[Breeding of excellent baker's yeast strain with good flocculation]

An excellent baker's yeast strain ZLTH-58 (MATa/alpha, leu-, FLO1) with high biomass, high-sugar-tolerance and good flocculation was constructed by primary screening, isolation of haploid, mutagenesis, cloning and expression of FLO1 gene and hybridization. The results showed that strain ZLTH-58 had excellent properties of the parental strains BL56 and BL61. The biomass of strain ZLTH-58 was 1.21 times of the parental strain BL56; The ability of high-sugar-tolerance of strain ZLTH-58 was higher than the parental strain BL61. The ability of flocculation of strain ZLTH-58 was better than the parental strains BL56 and BL61. The factors that affected the biomass of strain ZLTH-58 were also detected. Biomass reached 83.06 g/L under the optimal fermentation conditions, having a 1.35-fold improvement. Strain ZLTH-58 is also stable in genetics characters by analysis of genetic stability and it has the potential for use in industrial processes.