Eva Michalkova - Academia.edu (original) (raw)

Papers by Eva Michalkova

Enzyme and microbial technology, 1993

C. acetobutylicurn is a saccharolytic, spore forming anaerobe which has been used in the industri... more C. acetobutylicurn is a saccharolytic, spore forming anaerobe which has been used in the industrial production of a number of chemicals including solvents such as butanol and acetone. The organism has two distinct phases during its life cycle. The acidogenic first phase is characterized by vigorous growth and the production of organic acids, such as butyric and acetic acid, and molecular hydrogen. The solventogedic second phase is characterized by a slower growth rate and the production of solvents, mainly butanol, ethanol and acetone. Many of the changes that occur in the switch from acid to solvent production have been characterized and numerous studies on the levels of key enzymes have been performed. As a part of an ongoing study of regulation of acid and solvent production in C. acetobutylicum with the goal of developing genetically modified strains, the effects of rifampicin and chloramphenicol addition at various points in the fermentation were determined on product formation, enzyme activity and enzyme stability in vivo. The in vitro activities of phosphotransbutyrylase, butyrate kinase, CoA transferase, butyraldehyde dehydrogenase and butanol dehydrogenase were assayed over the entire fermentation. The enzymes in the solvent producing pathways were more effected by the addition of rifampicin and chloramphenicol than those in acid producing pathways. The position of butyraldehyde dehydrogenase as a branchpoint enzyme in die use of butyryl-CoA, coupled with the shon half life for butyraldehyde dehydrogenase in vivo indicates that butyraldehyde dehydrogenase may be a key enzyme in controlling the switch from the production of butyrate to the production of butanol.

ChemInform, Aug 22, 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Journal of Thermal Analysis and Calorimetry, Apr 10, 2014

TG-DTA, MS detections and XRD were used to characterize thermal behaviour of iron precipitates fr... more TG-DTA, MS detections and XRD were used to characterize thermal behaviour of iron precipitates from acid mine drainage prepared by precipitation with urea and natural iron precipitates sampled from sludge bed (settling pit Sedem žien and old abandoned adit Hodruša, mining area Banská Š tiavnica, Slovakia). The high-resolution transmission electron microscopy and scanning electron microscopy (SEM) techniques were used to characterize the surface microstructure and shape of the synthesized and sampled iron precipitates. The SEM micrographs of the iron precipitates (natural and precipitated with urea) show that the samples had formed into agglomerates, probably due to attractive forces of quite large surface area. During heating of the all samples up to 200°C, physically adsorbed water was removed. On further heating in the range from 250 to 350°C in natural iron precipitates, the less stable forms (goethite, ferrihydrite, and schwertmannite) transform to more stable forms like hematite. In case of synthetic samples, the transformation runs in two steps: first in the range from 250 to 350°C, and second in the range from 600 to 750°C.

Bioprocess Engineering, 1996

The permeabilized cells of Trigonopsis variabilis Cs2 CCY 15-1-3 having D-amino acid oxidase (DAA... more The permeabilized cells of Trigonopsis variabilis Cs2 CCY 15-1-3 having D-amino acid oxidase (DAAO) activity were D,~ used to convert cephalosporin C (CPS-C) into 7-(c~-ketoadipyl arnido) cephalosporanic acid (CO-GL-7-ACA) in a batch Ki bioreactor with good aeration and stirring during the process. Km~ The deacylation of 7-fl-(4-carboxybutanamido)-Km~ cephalosporanic acid (GL-7-ACA) to 7-cephalosporanic acid n (7-ACA) by permeabilized cells of Pseudomonas species 3635 % having 4-fl-(4-carbox3~butamido)-cephalosporanicacid acylase r~ (GL-7-ACA acylase) activity was performed in a batch bioreactor. A spectrophotometric method for the r2 determination of CO-GL-7-ACA and 7-ACA was proposed. Experimental data were fitted by non-linear regression with R parameters optimization. The sorption method (without S(F) reaction) was applied for the determination of cephalosporin effective diffusion coefficients in Ca-pectate gel beads. These t beads were prepared by dropping a potassium pectate gel

Biotechnology Techniques, Oct 1, 1993

ABSTRACT Direct activity determination by a flow-through microcalorimetry in the enzyme thermisto... more ABSTRACT Direct activity determination by a flow-through microcalorimetry in the enzyme thermistor system was employed for a fast comparison of (poly)acrylamide gel-entrapped penicillin G acylase preparations. Composition of the pre-polymerization cocktail and both the storage and operational stabilities of optimal gel-entrapped enzyme preparations isolated from the Escherichia coli industrial strain were optimized by this method. The validity of the results was corroborated by spectrophotometric measurements.

ChemPlusChem, 1992

Three new metabolites - (-)-mitorubrinol, 2-formyl-3,5-dihydroxy-4-methylbenzoic and 2-formyl-3,5... more Three new metabolites - (-)-mitorubrinol, 2-formyl-3,5-dihydroxy-4-methylbenzoic and 2-formyl-3,5-dihydroxy-4-hydroxymethylbenzoic acids - were isolated from the culture medium of Penicillium vermiculatum DANG. Hexane extract of the mycelium contained ergosterol and esters of fatty acids, linoleic, oleic and palmitic acids being the dominating ones.

Acta Oecologica, 2018

Although Carabidae is among the best-studied families of beetles in Europe from the faunistic poi... more Although Carabidae is among the best-studied families of beetles in Europe from the faunistic point of view, there is still a lack of available information on the ecological requirements of the particular carabid species. The habitat preferences that determine the distribution of species are largely influenced by habitat structure and microclimate. In addition to other factors, these habitat parameters are influenced by the nature of the vegetation. Therefore, our study investigated the influence of tree species on carabid beetle communities. We conducted the research at 9 stands in the Borová Hora Arboretum (Zvolen, Central Slovakia). Each studied site represents a monoculture of one of nine tree species. At each site, some soil and leaf litter attributes (pH, conductivity, and content of H, C, N and P) were evaluated. Ground beetles were collected by pitfall trapping during the vegetation periods in 2008-2011. In total, 3012 individuals of 29 species were obtained. Significant differences in the total dynamic activity and species richness of the carabid beetle communities among the compared forest stands were revealed. The results of the research confirmed statistically significant relationships among 1) the soil conductivity and both the richness and Shannon diversity of the ground beetle communities, 2) the litter and soil N content and richness, the Shannon diversity and the species composition of the ground beetle communities. The Shannon diversity and richness were negatively related to the soil conductivity and positively related with the N content. Our research showed that dominant tree species indirectly influence diversity and composition of carabid communities via the soil properties.

Biologia, 2017

Although harvestmen (Opiliones) are among the best studied groups of arachnids in Europe from the... more Although harvestmen (Opiliones) are among the best studied groups of arachnids in Europe from the faunistic point of view, there is still lack of available information on ecological requirements of the particular species. Habitat preferences that determine the distribution of species are largely determined by the habitat structure and microclimate. Besides other factors, these characteristics of habitats are also influenced by the nature of the vegetation. Therefore, our study dealt with the influence of tree species on harvestmen communities. We conducted the research on nine sites in the Borová hora arboretum (Zvolen town, Central Slovakia). Each studied site represents a monoculture of one of nine tree species. On each site also some attributes of soil and leaf litter (pH, conductivity, content of H, C, N and P) were evaluated. Harvestmen were collected by pitfall trapping during vegetation periods in 2008–2012. In total, 2515 individuals of 17 species and 3 families were obtaine...

Polish Journal of Environmental Studies, 2013

Extraction of coal, gold, and polymetallic ore, as well as their modifications, has left a lot of... more Extraction of coal, gold, and polymetallic ore, as well as their modifications, has left a lot of dumps of waste material, tailings, and abandoned mines in the world. Sulphide minerals in these deposits under aerobic conditions (air and water) are liable to microbio-chemical biodegradation by litotrophic bacteria and archaea, resulting in acid mine drainage (AMD) production. Processes caused by litotrophic microorganisms, namely Acidithiobacillus sp. and Leptospirillum sp, have occurred in the soil dump of pyritized hydroquartzite in the area of Banska Stiavnica – Sobov. They bring about AMD production, with dominant components of Fe, Al, and sulphates. This article deals with active modification/treatment (gaining of Fe-sorbents, Fe-pigments) and remediation (decreasing concentration of contaminants – heavy metal, sulphate) of AMD from this area. The products of various purities, phase compositions, and properties, including surface properties, can be synthesized from AMD depending on the reaction conditions. Obtained Fe-oxyhydroxides can be transformed thermally to hematite structure (basic ferric pigment). The other method of utilizing of Fe-sludge is the creation of ferrites (general structure MFe2O4 (M – Me +2 ), e. g. zinc ferrite. In an application of alkaline industrial effluents, especially red mud bauxite and blast furnace slag, in batch experiment and neutralization of AMD, it has been shown that it is possible to reduce contents of Fe, Al, Cu, Zn, Mn, and sulphates with these agents.

The problems of acidification of some environmental components by acid mine drainage (AMD) are we... more The problems of acidification of some environmental components by acid mine drainage (AMD) are well-known all over the world, mainly in the regions with developed mining industry and in the regions with abandoned mines. AMD production and its consequences can be found also in the spoil dump of pyritized hydroquartzite in the locality of Malý Šobov in the Banská Štiavnica region (central Slovakia). This paper presents the results of two-year soil moisture research, its distribution, regime in the AMD production in this locality. The seasonal soil moisture variability in the spoil dump corresponds with the AMD production intensity (in spring and autumn the spoil dump moisture of about 20 % and temperature create suitable conditions for the activity of autochthonous microflora). The space distribution of soil moisture identified the permeable zones in the spoil dump (where the primary process of pyrite decomposition is expected) and impermeable zones where water and AMD are retained. This knowledge could be useful in application of other remediation processes into the spoil dump.

Folia Microbiologica, 1999

Stabilization of immobilized D-amino-acid oxidase was achieved as follows. Yeast Trigonopsis vari... more Stabilization of immobilized D-amino-acid oxidase was achieved as follows. Yeast Trigonopsis variabilis producing D-amino-acid oxidase was used to deaminate cephalosporin C to glutaryi-7-aminocephalosporanic acid. Permeabilized cells were co-immobilized with manganese dioxide by entrapment in (poly)acrytamide gel so that hydrogen peroxide, liberated in the reaction, could be partially deactivated and both the enzyme and the substrate could be stabilized. Activity of entrapped cells was determined by HPLC and enzyme flow microcalorimetry. The process was evaluated in terms of activity, immobilization yield, storage stability and oxo-product formation by immobilized preparations. The storage stability of immobilized biocatalysts with MnO 2 was nearly doubled and production of 2-oxoadipyt-7-aminocephalosporanic acid was 2-3-fold higher than by entrapped cells without MnO 2. Glutatyl-7-aminocephalosporanic acid can be easily obtained from the resulting oxo-product by a non-enzymic reaction v/a externally added hydrogen peroxide. Abbreviations D-AAO D-amino-acid oxidase (EC 1A.3.3) GA 7-ACA 7-aminocephalosporanic acid Glu-7-ACA CPC cephalosporin C 2-OA-7-ACA EFMC enzyme flow microcalorimetry PAG glutaraldehyde glutaryl-7-aminocephaiosporanic acid 2-oxoadipyl-7-aminocephalosporanic acid (poly)acrylamide gel

Enzyme and Microbial Technology, 1991

C. acetobutylicurn is a saccharolytic, spore forming anaerobe which has been used in the industri... more C. acetobutylicurn is a saccharolytic, spore forming anaerobe which has been used in the industrial production of a number of chemicals including solvents such as butanol and acetone. The organism has two distinct phases during its life cycle. The acidogenic first phase is characterized by vigorous growth and the production of organic acids, such as butyric and acetic acid, and molecular hydrogen. The solventogedic second phase is characterized by a slower growth rate and the production of solvents, mainly butanol, ethanol and acetone. Many of the changes that occur in the switch from acid to solvent production have been characterized and numerous studies on the levels of key enzymes have been performed. As a part of an ongoing study of regulation of acid and solvent production in C. acetobutylicum with the goal of developing genetically modified strains, the effects of rifampicin and chloramphenicol addition at various points in the fermentation were determined on product formation, enzyme activity and enzyme stability in vivo. The in vitro activities of phosphotransbutyrylase, butyrate kinase, CoA transferase, butyraldehyde dehydrogenase and butanol dehydrogenase were assayed over the entire fermentation. The enzymes in the solvent producing pathways were more effected by the addition of rifampicin and chloramphenicol than those in acid producing pathways. The position of butyraldehyde dehydrogenase as a branchpoint enzyme in die use of butyryl-CoA, coupled with the shon half life for butyraldehyde dehydrogenase in vivo indicates that butyraldehyde dehydrogenase may be a key enzyme in controlling the switch from the production of butyrate to the production of butanol.

Chemical Papers, 2012

Preliminary results of research focused on the utilisation of specific waste from metallurgical a... more Preliminary results of research focused on the utilisation of specific waste from metallurgical and mining activities to obtain ferrite pigments are presented. As a source of iron in the spinel-type ferrites with the general structure MFe2O4 (where M is a bivalent metal such as Ca and Zn), three types of industrial wastes were used: metallurgical slag from the production of non-ferrous metals and two types of AMD (acid mine drainage) sludge: one of natural origin (Fe-sediment) and the second one synthetically prepared from AMD (Fe-precipitate). This waste was homogenised by ZnO and CaCO3 in various stoichiometric ratios n(Ca): n(Zn): n(Fe) and calcined at the temperature of 1000–1095°C. Mineralogical (XRD) analysis of the metallurgical slag pigments confirmed the formation of zinc ferrite and hematite only (Ca from reaction components entered into other phases). The ferric component of the AMD sludge (Fe-precipitate and Fe-sediment) formed a mixture of zinc ferrite, calcium ferrite,...

Bioprocess Engineering, 1996

The permeabilized cells of Trigonopsis variabilis Cs2 CCY 15-1-3 having D-amino acid oxidase (DAA... more The permeabilized cells of Trigonopsis variabilis Cs2 CCY 15-1-3 having D-amino acid oxidase (DAAO) activity were D,~ used to convert cephalosporin C (CPS-C) into 7-(c~-ketoadipyl arnido) cephalosporanic acid (CO-GL-7-ACA) in a batch Ki bioreactor with good aeration and stirring during the process. Km~ The deacylation of 7-fl-(4-carboxybutanamido)-Km~ cephalosporanic acid (GL-7-ACA) to 7-cephalosporanic acid n (7-ACA) by permeabilized cells of Pseudomonas species 3635 % having 4-fl-(4-carbox3~butamido)-cephalosporanicacid acylase r~ (GL-7-ACA acylase) activity was performed in a batch bioreactor. A spectrophotometric method for the r2 determination of CO-GL-7-ACA and 7-ACA was proposed. Experimental data were fitted by non-linear regression with R parameters optimization. The sorption method (without S(F) reaction) was applied for the determination of cephalosporin effective diffusion coefficients in Ca-pectate gel beads. These t beads were prepared by dropping a potassium pectate gel

This paper is focused to characterize the ochre precipitates and the mine water effluents of some... more This paper is focused to characterize the ochre precipitates and the mine water effluents of some old mine adits and settling pits after mining of polymetallic ores in Slovakia. It was shown that the mine water effluents from two different types of deposits (adits; settling pits) have similar composition and represent slightly acidic sulphate water (pH in range 5.60-6.05, sulphate concentration from 1160 to 1905 g.dm-3). The ochreous precipitates were characterized by methods of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and B.E.T. method for measuring the specific surface area and porosity. The dominant phases were ferrihydrite with goethite or goethite with lepidocrocide.

Biologia, 2018

During the years 2015-2016, we studied the fauna of epigeon in eight similar habitats in Slovakia... more During the years 2015-2016, we studied the fauna of epigeon in eight similar habitats in Slovakia and Serbia. The study material of Opiliones was obtained by a pitfall trap method. We focused on the comparison of the incidence of harvestmen in floodplain forests and ecotones alongside the Danube River in Slovakia and along the Tisa and Begej River in Serbia. We examined their dependence on anthropogenic impact (frequency of visits), cover of vegetation layers (herbs, shrubs and trees), plant diversity of vegetation layers, area of forest stands, distance to the forest edge, circumference of forest stands, age of forest stands, thickness of litter layer and physico-chemical properties of soil and litter (pH, conductivity, P, N, C, H). Total epigeic activity of harvestman showed significant positive relationship with proportion of N in litter. Community equitability was positively related with species richness of plant communities in shrub layer and negatively related with H content of soil. We did not find any significant correlations between diversity of harvestman communities and measured environmental characteristics.

Vysokoškolská učebnica sa zaoberá problémami znečisťovania ako dôsledok priemyselnej aktivity, al... more Vysokoškolská učebnica sa zaoberá problémami znečisťovania ako dôsledok priemyselnej aktivity, ale aj otázkami znižovania emisií, sanácie kontaminovaných území a využívania najlepších dostupných techník (BAT). Problematika skúmania environmentálnych aspektov má široké interdisciplinárne súvislosti a vyžaduje dokonalú spoluprácu celého radu odborníkov. Cieľom učebnice je pripraviť absolventov vysokoškolského štúdia na tímovú spoluprácu a oboznámiť ich s najnovšími legislatívnymi podmienkami týkajúcimi sa posudzovania vplyvov na životné prostredie a na zdravie obyvateľstva. V úvodných kapitolách sú rozoberané všeobecné aspekty environmentálnych vplyvov priemyselných činností (legislatíva, definície základných pojmov, vzťahov a vzájomných súvislostí, rozdelenie technológií, spôsoby znižovania emisií a pod.). Učebnica je ďalej členená na kapitoly zamerané na výrobu a analýzu vybraných príkladov základných priemyselných látok ako z oblasti anorganickej, tak aj organickej technológie a te...

Hydrometallurgy

The study describes a new way of treating of acid mine drainage (AMD) waters containing sulphate ... more The study describes a new way of treating of acid mine drainage (AMD) waters containing sulphate of Fe+3 and Al+3 as dominant components using homogenous thermal hydrolysis with urea. The model solution and the acid mine drainage solution were kept with urea at one of the selected temperatures (60°C, 80°C and 95°C) in thermostatic bath. X-ray powder diffraction spectra identified four main phases in the hydrolysis products, namely: goethite, schwertmannite, ferrihydrite and jarosite. No crystalline phases of aluminum were detected. Depending on the precipitation conditions, the prepared samples consist of spherical aggregates of nanocrystals of various modifications of hydrated iron oxides. The specific surface area results show that with increasing content of Al3+, the specific surface area in the final product decreases. The results reveal that by homogenous hydrolysis of acid mine drainage with urea, it is possible to prepare easily filterable relatively pure oxide precipitates w...

Journal of Chemical Technology and Biotechnology, 1998

ABSTRACT Screening of a representative series of immobilized penicillin G acylase biocatalysts (e... more ABSTRACT Screening of a representative series of immobilized penicillin G acylase biocatalysts (enzyme, cells) using enzyme flow microcalorimetry is described. Immobilized penicillin G acylase biocatalysts were either prepared in the laboratory by various techniques or obtained from four commercial manufacturers. An industrial strain of Escherichia coli was entrapped in (poly)acrylamide gel or hardened calcium pectate gel. Semi-purified enzyme was immobilized in various ways—either by covalent binding to oxirane-acrylic beads or chlorotriazine bead cellulose or by entrapment in (poly)acrylamide gel. The validity of the enzyme flow microcalorimetry results was corroborated by a pH-stat method, showing enzyme flow microcalorimetry to be a suitable method for rapid screening of immobilized biocatalysts regardless of the immobilization technique, carrier type or the biocatalyst source. © 1998 Society of Chemical Industry

Enzyme and microbial technology, 1993

C. acetobutylicurn is a saccharolytic, spore forming anaerobe which has been used in the industri... more C. acetobutylicurn is a saccharolytic, spore forming anaerobe which has been used in the industrial production of a number of chemicals including solvents such as butanol and acetone. The organism has two distinct phases during its life cycle. The acidogenic first phase is characterized by vigorous growth and the production of organic acids, such as butyric and acetic acid, and molecular hydrogen. The solventogedic second phase is characterized by a slower growth rate and the production of solvents, mainly butanol, ethanol and acetone. Many of the changes that occur in the switch from acid to solvent production have been characterized and numerous studies on the levels of key enzymes have been performed. As a part of an ongoing study of regulation of acid and solvent production in C. acetobutylicum with the goal of developing genetically modified strains, the effects of rifampicin and chloramphenicol addition at various points in the fermentation were determined on product formation, enzyme activity and enzyme stability in vivo. The in vitro activities of phosphotransbutyrylase, butyrate kinase, CoA transferase, butyraldehyde dehydrogenase and butanol dehydrogenase were assayed over the entire fermentation. The enzymes in the solvent producing pathways were more effected by the addition of rifampicin and chloramphenicol than those in acid producing pathways. The position of butyraldehyde dehydrogenase as a branchpoint enzyme in die use of butyryl-CoA, coupled with the shon half life for butyraldehyde dehydrogenase in vivo indicates that butyraldehyde dehydrogenase may be a key enzyme in controlling the switch from the production of butyrate to the production of butanol.

ChemInform, Aug 22, 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Journal of Thermal Analysis and Calorimetry, Apr 10, 2014

TG-DTA, MS detections and XRD were used to characterize thermal behaviour of iron precipitates fr... more TG-DTA, MS detections and XRD were used to characterize thermal behaviour of iron precipitates from acid mine drainage prepared by precipitation with urea and natural iron precipitates sampled from sludge bed (settling pit Sedem žien and old abandoned adit Hodruša, mining area Banská Š tiavnica, Slovakia). The high-resolution transmission electron microscopy and scanning electron microscopy (SEM) techniques were used to characterize the surface microstructure and shape of the synthesized and sampled iron precipitates. The SEM micrographs of the iron precipitates (natural and precipitated with urea) show that the samples had formed into agglomerates, probably due to attractive forces of quite large surface area. During heating of the all samples up to 200°C, physically adsorbed water was removed. On further heating in the range from 250 to 350°C in natural iron precipitates, the less stable forms (goethite, ferrihydrite, and schwertmannite) transform to more stable forms like hematite. In case of synthetic samples, the transformation runs in two steps: first in the range from 250 to 350°C, and second in the range from 600 to 750°C.

Bioprocess Engineering, 1996

The permeabilized cells of Trigonopsis variabilis Cs2 CCY 15-1-3 having D-amino acid oxidase (DAA... more The permeabilized cells of Trigonopsis variabilis Cs2 CCY 15-1-3 having D-amino acid oxidase (DAAO) activity were D,~ used to convert cephalosporin C (CPS-C) into 7-(c~-ketoadipyl arnido) cephalosporanic acid (CO-GL-7-ACA) in a batch Ki bioreactor with good aeration and stirring during the process. Km~ The deacylation of 7-fl-(4-carboxybutanamido)-Km~ cephalosporanic acid (GL-7-ACA) to 7-cephalosporanic acid n (7-ACA) by permeabilized cells of Pseudomonas species 3635 % having 4-fl-(4-carbox3~butamido)-cephalosporanicacid acylase r~ (GL-7-ACA acylase) activity was performed in a batch bioreactor. A spectrophotometric method for the r2 determination of CO-GL-7-ACA and 7-ACA was proposed. Experimental data were fitted by non-linear regression with R parameters optimization. The sorption method (without S(F) reaction) was applied for the determination of cephalosporin effective diffusion coefficients in Ca-pectate gel beads. These t beads were prepared by dropping a potassium pectate gel

Biotechnology Techniques, Oct 1, 1993

ABSTRACT Direct activity determination by a flow-through microcalorimetry in the enzyme thermisto... more ABSTRACT Direct activity determination by a flow-through microcalorimetry in the enzyme thermistor system was employed for a fast comparison of (poly)acrylamide gel-entrapped penicillin G acylase preparations. Composition of the pre-polymerization cocktail and both the storage and operational stabilities of optimal gel-entrapped enzyme preparations isolated from the Escherichia coli industrial strain were optimized by this method. The validity of the results was corroborated by spectrophotometric measurements.

ChemPlusChem, 1992

Three new metabolites - (-)-mitorubrinol, 2-formyl-3,5-dihydroxy-4-methylbenzoic and 2-formyl-3,5... more Three new metabolites - (-)-mitorubrinol, 2-formyl-3,5-dihydroxy-4-methylbenzoic and 2-formyl-3,5-dihydroxy-4-hydroxymethylbenzoic acids - were isolated from the culture medium of Penicillium vermiculatum DANG. Hexane extract of the mycelium contained ergosterol and esters of fatty acids, linoleic, oleic and palmitic acids being the dominating ones.

Acta Oecologica, 2018

Although Carabidae is among the best-studied families of beetles in Europe from the faunistic poi... more Although Carabidae is among the best-studied families of beetles in Europe from the faunistic point of view, there is still a lack of available information on the ecological requirements of the particular carabid species. The habitat preferences that determine the distribution of species are largely influenced by habitat structure and microclimate. In addition to other factors, these habitat parameters are influenced by the nature of the vegetation. Therefore, our study investigated the influence of tree species on carabid beetle communities. We conducted the research at 9 stands in the Borová Hora Arboretum (Zvolen, Central Slovakia). Each studied site represents a monoculture of one of nine tree species. At each site, some soil and leaf litter attributes (pH, conductivity, and content of H, C, N and P) were evaluated. Ground beetles were collected by pitfall trapping during the vegetation periods in 2008-2011. In total, 3012 individuals of 29 species were obtained. Significant differences in the total dynamic activity and species richness of the carabid beetle communities among the compared forest stands were revealed. The results of the research confirmed statistically significant relationships among 1) the soil conductivity and both the richness and Shannon diversity of the ground beetle communities, 2) the litter and soil N content and richness, the Shannon diversity and the species composition of the ground beetle communities. The Shannon diversity and richness were negatively related to the soil conductivity and positively related with the N content. Our research showed that dominant tree species indirectly influence diversity and composition of carabid communities via the soil properties.

Biologia, 2017

Although harvestmen (Opiliones) are among the best studied groups of arachnids in Europe from the... more Although harvestmen (Opiliones) are among the best studied groups of arachnids in Europe from the faunistic point of view, there is still lack of available information on ecological requirements of the particular species. Habitat preferences that determine the distribution of species are largely determined by the habitat structure and microclimate. Besides other factors, these characteristics of habitats are also influenced by the nature of the vegetation. Therefore, our study dealt with the influence of tree species on harvestmen communities. We conducted the research on nine sites in the Borová hora arboretum (Zvolen town, Central Slovakia). Each studied site represents a monoculture of one of nine tree species. On each site also some attributes of soil and leaf litter (pH, conductivity, content of H, C, N and P) were evaluated. Harvestmen were collected by pitfall trapping during vegetation periods in 2008–2012. In total, 2515 individuals of 17 species and 3 families were obtaine...

Polish Journal of Environmental Studies, 2013

Extraction of coal, gold, and polymetallic ore, as well as their modifications, has left a lot of... more Extraction of coal, gold, and polymetallic ore, as well as their modifications, has left a lot of dumps of waste material, tailings, and abandoned mines in the world. Sulphide minerals in these deposits under aerobic conditions (air and water) are liable to microbio-chemical biodegradation by litotrophic bacteria and archaea, resulting in acid mine drainage (AMD) production. Processes caused by litotrophic microorganisms, namely Acidithiobacillus sp. and Leptospirillum sp, have occurred in the soil dump of pyritized hydroquartzite in the area of Banska Stiavnica – Sobov. They bring about AMD production, with dominant components of Fe, Al, and sulphates. This article deals with active modification/treatment (gaining of Fe-sorbents, Fe-pigments) and remediation (decreasing concentration of contaminants – heavy metal, sulphate) of AMD from this area. The products of various purities, phase compositions, and properties, including surface properties, can be synthesized from AMD depending on the reaction conditions. Obtained Fe-oxyhydroxides can be transformed thermally to hematite structure (basic ferric pigment). The other method of utilizing of Fe-sludge is the creation of ferrites (general structure MFe2O4 (M – Me +2 ), e. g. zinc ferrite. In an application of alkaline industrial effluents, especially red mud bauxite and blast furnace slag, in batch experiment and neutralization of AMD, it has been shown that it is possible to reduce contents of Fe, Al, Cu, Zn, Mn, and sulphates with these agents.

The problems of acidification of some environmental components by acid mine drainage (AMD) are we... more The problems of acidification of some environmental components by acid mine drainage (AMD) are well-known all over the world, mainly in the regions with developed mining industry and in the regions with abandoned mines. AMD production and its consequences can be found also in the spoil dump of pyritized hydroquartzite in the locality of Malý Šobov in the Banská Štiavnica region (central Slovakia). This paper presents the results of two-year soil moisture research, its distribution, regime in the AMD production in this locality. The seasonal soil moisture variability in the spoil dump corresponds with the AMD production intensity (in spring and autumn the spoil dump moisture of about 20 % and temperature create suitable conditions for the activity of autochthonous microflora). The space distribution of soil moisture identified the permeable zones in the spoil dump (where the primary process of pyrite decomposition is expected) and impermeable zones where water and AMD are retained. This knowledge could be useful in application of other remediation processes into the spoil dump.

Folia Microbiologica, 1999

Stabilization of immobilized D-amino-acid oxidase was achieved as follows. Yeast Trigonopsis vari... more Stabilization of immobilized D-amino-acid oxidase was achieved as follows. Yeast Trigonopsis variabilis producing D-amino-acid oxidase was used to deaminate cephalosporin C to glutaryi-7-aminocephalosporanic acid. Permeabilized cells were co-immobilized with manganese dioxide by entrapment in (poly)acrytamide gel so that hydrogen peroxide, liberated in the reaction, could be partially deactivated and both the enzyme and the substrate could be stabilized. Activity of entrapped cells was determined by HPLC and enzyme flow microcalorimetry. The process was evaluated in terms of activity, immobilization yield, storage stability and oxo-product formation by immobilized preparations. The storage stability of immobilized biocatalysts with MnO 2 was nearly doubled and production of 2-oxoadipyt-7-aminocephalosporanic acid was 2-3-fold higher than by entrapped cells without MnO 2. Glutatyl-7-aminocephalosporanic acid can be easily obtained from the resulting oxo-product by a non-enzymic reaction v/a externally added hydrogen peroxide. Abbreviations D-AAO D-amino-acid oxidase (EC 1A.3.3) GA 7-ACA 7-aminocephalosporanic acid Glu-7-ACA CPC cephalosporin C 2-OA-7-ACA EFMC enzyme flow microcalorimetry PAG glutaraldehyde glutaryl-7-aminocephaiosporanic acid 2-oxoadipyl-7-aminocephalosporanic acid (poly)acrylamide gel

Enzyme and Microbial Technology, 1991

C. acetobutylicurn is a saccharolytic, spore forming anaerobe which has been used in the industri... more C. acetobutylicurn is a saccharolytic, spore forming anaerobe which has been used in the industrial production of a number of chemicals including solvents such as butanol and acetone. The organism has two distinct phases during its life cycle. The acidogenic first phase is characterized by vigorous growth and the production of organic acids, such as butyric and acetic acid, and molecular hydrogen. The solventogedic second phase is characterized by a slower growth rate and the production of solvents, mainly butanol, ethanol and acetone. Many of the changes that occur in the switch from acid to solvent production have been characterized and numerous studies on the levels of key enzymes have been performed. As a part of an ongoing study of regulation of acid and solvent production in C. acetobutylicum with the goal of developing genetically modified strains, the effects of rifampicin and chloramphenicol addition at various points in the fermentation were determined on product formation, enzyme activity and enzyme stability in vivo. The in vitro activities of phosphotransbutyrylase, butyrate kinase, CoA transferase, butyraldehyde dehydrogenase and butanol dehydrogenase were assayed over the entire fermentation. The enzymes in the solvent producing pathways were more effected by the addition of rifampicin and chloramphenicol than those in acid producing pathways. The position of butyraldehyde dehydrogenase as a branchpoint enzyme in die use of butyryl-CoA, coupled with the shon half life for butyraldehyde dehydrogenase in vivo indicates that butyraldehyde dehydrogenase may be a key enzyme in controlling the switch from the production of butyrate to the production of butanol.

Chemical Papers, 2012

Preliminary results of research focused on the utilisation of specific waste from metallurgical a... more Preliminary results of research focused on the utilisation of specific waste from metallurgical and mining activities to obtain ferrite pigments are presented. As a source of iron in the spinel-type ferrites with the general structure MFe2O4 (where M is a bivalent metal such as Ca and Zn), three types of industrial wastes were used: metallurgical slag from the production of non-ferrous metals and two types of AMD (acid mine drainage) sludge: one of natural origin (Fe-sediment) and the second one synthetically prepared from AMD (Fe-precipitate). This waste was homogenised by ZnO and CaCO3 in various stoichiometric ratios n(Ca): n(Zn): n(Fe) and calcined at the temperature of 1000–1095°C. Mineralogical (XRD) analysis of the metallurgical slag pigments confirmed the formation of zinc ferrite and hematite only (Ca from reaction components entered into other phases). The ferric component of the AMD sludge (Fe-precipitate and Fe-sediment) formed a mixture of zinc ferrite, calcium ferrite,...

Bioprocess Engineering, 1996

The permeabilized cells of Trigonopsis variabilis Cs2 CCY 15-1-3 having D-amino acid oxidase (DAA... more The permeabilized cells of Trigonopsis variabilis Cs2 CCY 15-1-3 having D-amino acid oxidase (DAAO) activity were D,~ used to convert cephalosporin C (CPS-C) into 7-(c~-ketoadipyl arnido) cephalosporanic acid (CO-GL-7-ACA) in a batch Ki bioreactor with good aeration and stirring during the process. Km~ The deacylation of 7-fl-(4-carboxybutanamido)-Km~ cephalosporanic acid (GL-7-ACA) to 7-cephalosporanic acid n (7-ACA) by permeabilized cells of Pseudomonas species 3635 % having 4-fl-(4-carbox3~butamido)-cephalosporanicacid acylase r~ (GL-7-ACA acylase) activity was performed in a batch bioreactor. A spectrophotometric method for the r2 determination of CO-GL-7-ACA and 7-ACA was proposed. Experimental data were fitted by non-linear regression with R parameters optimization. The sorption method (without S(F) reaction) was applied for the determination of cephalosporin effective diffusion coefficients in Ca-pectate gel beads. These t beads were prepared by dropping a potassium pectate gel

This paper is focused to characterize the ochre precipitates and the mine water effluents of some... more This paper is focused to characterize the ochre precipitates and the mine water effluents of some old mine adits and settling pits after mining of polymetallic ores in Slovakia. It was shown that the mine water effluents from two different types of deposits (adits; settling pits) have similar composition and represent slightly acidic sulphate water (pH in range 5.60-6.05, sulphate concentration from 1160 to 1905 g.dm-3). The ochreous precipitates were characterized by methods of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and B.E.T. method for measuring the specific surface area and porosity. The dominant phases were ferrihydrite with goethite or goethite with lepidocrocide.

Biologia, 2018

During the years 2015-2016, we studied the fauna of epigeon in eight similar habitats in Slovakia... more During the years 2015-2016, we studied the fauna of epigeon in eight similar habitats in Slovakia and Serbia. The study material of Opiliones was obtained by a pitfall trap method. We focused on the comparison of the incidence of harvestmen in floodplain forests and ecotones alongside the Danube River in Slovakia and along the Tisa and Begej River in Serbia. We examined their dependence on anthropogenic impact (frequency of visits), cover of vegetation layers (herbs, shrubs and trees), plant diversity of vegetation layers, area of forest stands, distance to the forest edge, circumference of forest stands, age of forest stands, thickness of litter layer and physico-chemical properties of soil and litter (pH, conductivity, P, N, C, H). Total epigeic activity of harvestman showed significant positive relationship with proportion of N in litter. Community equitability was positively related with species richness of plant communities in shrub layer and negatively related with H content of soil. We did not find any significant correlations between diversity of harvestman communities and measured environmental characteristics.

Vysokoškolská učebnica sa zaoberá problémami znečisťovania ako dôsledok priemyselnej aktivity, al... more Vysokoškolská učebnica sa zaoberá problémami znečisťovania ako dôsledok priemyselnej aktivity, ale aj otázkami znižovania emisií, sanácie kontaminovaných území a využívania najlepších dostupných techník (BAT). Problematika skúmania environmentálnych aspektov má široké interdisciplinárne súvislosti a vyžaduje dokonalú spoluprácu celého radu odborníkov. Cieľom učebnice je pripraviť absolventov vysokoškolského štúdia na tímovú spoluprácu a oboznámiť ich s najnovšími legislatívnymi podmienkami týkajúcimi sa posudzovania vplyvov na životné prostredie a na zdravie obyvateľstva. V úvodných kapitolách sú rozoberané všeobecné aspekty environmentálnych vplyvov priemyselných činností (legislatíva, definície základných pojmov, vzťahov a vzájomných súvislostí, rozdelenie technológií, spôsoby znižovania emisií a pod.). Učebnica je ďalej členená na kapitoly zamerané na výrobu a analýzu vybraných príkladov základných priemyselných látok ako z oblasti anorganickej, tak aj organickej technológie a te...

Hydrometallurgy

The study describes a new way of treating of acid mine drainage (AMD) waters containing sulphate ... more The study describes a new way of treating of acid mine drainage (AMD) waters containing sulphate of Fe+3 and Al+3 as dominant components using homogenous thermal hydrolysis with urea. The model solution and the acid mine drainage solution were kept with urea at one of the selected temperatures (60°C, 80°C and 95°C) in thermostatic bath. X-ray powder diffraction spectra identified four main phases in the hydrolysis products, namely: goethite, schwertmannite, ferrihydrite and jarosite. No crystalline phases of aluminum were detected. Depending on the precipitation conditions, the prepared samples consist of spherical aggregates of nanocrystals of various modifications of hydrated iron oxides. The specific surface area results show that with increasing content of Al3+, the specific surface area in the final product decreases. The results reveal that by homogenous hydrolysis of acid mine drainage with urea, it is possible to prepare easily filterable relatively pure oxide precipitates w...

Journal of Chemical Technology and Biotechnology, 1998

ABSTRACT Screening of a representative series of immobilized penicillin G acylase biocatalysts (e... more ABSTRACT Screening of a representative series of immobilized penicillin G acylase biocatalysts (enzyme, cells) using enzyme flow microcalorimetry is described. Immobilized penicillin G acylase biocatalysts were either prepared in the laboratory by various techniques or obtained from four commercial manufacturers. An industrial strain of Escherichia coli was entrapped in (poly)acrylamide gel or hardened calcium pectate gel. Semi-purified enzyme was immobilized in various ways—either by covalent binding to oxirane-acrylic beads or chlorotriazine bead cellulose or by entrapment in (poly)acrylamide gel. The validity of the enzyme flow microcalorimetry results was corroborated by a pH-stat method, showing enzyme flow microcalorimetry to be a suitable method for rapid screening of immobilized biocatalysts regardless of the immobilization technique, carrier type or the biocatalyst source. © 1998 Society of Chemical Industry