Global transcription machinery engineering (gTME) was employed to engineer xylose metabolism. Mutation of the transcription factor gene Sptl5 was introduced by error-prone PCR, followed by screening on media using xylose as the sole carbon source. One recombinant strain growing well on such media was chosen for further research. This strain showed modest growth rates in the media containing 50 g/L xylose or glucose at the condition of 30 degrees C, 200 r/min, 96 h, 94.0% and 98.9% of xylose and glucose were consumed, with the ethanol yield were 32.4% and 31.6%, respectively. The control strain had the ethanol yield of 44.3% under the glucose concentration of 50 g/L. When the carbon source was 50 g/L glucose/xylose (1:1), the utilization ratio of xylose and glucose was 91.7% and 85.9%, with the ethanol yield was 26%. Xylose was eventually exhausted. Concentration of the by-product xylitol was very low.
DNA-Directed RNA Polymerases ; genetics ; metabolism ; Ethanol ; metabolism ; Fermentation ; Genetic Engineering ; methods ; Glucose ; metabolism ; Saccharomyces cerevisiae ; genetics ; metabolism ; Transcription Factors ; genetics ; metabolism ; Transformation, Genetic ; Xylose ; metabolism

We used genetic methods to get a mutational spt15 gene from the recombinant strain Saccharomyces cerevisiae YPH499-3, screened by global transcription machinery engineering (gTME) approach. We transformed the gene into the original strain Saccharomyces cerevisiae YPH499 using the vector pYX212, then got a new recombinant strain. We studied the characteristic of this strain and found that it could metabolize xylose and co-ferment xylose and glucose. Under the fermentation condition of 30 degrees C, 200 r/min, 72 h, the utilization ratio of xylose was 82.0%, with 32.4% of ethanol yield when the carbon source in the media was 50 g/L xylose, while the utilization ratio of xylose and glucose was 80.4% and 100% respectively, with the 31.4% of ethanol yield when the carbon source was 50 g/L glucose/xylose (1:1). Meanwhile, the concentration of the by-product xylitol was very low. This study demonstrates the effect which the forward mutation of spt15 gene makes to the co-fermentation of xylose and glucose to ethanol by Saccharomyces cerevisiae.
Base Sequence ; Ethanol ; metabolism ; Genetic Engineering ; methods ; Glucose ; metabolism ; Molecular Sequence Data ; Mutation ; Saccharomyces cerevisiae ; genetics ; metabolism ; Saccharomyces cerevisiae Proteins ; genetics ; TATA-Box Binding Protein ; genetics ; Transformation, Genetic ; Xylose ; metabolism