Characterization of sulfate-reducing bacteria in yeast industry waste by microcalorimetry and PCR amplification

Sulfate-reducing bacteria (SRB) were isolated from anaerobic sludge of yeast factory wastewater treatment plant by cultivation on Postgate C medium. Microcalorimetry was used to monitor the anaerobic digestion processes and to measure the growth rates of sulfate-reducing bacteria. The maximum growth rates determined by microcalorimetry and ATP analysis were different—μ_max(dQ/dt) = 0.165 ± 0.008 h⁻¹ and μ_max(N_ATP) = 0.207 ± 0.013 h⁻¹. Experiments on the cultivation of SRB from yeast industry wastewater treatment plant in batch culture showed that during the first 20 h the concentration of sulfate decreased from 78.3 mM down to 62.2 mM while the increase of sulfide production was negligible. Perceptible amount of sulfide (7.82 mM) appeared on the 33.5 h of fermentation together with a peak on the power–time curve and considerable increase in the cell count (1.26 × 10⁹). First steps of sulfate metabolism (activation of sulfate by ATP sulfurylase, production of H₂) are accompanied by endothermic heat effects, therefore the values of thermal power remain moderate until the evolution of sulfide starts. The influence of green microalgae Chlorococcum sp. (preparation Biotreat 100) on the growth characteristics of microorganisms was also studied. Identification of one SRB strain was started by sequencing of PCR-amplified 16S rRNA gene. Two sets of primers were used for PCR amplification, both specific for domain Bacteria but giving different gene fragments. PCR-products were purified with JETQUICK kit according to the manufacturer instructions.     

Über die Wahl der Lösungsmittelsysteme bei der papierchromatographischen Trennung organischer Verbindungen

Zusammenfassung An praktischen Beispielen wurde gezeigt, in welcher Weise die Trennung organischer Verbindungen mittels Papierchromatographie erzielt werden kann. Man ist nicht auf einige bewährte Lösungsmittel systeme allein angewiesen, sondern kann von Fall zu Fall systematisch neue und geeignete Systeme benützen. Es hat sich bewährt, sich nach den elementaren Löslichkeitsregeln für organische Stoffe zu richten, unter der Voraussetzung, daß die zu chromatographierende Verbindung in der stationären Phase gut, in der mobilen Phase dagegen weniger löslich ist. Durch Änderung der stationären Phase (Wasser, nicht wäßriges, polares Lösungsmittel, nicht polares Lösungsmittel) oder der Polarität und Zusammensetzung der mobilen Phase kann man das Wandern der Flecke am Chromatogramm beeinflussen, beliebige R_fWerte erhalten und in vielen Fällen auch eine beliebige Reihenfolge der Verbindungen am Chromatogramm erzielen.Da die Löslichkeit organischer Verbindungen von intermolekularen Kräften abhängig ist, erscheint das Problem im Zusammenhang mit strukturellen Einflüssen sehr kompliziert und muß für jeden Fall auf eigene Weise gelöst werden. Die Löslichkeitseigenschaften können weiter durch Benutzung reaktiver Lösungsmittel beeinflußt werden, die z. B. die Verbindungen in wasserlösliche Salze überführen können. Dabei ist an die möglichen Komplikationen, die bei ionisierbaren Verbindungen durch Dissoziation und Hydrolyse entstehen können, zu achten.Von den Hauptfaktoren, die eine Trennung ermöglichen können, seien die folgenden erwähnt: funktionelle Gruppen, ihre Anzahl, Polarität, gegenseitige Stellung, bzw. ihre Basizität oder Azidität, C-Atomanzahl in homologen Verbindungen, inter- und intramolekulare Wasserstoffbindungen, sterische Faktoren u. a. Es ist dann von der Art des gewählten Lösungsmittelsystems abhängig, welche der genannten Faktoren im Vordergrund stehen und welche beseitigt werden.Wenn die Löslichkeitsunterschiede der zu trennenden Stoffe zu gering sind, um gute Trennungen zu ermöglichen, ist es zweckmäßig, die Verbindungen in solche Derivate zu überführen, deren Strukturunterschiede größer sind.

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Summary Practical examples are given to show how organic compounds can be separated by means of paper chromatography. The operator is not limited to tested solvent systems, but can use new suitable systems as the occasion demands. It has been found best to abide by the elementary rules of solubility of organic compounds, provided the compound to be chromatographed is quite soluble in the stationary phase but less soluble in the mobile phase. By altering the stationary phase (water, nonaqueous, polar solvent, non-polar solvent) or the polarity and composition of the mobile phase, the migration of the stains in the chromatogram can be influenced, selectedR _f -values can be obtained, and in many cases it is also possible to secure a desired succession of the compounds on the chromatogram.Since the solubility of organic compounds depends on intermolecular forces, the problem in connection with structural influences appears very complicated and must be solved individually for each case. Moreover, the solubility characteristics can be affected by using reactive solvents; for instance, the compounds can be converted into water soluble salts. Under such circumstances, sight must not be lost of the complications which may arise because of the dissociation and hydrolysis of ionizable compounds. The following are among the chief factors, which may make a separation possible: functional groups, their number, polarity, relative position, their basicity or acidity, C-atom number in homologous compounds, inter- and intramolecular hydrogen bonds, steric factors, etc. It then depends on the type of solvent system selected, which of these factors are predominant and which can be neglected or eliminated.If the solubility differences are too slight to permit good separations, the compounds to be separated should, if possible, be converted into derivatives whose structural differences are more pronounced.

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Résumé Des exemples pratiques montrent comment il est possible d'effectuer la séparation de combinaisons organiques par Chromatographie sur papier. Il n'est pas uniquement fait appel à des systèmes de solvants éprouvés mais, dans certains cas, de nouveaux systèmes appropriés sont systématiquement utilisés.Il s'est avéré satisfaisant de faire appel aux règles élémentaires de solubilité des substances organiques sous réserve que la combinaison à chromatographier soit suffisamment soluble dans la phase stationnaire et moins soluble dans la phase mobile. En faisant varier la phase stationnaire (eau, solvant non aqueux, solvant polaire, solvant non polaire) ou la polarité et la composition de la phase mobile, il est possible d'influencer la migration des taches du chromatogramme, d'obtenir des valeurs deR _f désirées et, dans de nombreux cas, d'obtenir les combinaisons dans un ordre déterminé sur le chromatogramme.La solubilité des combinaisons organiques étant fonction des forces intermoléculaires il en résulte que le problème se complique considérablement dans la mesure où l'on considère les influences structurelles et que chaque cas particulier doit recevoir une solution qui lui est propre. Les propriétés de solubilité peuvent en outre être influencées par l'emploi de solvants réactifs qui peuvent transformer, par exemple les combinaisons en sels solubles dans l'eau. Il faut alors tenir compte des possibilités de complications qui peuvent apparaître par dissociation et hydrolyse des combinaisons ionisables.Parmi les principaux facteurs qui permettent une séparation, il convient de mentionner les suivants: les groupes fonctionnels, leur nombre, leur polarité, leur position relative, ou encore leur acidité ou leur basicité, le nombre d'atomes de carbone de combinaisons homologues, les liaisons hydrogène inter- et intramoléculaires, les facteurs stériques, etc. Suivant la nature du système solvant choisi pourront alors varier les facteurs dont l'effet est prépondérant et ceux dont l'effet est nul. Lorsque les différences de solubilité des substances à séparer sont trop faibles pour permettre des séparations satisfaisantes, il est commode de transformer les combinaisons en dérivés dont les différences de structure soient plus importantes.

     

Metal-catalyzed di-tert-butylsilylene transfer: synthesis and reactivity of silacyclopropanes

Metal-catalyzed di-tert-butylsilylene transfer was developed as a mild, operationally simple, functional-group-tolerant method for silacyclopropane formation. Di-tert-butylsilylene was transferred from cyclohexene silacyclopropane 1 to an alkene through the use of a metal salt. Silacyclopropanation occurred at temperatures as low as -27 degrees C when AgOTf or AgOC(O)CF(3) were used as catalysts. Complex silacyclopropanes were formed stereospecifically and diastereoselectively from functionalized alkenes. Silacyclopropanes reacted with various carbonyl compounds, including aldehydes, ketones, formate esters, and formamides, in an overall process that efficiently converts alkenes into oxasilacyclopentanes with defined stereochemistry.     

Cobalt(II) Chloride Complex Formation in Acetamide–Calcium Nitrate Tetrahydrate Melts

The absorption spectra of Co(II) chloride complexes, containing variable concentrations of chloride ligand, in a molten mixture of 80 mol% acetamide–20 mol% calcium nitrate tetrahydrate, were studied at 313, 333, 353, and 363 K, in the wavelength range 400-800 nm. The melt contains three possible ligands (CH₃CONH₂, H₂O, and NO₃ ^-) for competition with added chloride ligand. Addition of chloride caused a shift of the absorption maximum of octahedral cobalt(II) nitrate towards lower energies and pronounced changes in the shape of the initial spectrum of cobalt(II) nitrate. The effect of temperature changes on the molar absorption coefficient of the Co(II) species was dependent on the chloride concentration and was attributed to the structural changes occurring in the cobalt(II) species. The STAR and STAR FA programs were applied to identify the complex ionic species and to calculate the stability constants of Co(II) complexes formed in this solvent. The results indicate the highest probability of formation of the following complex species: Co(NO₃)₄ ^2-, Co(NO₃)₂Cl₂ ^2-, and CoCl₄ ^2-. Stability constants of each complex were presented for the equilibria occurring at 313, 333, 353, and 363 K. Distribution of the Co(II) species was also calculated over the ranges of chloride concentration and temperature investigated.     

Selective pervaporation of water through a nonselective microporous titania membrane by a dynamically induced molecular sieving mechanism

Pervaporation experiments were performed on microporous titania membranes using several binary liquids containing 2-20 wt % water. The membrane was nonselective in the separation of water from alcohols and p-dioxane but showed a remarkably high selectivity in the separation of water from ethylene glycol/water mixtures with < or =15 mol % water. The absence of selectivity under most conditions is explained by the large pore size (0.9 nm) of microporous titania. The high selectivity for water in the separation from ethylene glycol can be explained by the formation of a hydrogen-bonded network of ethylene glycol in the micropores, which blocks transport of ethylene glycol, while water can still permeate through. These networks are disrupted by water at higher concentrations, leading to full loss of membrane selectivity.     

Continuous chemiluminescence determination of formaldehyde in air based on Trautz-Schorigin reaction

A new continuous method for the determination of formaldehyde in air is described. A cylindrical wet effluent diffusion denuder is used for the collection of formaldehyde from air into a thin film of absorption liquid (distilled-deionized water). Formaldehyde in the denuder concentrate is on-line detected employing a chemiluminescence flow method based on a reaction of formaldehyde and gallic acid with hydrogen peroxide in an alkaline solution. The collection efficiency of formaldehyde is quantitative at the air flow rate of 0.5 L min⁻¹ (absorption liquid flow rate of 336 μL min⁻¹). The limit of detection (S/N = 3) is 0.60 μg m⁻³ HCHO (0.49 ppb). The calibration graph is linear up to 300 μg m⁻³ HCHO (244 ppb). The relative standard deviations of chemiluminescence method for 1 × 10⁻⁶ and 5 × 10⁻⁶ M HCHO are 2.87% and 1.49%, respectively. Acetaldehyde interferes negligible, other compounds do not interfere. The method was employed for formaldehyde measurement in ambient air. The comparison measurement illustrates the good agreement of results obtained by proposed method with those obtained by reference fluorimetric method.     

Studies on adhesion characteristics and corrosion behaviour of vinyltriethoxysilane/epoxy coating protective system on aluminium

The corrosion stability of vinyltriethoxysilane/epoxy coating protective system on aluminium is strongly related to the strength of bonds forming at the metal/organic coating interface. This article is a study of adhesion, composition, electrochemical and transport properties of epoxy coatings electrodeposited on bare aluminium and aluminium pretreated by vinyltriethoxysilane (VTES) during exposure to 3% NaCl. The VTES film was deposited on aluminium surface from 2% vinyltriethoxysilane solution during 30 s. From the values of adhesion strength (pull-off test), time dependence of pore resistance and coating capacitance of epoxy coating (impedance measurements) and diffusion coefficient of water through epoxy coating (gravimetric liquid sorption measurements), the influence of VTES sublayer on the corrosion stability of the electrodeposited epoxy coating was shown.The work discusses the role of the VTES pretreatment in the enhanced adhesion and corrosion stability of epoxy cataphoretic coating. The electrochemical results showed that the aluminium pretreatment by VTES film improved barrier properties of epoxy coating (greater pore resistance and lower coating capacitance). The lower value of diffusion coefficient of water through epoxy coating indicates the lower porosity, while the smaller adhesion reduction points to better adhesion of epoxy coating on aluminium pretreated by VTES film. The composition of the deposited coatings investigated by XPS enabled the clarification of the bonding mechanism.     

Study of flame-retardant finishing of cellulose fibres: Organic–inorganic hybrid versus conventional organophosphonate

The aim of this study was to introduce a non-formaldehyde inorganic–organic hybrid sol–gel flame-retardant precursor (SiOP) containing phosphorous, nitrogen, and silicon and to compare its functional properties with those of the conventional formaldehyde-containing organic flame-retardant agent, organophosphonate (OP). SiOP was used at concentrations of 2%, 4%, and 8%, and OP was used at a concentration of 200 g/dm³. Both agents were applied to 100% cotton (CO) woven fabric by the pad-dry-cure method under the appropriate conditions. The presence of the SiOP and OP coatings on the CO fabric was confirmed by scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy. The results of the vertical tests of flammability and the thermogravimetric analyses showed that the presence of the SiOP coating changed the thermal degradation pathway of the CO fabric and resulted in an increase in the thermo-oxidative stability of the cellulose fibres. The thermo-oxidative stability was enhanced by the addition of higher amount of dry solids. At comparable dry solids contents, OP preserved significantly greater flame retardancy and thermo-oxidative stability than did SiOP. These results indicated that the SiOP precursor could not act as an effective alternative to the OP agent in the flame-retardant protection of CO fabric.     

Lattice Boltzmann simulation of two-sided lid-driven flow in a staggered cavity

In this article, the lattice Boltzmann method is employed in order to explore incompressible fluid flow inside a two-sided lid-driven staggered cavity. Results of the lattice Boltzmann simulation for antiparallel motion of lids are compared with the data from existing literature. For parallel motion of lids, the characteristics of flow pattern for a variety of Re numbers (50–3200) are presented. An asymmetric steady-state flow pattern for parallel motion of lids is obtained.