biological lignin depolymerization presentation for beto 2015 … · 2015. 4. 20. · lignin...

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1 | Bioenergy Technologies Office eere.energy.gov 2015 DOE BioEnergy Technologies Office (BETO) Project Peer Review Date: March 25 th , 2015 Technology Review Area: Biochemical Conversion Biological Lignin Depolymerization (WBS 2.3.2.100) Principal Investigators: Gregg Beckham (NREL) John Gladden (SNL) Organizations: National Renewable Energy Laboratory and Sandia National Laboratory

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  • 1 | Bioenergy Technologies Office eere.energy.gov

    2015 DOE BioEnergy Technologies Office (BETO) Project Peer Review Date: March 25th, 2015 Technology Review Area: Biochemical Conversion Biological Lignin Depolymerization (WBS 2.3.2.100)

    Principal Investigators: Gregg Beckham (NREL) John Gladden (SNL) Organizations: National Renewable Energy Laboratory and Sandia National Laboratory

  • 2 | Bioenergy Technologies Office

    Project Goal

    Residual Biorefinery Lignin

    Goal and Outcome: develop a biological approach to depolymerize solid lignin for upgrading of low MW aromatic compounds to co-products Relevance to BC Platform, BETO, industry: lignin valorization is key for meeting HC fuel cost and sustainability targets in integrated biorefineries

    Ligninolytic Enzymes

    Aromatic-catabolizing bacteria

  • 3 | Bioenergy Technologies Office

    Quad Chart

    • Start date: October 2014 • End date: September 2017 • Percent complete: ~30%

    • Bt-F Hydrolytic Enzyme Production • Bt-I Catalyst Efficiency • Bt-J Biochemical Conversion Process

    Integration

    Timeline

    Budget

    Barriers

    • BETO Projects: Pretreatment and Process Hydrolysis, Lignin Utilization, Biochemical Platform Analysis, Pilot Scale Integration, Enzyme Engineering and Optimization

    • BETO-funded National Lab Projects: Oak Ridge National Laboratory (A. Guss)

    • Office of Science funded efforts: Joint BioEnergy Institute, Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory (R. Robinson, E. Zink)

    • Academic collaborators: Swedish University of Agricultural Sciences, University of Portsmouth

    Partners and Collaborators

    FY14 Costs

    Total Planned Funding

    (FY15-Project End Date)

    DOE funded $222,410 $1,752,590

    Funds are split 50/50 between NREL and SNL

  • 4 | Bioenergy Technologies Office

    Project Overview

    Project History: • Began as a BETO seed project in FY14 between NREL and SNL • Achieved major milestone at end of FY14 • Complementary effort to other BETO-funded lignin projects

    Project Context: • Lignin valorization is a primary challenge in biochemical conversion processes • Leverage studies in biological lignin depolymerization with new synthetic biology

    techniques and new process concepts in biological funneling

    High-Level Objective: • Employ biology for depolymerization and aromatic catabolism of residual lignin

    Lignin Depolymerization

    • Focus on residual solids from Deacetylation-Mechanical Refining Prt.

    • Examine fungal and bacterial ligninolytic enzymes for solid lignin depolymerization

    • Develop effective enzyme secretion systems

    Lignin Upgrading • Develop aromatic metabolic map • Elucidate aromatic transport mechanisms • Understand rate limitations in aromatic

    catabolism • Develop optimized modules for production

    of value-added products

  • 5 | Bioenergy Technologies Office

    Technical Approach

    Substrate: residual lignin from deacetylation and mechnical-refining pretreatment and enzymatic hydrolysis (DMR-EH) Approach: • Characterize enzymatic degradation of DMR-EH lignin • Identify parameters for optimal biological lignin degradation • Engineer organisms convert depolymerized lignin into valuable bioproducts

    Primary challenges: • Effective analytical tools to quantify lignin depolymerization • Minimizing repolymerization of high MW lignin during depolymerization • Identifying and overcoming aromatic transport and catabolic limitations

    Lignin-degrading Enzymes: Laccases & Peroxidases

    Degraded lignin

    Biomass DMR Pretreatment

    Enzymatic Hydrolysis

    Sugars for fuels

    DDR-EH lignin

    Use microbial cell factories to upgrade

    lignin Success factors: • Achieving high yields of low MW lignin species • Generating aromatics that can be metabolized by microbes • Producing products with high market value from lignin

  • 6 | Bioenergy Technologies Office

    Management Approach

    Management Approach: • Use quarterly milestones to track

    progress and down-select options

    • Milestone priority dictated by depolymerization and overcoming key risks in yields

    • Phone calls every 3 weeks, site visits every 6 months

    • Contributions from both partners on lignin analytical chemistry leveraging respective expertise

    • Divide research in a manner that leverages each partners strengths

    Critical Success Factors: • Employ tools of synthetic biology and

    lignin analytical chemistry

    • Leverage experience from two biomass conversion centers

    • Strategic hire in biological lignin depolymerization

    • Work with Biochemical Platform Analysis Project to identify optimal co-product targets

    • Leverage input and collaborations from other BETO-funded projects in lignin

  • 7 | Bioenergy Technologies Office

    Technical Results – Outline

    • Examined purified enzymes and fungal-derived secretomes on several lignin substrates for ability to depolymerize lignin

    • Determined that reaction conditions and enzyme composition are key factors in promoting lignin depolymerization

    • Found evidence that lignin repolymerization is an issue that must be addressed to achieve maximum lignin depolymerization. Solution: microbial “sink”

    • For FY15, we have assembled a list of microbial “sinks” and initiated a detailed characterization of DMR-EH lignin

    Depolymerization Repolymerization

    Lignin

    Co-products

    Aromatic Catabolism

    Strain Consumes Aromatics

    Growth on Lignin

    Amycolatopsis sp. Y Y Pseudomonas fluorescens Y Y

    Pseudomonas putida KT2440 Y Y

    Etc… Y Y

    ENZYMES

  • 8 | Bioenergy Technologies Office

    FY15 Milestone: Characterization of solid DMR-EH

    Compositional analysis Molecular weight distribution

    Sample ID Content (%) Ash 2.18

    Lignin 66.0 Glucan 9.24 Xylan 9.36

    Galactan 1.04 Arabinan 1.62 Fructan 0.00 Acetate 0.72

    Total sugar 21.26 Total 90.2

    Mn Mw PD

    2,000 10,000 5.0

    2D-NMR for lignin chemical composition (HSQC)

    O O C H 3 H 3 C O

    R

    1 2 3

    4 5 6

    O O C H

    R

    1 2 3

    4 5 6

    O R

    1 2 3

    4 5 6

    1 2 3

    4 5 6

    O O C H 3

    R

    O O

    b a

    O R

    O O

    1 2 3

    4 5 6

    b a

    H

    G

    S

    FA

    PCA

    Moiety Abundance S 17% G 45% H 2%

    PCA 27% FA 9%

  • 9 | Bioenergy Technologies Office

    Microbial Lignin Depolymerization

    FY14 Research: Start with Fungi • Use purified fungal enzymes to optimize conditions for lignin depolymerization • Examine ligninolytic enzyme cocktails produced by basidiomycete fungi to

    optimize conditions and identify the enzymes present in natural secretomes

    Dye-decolorizing (DyP)

    Peroxidases Laccases

    Lignin (LiP) Manganese (MnP)

    Aryl-alcohol (AAO)

    Enzymatic cocktail

    LIGNIN DEPOLYMERIZATION

    H2O Free radicals

    H2O2 O2

    Versatile (VP)

    Enzymatic assays

  • 10 | Bioenergy Technologies Office

    Enzyme Function Source Organism Name

    Laccase Trametes versicolor Tv

    Laccase Agaricus bisporus Ab

    Laccase Rhus vernicifera Rv

    Laccase Pleurotus ostreatus Po

    Lignin

    Peroxidase Unknown LiP

    Top Enzymes

    Green enzymes used in ligninolytic cocktails

    Ligninolytic enzyme activity is a strong function

    of temperature and pH

    • Screened 9 commercial purified fungal laccases and peroxidases for ability to solubilize lignin

    • Used active enzymes to optimize the reaction conditions and create cocktail

    • pH and Temp are critical factors for depolymerization

    • Optimal enzyme loads depend on pH, T

    Optimizing Enzymatic Lignin Depolymerization

    -0.6

    -0.4

    -0.2

    0

    0.2

    0.4

    0.6

    0.8

    ugE/mgL 0.4 4 0.4 4

    Temp 30°C 30°C

    pH

    Lign

    in S

    olu

    bili

    zati

    on

    (AB

    S 2

    80

    nm

    )

    Ligninolytic Enzymes Depolymerize or Repolymerize Lignin Depending on Reaction

    Conditions

    Tv Lac

    Po Lac

    LiP

    -30

    -20

    -10

    0

    10

    20

    30

    40

    50

    60

    1x 0.5x 1x 0.5x

    20°C 30°C

    DDR-EH Ch

    ange

    in L

    ign

    in S

    olu

    bili

    ty (

    %)

    Solubilization of DMR-EH Lignin by Ligninolytic Cocktail

    Enzyme Loadings are also very important!

    Dep

    oly

    mer

    ize

    Rep

    olym

    erize

  • 11 | Bioenergy Technologies Office

    Screening of natural fungal secretomes

    Screen with 12 white-rot fungi • Pleurotus ostreatus • Irpex lacteus • Panus tigrinus • Bjerkandera adusta • Bjerkandera sp. • Cerioporopsis subvermispora • Pleurotus eryngii • Phellinus robustus • Polyporus alveolaris • Stereum hirsutum • Trametes versicolor • Phanerochaete chrysosporium

    Production of fungal secretomes in the presence of lignocellulose can induce and/or accelerate the production of ligninolytic and cellulolytic enzymes

    Ligninolytic Enzyme induction on DDR-EH lignin

    Production of ligninolytic cocktails ABTS assay

    Reactive Blue 19 assay

    Profile ligninolytic enzyme activities

  • 12 | Bioenergy Technologies Office

    • Identified organisms that produce the most activity of specific ligninolytic enyzmes

    • P. eryngii shows highest lignin depolymerization, lowest MW pH 7

    • Surpassed FY14 Go/No-Go • pH plays a major role in lignin

    depolymerization extents

    0

    500

    1000

    1500

    2000

    0 5 10 15

    mU

    /mL

    Days

    ABTS

    ABTS + H2O2

    ABTS + H2O2+ Mn

    9 days

    0

    500

    1000

    1500

    2000

    0 5 10 15

    mU

    /mL

    Days

    7 days

    0

    500

    1000

    1500

    2000

    0 5 10 15

    mU

    /mL

    ABTS

    ABTS + H2O2

    ABTS + H2O2+ Mn

    MnSO4

    Veratryl alcohol

    Veratryl alcohol+ H2O2

    RB 19

    Laccase x 10

    Laccase

    Peroxidase

    MnP I

    MnP II

    AAO

    LiP

    DyP

    Phellinus robustus

    (laccase, MnP, DyP, AAO)

    Pleurotus eryngii

    (laccase, AAO, VP, MnP )

    Days

    Bjerkandera sp.

    (MnPs)

    0

    1000

    2000

    3000

    4000

    5000

    6000

    7000

    8000

    9000

    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

    pH4.5

    pH7

    H2O2 + Mn+2 H2O2 + Mn

    +2

    Pleurotus eryngii Bjerkandera sp. Phellinus robustus

    Secretomes from:

    H2O2 + Mn+2

    Control

    Mo

    lecu

    lar

    wei

    ght

    aver

    age

    (kD

    a)

    60% decrease MW 50% decrease

    MW

    Characterization of ligninolytic cocktails

    0

    500

    1000

    1500

    2000

    0 5 10 15

    mU

    /mL

    Days

    9 days

  • 13 | Bioenergy Technologies Office

    P. eryngii secretome depolymerizes DMR-EH Lignin

    P. eryngii is able to depolymerize DDR-EH lignin to low MW species • 50% of lignin species are smaller than the control (Mn) in a single day of treatment • Apparent repolymerization by 4 days of incubation • Repolymerization may be prevented if we incorporate a low MW aromatic compound “sink” • Work in Pseudomonas putida suggests microbes are an ideal “sink”” as they can be used to

    convert the lignin degradation products into value-added compounds

    Depolymerization Repolymerization

    Lignin

    Need to create conditions

    that promote Depolymerization

    Number-averaged Molecular Weight Distribution upon

    ligninolytic enzyme treatment at pH 7

    0

    500

    1000

    1500

    2000

    2500

    1 2 3 4 5

    3 U laccase/g DDR

    11 U laccase/g DDR

    30 U laccase/g DDR

    No enzymes

    1 day

    2 days

    3 days

    4 days

    Mn (

    kDa)

  • 14 | Bioenergy Technologies Office

    One primary strategy going forward: microbial “sink”

    Fungal Laccases & Peroxidases

    Microbial “Sink”

    Re-polymerization

    Co-products

    High MW Lignin

    Utilize microbial sink to uptake aromatic species upon depolymerization • Similar to SSF or CBP concepts in polysaccharide valorization approaches • Requires understanding of aromatic transport and catabolism: “aromatic metabolic map” • Need a promiscuous microbe with broad substrate specificity, genetic tractability • Co-product selection will require consideration of separations and other process variables

    including oxygen demands in solid media

    Aromatic Catabolism

  • 15 | Bioenergy Technologies Office

    Conditioning DMR-EH lignin for biological treatments

    • FY15 Milestone: Identified 27 organisms (bacteria and fungi) that can metabolize lignin subunits and can grow on lignin

    • Remaining FY15 Milestones: Down-select to top microbial “sinks” and begin detailed characterization of aromatic metabolism

    • DMR-EH lignin is a challenging substrate to obtain high conversion yields to monomeric species.

    • pH will be crucial for obtaining high lignin solubilization as well as performing enzyme treatments and growing the organisms

    0.00

    0.10

    0.20

    0.30

    0.40

    0.50

    0.60

    7 8 9 10 11 12

    Gro

    wth

    (O

    D600)

    pH

    Effect of pH on Growth on DMR-EH Lignin

    5 8 14 22 24 31 33

    Organism

  • 16 | Bioenergy Technologies Office

    L-CBP: Bacteria also depolymerize lignin Salvachua et al., in review

    ALKALINE PRETREATED LIQUOR FROM CORN STOVER L-CBP Lignin Consolidated

    Bioprocessing

    OO

    HO

    HO

    OO

    OO

    High Mw Lignin

    Lig

    nin

    De

    po

    lym

    eriza

    tio

    n

    Mo

    no

    me

    rs fo

    r C

    ata

    bo

    lism

    DDR-EH

    lignin

    For fuels, materials,

    & chemicals

    Aromatic Monomers

    Laccases & Peroxidases

    Intracellular Or

    Extracellular Metabolites Production

  • 17 | Bioenergy Technologies Office

    Proteomics to fingerprint ligninolytic enzymes

    • Bacteria also depolymerize lignin with laccases and peroxidases, but produce much smaller amounts of enzymes than fungi

    • Proteomics studies will provide detailed information about fungal and bacterial enzymes implicated in lignin depolymerization and catabolism

    • Awarded competitive allocation for proteomics at EMSL, analysis ongoing

    EXTRACELLULAR INTRACELLULAR

    BACTERIA: Pseudomonas putida KT2440

    Acinetobacter ADP1 Amycolatopsis sp.

    Rhodococcus jostii RHA1

    1, 3, 5 days of bacterial culture

    FUNGI Pleurotus eryngii

    Analysis of the secretome at 9 and 15 days

    Control P. putida

  • 18 | Bioenergy Technologies Office

    Biomass Cellulase Enzymes Microbes

    Pretreatment

    Cellulosic Bioprocessing

    Sugars

    Lignin Ligninolytic Enzymes

    Low MW Aromatics

    Biofuels& Bioproducts

    Higher pH or Temperature

    or

    • Develop an effective lignin depolymerization approach that enables near complete conversion to co-products

    • Determine the optimal configuration of microbes and enzymes: multiple enzymes, multiple microbes, L-CBP

    Evaluating optimal depolymerization and sink

  • 19 | Bioenergy Technologies Office

    Lignin valorization will be essential to achieve 2022 HC fuel cost targets

    Highlighted in 2011 Review/CTAB as a key gap in BC Platform Key MYPP areas for process improvement via lignin utilization:

    Hydrolytic enzyme production • Evaluating ligninolytic enzymes • Demonstrated effectiveness of

    fungal secretomes at neutral pH on DMR-EH substrate

    Biochemical Conversion Process Integration • Examining ability of biological

    catalysts to function on a process-relevant substrate

    Key Stakeholders and Impacts:

    • Lignocellulosic biorefineries: TEA has shown that refineries must valorize lignin to be competitive with petroleum

    • Lignin-derived aromatics could be useful for the fuels, chemical, and material science industries

    • Efficient lignin depolymerization is a major barrier to lignin utilization

    • A successful outcome of this project will lead to technologies that can efficiently depolymerize lignin and simultaneously convert it into value-added bioproducts via microbial cell factories

    Catalyst efficiency • Combined depolymerization and

    sink concept for lignin • Selective transformation of lignin

    to advanced fuels and chemicals

    Relevance

  • 20 | Bioenergy Technologies Office

    Lignin Depolymerization • Use omic analysis to understand microbial lignin depolymerization • Engineer microbial sinks to depolymerize lignin by expression of heterologous enzymes • Examine ability of microbial “sinks” to depolymerize DMR-EH alone or with fungal enzymes

    Lignin Transport and Catabolism • Mine genomes of microbial “sinks” to identify catabolic pathways to leverage for products • Conduct metabolomics analysis with 13C labeled aromatics to identify intermediates • Identify genetic “parts” that can be used from metabolic engineering of microbes to produce

    bioproducts from lignin

    Future Work

  • 21 | Bioenergy Technologies Office

    1) Approach: • Develop a biological approach to depolymerize solid lignin for upgrading of low MW aromatic compounds to

    co-products

    2) Technical accomplishments • Examined purified enzymes and fungal-derived secretomes on several lignin substrates for ability to

    depolymerize lignin • Determined that reaction conditions and enzyme composition are key factors in promoting lignin

    depolymerization • Found microbial aromatic “sinks” may be critical for extensive lignin depolymerization

    3) Relevance • TEA shows lignin valorization is critical for lignocellulosic biorefineries • Low molecular weigh aromatics have value in several industries

    4) Critical success factors and challenges • Achieving high yields of low MW, upgradeable species • Minimizing lignin monomer repolymerization • Overcoming aromatic transport and catabolic rate limitations

    5) Future work: • Increase efficiency of biological lignin depolymerization • Implement a microbial aromatic “sink” to prevent lignin repolymerization and produce valuable bioproducts

    6) Technology transfer: • Generate IP around lignin depolymerization methodologies • Generate novel microbial lignin conversion strategies

    Summary

  • 22 | Bioenergy Technologies Office

    Acknowledgements

    • Edward Baidoo • Adam Bratis • Xiaowen Chen • Tanmoy Dutta • Rick Elander • Mary Ann Franden • Chris Johnson • David Johnson • Rui Katahira

    • Eric Karp • Payal Khanna • Bill Michener • Michael Resch • Davinia Salvachua • Blake Simmons • Melvin Tucker • Derek Vardon

    External Collaborators • Adam Guss, Oak Ridge National Laboratory • R. Robinson, E. Zink, EMSL Pacific Northwest

    National Laboratory • John McGeehan, University of Portsmouth • Jerry Ståhlberg, Mats Sandgren, Swedish

    University of Agricultural Sciences

  • 23 | Bioenergy Technologies Office

    Additional slides

    • Publications • Acronyms • Additional Technical Accomplishment Slides

  • 24 | Bioenergy Technologies Office

    Publications Publications in review: 1. D. Salvachua et al., “Lignin Consolidated Bio-Processing: Simultaneous lignin depolymerization and

    co-product generation by bacteria”, in review.

    Publications in print:

    2. A. Ragauskas, G.T. Beckham, M.J. Biddy, R. Chandra, F. Chen, M.F. Davis, B.H. Davison, R.A. Dixon, P. Gilna, M. Keller, P. Langan, A.K. Naskar, J.N. Saddler, T.J. Tschaplinski, G.A. Tuskan, C.E. Wyman, “Lignin Valorization: Improving Lignin Processing in the Biorefinery”, Science (2014), 344, 1246843.

  • 25 | Bioenergy Technologies Office

    Acronyms

    • DDR-EH Lignin: Deacetylated, Disk-Refined, Enzymatically Hydrolyzed Lignin • DyP: Dye-decolorizing Peroxidase • LiP: Lignin Peroxidase • MnP: Manganese Peroxidase • MW: Molecular Weight • VP: Versatile Peroxidase

  • 26 | Bioenergy Technologies Office

    Characterization of ligninolytic cocktails

    To measure enzyme activities, we utilized UV- and colorimetric assays to follow substrate oxidation Laccases: ABTS at pH 5 Reactive blue 19 at pH 3

    Manganese Peroxidase (MnP): ABTS + H2O2 at pH5 (also for DyP and VP) ABTS + H2O2 + Mn

    2+ at pH 5 MnSO4 + H2O2 at pH 5

    Lignin Peroxidase (LiP): Veratryl alcohol + H2O2 at pH 3

    Dye-decolorizing peroxidase (DyP): Reactive Blue 19 + H2O2 at pH 3

    Versatile peroxidase (VP): Reactive black 5 + H2O2 at pH 5

    Aryl-alcohol oxidase (AAO): Veratryl alcohol at pH 5

    ABTS assay

    Reactive Blue 19 assay

  • 27 | Bioenergy Technologies Office

    • In order to further develop depolymerization strategies and microbial aromatic “sinks” we must first have a detailed understanding of the DMR-EH lignin macromolecule and degradation products

    • Will employ a variety of analytical techniques to characterize the lignin, including mass spectrometry (MS), size exclusion chromatography (SEC), and nuclear magnetic resonance (NMR)

    NMR- linkages

    Nature Protocols 7, 1579–1589 (2012) Green Chem., 2014, 16, 2713-2727

    MS- identification SEC- size

    Detailed characterization of lignin depolymerization

  • 28 | Bioenergy Technologies Office

    Biological Lignin Depolymerization: Fungi

    Dye-decolorizing (DyP)

    Peroxidases Laccases

    Lignin (LiP)

    Manganese (MnP)

    Aryl-alcohol (AAO)

    Enzymatic cocktail

    LIGNIN DEPOLYMERIZATION

    H2O

    Free radicals

    H2O2

    O2

    Versatile (VP) Other

    oxidases

    • Laccases and peroxidases are the major enzymes involved in microbial lignin depolymerization

    • Require O2 and H2O2 respectively for activity

    Approach: • Characterized microbial degradation

    of DDR-EH lignin • Identify parameters for optimal

    biological lignin degradation

    FY14 Research: Start with Fungi • Use purified fungal enzymes to optimize conditions for lignin depolymerization • Examine the lignolytic enzyme cocktails produced by basidiomycete fungi

    to optimize conditions and identify the enzymes present in natural secretomes

  • 29 | Bioenergy Technologies Office

    Peroxidase* (U/g DMR)

    DMR-EH lignin depolymerization

    0

    1000

    2000

    3000

    4000

    5000

    6000

    7000

    8000

    9000

    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

    pH4.5

    pH7

    H2O2 + Mn+2 H2O2 + Mn

    +2

    Pleurotus eryngii Bjerkandera sp. Phellinus robustus

    Mp=300

    Mp=260

    AS

    Secretomes from:

    0 - 0- 0- 0 100- 100- 28- 28- 400- 400

    0- 90 - 0- 0.1

    30- 30- 8- 8

    0 - 7 -0.01 - 0.01 0 - 0- 0- 0

    H2O2 + Mn+2

    Control M

    ole

    cula

    r w

    eig

    ht

    ave

    rage

    (kD

    a)

    AS

    60% decrease MW

    50% decrease MW

    Laccase* (U/g DMR)

    P. eryngii secretome is an effective lignin degrading enzyme cocktail • Obtained major difference between pH 4.5 and 7 in both initial MW and MW change • P. eryngii samples seem able to produce a substantial amount of low MW species • Selected P. eryngii secretome at pH 7 for more in-depth experimental studies

  • 30 | Bioenergy Technologies Office

    GPC chromatogram

    Fungal ligninolytic enzymes are clearly depolymerizing lignin, however, as we can see at 4 days of incubation no more depolymerization is observed although the enzymes are still active. Is it due to repolymerization?

    Treatment of DMR-EH lignin with the P. eryngii secretome

  • 31 | Bioenergy Technologies Office

    Treatment of DMR-EH lignin with the P. eryngii secretome

    P. eryngii secretome Different enzyme dosages at pH 7 (3, 11, 30 U laccase/g substrate)

    DDR-EH lignin (2%) Autoclaved

    Time-course analysis

    GPC results: Mw and Mn are the values at which there are equal masses or number of molecules on each side, respectively.

    P. eryngii secretome shows rapid DDR-EH lignin depolymerization • 50% of lignin species are smaller than the control (Mn) in a single day of treatment • Control experiments with boiled enzymes and without enzymes show no

    depolymerization • Analyzed detailed molecular weight distributions (next slide)

    0

    500

    1000

    1500

    2000

    2500

    1 2 3 4 5

    3 U/g ND

    11 U7g ND

    30 U/g ND

    Control 1 day 2 day 3 day 4 day

    0

    1000

    2000

    3000

    4000

    5000

    6000

    7000

    1 2 3 4 5 Control 1 day 2 day 3 day 4 day

    KD

    a

    KD

    a

    3 U/g

    11 U/g

    30 U/g

    0d 4d 4d - Inactivated enzymes

    0d 4d 4d - Inactivated enzymes

  • 32 | Bioenergy Technologies Office

    Current Key Milestones and Findings

    • Examined purified enzymes and fungal-derived secretomes on several lignin substrates for ability to depolymerize lignin

    • Determined that reaction conditions and enzyme composition are key factors in promoting lignin depolymerization

    • Found evidence that lignin repolymerization is an issue that must be addressed to achieve maximum lignin depolymerization

    • Repolymerization may be prevented using a microbial “sink” to remove low molecular weight lignin products form the reaction

    • Superseded our FY14 Go/No-Go of attaining 20% lignin depolymerization

    • For FY15, we have assembled a list of microbial “sinks” and initiated a detailed characterization of DMR-EH lignin

  • 33 | Bioenergy Technologies Office

    Workflow

    Down-select and characterize lignin-enriched substrate

    Choose optimal method to quantify lignin depolymerization

    Screen isolated

    enzymes lignin substrate

    Develop and incorporate

    microbial sink

    Sufficient Depolymerization

    ?

    Sufficient Transport and Catabolism?

    Co-Product Engineering

    Endogenous (Secreted)

    Ligninolytic Enzymes?

    Exogenous Ligninolytic Enzymes?

    Challenges

  • 34 | Bioenergy Technologies Office

    FY15 Milestone: Characterization of solid DMR-EH

    Compositional analysis

    Molecular weight distribution

    Sample ID Content (%) Ash 2.18

    Lignin 66.0 Glucan 9.24 Xylan 9.36

    Galactan 1.04 Arabinan 1.62 Fructan 0.00 Acetate 0.72

    Total sugar 21.26 Total 90.2

    Mn Mw PD

    2,000 10,000 5.0

    2D-NMR (HSQC)

    Aromatic region

    Lignin side chain Carbohydrate region

    Saturated aliphatic region

    C1 in sugar

    PCAa+FAa

    G2

    S2/6

    (H3/5) G5 + G6

    (Pyridine)

    (Pyridine)

    (Pyridine)

    PCAb

    PCA2/6

    H2/6

    FAb Aa (b-O-4)

    Ab (b-O-4)

    OCH3

    Suga

    r

    O O C H 3 H 3 C O

    R

    1 2 3

    4 5 6

    O O C H

    R

    1 2 3

    4 5 6

    O R

    1 2 3

    4 5 6

    1 2 3

    4 5

    6

    O O C H 3

    R

    O O

    b a

    O R

    O O

    1 2

    3 4

    5 6

    b a

    H O

    O H O

    O C H 3

    O O C H 3

    b 4 1

    2 3

    4 5

    6

    ( H 3 C O )

    ( H 3 C O )

    g

    a

    H G

    S

    FA PCA

    A (b-O-4)

    S 17%

    G 45%

    H 2%

    PCA 27%

    FA 9%

    3

    Biological Lignin DepolymerizationProject GoalQuad ChartProject OverviewTechnical ApproachManagement ApproachTechnical Results – OutlineRelevanceFuture WorkSummaryAcknowledgementsAdditional slides