Advantages of fungal pretreatment and enzymes involved in lignin degradation.

1. Fungal Pretreatment Of
Lignocellulosic Biomass
PRESENTED BY
KHAN MISBAH FARHEEN
AALBORG UNIVERSITY,DENMARK

2. Pretreatment:
 The important step involved in production of bio-ethanol from various
biomass.
 Most costly step.
 It opens up the structure of lignocellulose.
 It increases the biomass accessibilty for enzymatic hydrolysis.
 Pretreatment types: Physical/Mechanical, Chemical and Biological.
www.intechopen.com

3. Physical & Chemical pretreatment:
These techniques require:
 Expensive corrosion resistant reactors.
 Processing large volumes of waste streams.
 Extensive washing of treated solids.
 Detoxification of fermentation inhibitory substances.
 More costly as comapred to biological pretreatment.

4. Fungal Pretreatment
(Biological method)
Many advantages over physical and chemical pretreatment which include:
 Simple techniques.
 Low energy requirements.
 No or reduced output of waste streams.
 Reduced cost of downstream processing.
 No fermentation inhibitors formation.
Fungal pretreatment results in degradation of lignin by ligninolytic enzymes.

5. Lignin-degrading microorganisms:
 White-rot fungi most effective for delignification.
 Brown-rot fungi
 Soft-rot fungi
 Some ruminant bacteria
Fungal activity
Moist straw
inoculated with
C. subvermispora

6. Fungal delignification:
Lignin degradation:
 Highly oxidative.
 Involve chemical oxidants: singlet oxygen and hydroxyl radicals.
 Involved reactions:
• Oxidation.
• Demethylation.
• Side-chain oxidation.
• Propyl side-chain cleavage.

7. Ligninolytic enzymes:
 Lignin peroxidase (LiP)
 Manganese peroxidase (MnP)
 Laccases
 Versatile peroxidase (VP) http://pubs.rsc.org/
Biological pretreatment of rubberwood after 90 d:
(a) C.subvermispora; (b) T.versicolor;
(b) (c) Mixed culture.
Nazarpour et al., Materials 2013, 6(5), 2059-2073.
AAU, Section for Sustainable Biote

8. Ligninolytic enzymes:
A)Lignin peroxidase:
1. Hemeprotein
2. Involved in oxidative cleavage of non-phenolic aromatic lignin
compounds.
B) Manganese peroxidase:
1. Oxidizes phenolic compounds.
2. Mainly oxidizes Syringyl and vinyl side-chain substrates.
3. Shows activity in presence of manganese ion(Mn+2)

9. Ligninolytic enzymes:
C)Laccases:
1. Copper-containing oxidase.
2. Acts on phenols and similar compounds.
3. Performing one-electron oxidation.
D)Versatile peroxidase:
1. Isolated from Pleurotus and Bjerkandera species.
2. Also called ”Third peroxidase” a LiP-MnP hybrid.
3. Mn+2 independent activity.
4. Capable of degrading both phenolic and non-phenolic compounds.

10. Factors affecting Solid state fungal
pretreatment:
 Inoculum.
 Moisture content: optimum range 70-80%
 Particle size of substrate.
 Supplements: Inducers like hydrogen peroxide,Mn+2 and other aromatic
compounds.
 Temperature: Optimal range 25°C-30°C.
 Aeration.
 Decontamination of feedstocks.
 Pretreatment time.

11. Applications of fungal pretreatment:
 Enzymatic hydrolysis of lignocellulose.
 Production of Biofuels.
 Biopulping and biobleaching.
 Ruminant feed.
 Enzyme production
 And manymore….

12. Reference:
1) C. Wan, Y. Li / Biotechnology Advances 30 (2012) 1447–1457 1451
2) Sánchez C. Lignocellulosic residues: biodegradation and bioconversion by
fungi. Biotechnol Adv 2009;27:185–94.
3) Sarikaya A, Ladisch M. Solid-state fermentation of lignocellulosic plant
residues from brassica napus by Pleurotus ostreatus. Appl Biochem
Biotechnol

13. THANK YOU