Microalgal Biotechnology: Potential and Production (eBook)

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Prof. Clemens Posten, Karlsruhe Institute of Technology, Karlsruhe, Germany; Dr. Christian Walter, University ofErlangen-Nürnberg, Germany.

Prof. Clemens Posten, Karlsruhe Institute of Technology, Karlsruhe; Dr. Christian Walter, Universität Erlangen-Nürnberg.

Preface 5
1 Introduction - Discovering Microalgae as Source for Sustainable Biomass 21
1.1 All life eminates from the sun! All life originates from the sea! 21
1.2 Sustainable microalgal biomass of the third generation 23
1.2.1 Microalgae produce 5 times more biomass per hectare than terrestrial crops 23
1.2.2 Microalgae can be cultivated in arid areas which are not suitable for agriculture 24
1.2.3 Microalgae exhibit high lipid contents over 50% and high titers of other products 24
1.3 The technical challenge 24
1.3.1 Microalgae can use CO2 and sunlight 24
1.3.2 Microalgae can deliver cheap sustainable biomass for bulk chemicals and biofuels 25
1.3.3 Microalgae can be produced nearly everywhere 25
1.3.4 Microalgae do not need pesticides and only little fertilizers 26
1.3.5 Closed photobioreactors as tools of choice 27
The biological potential of microalgae 29
2 Phylogeny and systematics of microalgae: An overview 31
2.1 Introduction 31
2.2 Diversity and evolution of microalgae 36
2.2.1 Algal diversity 36
2.2.2 Algal evolution 37
2.3 Cyanobacteria: The prokaryotic algae 39
2.4 Plantae or Archaeplastida supergroup: Green algae, red algae and glaucophytes 42
2.4.1 Viridiplantae: The green algae distributed over two phyla 42
2.4.2 Rhodophyta: Red algae 45
2.4.3 Glaucophytes 46
2.5 Chromalveolate algae: The photosynthetic Stramenopiles (heterokont algae) 46
2.5.1 Diatoms (Bacillariophyta photosynthetic Stramenopiles)
2.5.2 Eustigmatophyceae and Xanthophyceae (photosynthetic Stramenopiles) 49
2.5.3 Other photosynthetic Stramenopiles 50
2.5.3.1 Raphidophyceae 50
2.5.3.2 Synurophyceae and Chrysophyceae 50
2.5.3.3 Phaeophyceae 51
2.6 Chromalveolate algae: coccolithophorids and haptophyte algae 51
2.7 Chromalveolate algae: Dinoflagellates (Dinophyta) 52
2.8 Euglenoids (Excavata supergroup) 53
Acknowledgements 53
References 54
3 Balancing the conversion efficiency from photon to biomass 59
3.1 Introduction 59
3.2 Definition of important terms 60
3.2.1 Photosynthetic efficiency 60
3.2.2 Growth efficiency (photon to biomass efficiency) 61
3.3 Physiological dynamics of processes which control biological energy conversion efficiency 65
3.3.1 Absorption 65
3.3.2 Regulation and efficiency of photochemistry 66
3.3.3 Regulation of electron flow 67
3.3.4 Regulation of carbon allocation 68
3.4 Conclusions for microalgal biotechnology 70
References 71
4 Algae symbiosis with eukaryotic partners 75
4.1 Introduction to algae-specific symbiosis 75
4.1.1 Importance of algae symbiotic relationships 75
4.1.2 Modes of algae symbiosis with eukaryotes 76
4.2 Aquatic systems 78
4.2.1 Algae symbiosis with Cnidaria 78
4.2.1.1 Symbiont uptake and management 80
4.2.1.2 Flux of primary metabolites in host and symbiont 80
4.2.1.3 Optimizing photosynthesis for efficient metabolite exchange 81
4.2.1.4 Symbiont-derived secondary metabolites 81
4.2.1.5 Effects of environmental stress on symbiosis 82
4.2.2 Algae symbiosis with Porifera 82
4.2.2.1 Morphology of sponge-algae associations 83
4.2.2.2 Symbiont uptake, specificity and transmission 84
4.2.2.3 Flux of primary metabolites in host and symbiont 84
4.2.2.4 Symbiont-derived secondary metabolites 85
4.2.2.5 Effects of environmental stress on symbiosis 85
4.2.3 Algae symbiosis with Mollusca 86
4.2.3.1 Morphology of mollusc-algae associations 86
4.2.3.2 Symbiont uptake and maintenance 87
4.2.3.3 Flux of primary metabolites in host and symbiont 88
4.3 Terrestrial system 88
4.3.1 Lichens: Ecological pioneers 88
4.3.2 Modes of lichen symbiosis 89
4.3.3 Lichen taxonomy and evolution 89
4.3.4 Lichen morphology 90
4.3.5 Symbiotic interactions 91
4.3.6 Lichen growth and propagation 92
4.3.6.1 Lichen propagation 93
4.3.7 Symbiotic benefits for algal photobionts 93
4.3.8 Biotechnological aspects of lichen/mycobiont cultivation 96
4.3.9 Potential of bioactive lichen-derived metabolites 97
References 99
5 Genetic engineering, methods and targets 107
5.1 Introduction 107
5.2 Methods in genetic engineering of eukaryotic microalgae 107
5.2.1 Transformation 107
5.2.1.1 Glass beads and silicon whiskers 107
5.2.1.2 Particle bombardment 108
5.2.1.3 Electroporation 108
5.2.1.4 Agrobacterium tumefaciens-mediated transformation 108
5.2.2 Promoters 109
5.2.3 Gene silencing 111
5.2.4 Codon usage 111
5.2.5 Improvement of expression rates and secretion of proteins 111
5.2.6 Selection markers 113
5.2.7 Reporter genes 114
5.3 Examples for biotechnological relevant proteins 116
5.3.1 Proteins expressed in Chlamydomonas reinhardtii 116
5.3.2 Recombinant proteins in other microalgae 118
5.4 Future prospects/outlook 118
5.4.1 Methods for genetic engineering 118
5.4.2 Products from genetically modified microalgae 119
Acknowledgements 120
References 120
6 Algenics: Providing microalgal technologies for biological drugs 127
6.1 Background and inception of the company 127
6.2 Development and optimization of proprietary technologies 128
6.3 From proofs of concept to therapeutic product candidates 129
References 129
Technical Means for Algae Production 131
7 Raceways-based production of algal crude oil 133
7.1 Introduction 133
7.2 Raceways 134
7.2.1 General configuration 134
7.2.2 Flow in a raceway 135
7.2.3 Power consumption for mixing 138
7.2.4 Paddlewheel design 140
7.2.5 Location 141
7.2.6 Evaporation from raceways 141
7.2.7 Temperature variations 142
7.2.8 Culture pH and carbon dioxide demand 144
7.2.9 Oxygen removal 145
7.2.10 Potential for contamination 146
7.2.11 Irradiance variation with depth 146
7.2.12 Local and average values of specific growth rate 148
7.2.13 Raceway capital cost 149
7.3 Algal crude oil as replacement petroleum 150
7.4 Algae biomass production 151
7.4.1 Productivity of biomass and oil 152
7.4.2 Limits to algal biomass productivity 154
7.4.2.1 Photosynthetic efficiency 155
7.4.2.2 Why are microalgae more efficient than terrestrial plants? 156
7.5 Economics of algal crude oil 157
7.5.1 Residual biomass 159
7.6 Concluding remarks 161
7.7 Nomenclature 162
References 164
8 Cellana LLC: Algae-based products for a sustainable future 167
8.1 Introduction 167
8.2 Cellana technology and demonstration facility 167
8.3 Biorefinery approach 168
8.4 Prospects 170
References 170
9 Principles of photobioreactor design 171
9.1 Introduction 171
9.2 Major factors governing the production of microalgae 171
9.3 Open systems 173
9.3.1 Open raceways 173
9.3.1.1 Technical issues 175
9.3.1.2 Scale-up 177
9.3.1.3 Drawbacks 179
9.4 Enclosed photobioreactors 179
9.4.1 Flat-panel photobioreactors 179
9.4.1.1 Technical issues 181
9.4.1.2 Scale-up 186
9.4.1.3 Drawbacks 186
9.4.2 Tubular photobioreactors 187
9.4.2.1 Technical issues 188
9.4.2.2 Scale-up 194
9.5 Summary of major characteristics of large-scale algal cultures systems 197
Acknowledgements 198
References 198
10 Knowledge models for the engineering and optimization of photobioreactors 201
10.1 Introduction 201
10.2 Theoretical background for radiation measurement and handling 201
10.2.1 Main physical variables 201
10.2.2 Solar illumination 204
10.3 Modeling light-limited photosynthetic growth in photobioreactors 204
10.3.1 Overview of the modeling approach 204
10.3.2 Mass balances 206
10.3.3 Stoichiometry of photosynthetic growth 207
10.3.3.1 Simple stoichiometric equations 207
10.3.3.2 Structured stoichiometric equations 208
10.3.4 Kinetic modeling of photosynthetic growth 209
10.3.5 Energetics of photobioreactors 212
10.3.6 Radiative transfer modeling 214
10.3.6.1 Radiative transfer equation 215
10.3.6.2 Optical and radiative properties for micro-organisms 221
10.4 Illustrations of the utility of modeling for the understanding and optimization of cultivation systems 223
10.4.1 Understanding the role of light-attenuation conditions 223
10.4.1.1 Illuminated fraction y 223
10.4.1.2 Achieving maximal productivities with appropriate definition of light-attenuation conditions 224
10.4.1.3 Prediction of biomass concentration and productivity 226
10.4.1.4 Engineering formula for assessment of maximum kinetic performance in PBRs 230
10.4.2 Solar production 231
10.4.2.1 Prediction of PBR productivity as a function of radiation conditions 231
10.4.2.2 Engineering formula for maximal productivity determination 234
10.4.3 Modeling light/dark cycle effects 234
10.5 Acknowledgments 237
10.6 Nomenclature 237
References 240
11 Construction and assessment parameters of photobioreactors 245
11.1 Introduction 245
11.2 Technical design features 245
11.2.1 Material issues 246
11.2.2 Geometric parameters 246
11.2.3 Hydrodynamic parameters 248
11.3 Measured performance criteria 250
11.4 Mode and stability of operation 251
11.5 Conclusion 254
References 255
12 Autotrophic, industrial cultivation of photosynthetic microorganisms using flue gas as carbon source and Subitec’s flat-panel-airlift (FPA) cultivation system 257
12.1 Introduction 257
12.2 Subitec GmbH and the flat-panel-airlift system 257
12.3 From laboratory to pilot scale 259
References 262
13 Case study: Microalgae production in the self-supported ProviAPT vertical flat-panel photobioreactor system 263
13.1 Introduction 263
13.2 ProviAPT technology and features 263
13.3 Prospects 265
References 265
14 Case study: Biomass from open ponds 267
14.1 Introduction 267
14.2 Production process 267
14.2.1 Removal of coarse solids 268
14.2.2 Concentrating the biomass 268
14.2.3 Washing the biomass 269
14.2.4 Differences to closed photo-bioreactors 270
14.3 Energy consumption 270
14.4 Survey of process relevant data 271
References 272
15 Case study: Spiral plate technology for totally dewatering algae alive 273
15.1 Introduction 273
15.2 Separation technology 273
15.2.1 Evodos technology 273
15.2.2 Key design parameters 274
15.3 Operational characteristics 276
References 278
Index 279