Many more of ours needs in food,medicine,could be covered with products of nature,and often with molecules contained in microalgae. “The solution is out there,focus on microalgae”.
In this over view we are going to define some basic concepts to understand this amazing world of microalgae
Our planet is colonized every where by microalgae.Microalgae are present in all aquaticeco systems,lakes,rivers,oceans,liveinfresh, brackish,salty oreven hyper salinewaters.We know that the 30,000 currently cataloged are only the tip of the iceberg Figure1.
The biotechnology sector is using them every day more, enhancing and taking advantage of this great capacity in biosynthesis of molecules that are useful for our society.
Never forget the bases
Each cell of microalgae is as mall molecule factory that produce and stock many kinds of molecules for its life,multiplication,etc.
To set up suitable industrial culture methods, we mustrespect the structures, needs and behaviors of each species in culture. Many time good project and big team collapse forgotten this basis. The microalgae are simple eukary oticplants organisms.Ingeneral, they are photosynthetic,auto trophic but certain species can pass to mix otrophy to adapt the mortoresist in difficult condition.
Many times,as amestructure,behavior or composition can have a good aspect for aphase of the production chain and bad for other. They present an infinity of shapes,they are suspended in the water column,mobile or immobile and belong to phyto plankton.Figure2.
But certain species present at rend to the sedimentation in culture conditions.It can be a bad thing,among other,fooling in the bottom of the open pond and the wall of the tubes.This fooling reduces the entrance of light so the productivity of the culture,also it can be a focus of death cells,contamination and can reduce the quality of the whole biomass harvested. But nevertheless, this trend to sedimentation can be a factor to concentrate them in harvestor some down stream treatment.
Certain species have a weak cellular wall which can be damage in the culture medium with mechanic stress,injection of gas(CO2 and air) and bubbling,in culture or down stream process.Others present a strong cellular wall that complicated the rupture of the cell and the extraction.
They have an important metabolic plasticity and can use different metabolic pathways for the synthesis. Their metabolism and composition of biomass will depend on the species and the culture conditions.
Many times, the production is focus overly on the microalgae, light and temperature,but never we have to forget of the determinant importance of medium and the quality of water use and reused,fresh, brackish, artificial or seawater.
Microalgae are opport unistic,in eutrophic area,appear blooms of high concentration of microalgae.These blooms random,seasonal, and human population on the shore of the lakes,seas,oceans harvested and used them like source of food orothers.Figure3.
These blooms are random, and we could not sustain an industry on an unreliable production. To this end, structures called photobioreactors, have been designed, for the cultivation of photosynthetic species.
The first structure was the“open”pond,which means indirect contact with atmosphere.They are used for resistant rustic microalgae such as spiruline for the production of protein-rich food,pigments such as phycocyanin and haematococcus for the extraction of a valuablepigment,astaxanthin.Figure4.
In open pond, the installation cost is lower, (CAPEX) and operationcost(OPEX)butthecontrolofthecultureparametersis limited.Thissystemofcultureallows
A basic control on parameters of production
Obtain culture with single species, monospecific culture
But certain microalgae that are more sensitive to temperature change,pH,sedimentation,aggregation and contamination,cannot becultivated in open pond orwith great risk of failure.
To increase the control on culture,what is known as“closed” photobio reactors was designed.They are built with different materials, polycarbonate,methacrylate,glass.Figure5.
In this case, algae are separated from the environment by a transparentwall,which allows to protect the culture from the hostility of the outside,and to control the culture conditions.They are much more expensive in cost of facilities but have higher productivityin biomass.
These reactors have morever satility and in addition to spiruline and haema to coccus,many more species of microalgae can be grown to producew3,EPA,DHA,Exopoly saccharidesetc.
There are also other options for reactors such as vertical flat panel, sleeves or race way,plastic channel,which are an evolution of the open pond.It can also begrown under green house to reduce the hostility of the environment.
But becareful because the more complex aphoto bioreactor is,the more expensive is.
Taking advantage of microalgae but without burn the necessary steps:
The scale up of production and the project is a hugeaspect. Many industrial projects were based on laboratory results,with short as say in condition very different of the real conditions in outdoor. The outdoor biotic values are lower than in indoor photo bioreactor culture.
In other among,inertia of the big volume,changes of temperature, light,have an important influence in the response of the microalgae, on their productivity, composition and quality of the biomass produce.
Each species, in each production systems, must be test and maintain in industrial production no less than 6 months.(better12 months) before to conclude and carry out safe,reliable and profitable business. We can’t avoid the pilot phase, and pre-industrialphase. Figure6.
The pression for the cost a ofR+Diarehigh, push to shorten this phase,but with a new species,understanding a species not used in culture until the date,we need about 10 years,to developed,check, new production systems, photobioreactors, downstream, etc. to secure the production and satisfy a market and customers.
With the background obtain in research and development we have knowledges about several species to carry out reliable and profitable culture.In this case,we can settle our experience on this background, but always we need to test the strain in real out door condition of the area of culture,the quality of water use and is necessary treatment, also the photo bio reactors designed and the method of culturechosen.
In some case it is convenient to think about protecting intellectual property,but this topic is complex and not well defined in this sector yet.
Patentor license on photo reactors,methods of culture,strainsor both in what country? The approach of the legislation aspects is very different regarding with the country we select to produce microalgae. Exist also a duality between exchange information’s with the public sector to justify and pretend to obtain public finance or protect the background in a private business company.The frontier is complex and depend in the strategy of each company.
Wecouldciteanddiscussmanymoreaspects,butinsummary,in an overview, microalgae culture must be a global approach including biological, physical, chemical, financial, management, legislation aspects with a multi disciplinary team, to successful with the production and business.The biology of microalgae and his culture is a multifactorial network and weneed to know the impact of each parameters but also the relationship and influence of all of the mon
the culture,productivity and quality of the biomass produce.Figure7.
Estimate dates and real dates:
Many times,the dates use to elaborate the business plan is based on data extrapolated from results of short-term laboratories and small volumes.These data may be over valued and may not correspond to there sults that will be obtained in industrial cultivation outdoor and large volumes.
It is normal to see to use or announce photo synthetic yields of 5 and upto10% when in reality in out door conditions in large volume, with most species and on average does not exceed 2 to 3 % in the best case.
Specific grow rate: SGR
Values of growth rate around had been used in some estimation for production calculations, this rate can be measured in avery specificandisolatedcase,butingeneralitisnotover0.3,inmany cases it is close to0.1.
Becauseofthisusedgrowrate,theestimateduplicationtime is shorterthantherealobserved.Thismistakecanproduceahugeerror inthedurationoftheculturecycleinasemicontinuoussystemfor example.
DT= Ln (2)/ SGR (eq.2)
It appears a duality in the harvest concentration. High concentrationinthecultureharvestreducethecostoffiltration andcentrifugationtoconcentrateandextractthebiomass.Buthigh cellular concentration in culture can reduce the penetration of the lightinthecultureandreducethefinalproductivity.Determinethis optimalpoint,foreachspeciesandineachseason,needtimeand replicateexperiences.
Global composition, specific molecules and isomers:
Drybiomass,canbeusedasaproductwiththewholecomposition of the cell of the microalgae cultivates. It could be a source or ingredientsfoodandagoodchoicebetweenmarketsizeandproduct value.Wearetalkingabout30to200eurosperkilodependingonthe qualityofthecompositionandinparticularthepresenceofw3.
In this case, the composition of biomass is a standards composition, where we have the principal molecular families:
Proteins:About40%ofthecomposition,arevegetableproteins, butinthiscaseverycloseinbalanceofessentialaminoacidsofanimal proteins.Buttheyhaveacertaindeficiencyinessentialaminoacids, among others in amino acids with sulfur, methionine, cystine, but alsotryptophan,whichmeansthattheycannotcoveralltheneed forthesupplyofessentialaminoacidsinhumanfeed.Theycanbe incorporatedatahigherlevelthanotherkindofvegetablelikesoy protein,forexample,whichisalreadyaveryvaluableprotein,which isincorporatedupto20to30%infeedforexampleinaquaculturefor omnivorousorcarnivorousfishlikeseabream,seabass.
Lipids: about 20% lipids, microalgae produce polyunsaturated essentialfattyacids,dependingofthespecies(Becker,2013b),richin EPA, DHA,ARA.
Carbohydrates: about 20% of different carbohydrates.
11%minerals:potassium,magnesium,ironetc.veryinterestingas asourceoftraceelementsasfoodingredients.Pigments,depending on the species we can extract valuable antioxidants, natural colorants, markers,sunscreenandnaturaldyes.Butbecarefulandanalyses well whichisomersarepresentandiftheyareactive
Vitamins: Microalgae synthesize and contain several vitamins, generally one of them in low concentration [4,5].
Culture in “change conditions”, deficiency, “stress”
It refers to these modifications can be a lack of nutrients in themedium,themodificationofthemodelofilluminationofthe photobioreactors, intensity, photoperiod or composition of light, temperature,bothorothersparameters.Thesechangesaregoingto boostcertainmetabolicpathwayswithcertainspeciestoincreasethe biosynthesisofmoleculeswithhighinterestandvalue.
Nannochloropsis sp., In conditions of stress, lack in certain nutrients, for example, tend to produce more lipids, butmostly saturated that are concentrated in vacuoles, interesting for biofuel production.
InthecaseofDunaliellasp.,itcanbeobservedahighintracellular concentration in β carotene. In the case of Porphyridium sp., itobservedaproductionandexocytosisofexopolysaccharides, extractedasagelatin,canbeaddedincosmeticcreams.Onetime more,analyseswellwhichisomersarepresentandiftheyareactive forbenefitsought.Thesemoleculesareofgreatinterestbecause theyhaveveryinterestingpropertiesandgiveanaddedvaluetothe biomassesproduced.
Many more other aspects could be analyses and in more details. This is an over view on the some very important aspects we cannot forget, and we have to take in account to fulfill a project and raise the target. Many project collapses not for a lack of knowledge or capacity but due inset as ide finally some basic concept. The ultimate goal is not only to achieve the effectiveness of a technique but also to ensure that it is effective.
C Fuentes-Grünewalda, C Baylis, F Fonlut, E Chapuli (2016) Long- term dinoflagellate culture performance in a commercial photobioreactor: Amphidinium carterae case. Bioresource Technology 218:533-540.
Becker EW (2013) Microalgae for aquaculture: nutritional aspects. In: Richmond A, Qiang Hu (Eds), 2013, Handbook of microalgal culture: applied phycology and biotechnology, 2nd edition, Wiley-Blackwell:671-691
Garofalo R (2011) Algae and aquatic biomass for a sustainable production of 2nd generation biofuels. AQUAFUEL FP7 – 241301-2 Coordination Action FP7-ENERGY2009-1
DeRoeck-HoltzhauerY,QuereI,ClaireC(1991)Vitaminanalysisoffive planktonic microalgae and one macroalga. J. Appl. Phycol. 3: 259-264.
Becker (2013) In: Richmond, A., Qiang Hu (Eds), 2013, Handbook of microalgal culture: applied phycology and biotechnology, 2nd edition,Wiley-