Algae, a buzzword in the biofuel industry a few years ago and a diverse group of simple organ-isms, are the new game changer
in the animal feed industry.
Algae also contribute to the air we breathe, producing nearly 50 percent of the oxygen in the atmosphere and directly supporting the ocean life, thereby playing a major role in global productivity.
There are an estimated 800,000 species of algae that range from single-celled microor-ganisms to multi-celled organisms, such as the 200-foot long giant kelp.
Algae produce carbohydrates, oils, protein, vitamins, pigments and organic materials.
New applicationsWhile macroalgae (seaweed) dominate
the global aquatic plant production, the microalgae industry is growing rapidly as scientists continue to find new appli-
cations for the freshwater and marine species.
Today, the freshwater Chlorella and Arthrospira are primarily used for human dietary supplements and ingredients for animal feed. Other species are used for the extraction of high-valued components such as vitamins, w-fatty acids, natural pigments and antioxidants.
Microalgae are required in larval nutrition, either fed directly in the case of mollusks and peneid shrimp or indirectly as live prey food in small fish larvae (Spolaoree, et al.).
The nutritional composition and biochemi-cal diversity of microalgae have generated an enormous amount of interest in a variety of applications. Microalgae can have high protein content with an amino acid profile that can provide essential amino acids.
The lipid content can reach 70 percent, with a high concentration of omega-3 and omega-6 fatty acids. Microalgae can be a valu-able source of vitamins and minerals as well.
Most commercial production of micro-
algae is done autotrophically in open out-door circulating raceways or ponds. Under autotrophic growing conditions, microalgae use light energy to fix carbon dioxide, their carbon source into hydrocarbons with oxygen discharged as a waste product. However poor light diffusion; microbial, chemical and physical contamination; downstream processing and the growth of zooplankton and other species are all drawbacks of an open system.
Photobioreactors (PBR) have improved productivity of autotrophic production through the careful control of growth limiting and environmental parameters, however PBRs have not been deemed successful or eco-nomical for producing low cost, high volume end-products for the feed industry.
The other commercial production meth-od in growing algae is the heterotrophic system. Heterotrophic species get their energy from organic carbon compounds in much the same way as yeast, bacteria and animals. By eliminating light from the
MICROALGAE: A sea of opportunities for the aquaculture industry
by Dr Keith Filer, Alltech
High-quality micro-algae concentrates used in ‘early developmental’ aquafeedsby Pieter Boelens, Chief Operation Officer, Evodos
Micro-algae provide an impor-tant direct or indirect feed source for early developmen-tal stages of many farmed
finfish, shellfish and invertebrate species.
Hatcheries typically cultivate micro-algae in-house, but commercial concentrates are starting to be used, as a substitute.
Commercially available concentrates offer a convenient source for micro-algae hatcheries.
The number of micro-algae producers delivering algae concentrates to the hatcheries is growing. Only those micro-algae producers, which are delivering the right quality concen-trate, are successful.
From an aquaculture perspective, the key desire attributes for micro-algae concentrates are:• High cell concentration without dam-
aged cells• Increased shelf life• Easy to suspend uniformly in water
• Regularly available and affordableThe company Evodos focuses on 'harvesting'
micro-algae concentrates out of open ponds and photo bioreactors (PBR's) for aquafeed.
With the Evodos micro-algae harvesting solution you harvest a high quality micro-algae concentrate, the micro-algae cells are intact and undamaged.
During the harvesting process, the micro-algae don’t change in structure and tem-perature. All valuable components inside the micro-algae cells are fully retained.
Key micro-algae strainsEvodos has a growing client base by achiev-
ing a very high quality output with micro-algae species that play an important role in the Aquaculture market, like Dunaliella, Tetraselmis, Nannochloropsis, Chlorella, Diatoms and more.
Today, these key micro-algae strains are avail-able as concentrates processed by Evodos units. These are marketed as total replacements for living micro-algae or serve as a back-up against crashes and out-of-season shortages or supple-ment to live micro-algae produced in-house.
Available micro-algae concentrates also enables smaller enterprise to operate without an in-house micro-algae production capacity.
One of the successful micro-algae produc-ers is Tomalgae, a biotech company which
develops micro-algae based products for the aquaculture market. With the Evodos units, Tomalgae produces high quality micro-algae concentrate mainly for the larval stage.
“The diatoms belong to one of the most economically important groups of algae.
“For various applications, it is often very important that while algae cultures are concen-trated via centrifugation, the cells are not dam-aged and keep their integrity after the processing.
“Traditional methods of centrifugation typi-cally bring a serious damage to the cells break-ing or opening their frustules that usually dra-matically reduces the quality of the microalgal biomass obtained. In contrast, recently I repeat-edly had a chance to process large volumes of diatoms using The Evodos Dynamic Settler.
“The results of these tests proved to be uniformly identical: the perfect quality of con-centrated microalgal (diatom) paste – no dia-toms cells were detected that exhibited any signs of mechanical damage,” says Professor Viktor Chepurnov, Tomalgae.
With the Evodos micro-algae harvesting solution algae producers can produce the right quality micro-algae concentrates neces-sary for the aquaculture market: high quality micro-algae concentrate that is equal to the quality of living micro-algae.
30 | INTERNATIONAL AQUAFEED | July-August 2014
production process, any fermenter (such as those used for production of medicines, beverages and food additives) can be used for heterotrophic algal growth. Reaching 100,000 liters in size, these fermenters can generate large volumes of highly productive cultures making them less expensive than the autotrophic system.
One of the main differences between autotrophic and heterotrophic systems is the added nutritional benefits from heterotrophic algae. The heterotrophic method maintains a closed, controlled system that provides a more consistent, traceable and pure algal product that is more beneficial for the feed industry. For example, by manipulating the physical and chemical properties of the cul-tural medium, several species of microalgae can overproduce and accumulate higher levels of specific fatty acids. Xu et. al (2006) dem-onstrated that C. protothecoides had a lipid content as high as 55 percent, approximately four times greater than when grown auto-trophically.
Omega-3 fatty acidIn another study, Barclay et. al (1994)
showed that omega-3 fatty acid productiv-ity was two to three times higher when produced in heterotrophic rather than auto-trophic conditions.
Microalgae that contain large quantities of
high quality eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)are now being commercialised as sustainable alternative sources to fish oil. By providing a clean and consistent source of omega-3 fatty acids and high quality protein, heterotrophic microalgae offer more nutrition components to a diet than the autotrophic method.
The Marine Ingredients Organization (IFFO) sees microalgae as the most promising and sustainable alternative sources to EPA and DHA in fish oil.
Algal oils are now being commercialized as sustainable alternative sources to fish oils. They have been shown to be nutritionally equivalent and can successfully enrich larval feed and replace fish oil in fish diets.
Alltech has focused its research efforts on algae for the past five years, purchasing one of the largest heterotrophically grown micro-algae facilities in 2010. The 100,000-square foot state-of-the art facility in Winchester, Kentucky, uses proprietary algal technology to process heterotrophic algae because of its nutritional benefits.
A series of experiments in tilapia and trout were performed to evaluate the nutritional value of a high DHA strain of alga (SP1) pro-duced by Alltech’s Algae facility.
The algae were included at low levels in tilapia diets to evaluate the uptake of DHA in the fillet and added at high levels in trout to
determine the impact on performance. The tilapia fed 0.4 percent SP1 in the diet had higher DHA levels at the end of the 13-week feeding trial.
The 15 percent SP1 inclusion rate in the rainbow trout diet improved weight gain and also increased DHA levels in the fillet.
These trials indicated that heterotrophic microalgae can be included in tilapia and trout diets to increase DHA level in fish meat as well as improve fish performance. Work will continue with this strain of alga to define the nutritional value in marine species and shrimp.
The benefits of feeding microalgae
A two-fold contribution, the aquaculture indus-try can see the benefits of feeding microalgae to fish as well as marketing the enriched product to consumers. This can mean improving return while creating a healthier population of both humans and aquaculture all at the same time.
Beside the nutritional improvement that microalgae can bring to fish and food, it is one of the only biomass’ material that allows production with daily harvest all year round.
This could bring more security to an ever-changing market, and provide some options for the aquaculture industry, especially when fish oil supplies are depleting as it continues to be sold to the human side for a higher dollar amount.
July-August 2014 | INTERNATIONAL AQUAFEED | 31
Algae Harvesting Excellence
Evodos delivers micro-algae harvesting solutionsHarvest a high quality concentrate equal to living micro-algaeMicro-algae is harvested intact and undamaged which increases shelf life Proven replacement or supplement for living micro-algaeNo chemicals or additives needed for harvesting
Aquafeed – complete solutions from a single source.
Turn to Bühler for one of the most comprehensive lines of aquafeed process technology available anywhere: from raw material handling, cooking and shaping through extrusion to drying and coating of finished products. With an extensive know-how and a passion for quality we ensure not only product uniformity and production efficiency, but also maximum sanitation and safety. Bühler – gentle processing at its best. www.buhlergroup.com/aquafeed
• See the full issue• Visit the International Aquafeed website
• Contact the International Aquafeed Team
• Subscribe to International Aquafeed
Tilapia farming in China
Ukrainian Fish Farming:– Opportunities for growth
Volume 17 I s sue 4 2 014 - J u lY | AuGusT
INCORPORAT ING F I SH FARM ING TECHNOLOGY
El Niño – plan ahead and manage the risk
Fish Farming Technology supplement
- Stock protection
- Biomass control
- Technology round up
Microalgae:– A sea of opportunities for the
This digital re-print is part of the July | August 2014 edition of International Aquafeed magazine. Content from the magazine is available to view free-of-charge, both as a full online magazine on our website, and as an archive of individual features on the docstoc website. Please click here to view our other publications on www.docstoc.com.
To purchase a paper copy of the magazine, or to subscribe to the paper edition please contact our Circulation and Subscriptions Manager on the link above.