bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biochemical studies on sporulation in blue‐green algae. III. Effect of amino acids on glycogen accumulation
Authors: Sarma T. A. , Kanta Swarn 
Published: July 2010

AbstractThe effect of 21 amino acids was studied on glycogen accumulation during sporulation in the blue‐green alga Anabaena sp. All the amino acids enhanced the initial level of glycogen on the 4th day. The maximum amount of glycogen, on the 20th day, was noticed from l‐methionine, l‐tyrosine, glycine, and l‐histidine supplemented cultures. Others like l‐serine, l‐valine, l‐asparagine, dl‐alanine, l‐glutamic acid, l‐phenylalanine, l‐aspartic acid, l‐arginine, and dl‐lysine come next in the order. On the other hand, l‐cysteine and l‐cystine, although upto the 16th day they exhibited higher values of glycogen, did not show much variation in glycogen content over nitrogen‐free medium. Except in these two amino acids, in all others initiation of sporulation occurred on the 4th day, resulting in free spores on the 8th day. But in case of l‐serine, l‐asparagine, l‐isoleucine, and l‐phenylalanine free spores were noticed only on the 12th day while in dl‐lysine they were seen on the 16th day. l‐cysteine and l‐cystine supplemented media showed free spores on the 20th day as in nitrogen‐free control.
Bakterium MB 58, ein methylotrophes „Essigsäurebakterium”︁
Authors: Steudel A. , Miethe D. , Babel W. 
Published: July 2010

AbstractDas stäbchenförmige, gram‐negative und Katalase‐positive Bakterium MB 58 ist fakultativ methylotroph. Es unterscheidet sich z. B. von Acetobacter suboxydans ATCC 621 H, das ebenfalls Methanol assimilieren kann (Hexulosephosphat‐Weg), kaum, weder in der Fähigkeit zur Oxydation verschiedener Substrate (Methanol, Äthanol, Glucose, Acetaldehyd u. a.) noch in den Cytochromprofilen oder im Enzym‐Muster nach Wachstum auf Methanol bzw. Glucose.Beim Wachstum auf Glucose zeigt Bakterium MB 58 wie Gluconobacter oxydans diauxisches Verhalten, was darauf zurückgeführt wird, daß Glucose assimiliert und ein Teil davon gleichzeitig zu Gluconsäure oxydiert wird.Außerdem können Phagen von Bakterium MB 58 verschiedene Acetobacter‐ und Gluconobacter‐Species lysieren, und auch mit Hilfe der Immunofluoreszenz sowie der Objektträgeragglutination läßt sich Bakterium MB 58 von den genannten „Essigsäurebakterien”︁ nicht unterscheiden.Auf Grund dieser Befunde, die auf enge verwandtschaftliche Beziehungen hinweisen, wird vorgeschlagen, Bakterium MB 58 in die Gruppe der „Essigsäurebakterien”︁ einzuordnen.
Geomikrobiologische Untersuchungen XIV. Schwermetall‐Toleranz desulfurizierender Bakterien unter verschiedenen ökologischen Bedingungen
Authors: Brecklinghaus J. , Schwartz W. , Näveke R. 
Published: July 2010

AbstractTolerance and adaptation to heavy metals of Desulfovibrio‐ and Desulfotomaculum‐strains of different origin have been investigated in enrichment cultures under different conditions of sulphate supply. Three groups of low, medium, and high toxicity were found with As, V, and Mo in the first, Ni, Sb, Co, and Hg in the second, and Cd, Zn, U, and Cu in the third group. If the SO4″‐supply was restricted to heavy metal sulphates with a relation of 1:1 of heavy metal‐ and SO4″‐ions (2:3 with Sb2(SO4)3) the tolerance was somewhat lowered. Adaptation to higher concentrations of heavy metals was possible, if the strains had not yet been exposed and adapted to higher concentration levels at their natural habitats. The tolerance range of desulfurizers has been compared with the tolerance range of different biochemical types of microorganisms.
Inhibitor studies of phage T4 wild‐type and mutant DNA polymerases V. A summary of kinetic and inhibition data
Authors: Schroeder Cornella , Jantschak J. 
Published: July 2010

AbstractThe DNA polymerases of phage T4 wild‐type, the mutator mutant L98 and the antimutator mutant CB121 were purified about 100‐fold free of foreign enzyme activities interfering with the polymerase assay. The enzymes were characterized as to thermostability, exonuclease activity and kinetic data with DNA template primer, deoxythymidine 5′‐triphosphate, and a mixture of all four deoxynucleoside 5′‐triphosphates. The effects of eight inhibitors of DNA synthesis on the three enzymes were determined (Schroeder and Jantschak 1978 and 1980, Jantschak and Schroeder 1980) and are compared here. The most selective inhibitor, pyridoxal 5′‐phosphate, interacts with the active site of the polymerases while the two least discriminating drugs, distamycin A and actinomycin D, do not directly interact with the polymerases at all. The study was intended to test whether specific enzyme inhibitors elicit a differential response in temperature‐sensitive structural variants of this enzyme and whether, in principle, structural variants of virus enzymes or the respective ts‐ mutants in vivo are suitable as a screening system for selective antiviral agents.
Dihydroxyacetone kinase of methanol‐assimilating yeasts II. Partial purification and some properties of dihydroxyacetone kinase from Candida methylica
Authors: Hofmann K. H. , Babel W. 
Published: July 2010

AbstractDihydroxyacetone kinase (DHAK) from the cell‐free extract of methanol‐grown Candida methylica was partially purified about 100‐fold by a procedure employing streptomycine sulfate fractionation, ammonium sulfate fractionation, negative absorption on Cibacron blue F3G‐A sephadex G 200 and DEAE‐cellulose column chromatography. The enzyme was stable in 50 mm Tris‐HCl buffer pH 7.5 containing 60% glycerol at –18°C.The pH optimum for the activity of DHAK from C. methylica was 7.5. The purified enzyme phosphorylated dihydroxyacetone four times faster than d,l‐glyceraldehyde. The apparent Michaelis‐Menten constants for dihydroxyacetone and d,l‐glyceraldehyde were 0.011 mm and 0.024 mm. Other C3 compounds including glycerol were not phosphorylated. ITP and UTP were used as phosphate donors with a reaction rate of 11% and 3.1%, respectively, in relation to ATP, whereas the reaction rates of DHAK from C. methylica with CTP or GTP were much lower than 1%. The reaction of DHAK depends upon the presence of divalent cations in the assay. The highest activity was found with Mg2+ ions. The reaction rates with Co2+ or Ca2+ ions were only 57.3% and 30.3%, respectively, in relation to the assay with magnesium ions. Manganese chloride in the assay led to a complete loss of activity.
Microbiological implications of electric field effects II. Inactivation of yeast cells and repair of their cell envelope
Authors: Jacob H.‐E. , Förster W. , Berg H. 
Published: July 2010

AbstractThe inactivation of yeast cells in different growth phases by an electric field pulse was investigated. Cells of Saccharomyces cerevisiae in the logarithmic growth phase were found to be much more sensitive with respect to an electric discharge than those in the stationary phase. The influence of the electric field pulse characteristics on the inactivation as well as possible secondary effects were studied. The polyene antibiotic perhydrohexafungin (PHF) is used as a tool to sense defects in the yeast cell envelope brought about by electric field action. The repair kinetics of these defects was followed after the impulse. At least two repair stages can be distinguished, a fast one in the second range and a slower one which takes place after plating the cells on a nutrient medium. The obtained results are discussed in connection with current theories of reversible dielectric breakdown in biological membrane systems.
Studies on air‐borne fungi at Qena I. Seasonal fluctuations
Authors: Moubasher A. H. , Abdel‐Fattah H. M. , Swelim M. A. 
Published: July 2010

Abstract73 species which belong to 24 genera were collected in 200 and 35 esposures made during the period May 1976–October 1977 at each of two levels (2 m and 20 m).The air‐borne fungi showed seasonal periodicities and the highest incidence was recovered in spring and autumn and the least in summer.Aspergillus was the dominating genus. 17 species were collected at the two levels of which A. niger and A. flavus were the most common.Other common genera were Cladosporium which was represented by C. herbarum, C. cladosporioides, C. sphaerospermum, and C. macrocarpum. 7 species of Curvularia were identified of which C. pallescens was the most frequent at the low and C. spicifera at the high level. Drechslera was represented by 6 species of which D. halodes was the most common at the two levels. Only one Alternaria species, A. alternata was isolated at both levels. 10 Penicillium were recovered, P. notatum was the most frequently one isolated at the two levels.Many fungal spore showers of Cladosporium, Aspergillus, Curvularia, and Alternaria were recorded during the experimental period.
Light‐induced oscillations of the glutamate pool size and of the respiratory oxygen uptake in the blue‐green algaAnacystis nidulans
Authors: Metzler H. 
Published: July 2010

AbstractThe glutamate and glutamine pool contains about 75% of the free amino acids ofAnacystis nidulansharvested from a growing culture. Light pulses induced oscillations of the rate of oxygen uptake and of the size of the glutamate pool under certain physiological conditions. The frequencies of these oscillations were similar. During the oscillation the size of the glutamate pool was transiently reduced to about 50% of the dark level. The pool size of 2‐oxoglutarate did not show similar oscillations. A phase plane plot of the glutamate against the respiration oscillation supported a connection of both oscillations.
Microbial fixation of nitrogen in the presence of lanthanum sulphate
Authors: Ranganayaki S. , Bahadur K. , Mohan C. 
Published: July 2010

AbstractThe effect of lanthanum sulphate on five Azotobacter strains (4A7, 10, 5A2, 5A1, and 3A3) isolated from Allahabad soil consists in a considerable increase in the nitrogen fixation, carbon consumption and in the amount of nitrogen fixed in mg per g of carbon consumed. The presence of 200 μM, 300 μM and 400 μM lanthanum sulphate in culture media increases the fixation of nitrogen by all the nitrogen fixers significantly.
Response of a wild type and a non‐nitrogen‐fixing mutant of Anabaena doliolum towards different amino acids
Authors: Kumar Ashok , Kumar H. D. 
Published: July 2010

AbstractThe effects of various amino acids on growth and heterocyst differentiation have been studied on wild type and a heterocystous, non‐nitrogen‐fixing (het+ nif−) mutant of Anabaena doliolum. Glutamine, arginine and asparagine showed maximum stimulation of growth. Serine, proline and alanine elicited slight stimulation of growth of wild type but failed to show any stimulatory effect on mutant strain. Valine, glutamic acid, iso‐leucine and leucine at a concentration of as low as 0.1 mM were inhibitory to growth of parent type. Methionine, aspartic acid, threonine, cysteine, and tryptophan did not affect growth at concentrations lower than 0.5 mM. But at 1 mM, these amino acids were inhibitory. In addition to the stimulatory effects of glutamine, arginine and asparagine, the heterocyst frequency was also repressed by these amino acids. Glutamine and arginine at 2 mM completely repressed heterocyst differentiation in the mutant strain; however, other amino acids failed to repress the differentiation of heterocysts. Our results suggest that glutamine and arginine are utilized as nitrogen sources. This is strongly supported from the data of growth and heterocyst differentiation of mutant strain, where at least with glutamine there is good growth without heterocyst formation. Studies with glutamine and arginine on other N2‐fixing blue‐green lagae may reveal the regulation of the heterocyst‐nitrogenase sub‐system.
Regulation of ammonia assimilation in ammonia‐limited chemostat cultures of Escherichia coli ML 30: Evidence of bistability
Authors: Müller P. J. , von Frommannshausen Beate , Schütz H. 
Published: July 2010

AbstractIn a preceding paper evidence of two stationary stable states (bistability) in the specific activity of glutamine synthetase (GS) in ammonia‐limited steady‐state cultures of Escherichia coli ML 30 at dilution rates (D) about 0.15 h−1 was described (Müller et al. 1977). For better understanding of the regulation mechanisms leading to GS bistability chemostat experiments were performed over a wide range of dilution rates up to D = 0.8 h−1. For each steady state the specific activities of GS and glutamate dehydrogenase (GDH) – the other key enzyme of the two NH3 assimilation routes in E. coli – and in addition the remaining NH3 concentration in the culture liquid were determined.Parallel to GS bistability two states of GDH activity and NH3 concentration are found. The higher state of GS is connected with a lower GDH activity and NH3 concentration. With rising D the GS activities decrease whereas GDH activities and NH3 concentrations increase.Since no adenylation of the GS is detectable GS bistability seems to be regulated on the level of enzyme synthesis like GDH bistability.From the experimental findings a mathematical model is derived based on the bottle neck enzyme theory of growth. It describes the dependence between the specific growth rates on the one hand and the specific enzyme activities and NH3 concentration on the other. It is shown that the specific uptake rate of the limiting NH3 and the specific growth rates, respectively, depend on the simultaneous action of two bottle neck enzymes which are connected by a regulative link.
A comparison of the toxic effects of 2‐deoxy‐D‐glucose and 2‐deoxy‐2‐fluoro‐D‐hexoses on Saccharomyces cerevisiae cells and protoplasts
Authors: Biely P. , Rjazanova L. P. , Tsiomenko A. B. 
Published: July 2010

AbstractThe toxicity to the cells and protoplasts of Saccharomyces cerevisiae of the sugar analogues modified at carbon 2 increases in the order 2‐deoxy‐D‐glucose (DG), 2‐deoxy‐2‐fluoro‐D‐glucose (FG) and 2‐deoxy‐2‐fluoro‐D‐mannose (FM). The fluorohexoses, similarly as DG, behave generally as analogues of both glucose and mannose, depending on the hexose used as a carbon source in the medium. Relative inhibitions of glucan and mannan synthesis in protoplasts were found to be dependent more on glucose and mannose used as the growth support than on the type of the sugar analogue. Certain degree of structural relationship of fluorohexoses to the corresponding natural hexoses was reflected in their effects on growth of intact cells. Growth on glucose was inhibited most effectively by FM, growth on mannose by FG. The data obtained support the view that the sugar analogues interfere mainly with the glucose‐mannose interconversion catalyzed by hexosephosphateisomerases. A comparison of the effects of fluorohexoses and DG on the synthesis of extracellular invertase and intracellular α‐glucosidase and alkaline phosphatase in protoplasts pointed to the fact that all three sugar analogues tested also participate in metabolic control of enzyme synthesis.
Regulation of steroid 16α‐hydroxylation in Streptomyces olivoviridis
Authors: Dlugoński J. , Sedlaczek L. 
Published: July 2010

AbstractThe steroid 16α‐hydroxylase of Streptomyces olivoviridis was shown to be constitutive, but synthetized only in small amounts in the absence of cortisol. The induction of the enzyme with the steroidal substrate resulted in a distinct increase in the 16α‐hydroxylation rate. This increase in activity, however, could be demonstrated only in later phases of culturing, after the growth of the mycelium was completed. The possible mechanisms controlling the activity of the enzyme during the growth phase of the culture are discussed.
Charakterisierung von Strukturelementen in den Lipopolysacchariden von Pasteurella multocida
Authors: Erlee W. , Feist H. , Flossmann K. D. , Jacob B. , Pilarski A. 
Published: July 2010

AbstractIn the main fraction of oligosaccharides obtained after the acetic acid hydrolysis of the lipopolysaccharides of the strain PM were identified: terminal bound glucose and L‐glycero‐D‐mannoheptose, 1,2‐,1,3,4‐, and 1,3,4,6,‐linked heptose. The oligosaccharide of the strain 1297 S contains terminal linked galactose, 1,4‐ or 1,6‐linked glucose and 1,4‐linked N‐acetylglucosamine additionally. The molar ratios of these elements show the heterogenicity of the preparations. The determined molecular weights underline the R‐character of the LPSIn the by‐fractions of the acetic acid hydrolysis the known mannan and another polysaccharide with galactose and glucosamine were identified.
Propionate formation in Rhodospirillum rubrum under anaerobic dark conditions
Authors: Voelskow H. , Schön G. 
Published: July 2010

AbstractExperiments with 14C labelled propionyl‐CoA, methylmalonyl‐CoA and succinyl‐CoA showed that these compounds are intermediates of propionate synthesis in fermentative metabolism of Rhodospirillum rubrum. The rate of propionate and succinate production is dependent on the CO2 concentration of the medium. There is, however, no evidence for a transcarboxylation, and high concentrations of propionate in the medium did not inhibit propionate synthesis as is the case in propionibacteria. PEP‐carboxykinase (EC 4.1.1.32) and propionyl‐CoA‐carboxylase (EC 6.4.1.3) showed high activities, whereas the other two PEP‐carboxylases (EC 4.1.1.31, EC 4.1.1.38), and the pyruvate‐carboxylase (EC 4.1.1.1.) showed only very low activity. It is probable that in pyruvate fermentation metabolism of R. rubrum no specific enzymes are activated for propionate formation and all enzymes are still present from aerobic or phototrophic preculture.
Effect of sodium molybdate on microbial fixation of nitrogen
Authors: Ranganayaki S. , Mohan Chandra 
Published: July 2010

AbstractThe effect of 0, 100, 200, 300, 400, and 500 μM concentrations of sodium molybdate in the culture media of the five Azotobacter species isolated from Allahabad soil was studied. It was observed that the presence of molybdenum in the culture media of all the bacterial samples increased the fixation of nitrogen indicating that molybdenum is essential for increasing the efficiency of the nitrogen fixers for nitrogen fixation.
Optimierung von Kulturbedingungen für Acinetobacter calcoaceticus beim Wachstum auf n‐Alkanen in einem Laborfermentor
Authors: Fricke B. , Bergmann R. , Sorger H. , Aurich H. 
Published: July 2010

AbstractThe growth conditions for the cultivation of Acinetobacter calcoaceticus in a commercial laboratory fermenter have been optimized. This was done taking former results of shake cultures as a basis. At the end of the logarithmic phase up to 10 g/l dry weight were obtained.The following culture conditions have been used: The medium contained 10 ml/l n‐alkane and 6 g/l NH4Cl. The pH was adjusted to 6.5 and pO2 employed to 70% saturation.A 12 times higher amount of dry weight was observed compared with shake culture technique.
Transformation of 12‐deoxycardenolids with Streptomyces purpurascens
Authors: Albrecht K. , Máté G. , Láng T. 
Published: July 2010

AbstractStreptomyces purpurascens transforms primary and secondary 12‐deoxycardenolids into digoxin, 7β‐hydroxy‐digitoxin and 7β‐hydroxy‐digoxin, respectively. A metabolic pathway is proposed for cardenolid transformations and the enzymes participating in it are investigated. The substrate concentration in the medium can be increased by using a water‐miscible solvent of electron donor character. The newly developed procedure yields 0.5 g/l−1 of digoxin in a five‐day fermentation.
Regulation der PEP‐Carboxylase des fakultativ methylotrophen Acetobacter sp. MB 58
Authors: Loffhagen N. , Babel W. 
Published: July 2010

AbstractAcetobacter sp. MB 58 assimilates methanol via the fructose‐1,6‐bisphosphate variant of the hexulose phosphate pathway. Glyceraldehyde‐3‐phosphate originates as net product of an assimilation loop involving the regeneration of the C1‐acceptor ribulose‐5‐phosphate and must be available for the de novo synthesis of the C1‐acceptor as well as for the oxidative glycolysis.It is made probable in a regulatory model that this is accomplished via alternating anabolic and catabolic phases which are controlled by concerted action of PEP‐carboxylase and pyruvate kinase. Whereas Ac‐CoA is a crucial effector and ä‐ketoglutarate and aspartate are inhibitors for the PEP‐carboxylase, the pyruvate kinase is assumed to be regulated by energy charge.
Charakterisierung eines CaCl2‐abhängigen Transfektionssystems von Escherichia coli und T3‐Phagen‐DNS
Authors: Stompe H. , Michel S. , Mann W. , Richter G. 
Published: July 2010

AbstractTransfection by DNA isolated from bacteriophage T3 was studied using Escherichia coli 921/0 as host. The following conditions were found optimal:Competent E. coli 921/0 were obtained by harvesting the bacteria at the onset of late exponential growth (5 × 108 cells/ml) and treating the latter with 0.05 M CaCl2. Hereafter, the microbes were suspended in 50 mM Tris‐HCl buffer (pH 7.2) and the concentration adjusted to 7 × 109 cells/ml. T3 DNA was added and the suspension kept at 0°C for 15 min. Determination of the number of infectious centers was then carried out in the usual way. The efficiency of transfection under these conditions amounted to 104 p. f. u./μg DNA.Preincubation of competent bacteria with T4 DNA at 0°C before the addition of T3 DNA reduced the number of infectious centers. However, if T3‐ and T4 DNA were added simultaneously no decrease of the transfection efficiency occurred. Calf thymus DNA was without influence on transfection.
Aktivierung von Proteinbiosynthesen in auswachsenden Sporen von Bacillus subtilis
Authors: Wachlin G. , Hecker M. 
Published: July 2010

AbstractThe programme of protein synthesis as an indicator for the control of gene expression was examined during outgrowth of Bacillus subtilis spores. At various stages of outgrowth cells of Bacillus subtilis were labelled with 35S‐L‐methionine. Extracted proteins were separated on two‐dimensional gels according to O'FARRELL (1975). Three groups of proteins were synthesized during outgrowth:

During all stages of outgrowth a great number of “vegetative genes” is expressed. The programme of protein synthesis of the outgrowing cell is very similar to that of a vegetative cell.
Only a few proteins — probably the products of outgrowth‐genes — are synthesized especially in outgrowing spores and turned off at different stages of outgrowth.
The synthesis of a minor group of vegetative proteins is triggered during different stages of outgrowth.
In contrast to earlier assumptions (comp. TORRIANI and LEVINTHAL 1967, HANSEN et al. 1970, GALIZZI et al. 1976) we suggest that only a small portion of the genome is activated during outgrowth as a dependent sequence.These results are discussed on the basis of earlier concepts about the regulation of outgrowth as a developmentally regulated gene expression programme.
Steroid modifications with immobilized biocatalysts — use of immobilized enzyme‐requiring cofactor regeneration and of immobilized mycelium
Authors: Ergan F. , Atrai P. , Dhulster P. , Gellf G. , Kim M. N. , Legoy M. D. , Thomas D. 
Published: July 2010

AbstractTwo biological approaches have been investigated for specific modifications of steroids. The first one uses the purified enzyme for the specific dehydrogenation of androsterone to androstanedione. The enzyme used is 3α‐hydroxysteroid dehydrogenase which requires a cofactor (NAD). A cofactor regeneration is needed so that the process could work continuously. The conjugation of two points (immobilization of the enzyme and optimization of the ratio methanol‐water) allows a continuous work of the enzyme during 25 days. Moreover, we propose a chemical regeneration of the cofactor using methoxy derivative of phenazine methosulphate. Right now it is the limiting step of the process.The second approach of steroid modification uses a whole mycelium of Aspergillus phoenicis for the specific hydroxylation of progesterone to 11α‐hydroxy progesterone. The transformation of 90% of the progesterone is obtained with calcium alginate immobilization and the lowest number of products is obtained at pH lower than 2.5 with carrageenan and polyurethane immobilization.It seems promising to apply immobilized biocatalysts to the bioconversion of hydrophobic compounds in organic solvents system.