Microbial Exopolysaccharides as Novel and Significant Biomaterials

Preface
Contents
Editors and Contributors
1 Microbial Exopolysaccharides: An Introduction
	Abstract
	1 Introduction
	2 Novel Exopolysaccharides with Therapeutic/Industrial Significance
	3 Physiological Roles and Ecological Aspects of EPS
	4 Biosynthesis and Metabolic Regulations of EPSs
	5 Applications and Commercial Prospects of EPS
	6 Conclusions
	Acknowledgements
	References
2 Techniques Used for Characterization of Microbial Exopolysaccharides
	Abstract
	1 Introduction
	2 Isolation Methods of Extracellular Polysaccharides
	3 Characterization Methods
		3.1 Pulsed Amperometric Detection (PAD)
		3.2 Fast Atom Bombardment—Mass Spectrometry (FAB-MS)
		3.3 Turbidometric and Colorimetric Method
		3.4 Carbazole Method
		3.5 Uronic Acid Screening
		3.6 96-Well Assay
		3.7 High-Performance Liquid Chromatography (HPLC)
		3.8 Ultra-High Performance Liquid Chromatography-Electrospray Ionization/Mass Spectrometry(UHPLC-UV-ESI-MS)
		3.9 Multi Laser Light Scattering Spectrometer (Malls)
		3.10 Fourier-Transform Infrared Spectroscopy
		3.11 Attenuated Reflection Microscopy (ATR)
		3.12 Nuclear Magnetic Resonance spectroscopy
	4 Microscopic Techniques
		4.1 Scanning and Electron Microscopy
		4.2 Multiple Fluorescence Staining and Confocal Laser Scanning Microscopy (CLSM)
		4.3 Energy Dispersive X-Ray Analysis
		4.4 Atomic Force Microscopy
		4.5 Raman Microscopy
		4.6 Thermo Gravimetric Analysis
		4.7 Gas Chromatography (GC)
		4.8 Capillary Zone Electrophoresis (CE)
		4.9 Bioinformatics Methods
	5 Future Perspectives and Conclusions
	References
3 Molecular Basis and Genetic Regulation of EPS
	Abstract
	1 Introduction
	2 EPS Biosynthesis Pathways
		2.1 Wzx/Wzy-Dependent Pathway
		2.2 ATP-Binding Cassette (ABC) Transporter-Dependent Pathway
		2.3 Synthase-Dependent Pathway
		2.4 Extracellular Synthesis Pathway by Use of a Single Sucrase Protein
		2.5 Unidentified Pathways
	3 Genes Directing EPS Biosynthesis
		3.1 Xanthan—The Most Diverse Heteropolysaccharide Bearing a Long Side Chain
		3.2 Sphingan—A Family of Diverse Heteropolysaccharides
		3.3 Succinoglycan (SG)—A Heteropolysaccharide Composed of a Large Repeating Unit
		3.4 Colanic Acid (CA)—An Antigenic EPS
		3.5 Curdlan—A Water-Insoluble Homopolysaccharide
		3.6 Cellulose-Bacterial EPS of Biomedical Value
		3.7 Alginates-Heteropolysaccharide Synthesized Via an Envelope-Embedded Multiprotein Complex
		3.8 Hyaluronan—A Hydrophilic Heteropolysaccharide
		3.9 Amylovoran-Acidic Exopolysaccharide of Erwinia amylovora
		3.10 Dextran and Other Glucan Homopolymers
		3.11 Pullulan—A Glucose-Based Homopolysaccharide
		3.12 Levan and Inulin-Polyfructan Polymers
		3.13 Lactic Acid Bacteria (LAB)—A Versatile Group of EPS Producers
		3.14 Biofilms—A Matrix-Encase
		3.15 Cyanobacterial and Diatoms’ EPS
	4 Genes and Regulators that Influence EPS Biosynthesis
		4.1 RSI Circuit-Complex Network of Multiple Transcriptional Regulators
		4.2 RcsAB Box (Regulator of Capsule Synthesis AB)
		4.3 3 CysB—A Transcriptional Regulator in Xanthan Biosynthesis
		4.4 KinB and AlgB—Regulators of Alginate Biosynthesis
		4.5 PilB-Type IV Pilus Assembly ATPase
		4.6 IrrE—A Global Transcriptional Regulator
		4.7 HpaR1—A GntR Family Transcription Regulator
		4.8 MetR—A LysR-Type Transcriptional Regulator
		4.9 RpfR—An Integral Biofilm Regulator Between Sessile and Motile Cycles of Bacteria
		4.10 EmmABC—The Three-Component Regulatory Circuit
		4.11 The GacS/A System—A Regulator of Alginates Through SRNA
		4.12 PcoR and RfiA-LuxR Regulators of Alginate Production
		4.13 GlnA—Regulator of Curdlan Biosynthesis
		4.14 AmrZ and FleQ—Transcriptional Regulators of Cellulose Biosynthesis
		4.15 Multicomponent Regulation of EPS1
	5 The Multi-faceted Role of c-di-GMP
	6 Genetic Engineering Strategies to Modify EPS
		6.1 Modifying Glycosyltransferase Genes
		6.2 Modifying Central Metabolism Pathways
		6.3 Use of New Microbial Cell Factories
	7 Conclusions
	Acknowledgements
	References
4 Molecular Engineering of Bacterial Exopolysaccharide for Improved Properties
	Abstract
	1 Introduction
		1.1 Biological Role of EPS
		1.2 Properties and Applications of EPS
		1.3 Commercially Employed EPS
	2 Brief Pathways of EPS Production in Bacteria
	3 Metabolic Engineering Strategies for EPS Production
		3.1 Metabolic Engineering for Increase in Yield
		3.2 Metabolic Engineering for the Structural Changes
	4 Conclusion
	Acknowledgements
	References
5 Extremophiles: A Versatile Source of Exopolysaccharide
	Abstract
	1 Introduction
	2 Significance of EPS Production by Extremophiles
	3 Biofilm Production and EPS
	4 EPS Produced by a Diverse Group of Extremophiles
		4.1 Production of EPS by Thermophilic Microorganisms
		4.2 Production of EPS by Psychrophilic Microorganisms
		4.3 Production of EPS by Halophilic Microorganisms
		4.4 Production of EPS by Acidophilic Microorganisms
		4.5 Production of EPS by Alkaliphilic Microorganisms
	5 Biotechnological Application of Extremophilic EPS
		5.1 Application in Food Industry
		5.2 Application in Pharmaceutical Industry
		5.3 Application in Productions of Biomaterials
	6 Conclusion
	References
6 Pullulan: Biosynthesis, Production and Applications
	Abstract
	1 Introduction
	2 About Pullulan
		2.1 Structure and Properties
			2.1.1 Pullulan Degradation and Derivatization
	3 Biosynthesis of Pullulan
	4 Production
		4.1 Downstream Processing
		4.2 Quality
	5 Applications of Pullulan
		5.1 Food
		5.2 Biomedical
		5.3 Cosmetics
		5.4 Environmental
	6 Conclusion
	References
7 Exopolysaccharides in Drug Delivery Systems
	Abstract
	1 Introduction
	2 Chemical Structure of Exopolysaccharides
	3 Homoexopolysaccharides
		3.1 Levan as Drug Delivery System
		3.2 Pullulan as Drug Delivery System
		3.3 Curdlan as Drug Delivery System
		3.4 Other (1,3)-β-d-Glucans as Drug Delivery Systems
	4 Heteroexopolysaccharides
		4.1 Xanthan as Drug Delivery System
		4.2 Gellan as Drug Delivery System
		4.3 Alginate as Drug Delivery Systems
	5 Conclusion
	References
8 Exopolysaccharides in Food Processing Industrials
	Abstract
	1 Introduction
	2 Cellulose
	3 Pullulan
	4 Xanthan Gum
	5 Dextran
	6 Kefiran
	7 Curdlan
	8 Emulsan
	9 Alginate
	10 Gellan
	11 Carrageenan
	12 Hyaluronic Acid
	13 Levan
	14 Colanic Acid
	15 Welan
	16 Conclusion
	References
9 Microbial EPS as Immunomodulatory Agents
	Abstract
	1 Introduction
	2 Immunomodulatory Activity
	3 Microbial Polysaccharides and Their Immunomodulatory Activities
		3.1 Bacterial EPS as Immunomodulators
		3.2 Microalgal EPS as Immunomodulators
		3.3 Fungal EPS as Immunomodulators
	4 Factors Influencing the Immunomodulatory Activity of EPS
	5 Mechanism of Action of EPS Immunomodulators
		5.1 Activation of Macrophage and Immune Modulatory Cascade
			5.1.1 Toll-Like Receptors 2/4-Mediated Signalling Cascade
			5.1.2 Complement Receptor 3 (CR3) Mediated Cascade
			5.1.3 Mannose Receptors (MR)-Mediated Cascade
			5.1.4 Scavenger Receptors (SR)-Mediated Cascade
			5.1.5 Dectin-1-Mediated Cascade
		5.2 Activation of T/B Lymphocytes and Immune Modulatory Cascade
			5.2.1 Membrane Immunoglobulin (mIg) Mediated Cascade
			5.2.2 T Cell Receptor-Mediated Cascade
		5.3 Activation of Natural Killer Cells and Immune Modulatory Cascade
		5.4 Activation of the Complement System and Immune Modulatory Cascade
	6 Evaluation of Immunomodulatory Activity
		6.1 In Vitro Assays
		6.2 In Vivo Assays
	7 Conclusion
	References
10 Novel Insights of Microbial Exopolysaccharides as Bio-adsorbents for the Removal of Heavy Metals from Soil and Wastewater
	Abstract
	1 Introduction
	2 Microbial EPSs
		2.1 Diversity in Microbial EPSs
		2.2 Commercial Uses
	3 Characterization of EPS by Fourier Transform Infrared (FTIR) Spectroscopy
	4 EPS-Metal Interactions
		4.1 Bacteria EPS-Heavy Metal Interactions
		4.2 Mechanism
		4.3 Bioremediation of HM-Contaminated Soil
		4.4 Bioremediation of HM-Contaminated Water
		4.5 Advantages Over Conventional Methods
	5 Knowledge Gaps and Future Directions
	6 Conclusions
	References
11 Applications of EPS in Environmental Bioremediations
	Abstract
	1 Introduction
	2 Environment Pollutants
	3 Sustainable Bioremediation of Toxic Heavy Metals
	4 Applications of EPS in Bioremediation of Colorant-Containing Residual from Textile Effluent
	5 EPS in Bioremediation of Oil Spills and Petroleum-Contaminated Sites
	6 EPS in Bioremediation of Toxic Chemicals (PCBs, PAHs, CP)
	7 Concluding Remarks
	Acknowledgements
	References
12 Cost-Benefit Analysis and Industrial Potential of Exopolysaccharides
	Abstract
	1 General Introduction to Cost-Benefit Analysis of Microbial Exopolysaccharides (EPSs)
	2 Microbial EPSs Potential for Industrial Application
		2.1 Bacterial EPSs
		2.2 Fungal EPSs
		2.3 Yeast EPSs
		2.4 Microalgal EPSs
		2.5 Archaeal EPSs
	3 Factors Affecting Cost-Benefit Ratio in Industrial Application of Microbial EPSs
		3.1 Production Process
		3.2 Customer’s Preference
	4 Future Perspectives
		4.1 Technical Breakthrough Expected to Confer Benefits on Industrial Application of Microbial EPSs
			4.1.1 Metabolic Engineering to Enhance EPS Yield
			4.1.2 Nanoparticles
			4.1.3 Chemical and Enzymatic Modifications
			4.1.4 Ultrasound and Microwave Treatments
		4.2 Substantial Markets for Microbial EPSs
			4.2.1 Food Industry
			4.2.2 Pharmaceutical Industry
			4.2.3 Agricultural Industry
			4.2.4 Environmental Industry
			4.2.5 Cosmetic Industry
			4.2.6 Livestock Industry
	5 Concluding Remarks
	References