Titre du document / Document title
Starch fermentation by recombinant Saccharomyces cerevisiae strains expressing the α-amylase and glucoamylase genes from Lipomyces kononenkoae and Saccharomycopsis fibuligera
Auteur(s) / Author(s)
EKSTEEN J. M. (1) ;
VAN RENSBURG P. (1) ;
CORDERO OTERO R. R. (1) ;
PRETORIUS I. S. (1 2) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Institute for Wine Biotechnology, Department of Viticulture & Oenology, Stellenbosch University, Stellenbosch, 7600, AFRIQUE DU SUD
(2) The Australian Wine Research Institute, Adelaide, SA 5064, AUSTRALIE
Résumé / Abstract
Lipomyces kononenkoae and Saccharomycopsis fibuligera possess highly efficient α-amylase and/or glucoamylase activities that enable both of these yeasts to utilize raw starch as a carbon source. Eight constructs containing the L. kononenkoae α-amylase genes (LKA 1 and LKA2), and the S. fibuligera α-amylase (SFA1) and glucoamylase (SFG1) genes were prepared. The first set of constructs comprised four single gene cassettes each containing one of the individual amylase coding sequences (LKA1, LKA2, SFA1 or SFG1) under the control of the phosphoglycerate kinase gene (PGK1) promoter and terminator, while the second set comprised two single cassettes containing SFA 1 and SFG1 linked to their respective native promoters and terminators. The third set of constructs consisted of two double-gene cassettes, one containing LKA 1 plus LKA2 under the control of the PGK1 promoter and terminator, and the other SFA 1 plus SFG1 controlled by their respective native promoters and terminators. These constructs were transformed into a laboratory strain Saccharomyces cerevisiae (Σ1278b). Southern-blot analysis confirmed the stable integration of the different gene constructs into the S. cerevisiae genome and plate assays revealed amylolytic activity. The strain expressing LKA 1 and LKA2 resulted in the highest levels of α-amylase activity in liquid media. This strain was also the most efficient at starch utilization in batch fermentations, utilizing 80% of the available starch and producing 0.61g/ 100 mL of ethanol after 6 days of fermentation. The strain expressing SFG1 under the control of the PGK1 expression cassette gave the highest levels of glucoamylase activity. It was shown that the co-expression of these heterologous α-amylase and glucoamylase genes enhance starch degradation additively in S. cerevisiae. This study has resulted in progress towards laying the foundation for the possible development of efficient starch-degrading S. cerevisiae strains that could eventually be used in consolidated bioprocessing, and in the brewing, whisky, and biofuel industries.
Revue / Journal Title
Biotechnology and bioengineering
ISSN
0006-3592
CODEN BIBIAU
Source / Source
2003, vol. 84, n
o6, pp. 639-646 [8 page(s) (article)] (23 ref.)
Langue / Language
Anglais
Editeur / Publisher
Wiley, Hoboken, NJ, ETATS-UNIS
(1962)
(Revue)
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Localisation / Location
INIST-CNRS, Cote INIST : 9164, 35400011870764.0030
Nº notice refdoc (ud4) : 15239789
