Microalgal Biotechnology: Recent Advances, Market Potential, and Sustainability

Cover
Microalgal Biotechnology: Recent Advances, Market Potential, and Sustainability
Preface
Contents
Chapter 1 - Microalgae as Cell Factories:
Food and Feed-grade
High-value
Metabolites
1.1 Introduction
1.2 Classification of Microalgae
1.2.1 Cyanophyta
1.2.2 Glaucophyta
1.2.3 Chlorophyta
1.2.4 Charophyta
1.2.5 Haptophyta
1.2.6 Cryptohyta
1.2.7 Ochrophyta
1.2.8 Euglenophyta
1.2.9 Dinoflagellata
1.2.10 Rhodophyta
1.3 Natural Microalgae Products
1.3.1 Lipids and Fatty Acids
1.3.2 Amino Acids and Proteins
1.3.3 Carbohydrates and Polysaccharides
1.3.4 Pigments
1.3.5 Vitamins and Minerals
1.3.6 Phytosterols
1.4 Food and Feed Grade Products
1.5 Cons of Microalgae
1.6 Conclusion
References
Chapter 2 - Microalgal Biorefineries: Key Processes and Main Challenges
2.1 Introduction
2.2 Biorefinery Concept: Energy- vs
Product-driven
Biorefineries
2.3 Microalgal Biorefineries: Step-by-
step
Challenges
2.3.1 Laboratory-scale
Experiments
2.3.2 Microalgal Cultivation
2.3.2.1 Suspended vs Fixed
2.3.2.2 Suspended Cultivation Systems: Open vs Closed
2.3.2.3 Traditional vs Thin/Intensive
2.3.2.4 Batch vs Continuous Operation Modes
2.3.3 Biomass Harvesting
2.3.4 Cell Disruption
2.3.5 Product Extraction
2.4 Research Needs
2.5 Conclusions
List of Abbreviations
Acknowledgements
References
Chapter 3 - Recent Advancements in Algal Biorefineries
3.1 Introduction
3.2 Recent Advancements in Cultivation Systems
3.3 Perspectives on Culture Improvement
3.3.1 Stress Factors that Affect High-valueProducts
3.3.2 Genetic Engineering Strategies for Culture Improvement
3.3.3 Cultivation Modes for Improved Cultures
3.4 Microalgal Systems Biology
3.4.1 DNA and RNA based Approaches
3.4.2 Protein and Metabolite based Approaches
3.4.3 Metabolic Engineering
3.5 Environmental Impact Assessment and Sustainability
3.5.1 Upcycling of Nutrients
3.5.1.1 Wastewater Treatment in Microalgae Biorefinery
3.5.1.1.1
Nitrogen.Nitrogen is the growth limiting factor for plants and microalgae. It is highly abundant in the Earth's atmosphere in ga...
3.5.1.1.2
Phosphorus.Phosphorus is the major building block of vital organic molecules in a microalgal cell such as nucleic acids, ATP and...
3.5.1.1.3
Carbon.Dissolved in/organic carbon is the preferred carbon source for microalgal growth. The utilized carbon source is dependent...
3.5.1.1.4
Macro and Micronutrients.In typical wastewater, the macronutrients that are present in concentrations of 10−2 to 10−4 M are C, N...
3.5.1.1.5
Heavy Metals.In addition to their nutrient recovery ability, microalgae are also useful in removing heavy metals from wastewater...
3.5.1.1.6
Temperature.Solubility of CO2 and O2, pH and equilibrium of the ionic substances are dependent on the temperature of the wastewa...
3.5.1.1.7
Light.Similar to other abiotic factors such as temperature and pH, microalgae respond differently to varied light intensity. Mic...
3.5.1.2 Biological Reactor Types for Wastewater Treatment with Microalgae
3.5.1.3 Reuse of Microalgal Growth Medium
3.5.2 Renewable Power Utilization
3.5.2.1 Process Design Implementation
3.5.2.2 Overall Energy Production
3.5.2.3 Energy from Co-products
3.6 Techno-economic
Assessments
3.6.1 Techno-economic
Assessment of Biorefineries
3.6.2 Gaps and Challenges of the TEA Framework
3.6.3 Overview of TEA Applications in Algal Biorefineries
3.6.3.1 Techno-economic
Assessment of a Multi-product
Algal
Biorefinery
3.6.3.2 Technoeconomic Assessment of an Attached Growth Algal Biorefinery
3.6.3.3 Techno-economic
Assessment of Scaling-up
in an Algal
Biorefinery
3.6.3.4 Techno-economic
Assessment of Industrial Scale Algal
Biorefinery
3.6.3.5 Techno-economic
Assessment of Algal Biorefinery under
Technical Uncertainties
3.6.3.6 Techno-economic
Assessment of Optimal Algal
Biorefinery Concepts
3.6.3.7 Techno-economic
Assessment of an Integrated Algal
Biorefinery
3.6.3.8 Techno-economic
Assessment of a Large-scale
Integrated
Algal Biorefinery
3.7 Conclusions
List of Abbreviations
Acknowledgements
References
Chapter 4 - Technological Bottlenecks in Establishing Microalgal Biorefineries
4.1 Introduction
4.2 Overview of a Microalgae Biorefinery
4.3 Unresolved Bottlenecks: Current Status and New Accomplishments
4.4 What Comes Next
4.4.1 Zero-waste
Biorefinery Approach
4.4.2 Integration of a Microalgae Biorefinery into Consolidated Facilities
4.4.3 Recovery of all Possible Products
4.5 Patent Landscape on Microalgae Biorefinery
4.6 Final Considerations
References
Chapter 5 - Production of High-value
Metabolites from Microalgae
5.1 Introduction
5.2 Fatty Acids from Microalgae
5.3 Carotenoids from Microalgae
5.4 Phycobiliproteins from Microalgae
5.5 High-value
Carbohydrates from Microalgae
5.6 Microalgae as Alternative Protein Sources
5.7 Antimicrobial and Antiviral Compounds from Microalgae
5.8 Practical Aspects of High-value
Microalgae
Metabolite Production
5.8.1 Harvesting of Microalgae
5.8.2 Extraction of High-value
Metabolites
5.9 Conclusions
References
Chapter 6 - Microalgae as an Alternative Sustainable Source of Squalene
6.1 Introduction
6.2 Squalene Synthesis in Microalgae
6.3 Extraction and Qualitative Analysis of Squalene from Microalgae
6.4 Conclusion
Acknowledgements
References
Chapter 7 - Network of Metabolic Pathways
for Biosynthesis of High-value
Products in Microalgae
7.1 Introduction
7.2 Microalgal Metabolic Pathways for the
Biosynthesis of High-value
Compounds
7.2.1 Lipid Metabolism
7.2.1.1 Fatty Acid and Triacylglycerol (TAG) Biosynthesis
7.2.2 Carbohydrate Biosynthesis in Microalgae
7.2.3 Carotenoid Biosynthesis
7.2.4 Amino Acid Biosynthesis in Microalgae
7.2.5 Biosynthesis of Other High-value
Metabolites
7.2.5.1 Phycobiliproteins
7.2.5.2 Sterols
7.3 Conclusion and Future Perspectives
Acknowledgements
References
Chapter 8 - Genetic Engineering of Microalgae for the Production of High- value Metabolites: Status and Prospe
8.1 Introduction
8.2 Model Organisms
8.2.1 Chlamydomonas reinhardtii
8.2.2 Dunaliella salina
8.2.3 Haematococcus pluvialis
8.2.4 Chlorella vulgaris
8.2.5 Phaeodactylum tricornutum
8.2.6 Nannochloropsis spp
8.3 Methods Used in Genetic Engineering of Microalgae
8.3.1 Forward Genetics
8.3.1.1 Physical Mutagenesis
8.3.1.2 Chemical Mutagenesis
8.3.1.3 Insertional Mutagenesis
8.3.1.3.1
Electroporation.Electroporation is the procedure of using an electrical charge to temporarily open pores in the cell membrane to...
8.3.1.3.2
Glass Beads.The glass beads procedure was first reported in C. reinhardtii108 where the cells are agitated vigorously with DNA i...
8.3.1.3.3
Silicon Carbon Whiskers.In this procedure, silicon carbon whiskers replace the glass beads from the glass beads technique. C. re...
8.3.1.3.4
Agrobacterium.In the agrobacterium method the cells are incubated with bacteria carrying a foreign gene which is cloned into a t...
8.3.1.3.5
Particle Bombardment.In this procedure, the DNA is precipitated or coated onto the surface of small particles; particles are sho...
8.3.1.3.6
CRISPR-Łcas9.Over the past two decades, transcription activator-Łlike effector nucleases (TALENS)114 and zinc finger nucleases (...
8.3.2 Reverse Genetics
8.4 High-value
Metabolites
8.4.1 Carotenoids
8.4.1.1 Carotenoid Biosynthesis
8.4.1.1.1
Phytoene Synthase (PSY).Phytoene synthase, a key enzyme in carotenogenesis, was primarily reported in plants.149 The pathway in ...
8.4.1.1.2
1-ŁDeoxy-Łd-ŁXylulose 5-ŁPhosphate Synthase (DXS).The DXS gene, encoding 1-Łdeoxy-Łd-Łxylulose 5-Łphosphate synthase, is conside...
8.4.1.1.3
Beta-­carotene/Zeaxanthin Ketolase (BKT).β-­carotene/zeaxanthin ketolase enzyme is one of the key enzymes in the synthesis of as...
8.4.1.1.4
Beta-­carotene Hydroxylase (BCH).β-­carotene hydroxylase plays a major role in the conversion of β-­carotene to xanthophylls. Th...
8.4.1.1.5
Lycopene Cyclase (LCY).The lycopene cyclase enzyme, which is functionally and structurally conserved in all organisms, catalyzes...
8.4.1.1.6
Phytoene Desaturase (PDS).The phytoene desaturase enzyme that is restricted to the chloroplast55,148,188 catalyzes the productio...
8.4.1.1.7
Δ5-­Fatty Acid Elongase.The Δ5-­fatty acid elongase and Δ4-­fatty acid elongase enzymes are important in DHA synthesis as they a...
8.4.1.1.8
Δ6 Fatty Acid Desaturase.Except for the soluble acyl-­ACP (acyl carrier protein) desaturases found in plant plastids, all Δ6 fat...
8.5 Regulatory Genes and Future Prospects
8.6 Conclusion
Acknowledgements
References
Chapter 9 - Recent Advances in Closed Photobioreactors and Open Cultivation of Microalgae
9.1 Introduction to Algae Cultivation
9.2 Algae Culturing Systems
9.2.1 Open Pond Culture System
9.2.1.1 Types of Open Ponds
9.2.1.1.1
Raceway Ponds.Raceway ponds are usually built up by a group of raceways together, which may have single or multiple recirculatio...
9.2.1.1.2
Circular Ponds.Circular ponds are 45 m in diameter and 30–70 cm in depth, assisted with a pivoted agitator in the centre12 (Figu...
9.2.1.1.3
Unstirred Ponds.This is one of the least technical and most economical methods of all commercial culture methods. The ponds are ...
9.2.1.2 Factors Influencing Open Pond Cultivation
9.2.2 Closed Photobioreactors
9.2.2.1 Design of Closed Photobioreactors
9.2.2.1.1
Photo Efficiency of the Reactor.The intensity of the incident light is the key factor in the photosynthesis of microalgal cultur...
9.2.2.1.2
Geometric and Hydrodynamic Considerations.Efficient light exposure can be achieved, preferably through a large S/V ratio. Severa...
9.2.2.1.3
Gas Distribution, Temperature and Sterility Control.In addition to the above factors influencing photo efficiency, other importa...
9.2.2.2 Popular Designs of Closed PBRs
9.2.2.2.1
Tubular Photobioreactors.As the name suggests, these are PBRs with cylindrical geometries. The optical properties of the constru...
9.2.2.2.2
Flat-Łpanel Photobioreactors.Flat-Łpanel PBRs are constructed with transparent materials such as polyvinyl carbonate (PVC) or to...
9.2.3 Hybrid Cultivation System
9.3 Selection Criteria for the Best Culturing System
9.4 Automated System for Algae Cultivation
9.5 Concluding Remarks
References
Chapter 10 - Challenges in Scale-up
and Commercialization of
Microalgae Products
10.1 Introduction
10.2 Challenges in Microalgal Cultivation
10.2.1 Challenges in Screening and Selection of Strains
10.2.2 Challenges in Cultivation Systems
10.2.2.1 Photobioreactors (PBRs)
10.2.2.1.1
Mixing.Mixing is one of the most crucial requirements in microalgae cultivation, as it can alter nutrient availability, temperat...
10.2.2.1.2
Light.Light (intensity and duration) is one of the major limiting factors in large-Łscale algal production systems. Very high an...
10.2.2.1.3
Oxygen Build-Łup.PBRs with high area-Łto-Łvolume ratio are favourable for high productivities; however, oxygen build-Łup due to ...
10.2.2.2 Pond Cultivation
10.2.2.2.1
Evaporation Losses.Evaporation losses caused by the heating up of culture due to an increase in temperature and light exposure a...
10.2.2.2.2
Inefficient Use of CO2.In microalgal cultivation, CO2 serves as an inorganic carbon source and in combination with air, is inten...
10.2.2.2.3
Shading.The intensity of sunlight is ∼2000 µmol m−2 s−1 and algae require only 1/10th of this light for growth as excessive inte...
10.2.2.2.4
Water Circulation and Culture Mixing.Proper circulation of water in algae ponds is required for better mixing of nutrients and r...
10.2.2.2.5
Temperature Fluctuations.Temperature plays a vital role in algal growth. The optimal temperature range for most algal strains is...
10.2.3 Challenges Associated with Nutrient Availability/Absorption
10.2.3.1 Modes of Cultivation
10.2.3.1.1
Photo-Łautotrophy.In photo-Łautotrophy, algal cells perform photosynthesis by utilizing the inorganic carbon, i.e. CO2 from the ...
10.2.3.1.2
Heterotrophy.Heterotrophy does not require the presence of light, as the cells do not photosynthesize. The algal cells require a...
10.2.3.2 Nutrient Recovery and Recycling
10.2.4 Challenges in Water Management
10.2.4.1 Water Transportation
10.2.4.2 Water Loss Due to Leakage or Evaporation
10.2.4.3 Pumping of Water
10.2.5 Challenges in Crop Protection
10.3 Challenges in Microalgae Harvesting and Dewatering
10.3.1 Challenges in Physical Methods of Microalgae Harvesting
10.3.1.1 Filtration
10.3.1.2 Centrifugation
10.3.1.3 Sedimentation
10.3.2 Challenges in Chemically-aidedMicroalgae Harvesting
10.3.2.1 Coagulation–Flocculation
10.3.2.2 Flotation
10.3.3 Biological Methods of Harvesting and Their Challenges
10.3.3.1 Bio-flocculation
10.3.3.2 Auto-flocculation
10.3.4 Advanced Methods of Microalgae Harvesting and their Challenges
10.3.4.1 Genetic Engineering of Microalgae
10.3.4.2 Magnetic Separation
10.3.5 Challenges in Dewatering
10.3.6 Comparison of Microalgae Harvesting and Dewatering Methods
10.4 Challenges in Downstream Processing of
Microalgae for Crude Oil and Non-oil
Products
10.4.1 Challenges in Oil Extraction from Microalgae
10.4.2 Challenges in Extraction of Non-fuel
Bioproducts
from Microalgae
10.4.2.1 Astaxanthin from Haematococcus Pluvialis
10.4.2.2 β-­Carotene
10.4.2.3 Fucoxanthin
10.4.2.4 Omega-3Fatty Acids
10.5 Challenges in Consumer Acceptance of Microalgae Products
10.6 Conclusions and Future Prospects
References
Chapter 11 - Biosafety and Regulatory Issues Related to Genetically Modified Microalgae
11.1 Introduction
11.2 Comparison of Regulations Related to Genetic Modification of Crops in Different Geographies
11.3 Environmental Risk Assessment: Cardinal Concepts and Algal Extrapolation
11.3.1 Summary of Risk Scenarios
11.3.1.1 Risk Scenario 1
11.3.1.2 Risk Scenario 2
11.4 Risk Assessment in Genetically Modified Algae
11.5 Risk Assessment Paradigm in the Context of Genome Editing: How Would Algae Fare
11.6 Conclusion
List of Abbreviations
References
Chapter 12 - Application of Microalgae for Food Supplements and Animal Feed: Scientific, Sustainability and Socioeconomic Challenges
12.1 Introduction
12.2 Microalgae Based Food and Nutraceuticals:
Bio-efficacy
and Commercialization Challenges
12.2.1 Challenges in the Incorporation of Microalgae Biomass in Regular Food Products
12.2.2 The Challenge of Nucleic Acids
12.2.3 The Challenge of Digestibility and Bio-efficacy
of
Microalgae Nutrients
12.2.3.1 Microalgae Proteins
12.2.3.2 Extractability and Stability of Microalgae Nutraceuticals
12.3 Microalgae for Animal Feed
12.3.1 Challenges in the Processing of Algal Biomass for Feed Applications
12.4 Sustainability of Microalgae Production Technologies
12.4.1 Role of Bioprospection and Extremophiles in Sustainability
12.5 Socio-economics
of Microalgae Food Products
12.6 Microalgae-derived
Products: Safety and
Quality Aspects
12.6.1 Current Status on Regulations of Use of Microalgae for Food and Feed Applications
12.6.2 Current Scenario of Markets for Microalgae Products
12.7 Conclusion and Future Prospects
References
Chapter 13 - Life Cycle Assessment
Perspective of Microalgae
Cultivation for High-value
Nutraceuticals
13.1 Introduction
13.1.1 Microalgae – a Source of Value-addedProducts
13.2 Life Cycle Assessment (LCA)
13.2.1 Literature Review: LCA of Bioactive Compounds from Microalgae
13.2.2 LCA Case Study of Algal Biomass Production for Value-added
Products
13.2.2.1 Goal and Scope
13.2.2.2 Life Cycle Inventory
13.2.2.3 Life Cycle Impact Assessment
13.2.2.4 Results and Discussion
13.2.2.4.1
Primary Energy Demand and Global Warming Potential.The primary energy demand of algal biomass production in an open raceway pond...
13.2.2.4.2
Impact of Mode of Cultivation on the CO2 Sequestration Potential of Microalgae.The net emission ratio (NER) of CO2 was calculate...
13.3 Conclusion
Acknowledgements
References
Chapter 14 - Environmental Impact Assessment and Sustainability of Microalgae Production
14.1 Introduction
14.2 Sustainability of Microalgae Production
14.2.1 Evaluation of Environmental Impacts from Microalgae Cultivation and/or Production
14.2.2 Current Technologies and Limiting Factors
14.2.3 Life Cycle Assessment and Sustainability Analysis
14.3 Scenarios of Microalgae Production in Country-specific
Conditions
14.4 Challenges and Perspectives
References
Chapter 15 - Market Penetration, Potential and Sustainability of Algal Products
15.1 Introduction
15.2 Major Categories of Algal Products
15.2.1 Algae-based
Energy Options
15.2.1.1 Bio-oil
15.2.1.2 Bio-diesel
15.2.1.3 Bio-hydrogen
15.2.1.4 Bio-gas(Bio-methane)
15.2.1.5 Bio-ethanol
15.2.2 Algae-based
Non-energy
Options
15.2.2.1 Pharmaceuticals
15.2.2.2 Pigments
15.2.2.3 Nutraceuticals
15.2.2.4 Cosmeceuticals
15.2.2.5 Other Products and Applications of Commercial Importance
15.3 Commercialization of Algae-based
Products
15.3.1 Regional and Chronological Probing
15.3.2 Major Players in Algae-based
Products
15.3.3 Conferring the Economic Perspectives
15.4 Market Potential of Algae-based
Products
15.4.1 Coping with the Challenges of Forthcoming Entry of Novel Algal Products in the Global Market
15.4.2 Technology in Favour of Cost-cutting
Policy
15.4.3 Valorisation Adding into Final Revenue
15.4.4 Public Awareness may Increase the Demand of
Bio-based
Products in the Market
15.4.5 Bio-refinery
to Create a Sustainable Production System
15.4.6 Genetic Strain Improvement
15.4.7 Climate-smart
Approach to Turn By-products
into Co-products
15.4.8 Innovation in the Application of Algae Leading to Growth in the Market
15.4.9 Role of Synthetic Biology
15.4.10 Protein Shortage Solution
15.4.11 Multi-product
Approach for Economic Viability
15.5 Algae as a Sustainable Solution to
Non-renewability
15.5.1 Bio-based
Plastics and Polymers
15.5.2 Bio-
15.5.3 Biorefinery and Bioremediation
15.5.4 For CO2 Sequestration Microalgae Afford the Best Possible Solution
15.5.5 A Promising Substitute for Animal-based
Nutrition
and Other Conventional Food and Feed Options
15.6 Conclusion and Future Prospects
References
Subject Index