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1.
Vasileva-Tonkova E Galabova D 《Zeitschrift für Naturforschung. C, Journal of biosciences》2003,58(1-2):87-92
Fifteen bacterial monocultures were isolated from lubricant-contaminated wastewater of an electric power station in Sofia. Six isolates showed best growth in liquid media with 1.5% hexadecane, and on mineral salt agar plates supplemented with one of the following hydrocarbons: n-hexadecane, paraffin, kerosene and samples of wastewater. The ability of all isolates to produce extracellular hydrolytic enzymes and surface-active glycolipids was assessed on the basis of their growth on hydrocarbons. The study of this relatively closed micro-ecosystem revealed the existence of well-balanced microbial consortium where different members have their own role and support each other. On this basis, an alternative approach is proposed for bioaugmented clean up of wastewater contaminated with hydrocarbons and organic polymers using a mixed culture of indigenous bacteria that combines the best producers of glycolipids and hydrolytic enzymes. 相似文献
2.
Vasileva-Tonkova E Galabova D Stoimenova E Lalchev Z 《Zeitschrift für Naturforschung. C, Journal of biosciences》2006,61(7-8):553-559
The newly isolated from industrial wastewater Pseudomonas fluorescens strain HW-6 produced glycolipid biosurfactants at high concentrations (1.4-2.0 g l(-1)) when grown on hexadecane as a sole carbon source. Biosurfactants decreased the surface tension of the air/ water interface by 35 mN m(-1) and possessed a low critical micelle concentration value of 20 mg l(-1), which indicated high surface activity. They efficiently emulsified aromatic hydrocarbons, kerosene, n-paraffins and mineral oils. Biosurfactant production contributed to a significant increase in cell hydrophobicity correlated with an increased growth of the strain on hexadecane. The results suggested that the newly isolated strain of Ps. fluorescens and produced glycolipid biosurfactants with effective surface and emulsifying properties are very promising and could find application for bioremediation of hydrocarbon-polluted sites. 相似文献
3.
Anna Sotirova Tatyana Avramova Stoyanka Stoitsova Irina Lazarkevich Vera Lubenets Elena Karpenko Danka Galabova 《Current microbiology》2012,65(5):534-541
The antimicrobial properties of methyl (MTS) and ethyl (ETS) esters of thiosulfonic acid alone and in combination with rhamnolipid-biosurfactant (RL) have been characterized for their ability to disrupt the normal physiological functions of living pathogens. Bactericidal and fungicidal activities of MTS and ETS and their combination with rhamnolipid were demonstrated on strains of Pseudomonas aeruginosa, Bacillus subtilis, Alcaligenes faecalis, and Rhizopus ngtricans. It was found that the combination of rhamnolipid and thiosulfonic esters has a synergistic effect leading to decreasing of bactericidal and fungicidal concentrations of MTS and ETS. More extensively was studied the effect of rhamnolipid on the lipid composition of B. subtilis bacterial membrane. To our knowledge, in this article is reported for the first time a remarkable increase of negatively charged phospholipid cardiolipin in the presence of rhamnolipid. The capacity of RL as a surface-active substance was confirmed by scanning electron microscopy (SEM). The occurrence of surface infolds and blebs on B. subtilis shown by SEM, was not accompanied by changes in membrane permeability tested by a live/dead viability staining for fluorescence microscopy. When RL was applied in combination with MTS, a dramatic permeability shift for propidium iodide was observed in vegetative cells. 相似文献
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5.
A specific alkaline phosphatase from Saccharomyces cerevisiae with protein phosphatase activity 总被引:1,自引:0,他引:1
Boriyana Tuleva Evgenia Vasileva-Tonkova Danka Galabova 《FEMS microbiology letters》1998,161(1):139-144
In this paper, specific PHO13 alkaline phosphatase from Saccharomyces cerevisiae was demonstrated to possess phosphoprotein phosphatase activity on the phosphoseryl proteins histone II-A and casein. The enzyme is a monomeric protein with molecular mass of 60 kDa and hydrolyzes p-nitrophenyl phosphate with maximal activity at pH 8.2 with strong dependence on Mg2+ ions and an apparent Km of 3.6×10−5 M. No other substrates tested except phosphorylated histone II-A and casein were hydrolyzed at any significant rate. These data suggest that the physiological role of the p-nitrophenyl phosphate-specific phosphatase may involve participation in reversible protein phosphorylation. 相似文献
6.
Remichkova M Galabova D Roeva I Karpenko E Shulga A Galabov AS 《Zeitschrift für Naturforschung. C, Journal of biosciences》2008,63(1-2):75-81
The rhamnolipid biosurfactant PS-17 and its complex with the polysaccharide alginate, both produced by the Pseudomonas sp. S-17 strain, were studied for their antiviral activity against herpes simplex virus (HSV) types 1 and 2. They significantly inhibited the herpesvirus cytopathic effect (CPE) in the Madin-Darby bovine kidney (MDBK) cell line. The investigations were carried out according to the CPE inhibition assay protocol. The suppressive effect of the compounds on HSV replication was dose-dependent and occurred at concentrations lower than the critical micelle concentration of the surfactant. The 50% inhibitory concentration (IC50) of rhamnolipid PS-17 was 14.5 microg/ml against HSV-1 and 13 microg/ml against HSV-2. The IC50 values of the complex were 435 microg/ml for HSV-1 and 482 microg/ml for HSV-2. The inhibitory effects of the substances were confirmed by measuring the infectious virus yields with the multicycle virus growth experimental design as well: deltalog CCID50 of 1.84-2.0 against the two types of herpes simplex viruses by rhamnolipid PS-17 (20 microg/ml), and a strong reduction of the HSV-2 virus yield under the effect of the alginate complex at a concentration of 450 microg/ml. The results indicate that rhamnolipid PS-17 and its alginate complex may be considered as promising substances for the development of anti-herpetic compounds. 相似文献
7.
Summary Acid phosphatase activity and protein release were determined in cell suspensions ofYarrowia lipolytica andTorulospora delbrueckii at different stages of their growth by permeabilization with Triton X-100. The effect of the surfactant on the cell permeability did not depend on the cell age. 相似文献
8.
D. N. Galabova E. S. Vasileva-Tonkova M. A. Balasheva 《World journal of microbiology & biotechnology》1994,10(4):483-484
The phosphate-repressible acid phosphatase from Yarrowia lipolytica cells was more thermostable but more sensitive to urea denaturation and to the effect of Triton X-100 than the constitutive counterpart. The K
m values of the repressible and constitutive enzymes for p-nitrophenyl phosphate were 3.6 mM and 7.4 mM, respectively. They are judged to be distinct proteins.The authors are with the institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev str., Bl. 26, 1113 Sofia, Bulgaria; 相似文献
9.
Cystic endometrial hyperplasia (CEH) and pyometra in the bitch are dioestral syndromes, supposed to be caused by hormonal disturbances and changes in endometrial steroid hormone receptor levels. Histologically, the endometria show cystic dilated glands and, if bacteria succeed in invading the uterus, pyometra may develop in the following metoestrus. In this study, lectin histochemistry was performed on paraffin sections to compare carbohydrate expression of uterine glands and surface epithelium in healthy dogs and in dogs with CEH and pyometra. Lectin binding is a useful tool to identify glycoconjugates, especially of the glycocalyx, which has essential functions in the endometrium during reproduction. Uterine tissue was obtained from 18 healthy bitches in metoestrus or anoestrus and 18 bitches with a clinical diagnosis of CEH or pyometra. Normal endometria showed cycle-dependent changes in SBA, PNA, HPA and UEA binding during metoestrus and anoestrus. LCA did not show cycle-dependent changes and WGA bound to Golgi regions in the apical parts of surface epithelial cells only in metoestrous. Endometria with inflammatory alterations lost cycle-specific lectin binding patterns and, with increasing severity of pathological changes, showed a marked decrease in binding intensity to the glandular and surface epithelial glycocalyx and secretions. In dogs with CEH, unaltered glands with generally strong lectin binding to the glycocoalyx and Golgi regions were found adjacent to altered glands. The decrease of lectin binding in pyometra cases is supposed to be a result of glandular exhaustion after cystic hyperplasia. In addition, bacterial adhesion to sugar residues on the uterine surface epithelium might impede lectin binding. 相似文献
10.
Gergana Galabova Sylvia Brunner Gabriele Winsauer Claudia Juno Bettina Wanko Andreas Mairhofer Petra Lührs Achim Schneeberger Arne von Bonin Frank Mattner Walter Schmidt Guenther Staffler 《PloS one》2014,9(12)