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The Ochtinska Aragonite Cave became well-known due to its unique decoration created by fruticose-like aggregates of crystalline aragonite. The cave is located in the cadastral territory of the village of Ochtiná on the west side of the Hrádok Mt. that belongs to the Slovenské Rudohorie Mts. During the opening season the cave is frequented. In the last period, an increased amount of CO2 has been detected in air of the Ochtinska aragonite cave. The cave environment is created by caverns - relicts after mouldered ankerites and siderites in surroundings of Palaeozoic slates, limestones and dolomites. The residual ochre loams were created by weathering of carbonates. Probably, these processes held up till now and this fact may also result in the liberation of CO2. From the viewpoint of the enhanced CO2 content, the earths and waters occurred in the cave were found as its possible source. An enhanced CO2 content was also measured in old air-proof closed mine workings, with a possibility of rot processes of old organic mine working components. Probably, has the rich attendance of the cave during the season the highest influence on the enhanced CO2 content. The measurements of CO2 content have pointed to its different values in various periods. In the period without visits, the CO2 content in the cave exceeds that in the external surrounding air by 3-4 times, i. e. 310 330 ppm. In the period of visits, it is 8 10 times. Thus, the CO2 content in the cave depends on the number of visits. Up till now, no influence of the CO2 content variation on the unique karstic forms and the health status of the cave staff was not proven.

Hydrofóbnos a náboj buneènej steny sú rozhodujúce faktory poèiatoèného tádia adhézie baktérií na tuhé povrchy. Hydrofóbnos bakteriálnych buniek sa posudzuje najmä dvoma spôsobmi. Ako prvý spôsob, umoòujúci kvalitatívne urèenie hydrofóbnosti, sa vyuíva sledovanie adsorpcie iónogénnych surfaktantov, resp. elektroforetickej pohyblivosti ktorá ju sprevádza. Druhým spôsobom semikvan-titatívneho stanovenia hydrofóbnosti buniek je testovanie ich interakcie s kvapalnými uh¾ovodíkmi v tzv. BATH teste (Bacterial Adhesion To Hydrocarbons). Stanovenie hydrofóbnosti pouitím BATH testu je vak komplikované z dôvodu spolupôsobenia elektrostatickej interakcie, ktorú môme opä odhadnú z elektroforetickej pohyblivosti buniek.Cie¾om práce bolo posúdi hydrofóbnos buniek Thiobacillus ferrooxidans oboma uvedenými spôsobmi zvlá a v kombinácii, tj. BATH test bol uskutoènený v prítomnosti surfaktantov a súèasne bola meraná elektroforetická pohyblivos buniek metódou ELS (Electrophoretic Light Scattering). V neprítomnosti surfaktantov bola zistená záporná elektroforetická pohyblivos (náboj) a silná hydro-filnos povrchu baktérií. V prítomnosti katiónaktívneho surfaktantu (CTAB) sa v dôsledku jeho postupnej adsorpcie elektroforetická pohyblivos zniovala (dokonca pri vysokých koncentráciách prechádzala do kladných hodnôt). Súèasne sa indukovala hydrofóbnos buniek. Po prekroèení urèitej CTAB koncentrácie sa vak hydrofóbnos zaèala zniova, hoci elektroforetická pohyblivos bola stále na zostupe (èo svedèí o neustávajúcom raste adsorpcie CTAB). To svedèí o adsorpcii CTAB katiónov s polárnymi skupinami orientovanými smerom k povrchu buniek a hydrofóbnymi reazcami smerom do roztoku pri nízkych koncentráciách CTAB a o opaènej orientácii pri vyej koncentrácii CTAB. Po pridaní aniónaktívneho surfaktantu (SDS) k adsorpcii nedolo, o èom svedèí iba mierne zvýenie zápornej elektroforetickej pohyblivosti a skoro vôbec neovplyvnená pôvodná hydrofilnos buniek.Na základe toho môme predpoklada, e elektrostatické interakcie ovplyvòujú hydrofilnos/hydrofóbnos buniek T. ferrooxidans BATH testom iba v malej miere.

The surface charge and surface potential are parameters influencing the microbial adhesion phenomenon through the electrostatic interaction between bacteria and substrates. The Smoluchowski equation, originally developed for estimating the above parameters from the experimentally accessible electrophoretic mobility of rigid colloid particles, is however inapplicable to the elastic bacterial cells. The problem is that the outer cell wall of bacteria is a layer with a complex polyelectrolyte structure. In this article, the OhshimaLs model of the gsofth particle is applied to describe the surface electrostatics of Thiobacillus ferrooxidans cells by measuring their electrophoretic mobility in distilled water as a function of a (low) ionic strength and pH. In this model, the rigid core is considered to be covered with a charged ion-penetrable layer of polyelectrolytes. Two model parameters have been determined by the curve fitting at pH from 3.2 to 5.8, namely the number density of the dissociated groups N and the softness parameter 1/É of the polyelectrolyte layer of the bacterium. A disagreement of the best fit parameters (evaluated by the correlation coefficient) with the analogous parameters determined for other colloids (including bacterial cells) in aqueous solutions of a high ionic strength is discussed.

To explain the selective microbial adhesion of Thiobacillus ferrooxidans on pyrite, zeta potential of both the bacterium cells and the mineral was measured using the electrophoretic light scattering (ELS) technique. Simultaneously, relative hydrophobicity of the cells and the mineral was determined by the liquid-liquid partition (BATH) test and the thin-layer wicking method (TLW), respectively. Heteroaggregation of the cells with the pyrite particles has been evaluated qualitatively from the ELS spectra provided by their mixtures at different pH and interpreted in terms of the Lifshitz-van der Waals and acid-base surface thermodynamics model of microbial adhesion

For coal utilization the sulphur content is a decisive parameter for the quality of the coal. In many countries clean coal technologies have to be applied on the basis of regulations concerning fuel quality and emission standards for dust, CO, SO2 and NOx in the flue gas. It becomes quite obvious that it is always preferable to keep the sulphur levels in coal at a minimum. Bacterial oxidation of the sulphur present in coal could well be thought of as an effective alternative.Desulphurization by bacteria Thiobacillus ferrooxidans was applied to coal sample from Sokolov mine. Bacteria growing in batch culture on ferrous iron at initial pH 1.6 were harvested at the later growth phase. The ferric iron precipitates were separated from the cells by centrifugation and the rest medium by membrane filtration. Cell pellet captured on the filter was washed by hydrochloric acid and distilled water and finally suspended in fresh Waksmann & Joffe medium. The medium was previously acidified by 5M H2SO4 to pH 2. Initial concentration of sulphates in medium was 1.8 g L-1. Desulphurization of coal was studied in a stirred batch reactor at 10% w/v pulp density in diluted H2SO4 at pH = 2.The effect of bacterial leaching on mineral and organic matter of coal was followed by optical microscopy. Petrographic evaluation of the coal matter samples consisted of the determination of reflectance of gelified huminite macerals (R0), determination of maceral group contents of huminite, liptinite, inertinite and determination of the mineral content with emphasis on the various forms of iron sulphides. The sample examined were brown coal with higher liptinite and pyrite contents. The huminite reflectance of 0,33 % is corresponding to the lignitic metatype. Huminite concentration is 65,7 % and is the most abundant maceral group. The maceral ulminite and densinite contributes to the high huminite content. The concentration of attrinite, who be pass to liptodetrinite, textinite, gelinite and corpohuminite contents does not exceed 5 %. The maceral composition of liptinite was determined by a fluorescence measurement. The remaining liptinite macerals, i.e. liptodetrinite and bituminite, resinite, cutinite and fluorinite are accessories. The content of inertinite (fusinite, sklerotinite and inertodetrinite) is low (4,5 %).Coal contains sulphur in inorganic form (mainly pyrite and marcasite) and sulphur in organic form. Biological lixiviation has caused relatively significant change in FeS2, in some cases full or part elimination of dispersed framboids at mineralised detrite as well as at huminite macerals resulting in empty holes and hudge FeS2 grains were slightly disintegrated at the surface or dike - pyrite was relased irregularly after lixiviation.

V nadväznosti na flotáciu pyritu v uhlí sú zhrnuté súèasné poznatky o vplyve fyzikálno-chemických vlastností buneènej steny baktérie Thiobacillus ferrooxidans na jej adhéziu na povrch rôznych minerálov a uhlia. Aplikovaním modelu mikrobiálnej adhézie (kvarla, J. Chem. Soc. Faraday Trans., 89, 1993, p. 2913-2921) a vyuitím známych parametrov vstupujúcich do tohoto modelu bolo zistené, e k (reverzibilnej) adhézii T. ferrooxidans dochádza spravidla v sekundárnom minime. Pre posúdenie monosti vyuitia tohoto modelu na objasnenie selektívneho prichytenia T. ferrooxidans na pyrit je vak potrebné doplni chýbajúce údaje vstupujúce do tohoto modelu.

The abilities of microorganisms to mineralize a wide range of pollutants are well known. Biological processes for the removal of crude oil hydrocarbons from environment are attractive because they consume less energy than conventional physico-chemical processes and offer possibilities for recycling chemicals in the framework of integrated system.