Effects On Saccharomyces Cerevisiae Physiology Of MBP1 Deleted Mutation And Over-Expression

Saccharomyces cerevisiaeMBPl gene (ORF:YDL056W) codes Mbplp protein which is a transcription factor and binds to the gene’s promoter related to Gl/S transition process, and regulates the gene expression. In order to study the effects of MBP1 on physiological characteristics of MF1015 strain, YDL056W knockout component Loxp-KanMX-Loxp was constructed. Besides shuttle plasmid pYES2 was remoulded, making it obtain the G418 resistance selection marker. The YDL056W is inserted to the multiple cloning sites, downstream of the pGAL1, and then the yeast strains transform it to construct MBP1 over-expression strain; at last, physiological characteristics were researched.The results showed that mutants’budding rate is lower and the average cells volume is bigger than original strains by 19%. The mutant is easier to form pseudohyphae and cell wall physiological characteristicis also affected. When cultured at the shaking speed of 130r/min, the relative respiration (original strains/mutants) is 6.01; when static culture, the number is 1.53. In the medium containing 9% ethanol that original maximum OD600 is 3.48, and the mutants’is 3.15, besides, the relative activity of T-SOD, CAT, ADH and relative trehalose content (original strains/mutants) is 1.37,1.80,2.00 and 1.49 respectively. In cane molasses fermentation, the original strains and mutants largest ethanol concentration is 13.76% and 13.05% respectively, and original strains’glucose utilization rate is higher than mutants by 2%; In sucrose fermentation, the concentration is 13.80% and 13.40% respectively and glucose utilization rate is resemble. At 30℃, the relative OD6oo of MF1015-△YDL056W/pK and MF1015-△YDL056W/pKY is 1.16; MF1015-WT and MF1015-△YDL056W is 1.06; MF1015-WT/pK and MF1015-WT/pKY is 1.23, and the morphology of cells which containing pKY is changed in different degrees; Fluorescence quantitative PCR showed the relative expression levels of MBP1 in different cells is MF1015/pKY> MF1015-△YDL056W/pKY> MF1015.To sum up, in the background of industrial yeast strain MF1015, MBP1 deleted mutation may affects cell’s normal physiological function which is not conducive to adapt fermentation environment for yeast. Besides, MBP1 over-expression also can’t promote yeasts growth.