| 1. |
- Plekhanova, Yu V., et al.
(författare)
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Biosensor Monitoring of Microbial Treatment of Wastewater from Nonylphenol Polyethoxylates under Flow-through Conditions
- 2011
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Ingår i: Applied Biochemistry and Microbiology. - 0003-6838. ; 47:9, s. 846-851
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Tidskriftsartikel (refereegranskat)abstract
- Biodegradation of nonylphenol polyethoxylates (NPEO) has been studied in laboratory column bioreactors with a polyethylene carrier on which destructor bacteria of Pseudomonas surface-active compounds were immobilized. To monitor the efficiency of microbial treatment of model wastewater, a biosensor based on the oxygen Clark electrode and destructor bacteria of NPEO from bioreactors was designed. The designed biosensor allowed us to detect the content of polyethylene glycol monoalkyl phenyl ether on the basis of polymer distillate (OP-10), which is a commercial NPEO preparation, in samples in the range of 1-200 mg/l. Operation of the biosensor was stable within 7 days with the standard deviation of 1.35 mg/l for 20 consecutive measurements of OP-10 concentration, which was 20 mg/l (7%).
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| 2. |
- Pristavka, AA, et al.
(författare)
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Enzyme recovery in high-solids enzymatic hydrolysis of steam-pretreated willow: Requirements for the enzyme composition
- 2000
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Ingår i: Applied Biochemistry and Microbiology. - 0003-6838. ; 36:3, s. 237-244
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Tidskriftsartikel (refereegranskat)abstract
- In order to reduce the total enzyme consumption in high-solids static hydrolysis of nonwashed steam-exploded willow Salix caprea by mixed cellulase of Trichoderma reesei + Aspergillus foetidus, two different approaches were proposed. In the first case, the enzyme activity adsorbed on residual solids after extended hydrolysis was used for hydrolysis of the newly added substrate. The initial mixing of fresh and hydrolyzed substrates was sufficient for the adsorbed enzyme redistribution and conversion of the new substrate portion, and constant mechanical stirring was not required. Feeding of two additional portions of the exploded hardwood adjusted to pH 4 with dry caustic into the reactor with simultaneous replacement of accumulated sugars with fresh buffer (pH 4.5) resulted, on average, in a 90% conversion of cellulose at the final enzyme loading of 8 IFPU per g ODM substrate, an average sugar concentration of 12%, and a glucose/xylose ratio of 5 : 1. In the second approach, weakly adsorbed cellulase fractions were used for static high-solids hydrolysis followed by their ultrafiltration recovery from the resultant sugar syrup. In contrast to the initial cellulase mixture whose residual activity in a syrup did not exceed 5-10% at the end of hydrolysis (48 h), up to 60% of weakly adsorbed enzyme fraction could be separated from sugar syrups by ultrafiltration and then reused. Weakly adsorbed enzymes displayed a hydrolysis efficiency of not less than 80% per IFPU enzyme consumed in extended hydrolysis of pretreated willow as compared to the original enzyme mixture. An electrophoretic study of the weakly adsorbed enzyme fraction identified T. reesei cellobiohydrolase II as the predominant component, whereas clear domination of T. reesei cellobiohydrolase I was found by electrophoresis of proteins tightly bound to residual hydrolysis solids.
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| 3. |
- Pristavka, A, et al.
(författare)
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High-solids enzymatic hydrolysis of steam-exploded willow without prior water washing
- 2000
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Ingår i: Applied Biochemistry and Microbiology. - 0003-6838. ; 36:2, s. 101-108
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Tidskriftsartikel (refereegranskat)abstract
- A laboratory reactor equipped with a screw press was used for the hydrolysis of steam-SO2-exploded willow Salix caprea by a composition of Trichodemma reesei and Aspergillusfoetidus enzyme preparations at high substrate concentration. Optimal conditions providing the maximal volume of hydrolysis syrup with maximal sugar concentrations were determined. Two different hydrolysis procedures were developed in order to exclude the initial washing of steam-pretreated plant raw material by large volumes of water, which was necessary to eliminate the inhibitory effect of explosion byproducts on enzymatic hydrolysis. The first procedure included enzymatic prehydrolysis of the substrate for 1 h; separation of sugar syrup containing 40-60 g/l glucose, 20-25 g/l xylose, and up to 10 g/l disaccharides, as well as up to 35% of the initial enzymatic activity; then addition of a diluted acetate buffer (pH 4.5); and subsequent hydrolysis of the substrate by the adsorbed enzymes leading to the final accumulation of up to 140 g/l glucose and up to 15 g/l of xylose. In the second scenario, the exploded willow was initially adjusted by alkali to pH 4.5 and then hydrolyzed directly by the added enzymes over 24 h. This Procedure resulted in a nearly total polysaccharide hydrolysis and accumulation of up to 170 g/l glucose and 20 g/l xylose. The reasons for inhibition of enzymatic hydrolysis are discussed.
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| 4. |
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| 5. |
- Taranova, L A, et al.
(författare)
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Comamonas testosteroni strain TI as a potential base for a microbial sensor detecting surfactants
- 2004
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Ingår i: Applied Biochemistry and Microbiology. - 0003-6838. ; 40:4, s. 404-408
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Tidskriftsartikel (refereegranskat)abstract
- Strain Comamonas testosteroni TI, capable of degrading the nonionic surfactant (NIS) nonylphenolethoxylate (OP-10), was used for constructing a pilot cellular biosensor. The lower NIS detection limit for the biosensor was 0.25 mg/l. We studied the substrate specificity of the biosensor with respect to a wide range of organic compounds: surfactants, polyaromatic compounds (PAC), carbohydrates, alcohols, etc. It was shown that the biosensor based on Comamonas testosteroni TI did not respond to glucose, which was an advantage over the formerly described biosensor based on Pseudomonas rathonis T. The amplitude of the sensor response remained stable for 10 days.
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