SLIDE 1
Optimizing Pretreatment of Brown Midrib Maize Silage for Effective Fermentation at High Solids Loading High Solids Loading
Arun Athmanathan, Peter Friedemann, and Nathan S. Mosier
SLIDE 2 Acknowledgements
- Research, Inc. (CPBR), U.S. Department of Energy
(DOE) Prime Agreement no. DEFG36-02GO12026.
- Dow AgroSciences for funding and providing stover
and silage material
- Wilfred Vermerris (U of FL) for providing the A619
- Wilfred Vermerris (U of FL) for providing the A619
maize stover
- Purdue Agriculture Research Programs
- Michael Ladisch (Purdue)
- Yulin Lu, Isaac Emery, Youngmi Kim, Harini Kadambi,
Lauren Quig, Erin Rosswurm, Scott Stella, and Linda Liu
SLIDE 3
Amorphous Cellulose Lignin
Effect of Pretreatment of Corn Stover
Representation of Physical Changes Pretreatment Crystalline Region Amorphous Region Hemicellulose
Mosier et al, 2004
SLIDE 4 Goals:
Liquid Water Pretreatment
Determine conditions that:
- 1. During pretreatment
- 2. After pretreatment
SLIDE 5
Autohydrolysis during Pretreatment of Lignocellulose at 190 C
H Xn X Degradation Products k1 k3 k4 H* k2
H = labile hemicellulose H* = recalcitrant hemicellulose Xn = soluble xylans (oligosaccharides) X = xylose (monomer)
SLIDE 6
Liquid Hot Water Pretreatment at Lab Scale
4 ½ ” 33.75 mL Working Volume
Swagelok Fittings and Endcap 1” Stainless Steel Tubing
SLIDE 7 Lignin biosynthesis
COOH COOH NH2 OH OH O O O OCS-CoA OH H3CO OCS-CoA
bm3
OH OH OH OH OCH3 H3CO H3CO H2 COH H2 COH OH H3CO OH OCH3 H3CO H2 COH
H S G
bm1 OH
OH H3CO H2 COH
bm3
SLIDE 8 Brown Midrib Maize
› Known to have higher digestibility in ruminants – grown commercially for silage to feed dairy cows › Hypothesis:
–
SLIDE 9 Improved yield of fermentable sugars from brown midrib corn stover (no pretreatment)
150 200 250 g/g DW)
2x !
50 100 A619 bm1 bm2 bm3 bm4 bm1-bm3 bm2-bm3 bm3-bm4 glucose (mg
control
All mutants in the same genetic background (A619)
SLIDE 10
Dry matter composition of wild type and BMR maize stover: Commercial Hybrids
Composition (% dry mass) Wild Type BMR CAFI Maize Stover* Glucan 39% 41% 34% Xylan + Galactan 25% 27% 24% Arabinan 2.8% 3.1% 4.2% Arabinan 2.8% 3.1% 4.2% Acetyl 3.9% 3.5% 5.6% Lignin 22% 20% 17% Ash 4.1% 4.9% 6.1% Total 96.8% 98.5% 90.9% * Mosier et al., 2005a.
SLIDE 11
Pretreatment Method
› Liquid Hot Water Pretreatment
– !"# – $!°%&' – –
SLIDE 12 Mass Balance Around Pretreatment: Xylan
50% 60% 70% 80% 90% 100% ial Xylan 0% 10% 20% 30% 40% 50% 10 15 20 25 30 10 15 20 25 30 % Initial X (A) Wild Type Stover (B) bmr Stover Pretreatment Hold Time at 190C (minutes) Furfural Xylose Oligosaccharide Solids
SLIDE 13 Enzymatic Hydrolysis of Unwashed, Pretreated Maize Stover
eld (%) 50 60 70 80
BMR Pretreated W ild Type Pretreated BMR W ild-Type
Hydrolysis Tim e (hours) 10 20 30 40 50 Glucose Yield 10 20 30 40
SLIDE 14 Summary of BMR Stover
› Optimum pretreatment conditions same for both types › Lignin structure, but not amount, accounts for difference in enzymatic hydrolysis of untreated stover › Differences observed after pretreatment
– ()' *! – ()' *! – +! – (),!'
14
SLIDE 15
Biomass Storage Moisture Continuum
Dennis Buckmaster
SLIDE 16 Materials and Methods
›Silage
– +-'&
&.
– /''0
'- '- '
SLIDE 17
Composition of 2009 Silage (% dry matter)
Component TMF BMR % (Dry Mass) % (Dry Mass) Starch 33.6 36.2 Cellulose 25.8 35.1 Xylan/Galactan 12.8 15.3 Arabinan 1.3 2.0
17
Arabinan 1.3 2.0 Acetyl 0.5 0.5 Acid Insoluble Lignin 11.5 8.5 Acid Soluble Lignin 5.4 1.6 Ash 1.0 1.4 Mass Balance 92 101
SLIDE 18 Methods
› Stainless Steel Reactors (35ml volume) › Loading 20 w/w % (200 g/L) › Sandbath heat up and temperature control › Enzymatic Digestion › Enzymatic Digestion
– + # – 23 – %45'66 748",!
%(8"9#
SLIDE 19
Optimization of Silage Pretreatment
40% 50% 60% 70% 80%
Yield (24 hr)
0% 10% 20% 30% 40%
Glucose Yie Pretreatment Condition BMR Leafy
TMF
SLIDE 20 Glucose/Xylose Fermentation Results
60 70 80 90
n (g/L)
BMR Pretreated and Pre-Hydrolyzed
Ethanol Glucose
10 20 30 40 50
24 48 Concentration (
Time (Hours)
Xylose
SLIDE 21
Summary
› Brown Midrib variety of maize silage result in higher yields of glucose than regular varieties of maize before and after pretreatment › Ensiling cellulosic biomass has potential as a way to preserve feedstock quality for biofuels production between harvest seasons. seasons. › Liquid hot water pretreatment of maize silage requires less severity than dry maize stover (180C rather than 190C) to achieve similar results › Glucose released by enzymatic hydrolysis of pretreated silage is readily fermented to ethanol by S. cerevisiae
SLIDE 22
Thank you!
