Abstract:[Objective]There are a large numbers of tandem repeats in FLO1,which are highly dynamic components in genome leading to the unstable flocculation profiles in Saccharomyces cerevisiae. The effects of repeated unite B or D deletion on the function of flocculation protein was studied to provide theory basis for constructing genetically stable flocculation gene with minimal size.[Methods]We cloned the intact flocculation gene FLO1 from S.cerevisiae YS59 by PCR,and constructed the derived genes FLO1b and FLO1d with repeated unite B or D deletion respectively by fusion PCR. We analyzed the physiological characteristics of flocculation in yeast strains YSF1,YSF1b and YSF1d containing FLO1,FLO1b and FLO1d respectively.[Results]YSF1b and YSF1d displayed almost the same level of Flo1-type flocculation as YSF1. However,flocculation of YSF1b and YSF1d,especially YSF1d was more tolerant to pH change and mannose concentration than strain YSF1.[Conclusion]Tandem repeats regulate the function of flocculation protein. Deletion of repeated unite B or D,especially D increases the stability of flocculation protein.