Abstract
We have developed a relatively simple simultaneous saccharification and fermentation (SSF) technique to determine the ethanol production potential for large sets of biomass samples. The technique is based on soaking approximately 0.5 grams of a biomass sample in aqueous ammonia at room temperature and at atmospheric pressure for 24 h, then fermenting with Saccharomyces cerevisiae D5A for 24 h using Spezyme CP, for enzymatic hydrolysis of structural polysaccharides. We have tested the technique on a set of corn stover samples representing much of the genetic variability in the commercial corn hybrid population. The samples were weighed into modified Ankom filter bags (F57) before soaking to avoid biomass loss during the process. Fermentation samples were analyzed for ethanol after 24 h by HPLC. Percentages of theoretical maximum ethanol yields of the samples ranged between 44.9 and 73%. We observed that percentages of theoretical maximum ethanol yields were highly correlated (r 2 = 0.90) with acid detergent lignin concentration while a low correlation was observed between cellulose concentration and ethanol yield. Near infrared spectra of corn stover samples were also examined. The coefficient of determination (r 2) from regression of predicted versus measured percent theoretical maximum ethanol yield was 0.96. This result suggests that using NIRS is a promising method for predicting ethanol yield, but larger calibration sets are necessary for obtaining improved accuracy for larger sample populations. We conclude that the developed SSF technique could be applied to large numbers of biomass samples to rapidly estimate ethanol yields and to compare different biomass samples in terms of ethanol yields.
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Abbreviations
- SSF:
-
simultaneous saccharification and fermentation
- NIRS:
-
near infrared reflectance spectroscopy
- IVR:
-
in vitro ruminal
- FPU:
-
filter paper units
- rpm:
-
revolutions per minute
- ADL:
-
acid detergent lignin
- TEY:
-
percentage of theoretical maximum ethanol yield
- NDF:
-
neutral detergent fiber
- ADF:
-
acid detergent fiber
- ADL:
-
acid detergent lignin
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Acknowledgment
This research was funded in part by USDA Grant No. NRCS 68-3A75-4-137 and the Center for Global and Regional Environmental Research at the University of Iowa. This material is also based, in part, upon work supported by the National Science Foundation under Grant No. 0424700. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The authors would like to thank Dr. James Coors, Aaron Lorenz, and the University of Wisconsin—Madison for providing the corn stover samples grown in Wisconsin and Dr. Kendall Lamkey and Krystal Kirkpatrick in the Department of Agronomy at Iowa State University for providing the corn stover samples grown in Iowa. We also would like to thank Genencor for providing the enzyme, Trish Patrick for helping with the compositional analysis and NIR calibrations.
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Isci, A., Murphy, P.T., Anex, R.P. et al. A Rapid Simultaneous Saccharification and Fermentation (SSF) Technique to Determine Ethanol Yields. Bioenerg. Res. 1, 163–169 (2008). https://doi.org/10.1007/s12155-008-9015-9
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DOI: https://doi.org/10.1007/s12155-008-9015-9