Assessment of Xylanase Activity in Dry Storage as a Potential Method of Reducing Feedstock Cost
- 168 Downloads
Enzymatic preprocessing of lignocellulosic biomass in dry storage systems has the potential to improve feedstock characteristics and lower ethanol production costs. To assess the potential for endoxylanase activity at low water contents, endoxylanase activity was tested using a refined wheat arabinoxylan substrate and three commercial endoxylanases over the water activity range 0.21–1.0, corresponding to water contents of 5% to >60% (dry basis). Homogeneously mixed dry samples were prepared at a fixed enzyme to substrate ratio and incubated in chambers at a variety of fixed water activities. Replicates were sacrificed periodically, and endoxylanase activity was quantified as an increase in reducing sugar relative to desiccant-stored controls. Endoxylanase activity was observed at water activities over 0.91 in all enzyme preparations in less than 4 days and at a water activity of 0.59 in less than 1 week in two preparations. Endoxylanase activity after storage was confirmed for selected desiccant-stored controls by incubation at 100% relative humidity. Water content to water activity relationships were determined for three lignocellulosic substrates, and results indicate that two endoxylanase preparations retained limited activity as low as 7% to 13% water content (dry basis), which is well within the range of water contents representative of dry biomass storage. Future work will examine the effects of endoxylanase activity toward substrates such as corn stover, wheat straw, and switchgrass in low water content environments.
KeywordsEndoxylanase Water activity Water content Biomass Lignocellulose Storage Feedstock Preprocessing Stability
The authors thank Liz Taylor and Karen Delezene-Briggs of the Idaho National Laboratory Biological Systems department for their technical assistance and Robert Cherry of the Idaho National Laboratory Energy Systems and Technology department for his critical review. This work was supported by the United States Department of Energy, Office of the Biomass Program, under DOE-NE Idaho Operations Office Contract DE-AC07-05ID14517.
- 5.Nelson, N. (1977). Citation classics—photometric adaptation of Somogyi method for determination of glucose. Current Contents, 3, 13–13.Google Scholar
- 6.Somogyi, M. (1952). Notes on sugar determination. The Journal of Biological Chemistry, 195(1), 19–23.Google Scholar
- 7.McCleary, B. Nelson Somogyi Procedure. Frequently Asked Questions 2001 [cited 2007]; Assay procedure].Google Scholar
- 8.Acker, L. W. (1969). Water activity and enzyme activity. Food Technology, 23(10), 1257.Google Scholar
- 9.Mellor, J. D. (1978). Fundamentals of freeze-drying (p. 386). New York: Academic.Google Scholar
- 10.Greenspan, L. (1977). Humidity fixed-points of binary saturated aqueous-solutions. Journal of Research of the National Bureau of Standards Section a-Physics and Chemistry, 81(1), 89–96.Google Scholar
- 11.Devices, D. Application note AN1006-10: Moisture sorption isotherm method. Application Notes 2004 [cited 2007; Available from: www.decagon.com].
- 12.Devices, D. AquaSorb isotherm method application note. [Application Note] 2008 [cited 2008; Available from: http://www.decagon.com].
- 14.Labuza, T. P. (1968). Sorption phenomena in foods. Food Technology, 22(3), 15.Google Scholar
- 15.Brown, A. D. (1976). Microbial water stress. Bacteriological Reviews, 40(4), 803–846.Google Scholar
- 17.Devices, D. Application note AN1005-10: The definition of water activity. Application Notes 2001 [cited 2007; Available from: www.decagon.com].
- 20.Schwimmer, S. (1980). Influence of water activity on enzyme reactivity and stability. Food Technology, 34(5), 64.Google Scholar
- 22.Sorensen, H. R., Meyer, A. S., & Pedersen, S. (2003). Enzymatic hydrolysis of water-soluble wheat arabinoxylan. 1. Synergy between alpha-L-arabinofuranosidases, endo-1,4-beta-xylanases, and beta-xylosidase activities. Biotechnology and Bioengineering, 81(6), 726–731. doi: 10.1002/bit.10519.CrossRefGoogle Scholar
- 23.Sorensen, H. R., et al. (2007). Enzymatic hydrolysis of wheat arabinoxylan by a recombinant “minimal” enzyme cocktail containing beta-xylosidase and novel endo-1,4-beta-xylanase and alpha-(L)-arabinofuranosidase activities. Biotechnology Progress, 23(1), 100–107. doi: 10.1021/bp0601701.CrossRefGoogle Scholar