Original scientific paper
Integrative Expression of Glucoamylase Gene in a Brewer’s Yeast Saccharomyces pastorianus Strain
Zengran Liu
; Bioscience and Bioengineering College, Hebei Economics and Business University, 47 Xuefu Road, CN-050061 Shijiazhuang, PR China
Guangyi Zhang
; Bioscience and Bioengineering College, Hebei Economics and Business University, 47 Xuefu Road, CN-050061 Shijiazhuang, PR China
Jing Li
; Bioscience and Bioengineering College, Hebei Economics and Business University, 47 Xuefu Road, CN-050061 Shijiazhuang, PR China
Guohong Chen
; Shijiazhuang Xinle Beer Corporation, 3 Litang Street, CN-050700 Shijiazhuang, PR China
Abstract
The recombinant brewer’s yeast Saccharomyces pastorianus strain was constructed byintroducing the ilv2:GLA fragment released from pMGI6, carrying glucoamylase gene (GLA) and using the yeast α-acetolactate synthase gene (ILV2) as the recombination sequence. The strain was able to utilise starch as the sole carbon source, its glucoamylase activity was 6.3 U/mL and its α-acetolactate synthase activity was lowered by 33.3 %. The introduced GLA gene was integrated at the recipient genomic ILV2 gene, one copy of ILV2 gene was disrupted and the other copy remained intact. Primary wort fermentation test confirmed that the diacetyl and residual sugar concentration in the wort fermented by the recombinant strain were reduced by 65.6 and 34.2 % respectively, compared to that of the recipient strain. Under industrial operating conditions, the maturation time of beer fermented by the recombinant strain was reduced from 7 to 4 days, there were no significant differences in the appearance and mouthfeel, and the beer satisfied the high quality demands. That is why the strain could be used in beer production safely.
Keywords
glucoamylase; α-acetolactate synthase; brewer's yeast; diacetyl; fermentation; gene disruption
Hrčak ID:
22192
URI
Publication date:
14.3.2008.
Visits: 1.737 *