Frankfurt am Main, Germany
Frankfurt am Main, Germany

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Schmidt I.,Karl Winnacker Institute | Schewe H.,Karl Winnacker Institute | Gassel S.,Goethe University Frankfurt | Jin C.,Goethe University Frankfurt | And 4 more authors.
Applied Microbiology and Biotechnology | Year: 2011

The oxygenated β-carotene derivative astaxanthin exhibits outstanding colouring, antioxidative and health-promoting properties and is mainly found in the marine environment. To satisfy the growing demand for this ketocarotenoid in the feed, food and cosmetics industries, there are strong efforts to develop economically viable bioprocesses alternative to the current chemical synthesis. However, up to now, natural astaxanthin from Haematococcus pluvialis, Phaffia rhodozyma or Paracoccus carotinifaciens has not been cost competitive with chemically synthesized astaxanthin, thus only serving niche applications. This review illuminates recent advances made in elucidating astaxanthin biosynthesis in P. rhodozyma. It intensely focuses on strategies to increase astaxanthin titers in the heterobasidiomycetous yeast by genetic engineering of the astaxanthin pathway, random mutagenesis and optimization of fermentation processes. This review emphasizes the potential of P. rhodozyma for the biotechnological production of astaxanthin in comparison to other natural sources such as the microalga H. pluvialis, other fungi and transgenic plants and to chemical synthesis. © 2010 Springer-Verlag.


Donchev A.,Karl Winnacker Institute | Schutze M.,Karl Winnacker Institute | Kolitsch A.,Helmholtz Center Dresden | Yankov R.,Helmholtz Center Dresden
Ti 2011 - Proceedings of the 12th World Conference on Titanium | Year: 2012

Oxygen inward diffusion into standard Ti-alloys during high temperature exposure in oxygen containing environments leads to an oxygen enriched surface zone which is detrimental under mechanical load. Therefore, the operating temperature of these alloys is limited. An enrichment of Al in the surface zone of Ti-alloys leads to an improvement by the formation of intermetallic Ti sAly-phases with decreased oxygen solubility but this is not sufficient. Therefore, the combination of Al-enrichment in the surface zone to an extent that a TiAlTayer is formed and an additional F-treatment is proposed for the formation of a continuous stable alumina scale which prevents oxygen inward diffusion. In this paper the results of high temperature exposure tests in air of several Ti-alloys are presented without any treatment and treated with combined Al-enrichment plus fluorination. Post experimental investigations such as SEM revealed the formation of thin alumina layers on treated samples. Hardness measurements showed that no embrittlement was observed for the treated samples while untreated specimens showed increased hardness values corresponding with the oxygen diffusion profile in the subsurface zone.


Pashkova A.,University of Duisburg - Essen | Pashkova A.,Karl Winnacker Institute | Seisel S.,University of Duisburg - Essen | Seisel S.,Ruhr University Bochum
Zeitschrift fur Physikalische Chemie | Year: 2010

In this study the interaction of NO2 with ethylene soot particles has been studied in a temperature from 300 to 670 K and NO2 concentrations ranging from 5.1010 molecules cm-3 to 5.1012 molecules cm-3. The adsorption of NO2 takes place in the whole temperature range studied with a mean initial uptake coefficient of (5.9±1.0).10-2 independent of temperature and gas phase concentration. At low temperatures HONO and NO are formed as gas phase products. At higher temperatures NO and CO2 have been observed as gaseous products indicating the oxidation and gasification of soot. For the NO and CO2 forming reaction an activation energy of EA = (44.7±8.2).kJ molK1 has been determined. © by Oldenbourg Wissenschaftsverlag.


PubMed | Karl Winnacker Institute
Type: Journal Article | Journal: Applied microbiology and biotechnology | Year: 2011

The oxygenated -carotene derivative astaxanthin exhibits outstanding colouring, antioxidative and health-promoting properties and is mainly found in the marine environment. To satisfy the growing demand for this ketocarotenoid in the feed, food and cosmetics industries, there are strong efforts to develop economically viable bioprocesses alternative to the current chemical synthesis. However, up to now, natural astaxanthin from Haematococcus pluvialis, Phaffia rhodozyma or Paracoccus carotinifaciens has not been cost competitive with chemically synthesized astaxanthin, thus only serving niche applications. This review illuminates recent advances made in elucidating astaxanthin biosynthesis in P. rhodozyma. It intensely focuses on strategies to increase astaxanthin titers in the heterobasidiomycetous yeast by genetic engineering of the astaxanthin pathway, random mutagenesis and optimization of fermentation processes. This review emphasizes the potential of P. rhodozyma for the biotechnological production of astaxanthin in comparison to other natural sources such as the microalga H. pluvialis, other fungi and transgenic plants and to chemical synthesis.

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