat) or exposed to an increased atmospheric oxygen concentration. In general, the superoxide dismutase lever in these organisms was not altered by paraquat addition and had a varied response to oxygenation. Incorporation of paraquat in the growth medium resulted in minimally three‐fold higher levels of catalase. The peroxidase level varied as a response to oxygen stress whereas cellular catalase levels were generally higher.
Zur Heptoseregion der Lipopolysaccharide von Pasteurella multocida
Authors: Erler W. , Feist H. , Jacob Brigitte , Schade W.
Published: February 2007

The heptose region of the lipopolysaccharides (LPS) of Pasteurella multocida consists of the trisaccharide l Hep 1 → 2 l Hep 1 → 3 L Hep or l Hep 1 → 3 l Hep 1 → 2 l Hep. This trisaccharide and the oligosaccharide consisting of 3 moles heptose and 1 mole glucose were isolated from the LPS of the strain D 33. The data suggest that the LPS biosynthesis of P. multocida is different from that of Salmonella spp.
Purification and some properties of threonine dehydratase from Candida maltosa
Authors: Bode R. , Schult I. , Birnbaum D.
Published: February 2007

Threonine dehydratase has been purified about 200‐fold from extracts of Candida maltosa by chromatography on DEAE‐cellulose, Sephadex G‐200, and hydroxylapatite. The enzyme is fairly stable in solution in the presence of 250 mM phosphate buffer containing 40% glycerol. The molecular weight of the native enzyme was calculated to be approximately 190,000. The molecular weight of a subunit of the enzyme was estimated to be 46,000 by SDS gel electrophoresis. The enzyme seemed to have a tetrameric structure consisting of four identical subunits. The enzyme is subject to feedback inhibition by isoleucine and is stimulated by valine and phosphate ions. Kinetic studies indicate that there are more than one binding site for each effector on the enzyme. It is concluded from these investigations that the binding sites for threonine as well as for isoleucine are distinct from another, whereas the binding sites for valine and phosphate are identical or closely overlapping.
ARS‐Aktivität von Kinetoplasten‐DNA in Hefezellen
Authors: Gütter H.‐P. R. , Maslow D. A. , Kolesnikow A. A. , Börner Th.
Published: February 2007

Different fragments of the maxicircle of the kinetoplast DNA (kpDNA) from Crithidia oncopelti were cloned (Fig. 1, 2) and tested for ARS‐activity (ARS, autonomously replicating sequences). ARS‐avitivity was expressed as number of transformed yeast cells per μg plasmid DNA, as number of transformed cells per number of plasmid molecules (transformation efficiency, TE) and as number of transformed cells per kilobasepair of cloned kpDNA (specific transformation efficiency, TE8) (Fig. 3. Table 1). All DNA fragments studied showed ARS‐activity. Large fragments exhibited higher ARS‐activities than their smaller subfragments. The number of fragments showing ARS activity and their distribution within the maxicircles (Fig. 4) suggest that there was no strong correlation between sites with ARS‐activity and the replication origin of kpDNA.
Interaction of anthracycline antibiotics with biopolymers: Comparative studies of DNA binding and antimicrobial activity of rhodomycin‐type anthracycline antibiotics
Authors: Stutter E. , Walter Axel , Fleck Werner F.
Published: February 2007

The binding of the anthracyclines β‐rhodomycin‐I and β‐rhodomycin‐II to calf thymus DNA was investigated by both equilibrium and kinetic methods taking into account ligand dimerization (ionic strengthI= 0.2 M, pH 6.0). The analysis was based upon a cooperative single‐step binding mechanism with overlapping of potential binding sites on a linear homogeneous lattice. Equilibrium binding parameters were estimated from spectrophotometric titration experiments by means of a nonlinear fitting program. The results were compared with those obtained previously for the related antibiotic iremycin and were complemented by kinetic parameters determined from temperature‐jump experiments at high binding ratio.

The binding constants and the mean attachment times of the drugs were found to increase in the serial order iremycin, β‐rhodomycin‐I and β‐rhodomycin‐II, which is in line with their increasing antimicrobial activity onBacillus subtilisATCC 6633.
Tubular cytoskeletal elements in sporangia and zoospores of Phythophthora infestans (MONT.) DE BARY (Oomycetes, Pythiaceae)
Authors: Jelke E. , Oertel B. , Böhm K. J. , Unger E.
Published: February 2007

Sporangia and zoospores of the oomycete Phytophthora infestans are characterized by a number of tubular cytoskeletal elements: Single and bundled cytoplasmic microtubules, arising from electron dense material at the centrioles, form a network inside the zoospores of the fungus. Nucleus‐associated microtubules surround the nucleus in a basket‐like manner. Spindle microtubules occurring during mitosis in zoosporangia are partially maintained from the late telophase till the zoospore stage. The pattern of flagellar microtubules is identical to that of the typical eukaryotic flagella. The bundles of 15 nm‐tubules observed in ER‐cisternae of zoosporangia and zoospores are similar to preformed mastigonemes of tinsel flagella because of their dimensions. Microtubules, flagellar fragments, and mastigonemes, similar in substructure to those of other lower and higher eukaryotes, have been isolated from zoospores of Phytophthora infestans by lysis in Triton X‐100 on microtubule‐stabilizing conditions.
Differences in enzyme activities of Lipomyces starkeyi between cells accumulating lipid and proliferating cells
Authors: Naganuma T. , Uzuka Y. , Tanaka K. , Iizuka H.
Published: February 2007

Differences in intracellular enzyme activities between cells accumulating lipid and proliferating cells were studied with Lipomyces starkeyi, a fat‐producing yeast. When the cells were removed from a medium for lipid accumulation to a medium for cell proliferation, activities of several enzymes on the glycolytic pathway, pentosephosphate cycle, glycerol 3‐phosphate pathway, tricarboxylic acid cycle and fatty‐acid biosynthesis pathway changed. In the proliferating cells, activities of glycerol‐3‐phosphate dehydrogenase (GDH) and ATP citrate lyase were very low, as compared to those in the cells accumulating lipids. Activities of these two enzymes and 6‐phosphogluconate dehydrogenase, particularly GDH, decreased with the addition of zinc ion to the cell‐free extract of the cells accumulating lipid.
Physiologischer Untersuchungen zur Bildung von Hitzeschockproteinen in Bacillus subtilis
Authors: Hecker M. , Richter A.
Published: February 2007

The protein synthesis pattern was investiged in Bacillus subtilis relA after heat shock. Cells of B. subtilis relA can produce heat shock proteins at 44 °C, 48 °C, 50 °C and 52 °C. At 52 °C growth processes are inhibited because the synthesis of vegetative proteins is dramatically restricted. Under these conditions a relatively pronounced synthesis of heat shock protins can be detected (see RICHTER and EHCKRE 1986 for B. subtilis relA+).

When cells were exposed to hgh temperature for longer poids before puls‐labelling, the increased synthesis rate of several heat shock proteins is maintained but otehr heat shock proteins are synthesized with a reduced intensity. After a temperature‐shift down the accelerated rate of heat shock protein synthesis is drastically reduced imemdiately after the shift.

The function of heat shock proteins wil be discussed from a physiological point of view.
Influence of culture conditions on mycelial structure and polygalacturonase synthesis of Aspergillus niger
Authors: Hermersdörfer H. , Leuchtenberger A. , Wardsack Ch. , Ruttloff H.
Published: February 2007

Biosynthesis of polygalacturonase (PG) by A. niger strain R 1/214 correlates with the morphology of mycelium in submerged culture. The mean specific PG‐synthesis (PG‐U · g−1 · h−1) increases with the degree of compactness of mycelium. PG‐production can be optimized by a precise adjustment of the culture conditions after direct spore inoculation (diffuse mycelium) but the high synthesis as by compact mycelium is never obtained. Different reasons for the higher enzyme production by the pellet mycelium are discussed. PG‐synthesis is assumed to be strictly connected with a limitation of nutrient and oxygen supply.
Studies of the influence of nicotinamide on the development of heat resistance in Bacillus cereus T
Authors: Kalita D. K. , Singh R. P.
Published: February 2007

Effects of nicotinamide (NA) on the development of heat resistance and sporulation in Bacillus cereus T were studied. It was observed that NA produces more than 95% heat labile spores (80°C for 30 min). The growth and the utilization of poly‐β‐hydroxybutyrate (PHB) is not affected. The heat labile spores were morphologically comparable to untreated spores but the levels of spore specific proteins and dipicolinic acid (DPA) were only 15–20% of the maximum. NA‐treated spores germinate poorly ( 10%) and a storage of 2 months at 4°C causes complete loss of germination characteristics. However, the exogenous addition of DPA or l‐kynurenine completely reverses all effects indicating a possible involvement of L‐tryptophan metabolism in the development of heat resistance.
Glycerol production by Dunaliella bioculata
Authors: Ahmed A. M. , Zidan M. A.
Published: February 2007

Dunaliella bioculata, a marine unicellular euryhaline green alga, accumulated interacellular glycerol as a response to increaed osmolality due to increased concentrations of NaCl, KCl or sucrose, but not ethylene glycol. A decrease in salinity, below the normal, of the outer medium resulted in a decrease in the intracellular glycerol. Glycerol was retained (NaCl salinization) or released (KCl salinization) by the alga. Glycerol production slightly depended on photosynthesis since it took place in the light and in the dark.
Amikacin‐acetyltransferase (AAC‐6′/I) encoded by an IncH2 plasmid (pIE866) in Escherichia coli strains
Authors: Voigt Wolfgang , Tschäpe Helmut , Heier Horst
Published: February 2007

An amikacin resistance plasmid was detected in E. coli wild type strains isolated from polluted surface water. This conjugative 145 Md plasmid belongs to the IncH2 group and specifies amino‐glycoside‐acetyltransferase AAC‐6′/I activity.
Growth response of Calothrix marchica LEMM var. intermedia RAO to exogenous organic substrates and distillery effluent in the light and dark
Authors: Adhikary S. P.
Published: February 2007

Calothrix marchica LEMM. var. intermedia RAO has been found to grow abundantly in soil receiving the effluent of a molasses distillery. The effluent at low concentrations (1–10%, v/v) and at neutral pH increased the growth of the organism. The cyanobacterium grew photoheterotrophically as well as chemoheterotrophically in the medium supplemented with sucrose and lower concentration (10%, v/v) of neutralized distillery effluent. The exogenous carbon sources were also utilized probably in certain specific biosynthetic process, for example, in the synthesis of sheath layer around the trichome of the cyanobacterium. Formation of sheath was not observed in the medium with mannose, pentoses and organic acids which did not support the heterotrophic growth.
Strain selection in Kluyveromyces marxianus var. lactis for galactose production
Authors: Marin M.‐Hélène , Boze Hélène , Moulin G. , Galzy P.
Published: February 2007

After treatment with ethy1‐methane sulfonate (EMS) mutants of Kluyveromyces marxianus var, lactis altered in galactose metabolism were obtained which were further imporoved by genetic recombination. Six types of mutants were detected. In batch culture strains with double mutations — either in galactokinase and uridyltransferase, or in galactokinase and epimerase‐ and which also had a galactose permease transformed lactose to galactose and galactitol. Strains with the same double mutations but no galactose permease completely hydrolyzed lactose to galactose and galactitol under continuous culture.
An antibiotic‐overproducing mutant of Streptomyces granaticolor with impaired differentiation
Authors: Šťastná Jana , Blumauerová Margita , Janda Ivan , Ludvík Jiří , Čáslavská Jana
Published: February 2007

A thy− tetracycline‐resistant mutant of Streptomyces granaticolor was prepared by mutagenesis of the parental strain ETH 7437. The mutant exhibits a different morphology and an overproduction of granaticins. The ability to form an aerial mycelium and spores has been lost. The mutant cells have a round or an atypical shape and a thick cell wall, the membraneous system is enlarged by numerous mesosomes. Division septa are formed rarely. The mutant is more sensitive to both low and high temperature than the parental strain. The altered features are stably maintained for many generations. Ribosomal proteins of the mutant do not differ substantially from those of the original strain indicating that the mutant phenotype is not due to an alteration at the translational level.
The tricarboxy acid cycle in Acetobacter methanolicus
Authors: Müller‐Kraft Gabriele , Babel W.
Published: February 2007

The acidophilic methylotrophic Acetobacter methanolicus MB 58 possesses a complete set of TCA cycle enzymes. As in neutrophilic methylotrophs, during growth on C1‐compounds the cycle in acidophilic methylotrophs does not work to yield energy. This is also true for chemoheterotrophic growth of Acetobacter methanolicus. However, in the non‐methylotrophic Acetobacter pasteurianus when grown on glycerol, the citric acid cycle seems to operate to yield energy.
Bistable growth pattern of Streptomycetes during continuous cultivation in chemostat
Authors: Noack D.
Published: February 2007

Streptomycetes continuously cultivated in a chemostat exhibit a bistable growth pattern characterized by two different growth behaviours, a “disperse” one and a “pellet” one. There exists a distinct range of growth rates within which either growth behaviour can be exerted. The transition between them can be induced by shifting the growth rate above or below critical values by manipulating the dilution rate. Both of them are stable over the same range of growth rates provided that the changing of growth rate within this stability range proceeds successively in moderate steps. This bistable growth pattern is exerted at least by two different species, Streptomyces noursei and Streptomyces “lividans”.
The effects of some protein‐modifying reagents on the interaction of colicins A, E2, E3 and K with their respective Escherichia coli cell receptors
Authors: Šmarda J. , Macholán L.
Published: February 2007

Colicins attach themselves — through specific protein‐protein interactions — onto receptors in the outer membrane of sensitive bacterial cells. An attempt was made to analyze amino‐acid groups and attractive forces involved in this interaction, following treatment of either colicins A, E2, E3 and K or sensitive bacteria with various physico‐chemical factors and several protein‐modifying reagents. The amounts of colicin bound were checked by a quantitative biological assay.

Ionic conditions and specific spatial conformation of both colicin and its receptor molecules are crucial in their interaction and, hence, in the biological effect of colicin.

Formaldehyde, naphthalene‐diisocyanate and osmium tetroxide strongly inhibit the binding ability of all colicins tested. The results suggest that NH2 and SH groups are involved in their binding onto receptors; also, CH3S groups seem to be engaged in the attachment of colicins E2 and E3 and phenol‐OH groups in that of colicin K. The possible involvement of further groups (NH, SH etc.) should be checked using more specific reagents. The attitude of colicins E2 and E3 to their common receptor BtuB protein is nearly, but not completely the same.

Receptors for all colicins tested should be oxidized to achieve optimal interactions; obviously, carbonyl groups are produced and newly formed anions increase the negative load of bacterial surface. In agreement, reduction of at least colicins A and E3 enhances their receptor binding reactivity. The binding capacity of each receptor can be modulated by a set of amino acid reagents in a specific manner.
Biosynthesis of anthracyclinones
Authors: Eckardt K. , Wagner Ch.
Published: February 2007

Recent biosynthetic studies confirmed that anthraquinones are involved as intermediates in the pathway to anthracyclines. The present knowledge in this field has been reviewed. Furthermore, a new generalized order of biosynthetic intermediates from the hypothetical polyketide to aklavinone and related anthracyclinones has been proposed involving tricyclic precursors and 7‐hydroxy‐naphthacenequinones, which also have been found in mutants of anthracycline‐producing strains.
The production of lipases by some Candida and Yarrowia yeasts
Authors: Novotný Čenék , Doležalová Ludmila , Musil Petr , Novák Miroslav
Published: February 2007

The activities of the free and the cell‐bound lipases of Candida rugosa, Candida guilliermondii, Candida curvata, Candida deformans and Yarrowia lipolytica that had been grown on a complex medium with various carbon and nitrogen sources were examined. The highest activities were observed with citrate and succinate as the carbon sources. In some cases olive oil was used as the efficient inducer of the cell‐bound lipases.

The cells grown in the presence of the organic nitrogen sources (peptone, urea, soy flour) exhibited higher lipase levels than those cultivated in the medium containing ammonium as the nitrogen source. The extracellular enzyme was detected only in cultures grown with urea, peptone or soy flour as the nitrogen source.
Interaction of bacteriophage 1P with the cell surface components of Rhizobium trifolii 24SM
Authors: Zając Elżbieta
Published: February 2007

Phage 1P is a BRADLEY C type with an octahedron head 52 nm in diameter and a short tail 10.2 nm long. The process of phage adsorption in to the host cells has been studied. At first, virions attached themselves to the host exopolysaccharide (EPS) capsule, with subsequent penetration through the capsular layer towards the cell wall. Isolated EPS preparation, composed mainly of mannose, galactose and glucose did not neutralize the phages. The rate of attachment of phage 1P to the mucoid strain R. trifolii 24SM and to its nonmucoid, morphologically rough mutants, 24AR and 24R, is the same. The cell wall of R. trifolii 24SM contains lipopolysaccharide (LPS) receptors, which bind phage particles irreversibly. Purified LPS showed a PhI50 value of 0.05 μg ml−1. One particle of phase 1P is neutralized by 5 × 10−16 g of LPS.
Effect of some photosynthesis‐inhibiting herbicides on growth and nitrogenase activity of a new isolate of cyanobacteria, Nostoc G3
Authors: Gadkari Dilip
Published: February 2007

The effect of the photosynthesis‐inhibiting herbicides Goltix, Sencor, Tycor, Arelon, DCMU, paraquat and atrazine on growth and nitrogenase activity of a new isolate of cyanobacteria, Nostoc G3 was studied. Nostoc G 3 was cultivated under N2‐fixing photoautotrophic conditions. The used herbicide concentrations were in the range or recommended field rates. In the presence of Goltix (50 mg/l and 100mg/l), Arelon (15 mg/l und 30 mg/l), paraquat (10 mg/l and 20 mg/l) and DCMU (1 μM) the growth and nitrogenase activity of Nostoc G3 was almost completely inhibited. The most severe inhibitory effect was observed in the presence of paraquat. Even 1 h treatment of 1 mg/l paraquat caused a total inhibition of growth for 4 weeks. In contrast, the herbicides Sencor (10 mg/l and 20 mg/l) and Tycor (10 mg/l and 50 mg/l) did not cause inhibition of growth and nitrogenase activity. In the presence of atrazine (1 mg/l and 2 mg/l) the nitrogenase activity and the growth were partially inhibited. The results obtained in this study show that cyanobacteria occurring in natural environments are resistant against some of the photosynthesis‐inhibiting herbicides.
Influence of cations on the viability of Halobacterium mediter‐ranei cells
Authors: Muriana F. J. G. , Rodulfo J. D. , Alvarez‐Ossorio M. C. , Relimpio A. M.
Published: February 2007

The effects of monovalent and divalent cations on the cell viability of an extremely halophilic bacteria H. mediterranei were examined. High magnesium concentrations (≧72 mM) were required for stabilization of H. mediterranei cells, although calcium ions were more potent than magnesium in preserving viability. On the other hand, H. mediterranei cells are also able to survive in the presence of monovalent cations, such as ammonium and potassium, at least 14 days. The implications for maintaining stability and neutrality of several cell envelope components by monovalent and divalent cations are discussed.
Bioconversion of Egyptian lignocelluloses by microbial treatment, using Streptomyces viridosporus added to highly reactive polymeric acidified lignin
Authors: Adeeb Zenat , El‐Gammal Amira
Published: February 2007

Streptomyces viridosporus degraded lignin and lignocellulose, producing low molecular weight phenolic compounds for potential industrial use.

The main portion of lignin in the residues was released into the growth medium as a water soluble modified polymer. The polymer, an acid precipitable polyphenolic lignin (APPL), was recovered from spent culture media by an acid precipitation, and was shown to be mostly free of non‐lignin components, as compared to native lignin. Elemental and functional group analysis showed that APPL contained a higher hydrogen and oxygen content, lower carbon and also lower methoxyl group and higher phenolic content, than native lignin. From IR spectra, an absorption peak at 1,720 cm−1 appeared in the infrared spectra of APPL. The ratio of the absorbance at 1,720 cm−1 to the absorbance at 1.630 cm−1 increased, due to higher levels of carbonyl and carboxyl groups.
Assimilatory reduction of nitrate in Rhizobium meliloti
Authors: Sekiguchi Satoshi , Maruyama Yoshiharu
Published: February 2007

Nitrate and nitrite reductases in the crude extract of aerobically grown Rhizobium meliloti were determined with methylviologen as electron donor at pH 7. Nitrate reductase was detected in the cells grown in the medium that did not contain nitrate, and in the presence of nitrate the specific activity increased about 2‐fold.

Nitrite reductase was induced by nitrate and produced ammonia from nitrite.

In nitrate reducing cells, two kinds of O2 labile nitrate reductase were found. One enzyme had optimal pH at 7 and was stabilized to O2 by treating with DEAE‐Toyopearl 650M. The other had optimal pH at 9 and was stabilized by the addition of dithiothreitol and EDTA.

Nitrate reductase stabilized by DEAE‐Toyopearl 650M treatment was purified 3,360‐fold from crude extract. The purified enzyme showed a single protein band in polyacrylamide gel electrophoresis, and there was no absorption peak in the visible region. It had a molecular weight of 64,000 in SDS PAGE and 58,000 on Sephadex G‐100 gel filtration. Km for nitrate was 0.9 mM. It was inhibited by p‐chloromercuribenzoate, cyanide, and α,α'‐dipyridyl.
Factor C, a regulatory protein of Streptomyces griseus induces release of potassium from the mycelium
Authors: Szeszák F. , Vitális S. , Szabó G.
Published: February 2007

External potassium concentration was measured in suspensions of washed living mycelia of Streptomyces strains. An active uptake of K+ by the mycelium was observed from the medium at proper aeration and stirring.

The endogenous regulatory protein factor C. in very low concentrations (down to 0.7 ng ml−1), induced in a specific way the release of K+. Changes in the electrolyte composition of the medium had moderate effect on the factor C induced K+ release. Factor C proved to be active in nine different Streptomyces strains. Only S. griseus 45H, the producer of factor C, did not respond. Response to factor C was not affected by chloramphenicol or actinomycin D. The process followed a “slow kinetics” with 3–10 min latency of K+ release.

It was assumed that the factor C induced K+ release could be the consequence of a more rapid process realized at the level of existing macromolecules.
Inhibition of ornithine carbamoyltransferase from Pseudomonas syringae pv. syringae W50 by phaseolotoxin
Authors: Jahn O. , Sauerstein J. , Reuter G.
Published: February 2007

In contrast to the producer of phaseolotoxin and Orn‐P(O)(NH2)‐NH‐SO3H (PNSOrn), Pseudomonas syringae pv. phaseolicola, which possesses a sensitive and an insensitive type of ornithine carbamoyltransferase (OCT, E.C. 2.1.3.3.), in Pseudomonas syringae pv. syringae W50, an organism which produce neither phaseolotoxin nor PNSOrn, only one typ of OCT could be detected. This enzyme is highly sensitive to phaseolotoxin. This result supports our hypothesis that the existence of an insensitive ornithine carbamoyltransferase is an important prerequisite for the synthesis of phaseolotoxin in P. syringae pv. phaseolicola and that this enzyme does not occur generally in P. syringae spec.
Fungi on the claws of buffalo and cow in Egypt
Authors: Abdel‐Gewad Khyria M.
Published: February 2007

The frequency of occurrence of fungi in 120 claw samples of buffalo and cow from different localities at Assiut governorate was determined.

Thirty‐seven species which belong to twenty genera were collected from the two substrates and the most common genera wereChrysosporium(eleven species ofChrysosporiumwere isolated),AspergillusandScopulariopsis.From the preceding generaChrysosporium sulfureumwas common on cow claws butC. merdariumwas slightly dominant on buffalo claws than on cow claws.Aspergillus flavusandA. nigerwere dominant on buffalo claws, butScopulariopsis brevicauliswas prevalent on cow claws.

Also other dermatophytes were isolated such asTrichophyton terrestre, T. rubrum, Histoplasma capsulatum, Phialophora gougerotiiandMicrosporum distortum.
Mycoflora of anise and fennel seeds in Egypt
Authors: Moharram A. M. , Abdel‐Mallek A. Y. , Abdel‐Hafez A. I. I.
Published: February 2007

Using four medium types (glucose‐, cellulose‐, 50% sucrose‐ and 10% NaCl‐CZAPEK's agar), it was possible to isolate 15 fungal genera, 78 species and 6 varieties. The collective fungal spectrum varied from one medium to another where the highest number of species (57 species/1000 seeds) was obtained on glucose‐ and the lowest (31 species/1000 seeds) on 10% NaCl‐CZAPEK's agar.Aspergillus, Penicilliumand sometimesRhizopusandChaetomiumwere the most common genera on the different medium types. The most common fungal species especially on glucose‐ and cellulose‐CZAPEK's agar were,Aspergillus niger, A. flavus, A. ochraceus, A. fumigatus. A. flavusvar.columnaris, Penicillium chrysogenum, Rhizopus stoloniferandChaetomium globosum.Members ofA. glaucusgroup were more frequently recovered on 10% NaCl‐ and 50% sucrose‐CZAPEK's agar.
Screening of microorganisms for enzyme‐inhibiting activities
Authors: Angelov Theodor , Angelova Blaga , Kourteva Yordanka , Stephanova Liliana , Avramova Tatyana , Peretz Valya , Konova Olga
Published: February 2007

In the course of a screening for extracellular inhibitors of 8 different proteinases 140 actinomycete and 150 mould strains were examined. 130 fungal and 50 actinomycete strains were similarly tested for the production of extracellular inhibitors of dihydrofolate reductase (DHFR) and alkaline phosphatase (APh). Most of the inhibitors found in the culture media of the actinomycete and mould strains were specific against serine proteinases. Inhibitors of DHFR were discovered in the culture media of different actinomycetes and moulds. Inhibiting activities towards APh were found mainly in the fermentation filtrates of the mould strains. The approximate molecular sizes of the active substances were determined by using membrane filtration.
In vitrostudies on long‐term stability of R plasmids inEscherichia coliK12
Authors: Böttcher Ingolf , Stelzer Wolfgang
Published: February 2007

The maintenance and stability in anE. coliK12 host of environmental isolates of R plasmids encoding gentamicin resistance during multiple passages in antibiotic‐free and antibiotic‐containing broth were investigated in regard to the conferred resistance phenotypes and the respectiveEcoRI digestion patterns.

Only two plasmids belonging to theIncM group maintained stable endonuclease digestion patterns over a 15‐month period in both of the media applied. Other members of this group revealed a considerable variability in theirEcoRI digestion patterns, but a stability in their resistance determinants. TwoIncM plasmids and anIncK plasmid exhibited partial resistance loss under nonselective conditions. The complete segregation of resistance determinants fromIncOF plasmids resulted in a stably maintained cryptic core plasmid.
Keratinophilic and saprophytic fungi isolated from students' nails in Egypt
Authors: Abdel‐Hafez A. I. I. , El‐Sharouny H. M. M.
Published: February 2007

In order to determine the presence of dermatophytes and saprophytes in healthy toe and finger nails, 120 students (60 male and 60 female) from preparatory schools at Sohag Governorate (Upper Egypt) were studied. 54 species in addition to 3 varieties belonging to 17 genera were isolated. Six species of true dermatophytes were collected:Microsporum audouiniivar.rivalieri, M. cookei, Trichophyton mentagrophytes, T. simii, T. terrestreandT. verrucosum. Chrysosporium, a well‐known keratinophilic genus, was prevalent and represented by 7 species (C. asperatum, C. indicum, C. keratinophilum, C. luteum, C. pannorum, C. tropicumandChrysosporiumstate ofThielavia sepedonium). The commonest saprophytes in order of frequency were members of the generaAspergillus, Penicillium, Alternaria, Scopulariopsis, Fusarium, Paecilomyces, Chaetomium, Syncephalastrum, Mucor, RhizopusandAcremonium.
Algicidal properties of a bloom‐forming blue‐green alga, Oscillatoria sp.
Authors: Bagchi Suvendra Nath , Palod Archna , Chauhan Vikas Singh
Published: February 2007

An isolate of Oscillatoria from local eutrophic lake exhibits strong growth inhibitory effects, when phototrophically co‐cultured with a green alga and other blue‐green algae, including its natural predecessor. This effect was not observed on selected heterotrophic‐organisms. The characteristic interaction was also demonstrated with culture filtrates and cell‐free extracts, implying this effect to be due to some chemical released from Oscillatlia. From the mid‐log growth phase of the culture, a nonproteinaceous, moderately heat stable, and ether soluble metabolite was extracted by ether extraction. The primary site of the growth inhibitory substance (algicide) action appears to be the photosynthetic oxygen evolution, tested in Anacystis nidutlans. The characteristic algicidal substance may have a role, in nature, in species dominance.
Electroporation and expression of plasmid pBR322 in Klebsiella aerogenes NCTC 418 and plasmid pRK2501 in Pseudomonas putida CYM 318
Authors: Trevors J. T.
Published: February 2007

Klebsiella aerogenes NCTC 418 and Pseudomonas putida CYM 318 were transformed via high‐voltage electroporation with plasmids pBR322 and pRK2501, respectively. The number of transformants obtained was dependent on the applied voltage, capacitance, and cell recovery procedure. For example, 7.87 × 104 transformants/μg DNA were obtained at 2500 V, 25 μF when K. aerogenes cells were electroporated with pBR322 DNA. A lower voltage (1500) and capacitance (3 μF) yielded 2.4 × 103 transformants/μg DNA. P. putida CYM 318 required a 24 h outgrowth period to assist in the recovery of transformants containing pRK2501. Electroporation may be a useful protocol to transform bacterial strains that are not easily transformed by traditional methods.
Ultrastructure of a Bacillus sp. strain KL8 isolated from indoor dust
Authors: Kari Merja , Rönkkö Reijo , Valtonen Anne , Phparinen Heli , Kukkonen Maini , Pöyry Tuija , Nohynek Liisa , Nurmiaho‐Lassila Eeva‐Liisa , Lounatmaa Kari
Published: February 2007

A motile Gram‐positive bacterial strain (KL8) was isolated from indoor dust. It was identified by API‐test50 CHB as a species of Bacillus. This Bacillus sp. strain KL8 was described using different electron microscopic techniques: negative staining, thin sectioning, metal shadowing and freeze‐etching.

An additional surface layer (S‐layer) was the outermost layer of the cell wall of this flagellated bacterium. The hexagonally arranged protein lattice covering the cells had a lattice constant about 9–10 nm, which falls in the same range as that of Bacillus anthracis.
Aktivitäten gluconeogenetischer Enzyme in der Hefe Candida maltosa bei Wachstum auf Glucose und Ethanol
Authors: Hofmann K. H. , Polnisch Elke
Published: February 2007

The activities of fructose‐1,6‐bisphosphatase, malate dehydrogenase and PEP carboxykinase were tested during discontinuous growth of the n‐alkane‐assimilating yeast Candida maltosa on glucose or ethanol.

As expected, the highest activities of the enzymes were measured in the early log phase of growth on ethanol and the lowest in the early log phase of growth on glucose. However, the differences in the activities are much smaller than in Saccharomyces cerevisiae and other yeasts under similar conditions. Therefore, we conclude that catabolite repression does not play an essential role in the control of gluconeogenesis in Candida maltosa.
Anti‐staphylococcal serine proteinase and other serum factors in phagocytosis
Authors: Miedzobrodzki Jacek , Gorka Maria , Wasniowska Alicja , Tadeusiewicz Ryszard , Porwit‐Bobr Zofia
Published: February 2007

The interactions between polymorphonuclear cells (PMN), Staphylococcus saprophyticus cells and rabbit antibodies against Staphylococcus aureus V8 serine proteinase or normal rabbit serum proteins were investigated. The effect of opsonization on phagocystosis due to human peripheral polymorphonuclear cells was measured. The results were as follows: phagocystosis index values were relatively increased after the incubation of PMN cells with anti‐serine proteinase γ‐globulin serum fraction, anti‐serine proteinase IgG, non‐immunized rabbit serum or with complement.
L‐Carnitine metabolization and osmotic stress response in Escherichia coli
Authors: Jung Heinrich , Jung Kirsten , Kleber Hans‐Peter
Published: February 2007

Growth of Escherichia coli 044 K 74 in liquid medium of raised osmotic strength was stimulated by exogenous L‐carnitine, crotonobetaine and γ‐butyrobetaine, respectively. L‐Carnitine was accumulated within the cells in dependence on the salt concentration of the media. Osmotic stress during aerobic or anaerobic growth with glucose triggered the L‐carnitine uptake in E. coli 044 K 74 whereas L‐carnitine uptake by cells of this organism grown anaerobically on glycerol/fumarate was only slightly modified. Synthesis of the enzymes metabolizing L‐carnitine to γ‐butyrobetaine in glycerol/fumarate growing bacteria was found to be completely repressed by high NaCl‐concentrations. Together, these results indicate that most likely the L‐carnitine metabolization sequence does not play a role in osmoregulation in E. coli 044 K 74.
Biosynthesis of homoarginine and ornithine as precursors of the phytoeffector phaseolotoxin by the amidinotransfer from arginine to lysine catalyzed by an amidinotransferase in Pseudomonas syringae pv. phaseolicola
Authors: Márkisch U. , Reuter G.
Published: February 2007

In the phytopathogenic Pseudomonas syringae pv. phaseolicola an amidinotransferase was detected and characterized which catalyzes the amidinotransfer from arginine to lysine producing the phaseolotoxin precursors homoarginine and ornithine. The enzyme was purified 419‐fold by affinity chromatography on homoarginine‐Sepharose. It had an apparent mol. wt. of 200 000 and exhibited MICHAELIS‐MENTEN kinetics with Km 7.7 mM for arginine and Km 4.2 mM for lysine. Ornithine competitively inhibited the enzyme with a Ki of 0.8 mM. During cultivation of the pseudomonad the highest enzyme activity corresponds with the highest production rate of phaseolotoxin. At low toxin production, mutants exhibit a low enzyme activity and vice versa. Only those strains of different pathovarieties which are able to produce phaseolotoxin contain the enzyme. At 30 °C cultivation temperature, the enzyme activity was 50% of that at 18 °C, and toxin production decreased with increasing temperature. When microbes were grown on ribose, their enzyme activity was 60% lower than grown on glucose or glycerol. Toxin production was decreased to about 10% when growing on ribose. Amidinotransferase is considered to be one of the key enzymes of phaseolotoxin biosynthesis.
The effect of non‐ionic surfactants on the SOS‐inducing potency of 4‐nitroquinoline‐1‐oxide in Escherichia coli PQ37
Authors: Raabe Ferdinand , Janz Siegfried , Wolff Gerhard
Published: February 2007

Various non‐ionic surfactants affect the SOS‐inducing potency (SOSIP)1 of the model genotoxin, 4‐nitroquinoline‐1‐oxide, in Escherichia coli PQ37 to varying degrees, as measured by an automated version of the SOS chromotest. While there is little effect on the SOSIP value and other test parameters from Tween 20 and 80 and, with some reservation, Triton X305 and Tyloxapol, over the critical micelle concentration range, the SOSIP value increases in the presence of comparable concentrations of Triton X15, 45 and 100. A possible dependence of the tester strain's β‐galactosidase production and its growth inhibition on the HLB of the non‐ionic surfactants added is discussed.
Purification and properties of a malolactic enzyme from Leuconostoc oenos ATCC 23278
Authors: Naouri Pascal , Chagnaud Patrice , Arnaud Alain , Galzy Pierre
Published: February 2007

The malolactic enzyme of Leuconostoc ocnos ATCC 23278 was purified 136fold. The molecular weight was estimated at 132,000 when determined by gel filtration. The enzyme contained two identical subunits (Mw = 66,000 using sodium dodecyl sulfate gel electrophoresis). The malolactic enzyme catalyzes the NAD+‐ and Mn+‐dependent reaction L‐malate → L‐lactate + CO2. The apparent Km values for malic acid, NAD+, and Mn2+ were 17 mM, 0.044 mM, and 0.017 mM, respectively. The optimal pH and the optimal temperature for activity were 5.0, and 37 °C, respectively and the isoelectric point was pH 4.30. L‐lactate and ethanol were non‐competitive inhibitors, whereas succinate, citrate, and D‐tartrate showed competitive type inhibitions.
Immunochemical and structural analysis of the cell wall mannan as the basis of the taxonomic reidentification of a yeast strain
Authors: Pavliak Viliam , Kogan Grigorij , Sláviková Elena , Andula Jozef Š , Masler Ladislav
Published: February 2007

The immunochemical properties and structural features of D‐mannans from two Candida parapsilosis strains were studied. Weak cross‐reactivity of D‐mannans with antisera produced to C. parapsilosis strains was observed, as well as significant differences in the mannans structures were found by means of methylation analysis, acetolysis and 1H‐NMR spectroscopy. In view of the discrepancies found, new taxonomic identification of one strain was carried out. On the basis of assimilation of potassium nitrate and formation of hat‐shaped spores as well as other differences found by investigation of physiological characteristics, one strain of C. parapsilosis was reidentified as Hansenula anomala. This work demonstrates that immunochemical and structural investigations of cell‐wall polysaccharide components can serve as a basis for taxonomic identification of yeast strains.
Effect of organic soil amendments on the incidence of stalk rot of maize caused by Macrophomina phaseolina and Fusarium moniliforme
Authors: Osunlaja S. O.
Published: February 2007

Five organic materials, Calopogonium sp., rice straw, wood sawdust, fresh guinea grass and poultry manure, were added to soil in a field with a recent history of high stalk rot in maize caused by Macrophomina phaseolina and Fusarium moniliforme. The two stalk rot organisms reacted differently to the organic amendments. All the amendments significantly reduced the incidence of Fusarium stalk rot disease. Amendment of soil with fresh Calopogonium leaves had almost no effect in controlling the incidence of Macrophomina phaseolina. Organic amendment with poultry manure stimulated the disease. The other amendments appeared to be equally effective in checking the disease. Suppression of the disease appeared to be related in increased microbial activities.
Cellular role of DNA polymerase I
Authors: Savic Dragutin J. , Jankovic Mila , Kostic Tatjana
Published: February 2007

Escherichia coli possesses three well‐established DNA polymerases, I, II and III. DNA polymerase I (Pol 1) is the main repair polymerase in E. coli and also has a minor but important role in chromosomal replication. A major advantage of Pol I as an experimental system is its simplicity: unlike other replication enzymes, it is active as a single subunit. To a large extent, mutagenesis appears to be the result of (dis) functions of the DNA replication machinery. It is the purpose of this review to provide an integrated view of this relationship with particular emphasis on the role of Pol I in mutagenic events.
The Rice Yellow Mottle Virus situation in West Africa
Authors: Awoderu V. A.
Published: February 2007

The incidence and severity of the Rice Yellow Mottle Virus (RYMV) was monitored in various rice environments in West Africa. Its presence or absence being determinded through symptomatology and serological tests. RYMV was found in all the rice growing environments at different levels of incidence and severity which appear to be dependent on the type of variety planted, the rice environment and the climatic factors under which the rice is cropped. RYMV has been shown to cause losses ranging from 19.5% to 95.5%. Graminaceous weeds including some wild rices have been confirmed as alternate hosts for RYMV. Twenty five rice cultivars consisting of local and locally developed cultivars showed tolerant reactions to RYMV. Most of these varieties showed stable resistance to rice blast in an earlier study. The manifestation of RYMV symptoms on the uninoculated test rice varieties indicated the possibility of the virus being transmitted either through the virus vector or might be seedborne.
A solid‐phase enzyme immunoassay for the detection of tetanus toxin using human and murine monoclonal antibodies
Authors: Kiessig Stephan T. , Hentschel Christian , Jahn Sigbert , Mehl Michael , Starke Roland , Porstmann Thomas
Published: February 2007

Three human and three murine monoclonal antibodies were tested for their reactivity to tetanus toxin and toxoid and used to establish an enzyme immunoassay specific for tetanus toxin. The dissociation constants of the monoclonal antibodies were between 3.91 × 10−9 and 8.48 × 10−12. Two human monoclonal antibodies recognized conformation determinants on the toxin, whereas the others reacted to the heavy chain. Only a combination of antibodies of the two species allowed the development of an enzyme immunoassay for the detection of tetanus toxin with a lower detection limit of 1.2 μg/l.
Use of α‐aminoadipate and lysine as sole nitrogen source by Schizosacharomyces pombe and selected pathogenic fungi
Authors: Ye Zhi‐Hai , Garrad Richard C. , Winston Melissa K. , Bhattacharjee J. K.
Published: February 2007

α‐Aminodipate, an intermediate of the lysine biosynthetic pathway of fungi, or lysine when used as the sole nitrogen source in the medium was growth inhibitory and toxic to Saccharomyces cerevisiae. The fission yeast Schizosaccharomyces pombe and pathogenic fungi Candida albicans, Filobasidiella neoformans and Aspergillus fumigatus grew in the medium containing α‐aminoadipate as the sole nitrogen source. C. albicans, A. fumigatus, and one of the strains of F. neoformans also grew in the medium containing lysine as the sole nitrogen source. When grown in the α‐aminoadipate medium, only S. pombe accumulated a significant amount of α‐ketoadipate in the culture supernatant. Also, 14C‐α‐aminoadipate was converted to 14C‐α‐ketoadipate in vivo. In the ammonium sulfate medium, S. pombe cells converted 14C‐α‐aminoadipate to lysine. The levels of glutamate‐α‐ketoadipate transaminase, an enzyme responsible for the conversion of α‐aminoadipate to α‐ketoadipate, and α‐aminoadipate reductase, an enzyme required for the conversion of α‐aminoadipate to lysine, were similar in S. pombe cells grown in the α‐aminoadipate or ammonium sulfate medium. However, the level of homoisocitrate dehydrogenase, an enzyme before the α‐ketoadipate step, was twelvefold lower in S. pombe cells grown in the α‐aminoadipate medium compared to the level in cells grown in the ammonium sulfate medium. Pathogenic fungi used in this study did not accumulate α‐ketoadipate and α‐aminoadipate‐δ‐semialdehyde when grown in medium containing α‐aminoadipate and lysine, respectively, as sole nitrogen source. However, only pathogenic fungi used both lysine and α‐aminoadipate as sole nitrogen source. This unique metabolic property could be useful for the identification of these pathogens.
Optimization of nutrient medium for biosynthesis of gibberellic acid
Authors: Brückner B. , Blechschmidt D. , Recknagel R.‐D.
Published: February 2007

A new method of optimization of the medium composition by biostatistical methods is reported. The well‐known Box‐Wilson scheme combined with the method of optimum curves was applied for an exploration of the response surface. The primary goal has been to optimize the concentration of nutrients for the production of gibberellic acid by the fungusGibberella fujikuroiwith a minimum number of experiments. As the result, a nearly fivefold improvement yield of the was achieved performing only two experiments.