|CHEN, RUI - Michigan State University|
|THOMAS, BENJAMIN - Michigan State University|
|LIU, YAN - Michigan State University|
|LIAO, WEI - Michigan State University|
Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2014
Publication Date: 9/5/2014
Publication URL: http://handle.nal.usda.gov/10113/59639
Citation: Chen, R., Thomas, B., Liu, Y., Mulbry Iii, W.W., Liao, W. 2014. Effects of algal hydrolysate as reaction medium on enzymatic hydrolysis of lignocelluloses. Biomass and Bioenergy. 67:72-78.
Interpretive Summary: Algae have attracted attention for over five decades as a promising feedstock for biofuels production. Of particular interest is the coupling of algae-based wastewater treatment processes with conversion of the algal byproduct into complementary products (such as biofuels, chemicals, and fertilizers). The general goal of this research project was to evaluate potential uses of wastewater-grown algae beyond their own bioenergy value. The specific goal was to determine whether algal sugars and proteins would be helpful as additives in reactions with four biofuel feedstocks (poplar, corn stover, switchgrass, and anaerobically digested manure fiber). The results showed that a mixture of algal components improved the breakdown of two of the four feedstocks. These results will be useful for scientists and engineers involved in designing improved methods for producing biofuels.
Technical Abstract: Algal biomass has been proposed as a source of lipids and sugars for biofuel productions. However, a substantial portion of potentially valuable algal material remains as a liquid hydrolysate after sugar and lipid extractions. This study examined the effects of an algal hydrolysate on the enzymatic hydrolysis of lignocelluloses using four bioenergy feedstocks (poplar, corn stover, switchgrass, and anaerobically digested manure fiber). Feedstocks were pretreated using dilute acid or alkali prior to hydrolysis. Hydrolysis reactions were conducted using the neutralized algal hydrolysate, citrate buffer, or de-ioinized water as reaction media. Results demonstrated that algal hydrolysate significantly improved the efficiency of enzymatic hydrolysis of the two high-lignin containing feedstocks (poplar and anaerobically digested manure fiber), but did not improve the hydrolysis efficiency of corn stover or switchgrass. These results suggest that organic compounds such as proteins and/or other small molecules in the algal hydrolysate may block the enzyme-absorption sites of lignin, which led to increased enzyme accessibility for the hydrolysis. It is also possible that the algal hydrolysate could also provide a more nutrient-balanced and pH-buffered environment than the other reaction media tested. Since these experiments used only one source of algal material, additional studies are needed to extend these results using hydrolysates from different algal strains and other lignocellulosic feedstocks. This study suggests that algal byproducts from sugar and lipid extractions may have value as a supplemental feedstock to enhance the breakdown of lignocellulosic materials for bioenergy production. This additional value could substantially improve the overall viability of algal biofuel strategies.