Pichia stipitis

An acyclic enone, 2-ethyl-l-phenylprop-2-en-l-one, was reduced with the yeast Pichia stipitis CCT 2617 [19cj. The reduction proceeded chemo- and enantioselec-tively to afford (S)-2-ethyl-l-phenylprop-2-en-l-ol (65% yield, >99% ee). XAD-7 was used to decrease and control the concentration of both the substrate and the product (Figure 8.25). 

Figure 8.25 Reduction of ketone with Pichia stipitis n the presence of hydrophobic polymer XAD [19cj.

Den Haan, R. Van Zyl, W. H. (2003). Enhanced xylan degradation and utilisation by Pichia stipitis overproducing fungal xylanolytic enzymes. Enzyme and Microbial Technology, Vol. 33, 5, (October 2003), pp. (620-628), ISSN 0141-0229... 

Candida shehatae Cryptococcus Pichia stipitis Trichosporon cutaneum... 

Index Entries Biomass ethanol coimmobilization Ca-alginate Pichia stipitis steam explosion. 

Dupreez, J. C., Bosch, M., and Prior, B. A., The fermentation of hexose and pentose sugars by candida-shehatae and pichia-stipitis. Applied Microbiology Biotechnology 1986, 23 (3—4), 228-233. 

Jeffries, T. W., Dahn, K., Kenealy, W. R., Pittman, P., Sreenath, H. K., and Davis, B. P., Genetic-engineering of the xylose-fermenting yeast Pichia-Stipitis for improved ethanol-production. Abstracts of Papers of the American Chemical Society 1994, 207, 167-BTEC. 

In order to prove that cloning KD, AR or A R, and KK XD, XR, and XK structural genes fused to glycolytical promoters) is extremely important for cofermentation of feedstocks (or media) containing mixtures of glucose and xylose, we compared the fermentation of a mixture of glucose and xylose by 1400 (pLNH 32) and Pichia stipitis. As described above, the Pichia yeast is a na-... 

Fig. 10A, B. Comparison of cofermentation of glucose and xylose present in the medium under identical conditions by A genetically engineered Saccharomyces yeast strain 1400 (pLNH32) and by B Pichia stipitis. These results demonstrate that our genetically engineered 1400(pLNH32) can effectively coferment glucose and xylose to ethanol but not P. stipitis. Symbols square glucose circle xylose triangle ethanol...

In yeast and mycelial fungi, xylose is metabolized via coupled oxidation-reduction reactions . Xylose reductase is the enzyme involved in the reduction of xylose to xylitol. Sequential enzymatic events, through the oxidation of xylitol to xylulose, lead to the utilization of xylose. Many yeast species utilize xylose readily, but the ethanol production capability is very limited. Only a few yeast species effectively produce ethanol from xylose these include Pachysolen tan-nophilus, Candida shihatae and Pichia stipitis [80]. The production of ethanol from xylose by these three yeast strains has been studied extensively in recent years. Recently, genetically engineered yeast strains have been constructed for more effective conversion of xylose to ethanol. 

Although many facultatively fermentative yeasts utilize xylose as the carbon source for growth, the ability of these yeasts to produce ethanol from xylose is limited. Yeast strains that utilize xylose often produce xylitol from xylose extra-cellularly as a normal metabolic activity. However, only a few can produce significant quantities of ethanol. The prominent strains that produce ethanol from xylose include Pachysolen tannophilus, Candida shihatae and Pichia stipitis. However, the efficient production of ethanol from xylose is limited by the regulation of dissolved oxygen as well as by the imbalance of cofactors in the metabolic pathway during xylose utilization. In recent years, much effort has been put into improving yeast strains in order to produce ethanol from xylose more efficiently. 

Pichia stipitis. P. stipitis is the most effective natural yeast for the conversion of xylose to ethanol. This yeast species shares many characteristics with its close relative, C. shehatae. Toivola et al. [90] performed a systemic screening program with type strains of some 200 yeast species and identified P. stipitis as one of the yeast species that produces ethanol from xylose. There are many studies that have explored the property of this yeast in relation to its oxygen requirement, ethanol tolerance, enzyme cofactor s balance, etc. According to the reported literature [91,92], ethanol production from xylose by P stipitis exhibits the following characteristics ... 

Fermentation of Acid-pretreated Corn Stover to Ethanol Without Detoxification Using Pichia stipitis... 

Keywords Com stover Ethanol Sulfuric acid Pichia stipitis Adaptation Detoxification... 

Comparison of Wild Strains and Liquid-adapted Strains of Pichia stipitis... 

Prior, B. A., Kilian, S. G., Dupreez, J. C. (1989). Fermentation of d-xylose by the yeasts Candida shehatae and Pichia stipitis. Process Biochemistry, 24, 21-32. 

Amore, R., Kotter, P, Kuster, C., Ciriacy, M., Hollenberg, C. P. (1991). Cloning and Expression in Saccharomyces cerevisiae of the NAD(P)H- dependent xylose reductase- encoding gene (XYLl) from the xylose assimilating yeast Pichia stipitis. Gene, 109, 89-97. 

The yeasts exhibited a similar sugar utilization pattern (data not shown). Glucose and xylose were assimilated simultaneously, the former at a higher rate, enabling higher growth rates. Xylose was completely assimilated by P. stipitis and D. hansenii, but not by K. marxianus, which only consumed 70%. Arabinose was also assimilated by all yeasts simultaneously with late xylose assimilation, being only completely exhausted by D. hansenii. The other two yeasts, Pichia stipitis and K. marxianus, only consumed 31 and 45% of available arabinose, respectively. Furfural, acetic, and formic acid were also consumed (data not shown). 

Fermentation Kinetics for Xylitol Production by a Pichia stipitis D-Xylulokinase Mutant Previously Grown in Spent Sulfite Liquor... 

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