Applied Microbiology and Biotechnology

, Volume 95, Issue 4, pp 957–968 | Cite as

Codon-optimized glucoamylase sGAI of Aspergillus awamori improves starch utilization in an industrial yeast

  • Lorenzo Favaro
  • Tania Jooste
  • Marina Basaglia
  • Shaunita H. Rose
  • Maryna Saayman
  • Johann F. Görgens
  • Sergio Casella
  • Willem H. van Zyl
Applied genetics and molecular biotechnology


The development of a yeast that converts raw starch to ethanol in one step (called consolidated bioprocessing) could yield large cost reductions in the bioethanol industry. The aim of this study was to develop an efficient amylolytic Saccharomyces cerevisiae strain suitable for industrial bioethanol production. A native and codon-optimized variant of the Aspergillus awamori glucoamylase gene were expressed in the S. cerevisiae Y294 laboratory strain. Codon optimization resulted to be effective and the synthetic sequence sGAI was then δ-integrated into a S. cerevisiae strain with promising industrial fermentative traits. The mitotically stable recombinant strains showed high enzymatic capabilities both on soluble and raw starch (2425 and 1140 nkat/g dry cell weight, respectively). On raw corn starch, the engineered yeasts exhibited improved fermentative performance with an ethanol yield of 0.42 (g/g), corresponding to 75 % of the theoretical maximum yield.


Industrial yeast Codon optimization δ-integration Raw starch Ethanol production 



This work was partially financed by the BiotechIIbis and BiotechIII projects (Regione Veneto, Italy) and the National Research Foundation (South Africa). Dr. Lorenzo Favaro is recipient of “Assegno di ricerca Junior” grant (University of Padova). Stefania Zannoni (University of Padova) is acknowledged for HPLC analysis. Authors are grateful to Claudio Furlan (CUGAS, University of Padova) for performing SEM.


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Lorenzo Favaro
    • 1
  • Tania Jooste
    • 2
  • Marina Basaglia
    • 1
  • Shaunita H. Rose
    • 2
  • Maryna Saayman
    • 2
  • Johann F. Görgens
    • 3
  • Sergio Casella
    • 1
  • Willem H. van Zyl
    • 2
  1. 1.Department of Agronomy Food Natural Resources Animals and Environment (DAFNAE)University of Padova, AgripolisLegnaro PADOVAItaly
  2. 2.Department of MicrobiologyStellenbosch UniversityMatielandSouth Africa
  3. 3.Department of Process EngineeringUniversity of StellenboschMatielandSouth Africa

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