Enzyme phosphofructokinase 1 (Pfk1) is a key regulatory enzyme of the glycolysis. Posttranslational modification of the Pfk1 enzyme allows the formation of an active Pfk1 fragments which have significantly higher activity than original enzymes. Shorter human 47 kDa Pfk-M fragments are more prone to activation but also resistant to feedback inhibition. Increased metabolic flow through glycolysis results in an unbalance of the NADH/NADPH ratio. This prevents the growth of the cells with shorter Pfk-M fragment in the media under anaerobic conditions. Growth can be re-established with included heterologic malic enzyme, which enables additional production of the NADPH in the cells. The growth of S. cerevisiae yeast with the PFK genes of different origins and the MAEA gene encoding the malic enzyme was observed in fermentative media under anaerobic conditions. We demonstrated experimentally that the strains with genes for short fragments and the malic enzyme were able to grow on pentose sugars which is not possible for the wild type of yeast strains. Therefore, only by modifying the regulatory Pfk1 enzyme, the yeast can utilize the pentose sugars. In the media, the accumulation of the volatile product a 2-phenylethanol was observed with decreasing xylitol concentration. Thus, the degradation of pentose sugars does not only present the possibility of obtaining bioethanol from lignocellulosic materials but also other industrially important fermentative products.
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