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39 2.6.3 Hemicellulose Degradation The greater variability in the structural components of hemicellulose and the molecular bonds within the hemicellulose and that with lignin fractions, among various lignocellulosic biomass, represent hemicellulose as a very complicated polysaccharide and thus has higher degree of substitution (figure 6). Hemicellulose degrading enzymes (in general hemicellulases) are comprised of various enzymes that cleave different sugar and substituted groups off the parent polysaccharide (Shallom and Shoham, 2003 ; Highley and Dashek, 1998; Sinnott et al., 1999). 2.7 White-, Brown- and Soft-rot Fungi There have been a lot of studies in fungal degradation of wood in natural forest systems. Huge quantities of live and dead trees are under constant microbial attacks. Intensive scientific and ecological studies have reported many fungi and bacteria responsible for wood and organic matter decay. The following texts incorporate short discussion on white-, brown- and soft-rot fungi (table 2): 2.7.1 White-rot fungi
40 White-rot fungi, name given as such for the white crystalline cellulose deposits during wood degradation, are considered to be efficient lignin degraders (Kirk and Farrell, 1987) as they can completely mineralize lignin into carbon dioxide and water. These fungi represent the advanced fungal subdivision– basidiomycota. They produce laccases and peroxidases like lignin peroxidase and manganese peroxidase are for delignification process (Tuor et al., 1995). These ligninolytic enzymes are further complemented by consortia of cellulose and hemicelluloses degrading enzymes. The synergistic enzyme degradation mechanism helps these fungi to hydrolyze woody material and absorb simple sugars for their metabolism and growth. Non-selective degradation of lignocellulose by white-rot fungi including well-known Phanerochaete chrysosporium were reported (Eriksson et al., 1990). The fungi degrade not only lignin but also the holocellulose (hemicellulose and cellulose) so that they can release sugars by the virtue of their efficient enzyme consortia. In addition to their natural habitat, these fungi have also been successfully grown on agricultural and industrial residue for their extensive application in decontamination and removal of aromatic contaminants (Reddy, 1995). These fungi primarily colonize their hyphal cells in cell lumen. Non-selective degradation of secondary cell wall tissues proceeding towards middle lamella ultimately coalescing the adjusting damaged cells (Blanchette., 1991)
Page 1 and 2: Enhanced bioprocessing of lignocell
Page 3 and 4: iii 2.5.1 Physical Pretreatment 22
Page 5 and 6: v 4.4.2 Ethanol production in simul
Page 7 and 8: vii List of Tables Chapter 2: Table
Page 9 and 10: ix Chapter 4: Figure 1: Figure 2: F
Page 11 and 12: xi seven and T. reesei had the high
Page 13 and 14: 2 a network with hemicellulose and
Page 15 and 16: 4 incorporated into animal feed. De
Page 17 and 18: 6 1.2.4 Simultaneous saccharificati
Page 19 and 20: 8 approach. Literature review is co
Page 21 and 22: 10 brown-rot fungus Gloeophyllum tr
Page 23 and 24: 12 and exploration of renewable ene
Page 25 and 26: 14 tissues) towards degradation. Su
Page 27 and 28: 16 2.3 What is lignocellulose ? Pla
Page 29 and 30: 18 Figure 2: Structure of hemicellu
Page 31 and 32: 20 Table 1: Products from lignocell
Page 33 and 34: 22 cost for such pretreatment will
Page 35 and 36: 24 for 2 min) of rice straw followe
Page 37 and 38: 26 Concentrated hydrochloric and su
Page 39 and 40: 28 cellulase) from same or diversif
Page 41 and 42: 30 2.6 Enzyme systems for lignocell
Page 43 and 44: 32 Source: Ward et al., (2004)
Page 45 and 46: 34 exoglucanase to liberate cellobi
Page 47 and 48: 36 Similar mechanism of cellulose d
Page 49: 38 Figure 6: Different types of hem
Page 53 and 54: 42 2.7.2 Brown-rot fungi Contrary t
Page 55 and 56: 44 reported on cellulolytic enzyme
Page 57 and 58: 46 residues to produce biofuel and
Page 59 and 60: 48 6) Hall, D.O.; Rosillo-Calle, F.
Page 61 and 62: 50 23) Millett, M.A.; Baker, A.J.;
Page 63 and 64: 52 38) DeLong, E.A. Method of rende
Page 65 and 66: 54 52) Schulein, M. Cellulases of T
Page 67 and 68: 56 67) Shallom, D.; Shoham, Y. Micr
Page 69 and 70: 58 85) South, C.R.; Hogsett, D.A.,
Page 71 and 72: 60 hemi/cellulose from corn fiber i
Page 73 and 74: 62 Studies showed potential applica
Page 75 and 76: 64 shaking at 150 rpm and 37 o C fo
Page 77 and 78: 66 Sterile corn fiber (10 g) was ad
Page 79 and 80: 68 add corn fiber (10g) to densifie
Page 81 and 82: 70 3.4 Results and Discussion 3.4.1
Page 83 and 84: 72 Figure 3: Total sugars present i
Page 85 and 86: 74 The increase in total sugars in
Page 87 and 88: 76 Figure 4: Ethanol profile in cul
Page 89 and 90: 78 Figure 5: Acetic acid profile in
Page 91 and 92: 80 Figure 6: Lactic acid profile in
Page 93 and 94: 82 Table 2a: Specific enzyme activi
Page 95 and 96: 84 3.5 Conclusion Corn fiber from a
Page 97 and 98: 86 8) Highley, T. L.; Dashek, W. V.
Page 99 and 100: 88 CHAPTER 4: STUDY OF WOOD-ROT AND
Page 101 and 102:
90 recently been studied for produc
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92 Phanerochaete chrysosporium, hav
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94 Various pretreatment methods of
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96 After 4 days of solid-substrate
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98 4.3.5 Analytical Methods Every a
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100 Figure 2: Glucose concentration
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102 pretreatment. Shrestha et al. (
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104 4.4.1.2 Xylose profile Xylose r
Page 117 and 118:
106 Figure 3: Xylose profile during
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108 per 100 g corn fiber). Alkaline
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110 residual corn fiber starch (Tab
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112 4.4.4 Lactic acid production in
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114 4.5 Conclusion Saccharification
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116 Biodegradation; Saha, B. C., Ha
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118 21) Kim, S.B.; Lee, Y.Y. Fracti
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120 Keywords. Lignocellulose, corn
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122 fermentation of corn fiber (usi
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124 White-rot (P. chrysosporium), b
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126 5.3.4.3 Analytical Methods Star
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128 the time 0 tubes were mixed wit
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130 5.3.4.6 Total Protein Assay The
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132 mg glucose/l.min 14.00 12.00 10
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134 5.4.3 Enzyme activity over CMC
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136 Enzyme activity over Sigma cell
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138 Total Sugar Profile g total sug
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140 5.4.6 Total protein The total s
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142 5.5 Conclusion Solid-substrate
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144 7) Kadam, K.L. Cellulase Produc
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146 CHAPTER 6: GENERAL CONCLUSION T
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148 ACKNOWLEDGEMENTS I sincerely th
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