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The kinetic reduction of Cr(VI) by yeast Saccharomyces cerevisiae, Phaffia rhodozyma and their protoplasts

100%
Chwastowski J., Kołoczek H.
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2013
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vol. 60
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issue 4
829-834
EN
Chromium in the sixth oxidation state may easily penetrate cellular membranes via non-specific sulfate transporters due to its tetrahedral symmetry (high similarity to SO42- and HPO42-). This feature makes chromium a toxic and hazardous pollutant responsible for the deterioration of midland water quality. The aim of the study was to evaluate the capacity of two yeast species - Saccharomyces cerevisiae and Phaffia rhodozyma - and their protoplasts to reduce Cr(VI) to lower oxidation states. The study also deals with the behavior of the yeasts upon the presence of elevated sulfate ions as a competitive inhibitor of chromate transport by the sulfate transporters. The chromate-reducing activities were monitored by determination of Cr(V) free radical form with the use of L-band (1.2 GHz) EPR (electron paramagnetic resonance) spectroscopy. It was observed that both of the studied yeast strains exhibited the ability to reduce Cr(VI) applied at 4 mM. The cells of P. rhodozyma showed about 3.5 times higher reduction than S. cerevisiae. The reduction efficiency was significantly improved when the protoplasts of both strains were used and reached 100% in the first 10 minutes of the reduction process which suggests that the cellular wall may have a notable influence on the uptake and/or inhibition of chromium reduction process. The reduction effect of P. rhodozyma cells and protoplasts may be associated with the more sufficient production of metabolites (such as glutathione and cysteine), which may also be responsible for the increased tolerance of the strain towards high concentrations of toxic chromium.
2
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Computer modelling of human α^1-antitrypsin reactive site loop behaviour under mild conditions

81%
Kołoczek H., Jezierski G., Pasenkiewicz-Gierula M.
Acta Biochimica Polonica
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1996
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vol. 43
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issue 3
467-474
3
Content available remote

Immunological discrimination of diverse forms of human α^1-proteinase inhibitor

70%
Wawrzos I., Kitagawa Y., Kołoczek H.
Acta Biochimica Polonica
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1996
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vol. 43
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issue 3
481-487
4
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Methylotrophic extremophilic yeast Trichosporon sp.: a soil-derived isolate with potential applications in environmental biotechnology

61%
Kaszycki P., Czechowska K., Petryszak P., Międzobrodzki J., Pawlik B., Kołoczek H.
|
2006
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vol. 53
|
issue 3
463-473
EN
A yeast isolate revealing unique enzymatic activities and substrate-dependent polymorphism was obtained from autochthonous microflora of soil heavily polluted with oily slurries. By means of standard yeast identification procedures the strain was identified as Trichosporon cutaneum. Further molecular PCR product analyses of ribosomal DNA confirmed the identity of the isolate with the genus Trichosporon. As it grew on methanol as a sole carbon source, the strain appeared to be methylotrophic. Furthermore, it was also able to utilize formaldehyde. A multi-substrate growth potential was shown with several other carbon sources: glucose, glycerol, ethanol as well as petroleum derivatives and phenol. Optimum growth temperature was determined at 25°C, and strong inhibition of growth at 37°C together with the original soil habitat indicated lack of pathogenicity in warm-blooded animals and humans. The unusually high tolerance to xenobiotics such as diesel oil (>30 g/l), methanol (50 g/l), phenol (2 g/l) and formaldehyde (7.5 g/l) proved that the isolate was an extremophilic organism. With high-density cultures, formaldehyde was totally removed at initial concentrations up to 7.5 g/l within 24 h, which is the highest biodegradation capability ever reported. Partial biodegradation of methanol (13 g/l) and diesel fuel (20 g/l) was also observed. Enzymatic studies revealed atypical methylotrophic pathway reactions, lacking alcohol oxidase, as compared with the conventional methylotroph Hansenula polymorpha. However, the activities of glutathione-dependent formaldehyde dehydrogenase, formaldehyde reductase, formate dehydrogenase and unspecific aldehyde dehydrogenase(s) were present. An additional glutathione-dependent aldehyde dehydrogenase activity was also detected. Metabolic and biochemical characteristics of the isolated yeast open up new possibilities for environmental biotechnology. Some potential applications in soil bioremediation and wastewater decontamination are discussed.
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