Enzymes in the Valorization of Waste: Enzymatic Hydrolysis of Waste for Development of Value-added Products

Cover
Half Title
Series Page
Title Page
Copyright Page
Table of Contents
Preface
Acknowledgments
Editor
Contributors
Abbreviations
Chapter 1: Bioprocessing Approaches for Enzyme-based Waste Biomass Saccharification
	1.1 Introduction
	1.2 The Burgeoning Demand for Conventional Lignocellulosic Biomass
		1.2.1 Municipal Wastes as Alternate Sources of Lignocellulosic Biomass
	1.3 Pretreatment: Commonly Used Procedures, Their Limitations, and Recent Advancements
		1.3.1 Bioprocess Inhibitors Generated in Pretreatment Processes
		1.3.2 Techniques for Removal of Bioprocess Inhibitors
	1.4 Cellulases
		1.4.1 Enzyme-based Deconstruction of Lignocellulosic Biomass
		1.4.2 Cellulolytic Microbes
			1.4.2.1 Major Cellulolytic Fungi
				1.4.2.1.1 The Substrate Carbon Source’s Impact on Fungal Cellulase Production
				1.4.2.1.2 The Molecular Basis for Enzyme Production in Major Cellulolytic Fungi
			1.4.2.2 Major Cellulolytic Bacteria
				1.4.2.2.1 The Cellulosomal System
	1.5 Bioprocess Techniques for Microbial Cellulase Production
		1.5.1 Solid-state Fermentation – SSF
			1.5.1.1 Common Issues Pertaining to an SSF for Cellulase Production
			1.5.1.2 Process Improvements in an SSF for Cellulase Production
				1.5.1.2.1 The Impact of Pretreated Substrates in the SSF
				1.5.1.2.2 Fixed Volume Cyclic Fed-batch SSF
		1.5.2 Submerged Fermentation (SMF)
			1.5.2.1 Major Shortcomings of an SMF for Cellulase Production
			1.5.2.2 A Sequential Cellulase Induction-partial Saccharification-Catabolite Repression in an SMF for Cellulase Production
			1.5.2.3 Bottlenecks in the SMF Operation for Cellulase Production
			1.5.2.4 A Fed-batch SMF Operation for Improved Cellulase Yield
				1.5.2.4.1 Shortcomings of the Fed-batch SMF for Cellulase Production
	1.6 Integrated Bioprocesses for Improved Saccharification Yield
		1.6.1 The Biochemical Basis of an Enzymatic Saccharification Process
			1.6.1.1 Shortcomings of Traditional Enzymatic Saccharification
		1.6.2 Simultaneous Saccharification and Fermentation (SSF): The Process, Its Drawbacks, and Advancements
		1.6.3 Partial Saccharification and Simultaneous Saccharification and Fermentation (PSSSF)
		1.6.4 Semi-simultaneous Saccharification and Fermentation (SSSF)
		1.6.5 Semi-simultaneous Saccharification and Cofermentation (SScF)
		1.6.6 Consolidated Bioprocessing (CBP)
	1.7 Conclusion
	Acknowledgments
	References
Chapter 2: Developments in Hydrolysis Processes Toward Enzymatic Hydrolysis in Biorefinery
	2.1 Introduction
	2.2 Historical Background of the Hydrolysis Process
	2.3 Conventional Methods of Hydrolysis and Their Drawbacks
		2.3.1 Acid-catalyzed Hydrolysis
		2.3.2 Base-catalyzed Hydrolysis
		2.3.3 Hydrolysis in Ionic Liquid
		2.3.4 Drawbacks of Conventional Methods of Hydrolysis
	2.4 Enzymatic Hydrolysis
		2.4.1 Cellulase
		2.4.2 Hemicellulases
		2.4.3 Peroxidase
		2.4.4 Laccase
	2.5 Factors Affecting Enzymatic Hydrolysis
		2.5.1 Enzyme-related Factors
			2.5.1.1 Enzyme Loading
			2.5.1.2 Synergy of the Enzymes
			2.5.1.3 Recycling of Enzymes
		2.5.2 pH, Temperature, and Mixing
		2.5.3 Effect of Surfactants
		2.5.4 Substrate-related Factors
		2.5.5 Recent Advances in Enzymatic Hydrolysis
	2.6 Future Outlook
	2.7 Conclusion
	Acknowledgment
	References
Chapter 3: Overview of the Mechanism of Hydrolytic Enzymes and Their Application in Waste Treatment
	3.1 Introduction
	3.2 Different Classes of Hydrolytic Enzymes
		3.2.1 Cellulolytic and Hemicellulolytic Enzymes
			3.2.1.1 The Carbohydrate-active Enzymes Database
		3.2.2 Proteases
			3.2.2.1 Exopeptidases
				3.2.2.1.1 Aminopeptidases
				3.2.2.1.2 Carboxypeptidases
			3.2.2.2 Endopeptidases
				3.2.2.2.1 Serine Proteases
				3.2.2.2.2 Aspartic Proteases
				3.2.2.2.3 Cysteine/Thiol Proteases
				3.2.2.2.4 Metalloproteases
		3.2.3 Lipolytic Enzymes
	3.3 Mechanism of Action of Hydrolase Enzymes
		3.3.1 Glycosidic Hydrolases (GHs)
		3.3.2 Proteases
		3.3.3 Lipases
	3.4 Role of Hydrolytic Enzymes in Waste Management
		3.4.1 Treatment of Carbohydrate Wastes
		3.4.2 Treatment of Protein Wastes
		3.4.3 Treatment of Lipid Wastes
	3.5 Recent Advances in Enzymatic Hydrolysis of Wastes
	3.6 Current Challenges in the Enzymatic Hydrolysis of Wastes
	3.7 Conclusion
	Acknowledgments
	References
Chapter 4: Cellulase in Waste Valorization
	4.1 Introduction
	4.2 Cellulose
	4.3 Cellulase
		4.3.1 Types of Cellulase
		4.3.2 Catalytic Mechanism
	4.4 Role of Cellulase in Waste Valorization
		4.4.1 Cellulase in the Valorization of Agricultural Wastes
		4.4.2 Cellulase in Valorization of Cellulosic Waste from Industries
		4.4.3 Cellulase in the Valorization of Renewable Municipal Waste
	4.5 Valuable Products from Hydrolyzed Cellulosic Waste
		4.5.1 Cellulase Enzyme
		4.5.2 Biofuel
		4.5.3 Organic Acids
	4.6 Conclusion
	Acknowledgments
	References
Chapter 5: Cellulosic Bioethanol Production from Liquid Wastes Using Enzymatic Valorization
	5.1 Introduction
	5.2 About Liquid Wastes and Different Enzymes
		5.2.1 Sewage Sludge
		5.2.2 Animal Dung
		5.2.3 Kitchen Food Waste
	5.3 Cellulosic Biomethanol Production
		5.3.1 Pretreatment of Lignocellulosic Biomass and Feedstock Preparation
		5.3.2 Enzymes for Biofuel Production
			5.3.2.1 Cellulolytic Enzymes
			5.3.2.2 Amylases
			5.3.2.3 Proteases
			5.3.2.4 Pectinases
			5.3.2.5 Lactases
		5.3.3 Enzyme Hydrolysis
		5.3.4 Fermentation
		5.3.5 Distillation
	5.4 Conclusions and Future Recommendations
	References
Chapter 6: The Role of Pectinases in Waste Valorization
	6.1 Introduction
	6.2 Pectin and Its Structure
		6.2.1 Homogalacturonan (HG)
		6.2.2 Rhamnogalacturonan I (RGI)
		6.2.3 Rhamnogalacturonan II (RGII)
	6.3 Depolymerization of Pectin Substances
		6.3.1 Chemical Method
		6.3.2 Physical Method
		6.3.3 Enzyme Method
	6.4 Pectinolytic Enzymes
	6.5 Biochemical Properties of Pectinases
		6.5.1 Protopectinases (PPases)
		6.5.2 Polygalacturonases (PG)
		6.5.3 Pectin Esterases (PEs)
		6.5.4 Polygalacturonase (PGs)
		6.5.5 Pectin Lyases (PLs)
		6.5.6 Polygalacturonate Lyase (PGLs)
	6.6 Purification of Microbial Pectinases
		6.6.1 Production Techniques for Pectinases
			6.6.1.1 Fermentation Strategies
			6.6.1.2 Submerged Fermentation
			6.6.1.3 Solid-state Fermentation
			6.6.1.4 Immobilization of Cell Culture
		6.6.2 The Role of Genetic Engineering in Microbial Pectinase Production
		6.6.3 Fermentation Media Optimizations for Pectinase Production
		6.6.4 Factors Affecting Pectinase Production
			6.6.4.1 Role of the Substrate in Pectinase Production
			6.6.4.2 Effect of pH and Temperature on Enzyme Production
			6.6.4.3 Effect of Metal Ions on the Activity of Pectinases During Production
	6.7 Application of Pectinases in Waste Valorization
		6.7.1 Food and Agro-waste
			6.7.1.1 Food and Agro-waste Valorization Methods
				6.7.1.1.1 Composting
				6.7.1.1.2 Fermentation
				6.7.1.1.3 Anaerobic Digestion
			6.7.1.2 Recycling of Wastepaper
			6.7.1.3 Oil Extraction
			6.7.1.4 Animal Feed
			6.7.1.5 Wastewater Treatment
	6.8 Conclusion
	References
Chapter 7: Recent Advances in Enzyme-assisted Hydrolysis of Waste Biomass to Value-added Products
	7.1 Introduction
	7.2 Current Scenario of Waste Biomass Potential
	7.3 Environmental Impacts of Waste Biomass
	7.4 Structure, Composition, and Properties of Biomass Waste
	7.5 Significance of Enzymatic Hydrolysis Treatment
	7.6 Different Types of Enzymes and Their Role in Novel Waste Conversion Strategy
		7.6.1 Cellulolytic Enzymes
		7.6.2 Ligninolytic Enzymes
			7.6.2.1 Laccases
			7.6.2.2 Lignin Peroxidase (LiP)
			7.6.2.3 Manganese Peroxidase (MnP)
			7.6.2.4 Versatile Peroxidase (VP)
	7.7 Environmental and Socioeconomic Benefits of Reusing Waste Materials
		7.7.1 Eco-friendliness
		7.7.2 Sustainable and Abundant
		7.7.3 Cost-effectiveness
		7.7.4 Land Management
		7.7.5 Carbon Neutral
		7.7.6 Replacement for Petrochemical Resources
		7.7.7 Non-competitiveness with Food
		7.7.8 Other Benefits
	7.8 Value-added Products from Waste Biomass
		7.8.1 Nutrients
		7.8.2 Energy/Fuel
		7.8.3 Biopolymers
		7.8.4 Fertilizers
		7.8.5 Chemicals
		7.8.6 Medicines
	7.9 Conclusion and Future Prospects
	References
Chapter 8: Valorization of Recalcitrant Feather-waste by Extreme Microbes
	8.1 Introduction
	8.2 Recalcitrant Feather-waste
		8.2.1 Physical Characteristics of Feather-waste
		8.2.2 Chemical Characteristics
	8.3 Hazards and Management of Feather-waste
	8.4 Traditional Disposal Methods for Feather-waste
	8.5 Pre-treatment Technologies for Hydrolysis of Feather-waste
	8.6 Current Methods
		8.6.1 Hydrothermal
		8.6.2 Superheated Process or Thermal Hydrolysis
		8.6.3 Steam Explosion/Steam Pressure Cooking
		8.6.4 Acid and Alkali Treatments
		8.6.5 Oxidation and Reduction Method
		8.6.6 Ionic Liquids
		8.6.7 Microbial Hydrolysis
	8.7 Hydrolysis Using a Combination of Biological and Physicochemical Methods
	8.8 Emerging Technologies for Poultry Waste Hydrolysis
		8.8.1 Gasification
		8.8.2 Pyrolysis
		8.8.3 Sub/Super-critical Water Hydrolysis Treatment/Hydrothermal Liquefaction
		8.8.4 Deep Eutectic Solvents
		8.8.5 Anaerobic Digestion and Anaerobic Co-digestion
	8.9 Bio-hydrolysis of Feather-waste by Microorganisms and their Enzymes
		8.9.1 Hydrolysis of Feathers by Mesophilic Bacteria, Actinomycetes, and Fungi
		8.9.2 Microbial Cells and Mixed Culture Consortia for Large-scale Fermentation of Feather-waste
		8.9.3 Immobilized Whole Cells/Enzyme for Hydrolysis of Feathers
		8.9.4 Hydrolysis of Feathers by Extremophilic Bacteria, Actinobacteria, Fungi, and Archaea
	8.10 Mechanism of Complete Degradation of Feathers by the Synergistic Action of Protease, Disulfide Reductase, and Lipase
		8.10.1 Keratinase
		8.10.2 Disulfide Reductase
		8.10.3 Lipase
	8.11 Advantages of biochemical properties of extremozymes over non-extremozymes
	8.12 Biorefinery Circular Economy Platform Concept for Continuous Clean Technology for Feather Hydrolysis
	8.13 Economic Assessment of the Feather Hydrolysis Process and Feasibility of the Proposed Model
	References
Chapter 9: The Role of Halophilic Enzymes in Bioremediation of Waste in Saline Systems
	9.1 Halophiles
	9.2 Halophiles in Bioremediation
	9.3 Biodegradation of Organic Pollutants in Saline Wastewater
	9.4 Heavy Metal Bioremediation by Halophiles
	9.5 Halophilic Enzymes in Bioremediation and Mechanism of Enzyme action
		9.5.1 Microbial Oxidoreductases
		9.5.2 Microbial Oxygenases
		9.5.3 Monooxygenases
		9.5.4 Dioxygenases
		9.5.5 Laccase
		9.5.6 Azoreductases
		9.5.7 Alkane Hydroxylases
		9.5.8 Microbial Lipases
		9.5.9 Arsenite Methytransferase
		9.5.10 P 1B -type ATPases
	References
Index