The double d system generates
a fragment that is 2.8 kb smaller and is devoid of
unnecessary bacterial sequences. The integrative
cassette (YIpdSGSAd)-harboring yeast was designated
ATCC 9763/YIpdSGSAd. Recently, Kim et al.
(2010) reported d-integrated copy numbers of 46 for
the GA1 and AMY genes in the recombinant yeast
strain exhibiting high GA1 and AMY activities
(ATCC 9763/YIpdAGSAd), as determined by realtime
PCR analysis. Such stable integrations of DNA
containing GA1, GAM1 and AMY genes lacking
bacterial DNA sequences is expected to facilitate
industrial-scale ethanol production from starchy
materials in both the beverage and bioenergy industries
(Marin et al. 2001).