Construction of Hansenula polymorpha strains with improved thermotolerance.

The methylotrophic yeast Hansenula polymorpha has the potential to be used in the process of simultaneous saccharification and fermentation (SSF) of xylan derived xylose at elevated temperatures. To improve parameters of high-temperature resistance and high-temperature fermentation of H. polymorpha, strains carrying deletion of acid trehalase gene (ATH1) and overexpressing genes coding for heat-shock proteins Hsp16p and Hsp104p were constructed.

Production of flavin mononucleotide by metabolically engineered yeast Candida famata.

Recombinant strains of the flavinogenic yeast Candida famata able to overproduce flavin mononucleotide (FMN) that contain FMN1 gene encoding riboflavin (RF) kinase driven by the strong constitutive promoter TEF1 (translation elongation factor 1alpha) were constructed. Transformation of these strains with the additional plasmid containing the FMN1 gene under the TEF1 promoter resulted in the 200-fold increase in the riboflavin kinase activity and 100-fold increase in FMN production as compared to the wild-type strain (last feature was found only in iron-deficient medium). Overexpression of the FMN1 gene in the mutant that has deregulated riboflavin biosynthesis pathway and high level of riboflavin production in iron-sufficient medium led to the 30-fold increase in the riboflavin kinase activity and 400-fold increase in FMN production of the resulted transformants.

Development of strains of the thermotolerant yeast Hansenula polymorpha capable of alcoholic fermentation of starch and xylan.

The thermotolerant yeast Hansenula polymorpha ferments glucose and xylose to ethanol at high temperatures. However, H. polymorpha cannot utilize starchy materials or xylans.

Overexpression of pyruvate decarboxylase in the yeast Hansenula polymorpha results in increased ethanol yield in high-temperature fermentation of xylose.

Improvement of xylose fermentation is of great importance to the fuel ethanol industry. The nonconventional thermotolerant yeast Hansenula polymorpha naturally ferments xylose to ethanol at high temperatures (48-50 degrees C). Introduction of a mutation that impairs ethanol reutilization in H.

Engineering of xylose reductase and overexpression of xylitol dehydrogenase and xylulokinase improves xylose alcoholic fermentation in the thermotolerant yeast Hansenula polymorpha.

Background: The thermotolerant methylotrophic yeast Hansenula polymorpha is capable of alcoholic fermentation of xylose at elevated temperatures (45 - 48 degrees C). Such property of this yeast defines it as a good candidate for the development of an efficient process for simultaneous saccharification and fermentation. However, to be economically viable, the main characteristics of xylose fermentation of H.

Overexpression of bacterial xylose isomerase and yeast host xylulokinase improves xylose alcoholic fermentation in the thermotolerant yeast Hansenula polymorpha.

The thermotolerant methylotrophic yeast Hansenula polymorpha is able to ferment xylose to ethanol. To improve characteristics of xylose fermentation, the recombinant strain Delta xyl1 Delta xyl2-ADelta xyl2-B, with deletions of genes encoding first enzymes of xylose utilization (NAD(P)H-dependent xylose reductase and NAD-dependent xylitol dehydrogenases, respectively), was constructed and used as a recipient for co-overexpression of the Escherichia coli xylA gene coding for xylose isomerase and endogenous XYL3 gene coding for xylulokinase. The expression of both genes was driven by the H.

Plate ethanol-screening assay for selection of the Pichia stipitis and Hansenula polymorpha yeast mutants with altered capability for xylose alcoholic fermentation.

A new method for the selection of Pichia stipitis and Hansenula polymorpha yeast mutants with altered capability to ferment xylose to ethanol was developed. The method is based on the ability of P. stipitis and H.

Insertion mutagenesis of the yeast Candida famata (Debaryomyces hansenii) by random integration of linear DNA fragments.

The feasibility of using random insertional mutagenesis to isolate mutants of the flavinogenic yeast Candida famata was explored. Mutagenesis was performed by transformation of the yeast with an integrative plasmid containing the Saccharomyces cerevisiae LEU2 gene as a selective marker. The addition of restriction enzyme together with the plasmid (restriction enzyme-mediated integration, REMI) increased the transformation frequency only slightly.

Expression of xylA genes encoding xylose isomerases from Escherichia coli and Streptomyces coelicolor in the methylotrophic yeast Hansenula polymorpha.

The thermotolerant methylotrophic yeast Hansenula polymorpha is able to ferment xylose to ethanol at high temperatures. H. polymorpha xylose reductase and xylitol dehydrogenase are involved during the first steps of this fermentation.

Candida famata (Debaryomyces hansenii) DNA sequences containing genes involved in riboflavin synthesis.

Previously cloned Candida famata (Debaryomyces hansenii) strain VKM Y-9 genomic DNA fragments containing genes RIB1 (codes for GTP cyclohydrolase II), RIB2 (encodes specific reductase), RIB5 (codes for dimethylribityllumazine synthase), RIB6 (encodes dihydroxybutanone phosphate synthase) and RIB7 (codes for riboflavin synthase) were sequenced. The derived amino acid sequences of C. famata RIB genes showed extensive homology to the corresponding sequences of riboflavin synthesis enzymes of other yeast species.