Fundamental Understanding of the Biochemical Conversion of Buddlejadavidii to Fermentable Sugars

Department of Chemistry
The Chemistry Department is pleased toinvite you to a general lecture entitled
Fundamental Understanding of theBiochemical Conversion of Buddleja davidii to Fermentable Sugars
Presente
d by
Dr. Bassem Hallac
Lignocellulosic bioethanol is currently being expl
ored as a substitution to fossil fuels. Many lignocellulosic materials are
being examined but the importance is to find those with attractive agro-ene
rgy features. Producing lignocellulosic ethanol is challenging because lign
ocellulosic biomass is resistant to chemical and biological degradation. Toreduce biomass recalcitrance, a pretreatment stage is required. Pretreatm
ent is considered to be the most intensive operating/operating cost compone
nt of cellulosic ethanol production. Therefore, research is heavily focuse
d on understanding the effect of pretreatment technologies on the fundament
al characteristics of lignocellulosic biomass.
A plant call
ed Buddleja davidii was used as a resource for bioethanol production becaus
e it has unique properties to become an agro-energy crop. B. davidii exhibi
ts a very wide range of growth habitat and is well adapted to growing in po
or soil conditions. The plant is perennial, has moderate growth dimensions
, and is susceptible to very few pests or diseases. The work focuses on t
he determination of ash, extractives, lignin, hemicellulose, and cellul
ose content in this plant, as well as detailed elucidation of the chemicalstructures of both lignin and cellulose by NMR spectroscopy. The study sho
wed that B. davidii has several unique agro-energy features but on the othe
r hand some undesired characteristics.
The research continuedto focus on the ethanol organosolv pretreatment (EOP) of B. davidii and it
s ability to produce enzymatically hydrolysable substrates. It was conclude
d that the removal of hemicellulose, delignification, reduction in the de
gree of polymerization (DP) of cellulose, and the conversion of crystallin
e cellulose dimorphs (Iα/Iβ) to the easily degradable para-crystalline and
amorphous celluloses were the characteristics accounted for efficient enzym
atic deconstruction of B. davidii after EOP.
Furthermore, adetailed elucidation of the chemical structure of ethanol organosolv ligni
n (EOL) of B. davidii was investigated by NMR spectroscopy. Such research w
as needed to understand the pretreatment mechanism in the context of delign
ification and alteration of the lignin structure. Future applications of th
e resulted EOL will be valuable for industrially viable bioethanol producti
on process. EOP mainly cleaved β-O-4' interlinkages via homolysis, decreas
ed the DP of lignin, and increased the degree of condensation of lignin. E
OL had low oxygen content, molecular weight, and aliphatic OH as well as
high phenolic OH, which are qualities that make it suitable for different
co-product applications.
Finally, the anatomical characteris
tics of pretreated B. davidii biomass after EOP were studied. The importanc
e of this research was to further understand the alterations that occur to
the cellular structure of the biomass which can then be correlated with itsenzymatic digestibility. The results concluded that the physical distribut
ion of lignin within the biomass matrix and the partial removal of middle l
amella lignin were key factors influencing enzymatic hydrolysis