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Deciphering ligninocellulosic biodegradation in soil: Perspective and

advances.

Mythreyi Chandoor, Deepak Singh, Dhrubojyoti D. Laskar, Ann Kennedy and Shulin Chen*

Department of Biological Systems Engineering, Washington State University, Pullman,

WA 99164

* Corresponding author. Tel.: +1 509 335 3743; fax: +1 509 335 2722

E-mail address: chens@wsu.edu (S. Chen)

Abbreviations: Soil organic matter (SOM), Lignin peroxidase (LiP),

Manganese peroxidase (MnP), Ammonia fiber explosion (AFEX).

Keywords: Lignocellulosics, Biofuels, Biological pretreatment,

Bioconversion, Lignin degradation, Microorganisms and Humification.

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Abstract:

"In all things of nature there is something of the marvelous.”—Aristotle.

The lignin degradation pathway in soil has the potential to improve biological pretreatment of the

lignocellulosic biomass for efficient conversion to biofuel/bioproducts and chemicals. Soil is a

natural reservoir for life that controls biogeochemical cycles through the regenerative and

degradative processes, thus can be considered as an effective natural system for studying the

lignin biodegradation. Critical structural changes and chemical modification/functionalization of

lignin were associated with the enzymatic action of the soil microcosm, concomitantly; the

resulted modified lignin forms a part of humus by reacting with the soil organic matter. The

understanding of the formation of these humus-derived compounds will help in elucidating the

lignin deconstruction/modification mechanism in soil. This could be important towards

promotion of the biological degradation of lignocellulosic materials to employ and evaluate

potential application as valuable chemicals. The purpose of this review is to confer the current

knowledge in soil biodegradation system particularly in the lignin degradation process, thereby,

would provide us with new perspective of pretreatment technology during the process of biofuel

production from lignocellulosic feedstock in a cost efficient and enhance the formulation of high

value products from displaced lignin.

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1. Introduction

The The U.S ethanol consumption is predicted to increase from 5.6 billion gallons (in 2008)

to 13.5 billion gallons in 2012 (Thomson Reuters, 2009). If bioenergy is to become a viable

means to reduce fossil fuel dependency, a balance between long-term sustainability and short-

term productivity goals is needed. The history of bioenergy is often referred to first, second and

later generation. A generation refers to the conversion technologies and substrate used for

Biofuel production (Henry, 2010). Primarily the biofuels were derived from corn kernels,

sugarcane or soybean oil, and later with the increased demand for the biofuel, there was a shift

observed in the selectivity of the crop generating starch, sugar or bio-oil depending mainly on

the environmental conditions specific to a particular area (Blottnitz, 2006). Soy oil is the largest

feedstock for biodiesel, while the use of algae for the production of biodiesel, categorized under

second generation biofuel, however, is not in competition with the land for food crops. In this

regard, the biodiesel crops yield comparatively less energy per unit of crop area than that

available for ethanol crops.

Compared to the total production of bioethanol in U.S, Biodiesel is about 0.45bg/y which is

approximated to 7% of bioethanol (Hoekman, 2009). The accessibility biomass for subsequent

utilization in the bioconversion process is adversely affected by the limited sources of

agricultural land, water resources, and the food vs. fuel adjustment, which has amalgamated as

one of the prime challenges towards increasing the efficiency in the production of bioethanol

from biomass. Thus, this requires a need to focus more on development of cellulosic ethanol

processes for long term sustainability (Hoekman, 2009). In the production of bioethanol,

currently focus is directed for the utilization of lignocellulosic materials from abundant sources,

such as wheat straw, corn husks, prairie grass, discarded rice hulls or trees (Schubert, 2006).

The lignocellulosic biomass sources are considered a cheap and easily available material to

make biofuels and, in general, comprised of 30 to 50% cellulose, 20 to 30% hemicellulose and

20 to 30% lignin. In this context, the continuous challenge in biofuels production is the

inefficiency towards converting biomass into the desired bioproduct (Hoekman, 2009) and

consequently recovering the biomass-derived components in a cost effective way, requires

effective pretreatment process. The ethanol yield (g ethanol/ g biomass) from lignocellulose is

less than that from sugar and starch crops as the cell wall of lignocellulosic biomass contains

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lignin apart from cellulose and hemicelluloses along with protein and fats comparatively smaller

proportion (Banerjee, 2009). Lignin is a complex aromatic macromolecular structure derived

from hydroxycinnamyl alcohol or monolignols, such as p-coumaryl alcohol (H), coniferyl

alcohol (G), and synapyl alcohol (S) and accordingly classified on the nature of monolignol

present (H/G/S). These monomers are incorporated in the lignin primary structure in the form of

various substructures and /or inter-unit linkages such as β-O-4, β-β, β-5, etc, as result of

oxidative coupling process. The cellulose is protected in a matrix of lignin and hemicelluloses

fibers (Ralph, 2004) which makes it difficult for the enzymes to access the surface area of

cellulose. As the amount of sugars released is limited to the constraint that it is protected by

lignin, thus, to utilize lignocellulosic biomass for biofuel production, the greatest challenge lies

in the deconstruction of lignin, which protects the hemicellulose (source for C-5 sugars) and

cellulose (source of C-6 sugars) fibrils. Though there are various pretreatment technologies

which are used to treat the lignocellulosic biomass before the sugar utilization, they constitute

about 18-20% of the total cost (Yang, 2008 and Aden, 2002 and Banerjee, 2009).

Till date, different kinds of pretreatment technologies were developed, depending on the

composition and distribution of lignin, a factor which determines the nature of wood

(Taherzadeh, 2008). For example, softwood is more recalcitrant than hardwood as it is

composed of only guaiacyl units (G) which prevent the fiber swelling and thus reducing the

exposure of cellulose fibers, where as the hardwood is composed of both guaiacyl and syringyl

units(Ramos, 1992). The most extensively used pretreatment technologies and their details are

briefly summarized in Table 1. At present, chemical and physicochemical pretreatments such as

ammonia fiber explosion (AFEX), lime pretreatment, hot water pretreatment, acid pretreatment

are industrially applied for the deconstruction of lignocellulose matrix. Lignin during the

ammonia and lime pretreatment process is removed by modification in its chemical structure.

However, with such pretreatment process, lignin is chemically altered thus making it unsuitable

for to be used to produce high value products such as carbon fiber composites, resins, adhesive

binders and coatings, polyurethane-based foams, rubbers and elastomers, plastics, films, paints,

nutritional supplements, food and beverage additives. Moreover, the liquid hot water

pretreatment, though the organic acids released due to the substitutions in hemicelluloses

structure, account for removal of oligosaccharides, but the mechanism is hindered by the

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cleavage of O-acetyl and uronic acid substitutions from hemicellulose to generate acetic and

other organic acids (Walsum et al, 1996).

Thus there is a need for an efficient lignin removal system which completely exposes the

cellulose fibers, and retains lignin aromatic quality. Soil system offers to be a potential natural

system as the process of deconstruction of lignin is a thermo-chemical and microbial process

though the time takes for its complete degradation of the lignin is a point of concern. This review

addresses the mechanistic and structural aspects of lignocellulosic biodegradation in the soil

system, some of which are still only partly understood or resolved at the time of writing.

2. Soil as a potential environment for lignocellulose degradation

The degradation of the plant and other organic material occurs in the soil which forms as a

medium for the growth of several microcosms playing a major role in the natural recycling

mechanism of the complex organic component of soil into their respective elemental forms

(Skipper et al, 2005). Several microorganisms (both aerobic and anaerobic) inhabiting soil can

utilize lignocellulosic materials and animal bodies as carbon and nitrogen sources where they

degrade the material sequentially to increase the soil organic matter. Microbial decomposition of

plant biomass, the conversion of litter carbon to CO2 by microbial respiration, is one of the major

processes controlling terrestrial CO2 fluxes and ecosystem carbon storage (Raich and

Schlesinger, 1992, Couteaux et a, 1995, Aerts 1997).

Soil polysaccharides are contributed by the plant carbohydrates and microbial sugars. Time

period of the presence of organic matter might significantly influence SOM composition

(Nierop, 2000). Microorganisms living in the soil environment are responsible for moderating

the microenvironment by their enzymatic activity (Hatfield et al, 1994). The enzymes released

by the microorganism not only affect the biomass directly but also indirectly act as inhibitors and

activators for other microorganisms (Tuomela et al, 1999). Apart from microbial action,

temperature also plays a major role in decomposition of organic material. The relationship

between the temperature sensitivity of decomposition in soil and carbon(C) quality can be

realized as a complex interactions system, whilst acting between temperature and a range of

other factors influencing the rate of decomposition(Fierer, 2005).

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Sometime the photochemical affects also acts as a factor which helps lignin act as a

facilitator of carbon turnover in terrestrial ecosystems (Swift, 1979). During this process, the

factors which determine the net effect of lignin to be a driver-dependent might be other biotic

factors present in soil apart from the photochemical effects (Austin, 2010). During degradation

process of lignocellulosic materials in soil the products form as a result of carbon and energy

cycle where in they breakdown into elemental forms through the process of humification (Miguel

et al, 2002). Humification process and degree of oxidation is dictated by the increase in the O-

alkyl C, resistant aliphatic components (partly from lignin polysaccharide and non-

methoxyphenolics, such as tannins) and are determined by calculating the acid/aldehyde ratio.

Determination of factors which influence the soil organic matter and humification process

generally is vegetation specific (Nierop, 2000). In any case, during the degradation of

lignocellulosic biomass, the cellulose and hemicelluloses are easily degraded whereas lignin

follows a specific pathway for its degradation (Stevenson, 1994). The net desired compost is a

result of micro environmental factors such as variations in temperature, pH, pressure, and also

due to the microbial interactions which have a direct or indirect effect on the enzyme production

system of the microorganism (Philippe et al, 2005). This probably explains why the soil can be a

potential system to depict the natural degradation of lignocellulosic biomass.

In addition to this, diversity in soil exceeds beyond that of eukaryotic organisms, apart from

their role in formation of soil aggregates, they play a major role during nutrient cycle by being a

hub for all kinds of interactions systems between different living organisms (from eukaryotes to

unicellular microorganisms), and they form the major contributors’ in the complex interlinked

food webs (Teuscher et al, 1960). Although the deconstruction of the lignin polymer in soil

considered a slow process, the plausible chemical modification/functionalization within the

lignin proper makes it feasible for the formation of a colloid. This would result in further

cleavage of lignin primary structure, as the nature of formation of aggregate colloid and chemical

modification are interrelated in the lignin degradation pathway. (Figure 1).

3. Soil microbes involved in lignocellulose degradation Microorganisms are responsible for the decomposition of residue and the release of plant-

available nutrients. The biomass in soil is first acted by the Dematicea, a family of dark

pigmented soil fungi which belong to the class Hyphomycetes of division Ascomycota. These soft

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rot fungi produce enzymes such as xylanase, and very low amount of lignin degrading

peroxidases and manganese peroxidases(Thurston, 1994, Orth, 1995 and Yanna, 2002) which act

on the biomass to modify the lignin (biodegradation). At the site of action the soft rot fungi form

cavities near the S2 woody cell wall layer near the vicinity of cellulose fibrils during the hyphae

penetration, as a result of which the cellulose fibrils are exposed (Rayner ,1988 and Daniel,

1998). Apart from fungi, bacteria also participate in the biodegradation process of the plant litter.

Bacteria and fungi competitively feed on biomass polysaccharides in reciprocated as well as

other contemporary interactions (Wietse et al, 2004), although, most of the cellulose degradation

occurs due to fungal action in soil.

Fungi responsible for cellulose degradation in soil are Hyphochytridiomycete and Oomycete

classes of Eucomycota and Myxomycete (Arora et al, 1991). Apart from competitive relationship,

there is also a communal interaction system (mutualism), where in bacteria derive their energy

source from the degraded products released by fungi as a result of exoenzyme activity (Buyer,

2004). Bacteria such as nitrogen fixing bacteria, also acts on toxic solutes thereby, increase

nitrogen content that positively effects and hinders fungal growth (Greaves, 1971) (Hendrickson,

1991). The biomass is the soil is consumed by different mesofauna such as Oribatida,

Collembolan, Enchytraeidae which is infected by these soft rot fungi (Knight et al, 1967, Sadaka

et al, 1998). Small chemical oxidizers such as activated oxygen species and enzyme mediators

are probably involved in the initial steps of lignocellulosic degradation in soil (Angel et al,

2005). Basidiomycetes (White rot) and brown rot fungi produce extracellular lignin degrading

enzymes (Singh et al, 2008) which are responsible for modifying lignin (Eriksson et al, 1990,

Ten Have et al, 2001, Bennett et al, 2002 and Rabinovich et al, 2004, Carmen, 2009). In addition

to lignin degradation, white rot fungi have the potential to degrade cellulose and hemicelluloses

simultaneously or selectively. Apparently, different kinds of other fungi and insects which

produce laccases are also documented, that have the potential to modify lignin structures (Mayer

et al, 2002). Saccharomyces, Zymomonas mobilis, Pichia stipitis, Candida shehatae, Escherichia

coli, Trichoderma reesei, Clostridium thermocellum, Clostridium papyrosolvens, Neospora

crassa, Fusarium oxysporium degrade hexose sugars, while pentoses are degraded by

Zymomonas mobilis, Trichoderma reesei, Clostridium Papyrosolvens, Fusarium oxysporium

(Lee, 1996).

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Some of the microbes considered important for the biomass dergradation process in soil and

commercially, with their roles in context to soil system are depicted in Table1. Lignin peroxidase

(LiP) and manganese peroxidase (MnP) produced by P. chrysosporium are described as true

ligninases because of their high redox potential (Martinex, 2002, Gold et al, 2000). LiP acts on

the non phenolic components where as MnP acts on both phenolic and non phenolic lignin

components using Mn3+ as a catalytic oxidizer through a series of lipid peroxidation reactions

(Jensen et al, 1996, Angel et al, 2005). It is noteworthy to mention here that, such processes also

facilitates biodegradation of cellulose and other simpler organic compounds, in contrast to the

extent and/or scope of biochemical modification of lignin structure in the biomass.

4. Biodegradation of lignocellulosic components in soil

It is well documented that, the microfungi and bacteria which initially feed on fresh litter in

the soil are consumed by microfauna and macrofauna which consist of nematodes, protozoa and

earthworms, snails, slugs and diplopods respectively (Mark et al, 2002). These macro and

microfauna utilize the enzymes produced by the fungi and bacteria there by enhance the

digestion in their gut (External rumen hypothesis) (Swift et al, 1979, Mark et al, 2002). In this

context, carbohydrates, proteins, lipids, and modified lignin form part of soil organic matter after

the initial microbial action by different bacteria and fungi present in soil and digestive system of

animals present in soil (Tuomela et al, 1999). Whilst, cellulose being a simple chain of glucose

monomer units, its cellulolysis forms the major contributor to the carbon and energy flux in soil

(Lynch, 1981). In contrast, hemicellulose is a polysaccharide, composed of D-xylose, D-

mannose, D-galactose, D-glucose, L-arabinose, 4-O-methyl-glucoronic, D-galacturonic and D-

glucoronic acids linked by β-1,4- and sometimes by β-1,3-glycosidic bonds (Carmen, 2009 and

Schwarz, 2001), whereas, lignin being considered a complex, variable, hydrophobic, cross-

linked, three-dimensional aromatic polymer of p-hydroxyphenylpropanoid units connected by C–

C and C–O–C links (Jeewon et al, 1997).

Chemical modification of lignin structures takes place in the presence of oxygen where the

microorganisms produce enzymes of the peroxidase type. These enzymes in the presence of

hydrogen peroxidase chemically modify the structure by cleavage of the lignin side chains.

During the biodegradation process of lignin, the lignin structure is modified with the help of

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enzymes such as laccase, peroxidases and esterases which are released by lignin degrading fungi

initially as the breakage of bonds is not a feasible. Thus the intermediates are unstable and form

hydrophobic partially degraded structures in the presence of water or oxygen. In the absence of

oxygen and water, lignin is not degraded and accumulation of these complex polymers occurs in

soil (Kovalev et al, 2008). A plausible degradation pathway indicative with the proposed

cleavage sites of lignin macromolecular assembly (a representative lignin model with 8–O–4' and

8–1 inter-unit linkage) is depicted in Figure 2. The pathway of degradation of lignin proper is

believed to proceed via an oxidative C–C bond cleavage, initiated at the C7 and C8 position of

various substructures/inter-unit linkages (e.g. 8–O–4' and 8–1) within the lignin primary

structure (Reference needed). As a consequence of such C–C bond cleavage,

hydroxybenzaldehyde (1) derivatives were generated, namely, 4- hydroxybenzaldehyde (R1, R2 =

–H, from H-unit), vanillin (R1 = –H, R2 = –OCH3, from G-unit) and syringylaldehyde (R1, R2 = –

OCH3, from S-unit), respectively. The degradation pathway could also account for the formation

of cleaved diol product (3) with subsequent oxidation to its corresponding ketal (4), however,

these products (2, 3 and 4) would also be susceptible for undergoing further cleavage towards the

conversion to hydroxybenzaldehyde derivative (1) (Figure 2).

In a representative manner, the parts of the soil components which are chemically modified

along with modified or partially degraded lignin undergo a dehydrative condensation to form

humus. Moreover, humic substances considered as a major reservoir of organic carbon in soils

and aquatic environments (Aiken et al, 1985 and Sanchez-cortes et al, 2001) revealed that the

polyphenolic compounds form as intermediates during the humus formation. Apart from the

lignin molecule there are many kinds of other complex structures present in soil. As a result of

chemical modification of lignin in soil, the partially degraded hydrophobic compounds in

association with other available organic compounds and poly urinoids form macro aggregates.

Thus, the degradative process in soil consists of incorporation of complex organic molecules and

other related compounds with their transformation into humus (Figure 3).

In this regard, Stevenson (1994) proposed a theory of humus formation where the lignin

after it is chemically modified forms quinones that undergo polymerization in combination with

various released amino acids to generate humus macromolecules. These forms a major part of

humus composition which is further degraded into humic acid, humin and fulvic acid. The

humus has a very high affinity towards calcium and magnesium ions and act as polyelectrolyte

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making the compound attach to more cations (Stevenson, 1994). Furthermore, the structural

analysis of non nitrogenous fraction of humic acid also resembles modified lignin (Gillam,

1940). The presence of nitrogen content in humic acid is attributed from the contributing amino

acid nitrogen, which results from the reaction between altered lignin from the plant litter

(Bremner, 1955). Thus, humus formation is a result of auto oxidation of modified lignin and

ammonia fixation (Handley, 1954). Humus is the end product of the humification process, in

which compounds of natural origin are partially transformed into relatively inert humic

substances (Figure 4). After the humus formation, it undergoes dehydration and demethylation

reactions which lead to decrease in hydrogen to carbon ratio. The process of degradation of

humus substances is very slow despite of the availability of organic nutrients in the soil

environment.

5. Conclusion

In conclusion, soil can be regarded as an effective tool to transform lignocellulosic biomass

to various economically valuable products via humification process. The soil system can be

mimicked with systems approach; the relation would be a network between the elements of the

system which would give a different perspective of being cyclical rather than linear cause and

effect system. This kind of framework would be based on the belief that the elements of the soil

system would be dependent on the context of relationships with each other and with other

systems (mutualism, symbiosis, commensalism, and parasitism), rather than a single unit.

Understanding the detailed explanation of critical changes occurring in lignin structure facilitates

the utilization of lignocellulosics by the soil organisms. Thus, to devise soil as an efficient

bioconversion process, several factors responsible for lignocellulosic biodegradation, needs to be

addressed and explored in the soil system. This review, supplemented with relevant literature and

in depth discussion for the simultaneous application of the all soil microorganism synergistically

in the lignin biodegradation and/or structural modification. This would provide the means to

deploy lignin as a novel renewable feedstock required to harness the production of desired high

valued product.

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Acknowledgements

The authors would like to thank Agriculture Research Center, Washington State

University for financial support.

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Table 1: The different types of biomass used for the Biofuel production and their respective energy yields.

Sno Type of Biofuel resource

Yield Reference

1 Grass Species 10 tones/ha/year McLaughlin et al., 1999

2 Sugarcane 100 tones dry matter/ha/year Bull andGlasziou, 1975

3 Woody Biomass 15 tones/ha/year Boehmel et al., 2008

4 Eucalypt species >100 tones/ha/year Ugalde and Perez, 2001

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Table 2: Different kinds of pretreatment and their working process, and limitations.

Sno Pretreatment

technology

Site of action Disadvantages Reference

1 Uncatalyzed

steam explosion

Hemicelluloses Alters Lignin Structure Avellar and Glasser, 1998 Glasser and Wright, 1998, Heitz et al, 1991, Ramos et al, 1992

2 Liquid hot water

pretreatment

Hemicelluloses Cannot be used for softwood. Aldehydes from

hexoses are inhibitory to microbial

fermentation.

Bobleter, 1994, Walch et al, 1992, Mok and Antal, 1992, Kohlman et al., 1995, Allen et al., 1996, Van Walsum et al., 1996.

3 Acid pretreatment Hemicelluloses Gypsum is used during this process which has a nature of reverse solubility. Apart from this there are few inhibitors released which inhibit biomass fermentation.

McMillan, 1994, Hsu 1996, Jacobsen and Wyman 1999, Lee et al., 1999.

4 Flow through

acid pretreatment

Partial lignin and hemicelluloses

Very high energy consumption Sharmas et al, 2002 Glasser et al., 1998,

Heitz et al, 1991

5 Lime pretreatment Lignin and hemicelluloses

Some of the alkali is converted to irrecoverable salts or incorporated as salts into the biomass.

Sharmas et al, 2002, Fox et al, 1989, Chang and Holtzapple, 2000.

6 Ammonia

pretreatment

Lignin-carbohydrate linkage

Partially chemical nature of lignin is modified

which inhibits the formation of high value

products. Ammonia recovery is costly.

Kim and Lee, 1996, Kim et al, 2002,Holtzapple et al, 1992.

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Table 3: Different kinds of fungi which feed on biomass, their specificity of degradation on the various lignocellulosic

components

Microbial activities

Wood-degrading fungiWhite rot Brown rot Soft rot

Appearance of the degraded biomass

Bleached appearance, drasticloss of wood strength at initialstage of decay. Very uniformontogeny of wood decay.

Soft consistency in wet environments. Brown and crumbly in dry environments.Generally uniform ontogeny of wood decay.

Lignocellulose-type

Selective delignification of hardwood, rare degradation of softwood. Degrades straw.

Degrades softwood; seldom attacks hardwood.

Degradation of cell-wall constituents

Cellulose, lignin and hemicellulose. Cellulose, hemicelluloses.Lignin is slightly modified.

Cellulose and hemicelluloses,Lignin is slightly altered.

Causal agents Basidiomycetes(e.g. T. versicolor,Irpex lacteus,P. chrysosporiumand Heterobasidiumannosum)and some Ascomycetes(e.g. Xylariahypoxylon).Basidiomycetes (e.g.Ganoderma australe,Phlebia tremellosa,C. subvermispora,Pleurotus spp. andPhellinus pini).

Basidiomycetes exclusively(e.g. C. puteana,Gloeophyllum trabeum,Laetiporus sulphureus,Piptoporus betulinus,Postia placenta andSerpula lacrimans).

Ascomycetes (Chaetomiumglobosum, Ustulina deusta) and Deuteromycetes(Alternaria alternata,Thielavia terrestris,Paecilomyces spp.), and some bacteria. Some white (Inonotus hispidus) and brown-rot (Rigidoporuscrocatus)

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Figure legends

Figure 1. Soil interaction system between microbes and animals; the figure describes the various

interaction mechanisms between the microorganisms present in the soil and various kinds of

animals and insects in soil and its enzyme effects on the plant biomass in soil.

Figure 2: Proposed pathway for cleavage of lignin macromolecule assembly by soil microcosm.

Dashed bonds (in red) as represented in the 8–O–4' and 8–1 linked lignin substructure model,

indicate the sites of C–C bond cleavages.

Figure 3: Soil system for lignocellulosic degradation and humification process; the figure

describes the fate of lignocellulosic biomass in soil its relation with the humus formation and

degradation into humic acid, fulvic acid and humin.

Figure 4: The chemical interaction system of lignocellulosic biomass in soil system for

lignocellulosic degradation and humification process; the figure describes the fate of

lignocellulosic biomass in soil its relation with the humus formation and degradation into humic

acid, fulvic acid and humin.

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Macro FaunaEarthworms, Snails and Slugs Diplopods.

Increase aeration, Degrade Cellulose and High nitrogen Content Enzymes Released:Cellulase, xylanase, chitinase Micro fauna

Nematodes: Dark pigmented Fungi Protozoa Dark pigmented Fungi Enzymes Released:Cellulase, xylanase.

Mesofauna Oribatida Micro fungiCollembolan Litter feeding fungiEnchytraeidae Litter Feeding Fungi and bacteria Enzymes Released:Amylase,cellulose,chitinase,trehalase,

DematiaceaEnzymes Released:, Xylanase, esterase, Lacassae Lip’s,Mnp’s (in very low amounts)

Plant Biomass Feeds on lignin

Feeds on Biomass, Cellulose,

hemicellulose and lignin

Feeds on Biomass, Cellulose,

hemicellulose and lignin

BacteriaEnzymes Released:, Xylanase, esterase, Lacassae Lip’s,Mnp’s (in very low amounts)

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Figure 1:

Figure 2.

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Figure 3:

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Figure 4:

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