Effects of an algal hydrolyzate on the enzymatic hydrolysis of lignocelluloses were examined 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 hydrolyzate, citrate buffer, or deioinized water as reaction media. Results demonstrated that algal hydrolyzate significantly improved the efficiency of enzymatic hydrolysis of lignin-rich or structurally recalcitrant biomass such as poplar and anaerobically digested manure fiber. This study showed that algal biomass can be used as not only a biofuel feedstock for direct diesel and ethanol production, but also a supplemental feedstock to enhance the performance of lignocellulosic biorefining. (C) 2014 Elsevier Ltd. All rights reserved.