lgae, 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
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.
While 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
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
concentrates used in ‘early
by Pieter Boelens, Chief Operation
icro-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-
• Increased shelf life
• Easy to suspend uniformly in water
• Regularly available and affordable
The 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
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 strains
Evodos 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-
Omega-3 fatty acid
In 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-
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
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
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
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
July-August 2014 | INTERNATIONAL AQUAFEED | 31
Algae Harvesting Excellence
Evodos delivers micro-algae harvesting solutions
Harvest a high quality concentrate equal to living micro-algae
Micro-algae is harvested intact and undamaged which increases shelf life
Proven replacement or supplement for living micro-algae
No chemicals or additives needed for harvesting
P +31 76 571 1170
Innovations for a better world.
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
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Tilapia farming in China
Ukrainian Fish Farming:
– Opportunities for growth
Volume 17 Issue 4 2014 - JulY | AuGusT
FISH FARMING TECHNOLOGY
– plan ahead and manage the risk
Fish Farming Technology supplement
- Stock protection
- Biomass control
- Technology round up
– A sea of opportunities for the
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