Masahide Sato

Breeding of Brewer's yeast by hybridization between a top-fermenting yeast Saccharomyces cerevisiae and a cryophilic yeast Saccharomyces bayanus

To improve the fermentability of a top-fermenting yeast at low-temperature, we performed hybridization trials between four top-fermenting Saccharomyces cerevisiae strains and a cryophilic yeast Saccharomyces bayanus YM84 with good fermentability at low-temperature. The hybrids selected using 5-bromo-4-chloro-3-indolyl-alpha-D-galactopyranoside were checked with pulsed-field gel electrophoresis and their brewing performance at the low-temperature of 10.5 degrees C was observed using small-scale (2 l) fermentation trials.

Analysis of an inactivated Lg-FLO1 gene present in bottom-fermenting yeast

During the course of investigating a flocculation-related gene of a bottom-fermenting yeast, we identified a new Lg-FLO1 homologue which contains the N-terminal domain of the Lg-FLO1 gene. The results of the partial DNA sequence analysis of the amplified product obtained by inverse-PCR suggested that the homologue contains a sequence present in the YIL169c (chr. IX of Saccharomyces cerevisiae). Southern blot analyses using the VTH1, HXT12, SDL1 and UBP7 genes as probes for chr. IX strongly indicated that an approximately 20-kb region from the YIL169c ORF to the left telomere in chr. IX translocated to the Lg-FLO1 ORF region in chr. VIII of bottom-fermenting yeast. This translocation might convert a flocculent cell to a non-flocculent one.

Conversion of a non-flocculent brewer's yeast to flocculent ones by electrofusion: 2. Small-scale brewing by fusants

Abstract A non-flocculent brewers yeast was converted to flocculent ones by electrofusion using Saccharomyces cerevisiae (FL05) , and the fusants were characterized from chromosomal DNA (Urano et al., 1993). In this study, small-scale brewing (2 1) by the fusants was carried out and DNA patterns compared with microbial quality. The brewing reaction rate, number of floating and sedimenting yeasts in the fusants were varied and intermediate between those of parent strains. Physiological activities of the fusants, from viability to ploidy, were also investigated after brewing. With some exceptions, the fusants showed a good relationship between DNA patterns and brewing and F(100) was closely related to a commercial strain of brewers yeast.