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PROPERTIES OF A GENETICALLY‐ENGINEERED DEXTRIN‐FERMENTING STRAIN OF BREWERS' YEAST
Author(s) -
Perry Caroline,
Meaden Philip
Publication year - 1988
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1988.tb04558.x
Subject(s) - dextrin , fermentation , strain (injury) , yeast , transformation (genetics) , plasmid , food science , biology , amylase , saccharomyces cerevisiae , recombinant dna , biochemistry , chemistry , enzyme , gene , starch , anatomy
A dextrin‐fermenting strain of brewer's yeast was obtained by transformation with a recombinant plasmid (pLHCD6) containing a DEX gene. The transformant produced five‐fold more extracellular amyloglucosidase (AMG) than the strain of Saccharomyces diastaticus from which DEX was cloned. The growth rate, however, was adversely affected and, consequently, the transformant fermented wort more slowly than the parental (untransformed) strain. A mixed culture was therefore used at pilot‐scale, to maintain a rate of fermentation similar to that of the parental strain. The transformant by itself was capable of superattenuating wort (original gravity 1.040) to a specific gravity of 1.0023 (compared with 1.0046 for the parental strain). This represents the expected degree of dextrin breakdown by an AMG with no “debranching” activity which can only hydrolyse alpha‐1,4 linkages. A high copy number for the plasmid pLHCD6 was maintained throughout fermentation. The beers produced using the Dex+ transformants were judged to be of sound quality.