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Contents
9
Biodegradation of Plastics by Microorganisms
123
Md. Anisur R. Mazumder, Md. Fahad Jubayer, and Thottiam V. Ranganathan
9.1
Introduction
123
9.2
Definition and Classification of Plastics
124
9.2.1
Definition of Plastic
124
9.2.2
Classification
125
9.2.2.1
Based on Biodegradability
125
9.2.2.2
Based on Structure and Thermal Properties
126
9.2.2.3
Characteristics of Different Biodegradable Plastics
126
9.3
Biodegradation of Plastics
128
9.3.1
General Outline
128
9.3.2
Biodegradation Phases and End Products
129
9.3.2.1
Aerobic Biodegradation
129
9.3.2.2
Anaerobic Biodegradation
130
9.3.3
Mechanism of Microbial Degradation of Plastic
130
9.3.4
Factors Affecting Biodegradation of Plastics
131
9.3.5
Microorganisms Involved in the Biodegradation Process
132
9.3.6
Enzymes Involved in the Plastic Biodegradation
133
9.3.6.1
Cutinases (EC 3.1.1.74)
135
9.3.6.2
Lipases (EC 3.1.1.3)
135
9.3.6.3
Carboxylesterases (EC 3.1.1.1)
135
9.3.6.4
Proteases
135
9.3.6.5
Lignin Modifying Enzymes
136
9.4
Current Trends and Future Prospects
136
List of Abbreviations
137
References
138
10
Enzyme Technology for the Degradation of Lignocellulosic
Waste
143
Swarrna Haldar and Soumitra Banerjee
10.1
Introduction
143
10.2
Enzymes Required for the Degradation of Lignocellulosic Waste
144
10.2.1
Degradation of Cellulose
144
10.2.1.1
Microbial Production of Cellulase
144
10.2.1.2
Enzymes Responsible for Cellulose Degradation
145
10.2.1.3
Physical Pre-treatments to Break down Cellulose
145
10.2.2
Degradation of Hemicellulose
146
10.2.2.1
Enzymes Responsible for Degradation of Hemicellulose
146
10.2.2.2
Microbial Production of Hemicellulases
147
10.2.2.3
Physical Pre-treatments to Break down Hemicellulose
147
10.2.3
Degradation of Lignin
148
10.2.3.1
Microbial Production of Lignin Degrading Enzymes
148
10.2.3.2
Enzymes Responsible for the Degradation of Lignin
148
10.2.4
Degradation of Pectin
149
10.3
Utilizing Enzymes for the Degradation of Lignocellulosic Waste
150