Reducing glucoamylase usage for commercial-scale ethanol production from starch using glucoamylase expressing Saccharomyces cerevisiae

Bioresources and Bioprocessing

Table 3 Product formation by the CIBTS1522 strain after 72 h of fermentation in the corn starch liquefied slurry at small-scale

CIBTS1522	AQ + 100% GA	1522 + 50% GA	1522 + 30% GA	1522 + 0% GA
Final ethanol (%, v/v)	15.12	15.13	15.02	12.64
Glycerol (%, w/v)	1.18	1.09	1.03	0.80
Acetic acid (%, w/v)	0.06	0.04	0.04	0.03
Residual reducing sugars (%, w/v)	0.30	0.28	0.33	0.65
Ethanol productivity (g/L h)	2.10	2.10	2.09	1.76
Estimated ethanol yield (% of theoretical yield)^a	85.28	85.34	84.72	71.30

The data represent the average of three independent tests
GA glucoamylase, AQ CCTCC M94055 strain
^a34.25% (dw/v) raw starch loading is equivalent to 177.28 g/L ethanol (6.95 mol carbon), the theoretical ethanol yield from glucose is 0.51