Showing papers in "Folia Microbiologica in 1975"
TL;DR: Tritium-labeled 4-deoxy-D-glucose (4-dglc) and 6deoxyd-Dglc were prepared by catalytic hydrogenolysis of the corresponding deoxyiodo derivatives with gaseous tritium as mentioned in this paper.
Abstract: Tritium-labelled 4-deoxy-D-glucose (4-dglc) and 6-deoxy-D-glucose (6-dglc) were prepared by catalytic hydrogenolysis of the corresponding deoxyiodo derivatives with gaseous tritium. The two sugars are transported intoSaccharomyces cerevisiae by both the constitutive glucose and the inducible galactose carrier. Uranyl ions are powerful inhibitors. The pH optimum in uninduced cells lies at 5.5 for both sugars, the apparent activation energies (between 15 and 35°C) are 25.1 kJ/mol and 16.5 kJ/mol, respectively. The steady-state intracellular concentration of both sugars is less than the extracellular one (no uphill transport). Neither of them is a substrate of yeast hexokinase. 4-Deoxy-D-glucose undergoes a dinitrophenol-sensitive conversion to an unknown metabolite which is not phosphorylated and may represent one of its oxidation products.
30 citations
TL;DR: It can be concluded that Pleurotus ostreatus yields a suitable raw material in the food industry and possibly also a fodder based on the basis of solid, cellulose-containing wastes.
Abstract: The balance of nitrogen and nitrogen compounds in Pleurotus ostreatus, cultivated on waste materials, corn straw and maize residues, was investigated. The results show that this organism has a considerable ability to fix atmospheric nitrogen, fixing 312 g of total nitrogen per 100 kg dry weight. When recalculating with respect to a decrease of the substrate during growth of the organism a value of 9.7 mg per 1 g of the decrease in material is obtained. Fruiting bodies, as well as the produced substrate contain 17-19 amino acids. In the produced substrate the content of the protein nitrogen represents only 30% of the total. It can concluded that Pleurotus ostreatus yields a suitable raw material in the food industry and possibly also a fodder based on the basis of solid, cellulose-containing wastes.
28 citations
TL;DR: The differential rate of synthesis of penicillinamidohydrolase was studied in Escherichia coli growing in some chemically defined media and in a complex medium to find the highest rate of the enzyme synthesis is reached in a medium containing phenylacetic acid as the only source of carbon and energy.
Abstract: Synthesis of penicillinamidohydrolase (penicillin acylase, EC 3.5.1.11) inEscherichia coli is subjected to the absolute catabolite repression by glucose and partial repression by acetate. Both types of catabolite repression of synthesis of the enzyme inEscherichia coli are substantially influenced by cyclic 3,′5′-adenosinemonophosphate (cAMP). Growth diauxie in a mixed medium containing glucose and phenylaoetic acid serving as carbon and energy sources is overcome by cAMP. cAMP does not influence the basal rate of the enzyme synthesis (without the inducer). Derepression of synthesis of penicillinamidohydrolasa by cAMP in a medium with glucose and inducer (phenylacetic acid) is associated with utilization of the inducer, due probably to derepression of other enzymes responsible for degradation of phenylacetic acid. Lactate can serve as a “catabolically neutral” source of carbon suitable for the maximum production of penicillinamidohydrolase. The gratuitous induction of the enzyme synthesis in a medium with lactate as the carbon and energy source and with phenylacetic acid is not influenced by cAMP; however, cAMP overcomes completely the absolute catabolite repression of the enzyme synthesis by glucose.
28 citations
TL;DR: The fungi were found to contain a novel form of bound magnesium, a polymeric magnesium orthophosphate (POMg), which appears to take part in the control of free magnesium level in Penicillium chrysogenum Q-176, which is proportional to the growth rate.
Abstract: The content of total, bound and osmotically free magnesium was estimated in various fungi and in the yeastSaccharomyces cerevisiae. Total magnesium increases at lower growth rates ofEndomyces magnussi andPenicillium chrysogenum 140A as well as during the logarithmic stage of growth ofPenicillium chrysogenum Q-176. The binding of magnesium requires orthophosphate, decreasing during lack of external phosphate when the intracellular concentration of free magnesium rises. The fungi were found to contain a novel form of bound magnesium, a polymeric magnesium orthophosphate (POMg), which appears to take part in the control of free magnesium level inPenicillium chrysogenum Q-176. The level of free magnesium is proportional to the growth rate ofEndomyces magnusii andPenicillium chrysogenum Q-176 and 140A. Total, as well as free, magnesium changes less than three-fold as external Mg concentration is changed 13,000-fold. The magnesium up against concentration gradients of 1∶25 to 1∶1300, the metal being distributed non-uniformation the cells ofSaccharomyces cerevisiae.
25 citations
TL;DR: Both the cells and the cell-free extract contained catalase which participated in the oxidation of methanol to formaldehyde; the enzyme was constitutively formed by the yeast.
Abstract: Oxidation of methanol, formaldehyde and formic acid was studied in cells and cell-free extract of the yeast Candida boidinii No 11Bh Methanol oxidase, an enzyme oxidizing methanol to formaldehyde, was formed inducibly after the addition of methanol to yeast cells The oxidation of methanol by cell-free extract was dependent on the presence of oxygen and independent of any addition of nicotine-amide nucleotides Temperature optimum for the oxidation of methanol to formaldehyde was 35 degrees C, pH optimum was 85 The Km for methanol was 08mM The cell-free extract exhibited a broad substrate specificity towards primary alcohols (C1--C6) The activity of methanol oxidase was not inhibited by 1mM KCN, EDTA or monoiodoacetic acid The strongest inhibitory action was exerted by p-chloromercuribenzoate Both the cells and the cell-free extract contained catalase which participated in the oxidation of methanol to formaldehyde; the enzyme was constitutively formed by the yeast The pH optimum for the degradation of H2O2 was in the same range as the optimum for methanol oxidation, viz at 85 Catalase was more resistant to high pH than methanol oxidase The cell-free extract contained also GSH-dependent NAD-formaldehyde dehydrogenase with Km = 029mM and NAD-formate dehydrogenase with Km = 55mM
22 citations
TL;DR: Acyclic polyols (erythritol, xylitol, ribitol, D-arabinitol, mannitol, sorbitol and galactitol) are not metabolized by Saccharomyces cerevisiae and are taken up by a fast non-active process, reaching 402–70% distribution referred to total cell water.
Abstract: Acyclic polyols (erythritol, xylitol, ribitol, D-arabinitol, mannitol, sorbitol and galactitol) are not metabolized by Saccharomyces cerevisiae. They are taken up by a fast non-active process, reaching 40-70% distribution referred to total cell water. The uptake is insensitive to temperature, pH (between 4 and 8), 2,4-dinitrophenol and uranyl ions. Its initial rate rises linearly with concentration from 10(-5)M to 1M. The process resembles simple diffusion through large pores or the trapping of the whole solution on the surface. Protoplasts behave like whole cells in this respect. Only erythritol shows a second type of uptake which is inhibitor-insensitive but temperature-dependent.
22 citations
TL;DR: A proteolytic activity hydrolyzing denatured proteins of Bacillus megaterium labelled with35S or14C amino acids was detected in cells of the asporogenic strain ofBacillus megatium, which is almost completely inhibited by EDTA ando-phenanthroline.
Abstract: A proteolytic activity hydrolyzing denatured proteins ofBacillus megaterium labelled with35S or14C amino acids was detected in cells of the asporogenic strain ofBacillus megaterium. The substrate is hydrolyzed by the enzyme or enzymes at optimum pH around 7, their activity being almost completely inhibited by EDTA ando-phenanthroline. PMSF, the inhibitor of serine proteases, is slightly inhibitory. Gel filtration on a Sephadex column separated the protease activity to two or three fractions.
21 citations
TL;DR: S-sulphocysteine, detected chromatographically and determined quantitatively, originated in large quantities by the reaction of sulphite with cystine in the medium and was produced especially during first phases of growth, where its quantity was higher than that of sulphate and its maximum concentration exceeded 1 mg/ml.
Abstract: The dermatophyte Microsporum gypseum was cultivated in media containing 0.5% cystine in suspension, and 0.05% peptone or 1% glucose and 0.05% peptone. During growth on cystine the excess sulphur was oxidized and excreted into the medium not only in the form of sulphate but also in the form of sulphite. Sulphite was produced especially during first phases of growth, where its quantity was higher than that of sulphate and its maximum concentration exceeded 1 mg/ml. S-sulphocysteine, detected chromatographically and determined quantitatively, originated in large quantities by the reaction of sulphite with cystine in the medium. Both sulphite and S-sulphocysteine were further oxidized to sulphate. After exhaustion of cystine 90-93% of the sulphur present was converted to sulphate in the cultivation medium.
19 citations
TL;DR: The fungal and bacterial flora of the leaf surfaces of five plants growing in Egypt were studied, with Aspergillus and Penicillium being most common and Micrococci most predominant among the epiphytic bacteria.
Abstract: The fungal and bacterial flora of the leaf surfaces of five plants growing in Egypt were studied. The fungal flora showed seasonal fluctuations with at least one peak. Twenty three genera with fifty three species were found, Aspergillus and Penicillium being most common. Other fungi showed variable percentages of the total count. Nitrogen-fixing bacteria were not isolated from the phyllosphere of the five plant species. Micrococci were most predominant among the epiphytic bacteria. Spore-forming bacteria and actinomycetes were less frequent on the leaf surfaces of the associalte plants.
17 citations
TL;DR: Effects of volatile and gaseous metabolites of swelling seeds of pea, bean, wheat, corn, cucumber, tomato, lentil, carrot, red pepper and lettuce on germination of spores of five genera of fungi were found to depend rather on the fungal than on the plant genus.
Abstract: Effects of volatile and gaseous metabolites of swelling seeds of pea, bean, wheat, corn cucumber, tomato, lentil, carrot, red papper and lettuce on germination of spores of five genera of fungi were found to depend rather on the fungal than on the plant genus. Germination of spores of Botrytis cinerea, Mucor racemosus and Trichoderma viride was most severely inhibited. Spores of Verticillium dahliae were less sensitive and germination of spores of Fusarium oxysporum was inhibited only in two cases. On the other hand, exudates of pea and bean stimulated germination of spores of Fusarium oxysporum. Also spores of Trichoderma viride germinated better in an atmosphere enriched with exuded metabolites of swelling lettuce seeds. When carbon dioxide produced by the swelling seeds was absorbed in potassium hydroxide, spores of Trichoderma viride and Verticillium dahliae did not germinate at all, the inhibitory effects of volatile and gaseous exudates on germination of spores of Mucor racemosus were accentuated, and also the percentage of germinated spores of Fusarium oxysporum decreased. Germination of spores of Botrytis cinerea was not influenced. Absorption of volatile and gaseous metabolites in a solution of potassium permanganate decreased in most cases their inhibitory effects, particularly in Botrytis cinerea.
16 citations
TL;DR: Formation of extracellular xylanase was studied in 10 strains of wood-destroying fungi belonging to Basidiomycetes during their submerged cultivation with willow sawdust and the highest enzyme activity was found in the fungus Trametes hirsuta.
Abstract: Formation of extracellular xylanase was studied in 10 strains of wood-destroying fungi belonging toBasidiomycetes during their submerged cultivation with willow sawdust. The highest enzyme activity was found in the fungusTrametes hirsuta (Wulf.) Pilat. The effect of sources of carbon and nitrogen, cultivation time and initial pH of the cultivation solution on the formation of xylanase by the fungusTrametes hirsuta was investigated. The highest production of the enzyme was reached during cultivation in the presence of willow sawdust, asparagine and at the initial pH of 5.0. The presence of xylanase, cellulase, mannanase and amylase as well as of beta-xylosidase, beta-glucosidase, beta-mannosidase and betagalactosidase was demonstrated in the enzyme preparation obtained after a 10-day submerged cultivation ofTrametes hirsuta under optimal conditions.
TL;DR: The protective effect of pig immune colostrum, serum and immunoglobulins IgG, IgM and IgA against the enterotoxic strain of Escherichia coli O55, was studied in newborn germfree piglets, with IgA being most effective.
Abstract: The protective effect of pig immune colostrum, serum and immunoglobulins IgG, IgM and IgA against the enterotoxic strain ofEscherichia coli O55, was studied in newborn germfree piglets. This strain produced accumulation of fluid and dilatation of intestine when injected into the ligated ileal segment of germfree piglets, which is considered to be the typical effect of enterotoxins. Erosion of the intestinal epithelium and penetration of bacteria into the submucosa were also observed. Immune serum, colostrum and all the immunoglobulin classes used produced a local protective effect, IgA being most effective. The mechanism of protection conferred by these immunoglobulins is discussed with respect to the possible pathogenic action of enterotoxicEscherichia coli O55 in the intestinal tract of immunologically virgin germfree piglets.
TL;DR: In this article, the authors studied the differential rate of synthesis of penicillinamidohydrolase (penicillin acylase -- EC 3.5.1.11) in Escherichia coli growing in some chemically defined media and in a complex medium.
Abstract: The differential rate of synthesis of penicillinamidohydrolase (penicillin acylase -- EC 3.5.1.11) was studied in Escherichia coli growing in some chemically defined media and in a complex medium. The enzyme is synthesized at a constant rate only during the exponential phase of growth of cells. Its synthesis is induced most effectively (with respect to quantity) by phenylacetic acid. The induction lag of the enzyme synthesis in a medium with acetate corresponds to two generation times. The highest rate of the enzyme synthesis is reached in a medium containing phenylacetic acid as the only source of carbon and energy. The enzyme synthesis is fully repressed by an increased concentration of dissolved oxygen in the medium, even when Escherichia coli is cultivated in the medium with phenylacetic acid as the only carbon and energy source.
TL;DR: The formation of protoplasts of the fission yeasts after the combined application of snail enzymes and Trichoderma viride enzymes in an osmotic stabilizer was studied by light and electron microscopy and the effect of the enzymes used leads during 30 min to the formation of 100% protoplast population.
Abstract: The formation of protoplasts of the fission yeasts Schizosaccharomyces pombe and Schizosaccharomyces versatilis after the combined application of snail enzymes and Trichoderma viride enzymes in an osmotic stabilizer (0.4M KCl, pH 5.5) was studied by light and electron microscopy. The effect of the enzymes used leads during 30 min to the formation of 100% protoplast population. Using electron microscopy no original walls or wall remnants were detected in the suspension of protoplasts. Protoplasts are viable and in liquid nutrient medium they regenerate cell walls and revert into normal cells. Such a protoplast population may be useful for biochemical study of protoplast metabolism by quantitative methods as well as for the chemical study of regenerating cell walls.
TL;DR: The addition of the antibiotic to a growing colony of Botrytis cinerea induces dichotomic ramification of terminal hyphae and formation of vesicular structures in phytopathogens.
Abstract: Ramihyphin A at subfungistatio concentrations stimulates ramification of hyphae of filamentous fungi. Stimulation of terminal ramification of hyphae that can be observed particularly in phytopathogenic fungi is most frequent. Hyphae ofMicrosporon canis, Trichophyton mentagrophytes, Blastomyces dermatitidis, Coccidioides immitis andHistoplasma capsulatum ramify intensively laterally. Stimulation of the lateral ramification was observed inMonilia fructigena, Penicillium marneffei andPenicillium chrysogenum. The antibiotic induces also formation of vesicular structures in phytopathogens. Due to the substantial ramification of hyphae, both terminal and lateral, the growth of colonies is interrupted. The addition of the antibiotic to a growing colony ofBotrytis cinerea induces dichotomic ramification of terminal hyphae after 3 h of growth. Lateral hyphae begin to grow later and further ramify dichotomically. Dense bundles of ramified hyphae are formed after 24 h due to the unbalanced ramification and the colony no longer increases its size.
TL;DR: Intracellular ricinoleic acid was an indicator of differentiation of the culture towards alkaloid formation and also of alkaloids synthesis in the submerged culture of theClaviceps purpurea strain studied.
Abstract: The submerged culture of theClaviceps purpurea strain studied was polymorphous. In. the process of alkaloid synthesis, cytodifferentiation preceded biochemical differentiation. The onset of the alkaloid phase was characterized by. predominance of chlamydospores in the culture, the presence of vegetative cells with reduced or arrested proliferation, maximum acetylCoA carboxylase activity, the maximum amount of total fatty acids, an over-average cell pool tryptophan level and minimum tryptophan synthetase activity. Intracellular ricinoleic acid was an indicator of differentiation of the culture towards alkaloid formation and also of alkaloid synthesis. The cytodifferentiation period in the initial phases of fermentation, when the cell has several alternative possibilities of development, is regarded as the most sensitive sector of the regulatory mechanisms of alkaloid formation.
TL;DR: Actinomycin D, 5-fluorouracil, cycloheximide, ramihyphin A and partially also sodium iodoacetate inhibit to a different degree the photoinduced formation of conidia.
Abstract: Some antibiotics and synthetic inhibitors affect, in several ways, the life cycle of Neurospora crassa (germination of conidia leads to myceliar growth leads to formation of conidia). Bikaverin, cyanein, scopathricin and phenethyl alcohol retard the germination of conidia, without inhibiting it completely. 5-Fluorouracil, ramihyphin A and zygosporin A (cytochalasin D) do not inhibit the germination. Bikaverin brings about a thickening of the hyphae of growing mycelium. Ramihyphin A, cyanein, scopathricin and zygosporin A stimulate the ramification of hyphae while 5-fluorouracil and phenethyl alcohol do not affect the myceliar morphology apart from their inhibitory effect on growth. Actinomycin D, 5-fluorouracil, cycloheximide, ramihyphin A and partially also sodium iodoacetate inhibit to a different degree the photoinduced formation of conidia. The inhibition by 5-fluorouracil is very conspicuous when the agent is present during the photoinduction but considerably weaker when it is applied 2 h after the photoinduction.
TL;DR: Of the eight species capable of producing gluconic acid, Penicillium puberulum gave the maximum yield and peptone was the best nitrogen source for acid fermentation and glucose was superior to sucrose.
Abstract: Twenty-five Penicillium species isolated from Egyptian soil were examined for their ability to produce gluconic acid in surface culture. Of the eight species capable of producing gluconic acid, Penicillium puberulum gave the maximum yield (91% gluconic acid from glucose after 7 days of fermentation with 3% CaCO3). Peptone was the best nitrogen source for acid fermentation and glucose was superior to sucrose. Addition of low concentrations of KH2PO4 and MgSO4 - 7 H2O stimulated acid production. An initial pH of 6.1 was most favourable for acid accumulation and addition of CaCO3 was necessary for maximum acid production.
TL;DR: During the budding proper the outer layers of the cell wall protrude and the end of the encircling region, together with the adjacent electron-dense layer, acquire their definitive appearance of rings, observed as marked electron-transparent and electron-Dense tears on ultrathin sections.
Abstract: Differentiation of the cell wall of Saccharomyces cerevisiae at the site of the future bud was followed. A lentil-like structure originates on the inner side of the cell wall during the first phase. At the same time, an electron-dense layer occurs at the boundary between the inner layer of the cell wall and the lentil-like structure. During the second phase granular material is accumulated at the lower side of the lentil-like structure. During the third phase the lentil-like structure is split apart due to proliferation of the granular material resulting in formation of the base of the encircling region. The marked electron-dense layer observed from the first phase is attached to the surface of the encircling region during differentiation of the latter. During the budding proper the outer layers of the cell wall protrude and the end of the encircling region, together with the adjacent electron-dense layer, acquire their definitive appearance of rings, observed as marked electron-transparent and electron-dense tears on ultrathin sections.
TL;DR: Colicin E3 has been found to be a specific endoribonuclease, able to cleave a terminal fragment from the 16 S rRNA also in isolated Ribosomesin vitro: not only in ribosomes from sensitivive bacteria, but also in those from resistant ones and from eukaryotic cells.
Abstract: According to the theory of Fredericq (1949) and Nomura (1964), colicins are attached by specific receptor sites in the cell walls of sensitive bacteria, which mediate their inhibitive effects. During last years, a great variety of experimental data have been accumulated, some of which cannot be easily interpreted in terms of this theory. There exist considerable discrepancies concerning the chemical nature and molecular weight of isolated receptors. The attachment of a colicin onto its receptor need not be irreversible. The inhibition of numerous membrane-associated functions in colicin-tolerant mutants suggests their pleiotropic deletion nature. The difference between colicin resistance and colicin tolerance does not seem to be clear-cut. Cells of stable L-forms of protoplast type, completely devoid of their walls, retain in most cases the same patterns of sensitivity to colioins as rods of the same strains. Experimental changes in the relationship between the cell wall and the cytoplasmic membrane decrease colicin sensitivity of the cells. Colicin E3 has been found to be a specific endoribonuclease, able to cleave a terminal fragment from the 16 S rRNA also in isolated ribosomesin vitro: not only in ribosomes from sensitivive bacteria, but also in those from resistant ones and from eukaryotic cells. A destabilization of the DNA helix was induced by colicin E2in vitro asin vivo. It seems that there exist two distinct types of colicin receptors with different functions: those in the cell wall, and those in the cytoplasmic membrane. Only the contact of colicins with the latter ones is biologically effective and starts both stages of their inhibitive effect: the reversible and the irreversible ones.
TL;DR: Experiments aimed at transferring the R factor from strainsEscherichia coli K-12 toMycobacterium phlei were unsuccessful and a further transfer from cultures of the cellsade+ Stmr to cells ade could not be demonstrated.
Abstract: Results obtained when studying conjugation in mycobacteria by means of different methods are summarized. The method of conjugation on surface of a solid complete medium was tested with different auxotrophic mutants of different strains of Mycobacterium smegmatis. It was not possible to obtain positive results even by means of the above method. This was probably due to unsuitability of the chosen strains of Mycobacterium smegmatis. Preparation of the donor strain by transfer of the F factor from Escherichia coli F'ORF 1 ade+ lac+ pro+ to Mycobacterium phlei PA ade Stmr by means of sexduction is described. Frequency of the phenotype PA ade+ Stmr increased in the average by two and a half orders of magnitude with respect to the control, however, a further transfer from cultures of the cells ade+ Stmr to cells ade could not be demonstrated. Experiments aimed at transferring the R factor from strains Escherichia coli K-12 to Mycobacterium phlei were unsuccessful.
TL;DR: The evenly granulated, electron-optically dense content of the cells became clearer in cells affected by the viruses, and fibrillar structures of different thickness and small dense areas appeared in cells assumed to be in the preliminary stages of lysis.
Abstract: Morphology and adsorption of a globular virus, lysingAcholeplasma laidlawii were studied in ultrathin sections of plaques in a lawn of the host strain. The virus was globular, about 50 to 90 nm in diameter, with a clearly defined membrane, 6.5 to 8 nm thick. A protuberance about 25 to 35 nm long and 12 to 20 nm thick was observed on numerous virus particles. The evenly granulated, electron-optically dense content of the cells became clearer in cells affected by the viruses. Fibrillar structures of different thickness and small dense areas appeared in cells assumed to be in the preliminary stages of lysis. The interactions in the virus-host system and possible development stages of the virus are discussed.
TL;DR: It is concluded that glucose transport can be driven by a high-energy state of the membrane or by the membrane potential.
Abstract: A new procedure for the isolation of membrane vesicles fromAcholeplasma laidlawii cells is described. The membrane vesicles are completely free from contaminations of whole cells and cell debris and represent a homogeneous fraction as shown by electron microscopy, Ficoll density-gradient centrifugation, and titration on agar plate. Absence of cytoplasmic contaminations was confirmed by double-labelling of membranes with3H-oleic acid and14C-uridine, as well as by distribution of specific marker enzymes of membranes and cytoplasm. On the basis of light-scattering and electron microscopy, the vesicular nature of these membranes was established. The vesicles had the same orientation as intact cells (absence on membrane vesicles of ATPase and NADH dehydrogenase activities, localized in the inner surface of membrane). The respiratory activity of the membrane vesicles was low and was not stimulated by exogenous substrates, the respiratory chain of the vesicles being reduced and terminated by flavoproteins. The ability of membrane vesicles to take up carbohydrates was shown.
TL;DR: The substrate specificity of the bacterial penicillinamidohydrolase (penicillinacylase, EC 3.5.1.11) from Escherichia coli was determined by measuring initial rates of enzyme hydrolysis of different substrates within zero order kinetics.
Abstract: Substrate specificity of the bacterial penicillinamidohydrolase (penicillinacylase, EC 3.5.1.11) from Escherichia coli was determined by measuring initial rates of enzyme hydrolysis of different substrates within zero order kinetics. Some N-phenylacetyl derivatives of amino acids and amides of phenylacetic acid and phenoxyacetic acid of different substituted amides of these acids or amides, structurally and chemically similar to these compounds, served as substrates. Significant differences in ratios of initial rates of the enzyme hydrolysis of different substrates were found using a toluenized suspension of bacterial cells or a crude enzyme preparation, in spite of the fact that the enzyme is localized between the cell wall and cytoplasmic membrane, in the so-called periplasmic space. N-phenylacetyl derivatives are the most rapidly hydrolyzed substrates. Beta-phenylpropionamide and 4-phenylbutyramide were not utilized as substrates. The substrate specificity of the enzyme is discussed with respect to a possible use of certain colourless compounds as substrates, hydrolysis of which yields chromophor products suitable for a simple and rapid assay of the enzyme activity.
TL;DR: The relationship between the presence of linolenic acid and the ability to form respirationdeficient mutants induced by acriflavin has been established and the metabolic coefficients and the composition of fatty acids in samples metabolizing lactose are presented.
Abstract: The relationship between the presence of linolenic acid and the ability to form respirationdeficient mutants induced by acriflavin has been established. The metabolic coefficients and the composition of fatty acids in samples metabolizing lactose are presented.
TL;DR: FDP aldolase was found to be present in the cell-free extracts of Rhizobium leguminosarum, RhZobium phaseoli, Rhzobium trifolii, RhIZobium meliloti, Rhiz Obium lupini, Rhzeobium japonicum and RhizOBium species fromArachis hypogaea andSesbania cannabina.
Abstract: FDP aldolase was found to be present in the cell-free extracts ofRhizobium leguminosarum,Rhizobium phaseoli, Rhizobium trifolii, Rhizobium meliloti, Rhizobium lupini, Rhizobium japonicum andRhizobium species fromArachis hypogaea andSesbania cannabina. The enzyme in 3 representative species has optimal activity at pH 8.4 in 0.2m veronal buffer. The enzyme activity was completely lost by treatment at 60°C for 15 min. The Km values were in the range from 2.38 to 4.55 × 10−6M FDP. Metal chelating agents inhibited enzyme activity, but monovalent or bivalent metal ions failed to stimulate the activity. Bivalent metal ions in general were rather inhibitory.
TL;DR: In this article, it was shown that glucose uptake by membrane vesicles is inhibited by anaerobiosis and by electron transfer inhibitors, such as rotenone and amytal, but not by 2-heptyl-4-hydroxyquinoline N-oxide, antimycin A, cyanide and azide.
Abstract: Membrane vesicles obtained from Acholeplasma laidlawii accumulate glucose as well as maltose and fructose against their concentration gradient in the absence of exogenous energy sources. Glucose uptake by membrane vesicles is inhibited by anaerobiosis and by electron transfer inhibitors, such as rotenone and amytal, but not by 2-heptyl-4-hydroxyquinoline N-oxide, antimycin A, cyanide and azide. Rotenone, cyanide and amytal also produce a rapid efflux of glucose from the membrane vesicles. Arsenate, oligomycin and N,N'-dicyclohexylcarbodimide do not inhibit glucose transport. Transport of glucose is markedly inhibited by proton conductors such as CCCP and pentachlorophenol. It is concluded that glucose transport can be driven by a high-energy state of the membrane or by the membrane potential.
Journal Article•
TL;DR: UV irradiation of pigeon droppings resulted in an increased concentration of some inhibitors (peroxides) of growth ofCryptococcus neoformans, which may be, in addition to the direct germicidal action of sunshine, another cause of the rare occurrence of this fungus in pigeon Droppings on unsheltered sites in natural habitats.
Abstract: UV irradiation of pigeon droppings resulted in an increased concentration of some inhibitors (peroxides) of growth ofCryptococcus neoformans. This may be, in addition to the direct germicidal action of sunshine, another cause of the rare occurrence of this fungus in pigeon droppings on unsheltered sites in natural habitats.