As anticipated, the raw starch content was reduced
in inverse proportion to the increase in ethanol
concentration during fermentation. Residual starch
was 4.2% (w/v) after 6 days of fermentation. In
contrast, ATCC 9763/YIpdAGSGd, which secretes
GA1 and GAM1, generated 2.6% (v/v) ethanol
after 6 days. This result indicates that AMY-encoded
a-amylase performs a crucial function in the degradation
of raw starch because GA1 hydrolyzes raw starch
slowly. The synergistic use of GA1 and AMY can
quickly hydrolyze raw corn starch. Moreover, ATCC
9763/YIpdSGSAd, which secretes GAM1 and AMY,
generated 4.5% (v/v) ethanol after 6 days although
neither GAM1 nor AMY has been identified as raw
starch-degrading enzymes (RSDE) (Eksteen et al.
2003; Sun et al. 2010). Yamada et al. (2010) has
reported that a tetraploid strain of S. cerevisiae that
secretes Streptococcus bovis a-amylase to hydrolyze
raw starch and Rhizopus oryzae glucoamylase was
constructed from haploid strains via d-integration,
As anticipated, the raw starch content was reduced
in inverse proportion to the increase in ethanol
concentration during fermentation. Residual starch
was 4.2% (w/v) after 6 days of fermentation. In
contrast, ATCC 9763/YIpdAGSGd, which secretes
GA1 and GAM1, generated 2.6% (v/v) ethanol
after 6 days. This result indicates that AMY-encoded
a-amylase performs a crucial function in the degradation
of raw starch because GA1 hydrolyzes raw starch
slowly. The synergistic use of GA1 and AMY can
quickly hydrolyze raw corn starch. Moreover, ATCC
9763/YIpdSGSAd, which secretes GAM1 and AMY,
generated 4.5% (v/v) ethanol after 6 days although
neither GAM1 nor AMY has been identified as raw
starch-degrading enzymes (RSDE) (Eksteen et al.
2003; Sun et al. 2010). Yamada et al. (2010) has
reported that a tetraploid strain of S. cerevisiae that
secretes Streptococcus bovis a-amylase to hydrolyze
raw starch and Rhizopus oryzae glucoamylase was
constructed from haploid strains via d-integration,
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