title: Co-hydrolysis of lignocellulosic biomass for microbial lipid accumulation.
abstract: The herbaceous perennial energy crops miscanthus, giant reed, and switchgrass, along with the annual crop residue corn stover, were evaluated for their bioconversion potential. A co-hydrolysis process, which applied dilute acid pretreatment, directly followed by enzymatic saccharification without detoxification and liquid-solid separation between these two steps was implemented to convert lignocellulose into monomeric sugars (glucose and xylose). A factorial experiment in a randomized block design was employed to optimize the co-hydrolysis process. Under the optimal reaction conditions, corn stover exhibited the greatest total sugar yield (glucose + xylose) at 0.545 g g(-1) dry biomass at 83.3% of the theoretical yield, followed by switch grass (0.44 g g(-1) dry biomass, 65.8% of theoretical yield), giant reed (0.355 g g(-1) dry biomass, 64.7% of theoretical yield), and miscanthus (0.349 g g(-1) dry biomass, 58.1% of theoretical yield). The influence of combined severity factor on the susceptibility of pretreated substrates to enzymatic hydrolysis was clearly discernible, showing that co-hydrolysis is a technically feasible approach to release sugars from lignocellulosic biomass. The oleaginous fungus Mortierella isabellina was selected and applied to the co-hydrolysate mediums to accumulate fungal lipids due to its capability of utilizing both C5 and C6 sugars. Fungal cultivations grown on the co-hydrolysates exhibited comparable cell mass and lipid production to the synthetic medium with pure glucose and xylose. These results elucidated that combining fungal fermentation and co-hydrolysis to accumulate lipids could have the potential to enhance the utilization efficiency of lignocellulosic biomass for advanced biofuels production.
authors.affiliation: Department of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Ruan
authors.forename: Michael
authors.initials: M
authors.lastname: Zanotti
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhong
authors.forename: Wei
authors.initials: W
authors.lastname: Liao
authors.forename: Chad
authors.initials: C
authors.lastname: Ducey
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
mesh_terms: D018533:Biomass; D050260:Carbohydrate Metabolism; D006868:Hydrolysis; D008031:Lignin / Q000378:metabolism*; D050356:Lipid Metabolism
chemical_list: C036909:lignocellulose; D008031:Lignin