Ethanol Production from Xylose by a RecombinantCandida utilisStrain Expressing Protein-Engineered Xylose Reductase and Xylitol Dehydrogenase

Cofactor engineering for advancing chemical biotechnology

“…Overexpression of a Kluyveromyces lactis NADPH-forming GAPDH reduced xylitol production [1]. Protein engineering of xylose reductase to a NADH-preferring enzyme gave high ethanol productivity [6]. A study with the NADH-NADPH utilizing Scheffersomyces stipitis xylose reductase suggested formation of glucose 6-phosphate via gluconeogenesis was limiting [4].…”

“…Some examples illustrating the requirement for cofactor balance and availability include: the conversion of biomass feedstocks containing xylose to ethanol where the formation of xylitol is a problem [1][2][3][4][5][6][7]; as a driving force for more effective production of reduced compounds such as biofuels [8]; in using cytochrome P450s in specific oxidation reactions where the recycling of active enzyme is required [9][10][11]; and the production of chiral pharmaceutical intermediates where specific reductions require a certain cofactor [12,13]. Experimental studies along with more complete computational models have shown a global picture of the flow of reducing equivalents and its connection to cell physiology and allowed these insights to be considered for metabolic engineering purposes [14][15][16][17].…”

“…The synthetic biology revolution has allowed easier ways to construct combinations of redox complexes and connect them to give a focused controllable circuit that can be directed to a desired metabolite [18]. Advances in protein engineering also have helped direct cell redox metabolism toward desired ends [6,[19][20][21][22][23]. These advances intertwine with the theme of generating effective bioprocesses for fuels and chemicals from biomass and more recently from H 2 /CO 2 or electrodes [24,25].…”

Candida utilis and Cyberlindnera (Pichia) jadinii: yeast relatives with expanding applications

“…Subsequently, glucose was replaced by xylose as an inexpensive carbon source for lactate production using a strain synthesizing a heterologous fungal NADH-referring mutated xylose reductase (XR), as well as heterologous fungal xylitol dehydrogenase and xylulokinase in the pdc1 mutant background (Tamakawa et al 2010a). In the absence of the pdc1 mutation, these heterologous enzymes led to 0.4 g ethanol per gram of xylose per liter by C. utilis (Tamakawa et al 2010b(Tamakawa et al , 2013a(Tamakawa et al , 2013b. Furthermore, heterologous expression of genes encoding acetoacetyl-CoA transferase and a primarysecondary alcohol dehydrogenase derived from Chlostridium species yielded isopropanol from glucose with a yield of 41.5 % (Tamakawa et al 2013b).…”

Microbial Degradation of Lignocellulosic Biomass

“…Therefore, genetic improvement of yeasts is a valuable tool to obtain strains able to ferment pentoses, hexoses and, in addition, produce ethanol with a high yield and a high ethanol tolerance as well. Genetically engineered organisms with C5 fermenting capabilities already include S. cerevisiae, Escherichia coli, Zymomonas mobilis and Candida utilis [28][29][30][31]. Studies on fungi degradation of lignocellulosic material could yield promising candidate genes that could be subsequently used in engineering strategies for improved cellulosic biofuel production in these yeast strains.…”