In the eustigmatophycean Nannochloropsis limnetica the content of polyunsaturated fatty acids (PUFA) is extremely high in comparison to different planktonic green algal taxa in freshwater ecosystems. The sums of n-6 and n-3 fatty acids in N. limnetica were ten-fold higher than in the other picoplankton Choricystis minor and Pseudodictyosphaerium jurisii, and higher than in the nanoplanktonic green algae Chlorella vulgaris, Monoraphidium neglectum and Scenedesmus obtusiusculus. The content of fatty acids in N. limnetica was highly variable under different culture conditions. The highest concentrations of PUFA in N. limnetica were found in non-aerated suspension cultures, with a high content of phosphate (40 mg/L K2HPO4) in the culture medium: linoleic acid 22.19 mg/g DW, arachidonic acid 10.52 mg/g DW, and eicosapentaenoic acid 55.56 mg/g DW. N. limnetica represent a high-quality food resource in freshwater food chains. Furthermore, cultures of this eustigmatophycean alga have a high potential for use in biotechnology and aquaculture.

1. Paper Review
The high content of polyunsaturated fatty acids in
Nannochloropsis limnetica (Eustigmatophyceae)
and its implication for food web interactions,
freshwater aquaculture and biotechnology
Krienitz L. and Wirth M.
Vijendren s/o Krishnan
Supervisor: Prof. Dr. Uemura Y.
(12 Mac 2014)

2. Abstract
In the eustigmatophycean Nannochloropsis limnetica the content of
polyunsaturated fatty acids (PUFA) is extremely high in comparison to different
planktonic green algal taxa in freshwater ecosystems. The sums of n-6 and n-3
fatty acids in N. limnetica were ten-fold higher than in the other picoplankton
Choricystis minor and Pseudodictyosphaerium jurisii, and higher than in the
nanoplanktonic green algae Chlorella vulgaris, Monoraphidium neglectum and
Scenedesmus obtusiusculus. The content of fatty acids in N. limnetica was highly
variable under different culture conditions. The highest concentrations of PUFA in
N. limnetica were found in non-aerated suspension cultures, with a high content of
phosphate (40 mg/L K2HPO4) in the culture medium: linoleic acid 22.19 mg/g
DW, arachidonic acid 10.52 mg/g DW, and eicosapentaenoic acid 55.56 mg/g DW.
N. limnetica represent a high-quality food resource in freshwater food chains.
Furthermore, cultures of this eustigmatophycean alga have a high potential for use
in biotechnology and aquaculture.
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3. Introduction
• Nannochloropsis have been used as food for
marine aquaculture & cultured in industrial scale.
• Contains high eicosapentanoic acid.
• Five species in marine water & one species in
fresh water.
• Categorized into picoplankton and nanoplankton.
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4. Objectives
• To compare the fatty acid content in N. limnetica
with other freshwater picoplankton (Choricystis
minor and Pseudodictyosphaerium jurisii) and
nanoplankton (Chlorella vulgaris, Scenedesmus
obtusiusculus, Monoraphidium braunii)
• To investigate effect of K2HPO4 on FA content
• To investigate effect of aeration on FA content
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5. Methodology
• N. limnetica cultured in Bourrely medium
• K2HPO4 at various concentration (40, 20,
10, 4 mg/L) studied for FA production
• Culture condition
– Aerated suspension without CO2 enrichment
• Continuous illumination, Temp 20oC
– Non-aerated suspension (shaken twice a day)
• Light/dark 14h/10h Temp 20oC
• 180 μmolm-2s-1
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6. FA analyses
Weighed sample transferred to tube containing 5ml
CCl4/MeOH (2:1) and 0.4mg tricosan acid
Held in ultrasonic device for 90min for lipid extration
Filtered and washed twice with extraction solvent
Samples evaporated, and added with 5 ml
MeOH:H2SO4 (95:5) to convert FA to methyl ester
Sample heated for 4h at 80oC, then 10ml H2O added
FAME extracted twice with 2ml n-hexane
FAME analysed by GC
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7. Fatty acid content in five different green algal species under aerated
suspension cultures in the stationary phase of growth
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8. Fatty acid content in suspension cultures of aerated and non-aerated
culture conditions and different phosphate concentrations
Fatty acids Aerated cultures Non aerated cultures (K2HPO4)
exponential
phase
stationary
phase
4mg/L 10mg/L 20mg/L 40mg/L
14:0 7.5 6.30 0.92 4.97 3.66 22.37
16:0 30.85 36.06 4.17 20.94 17.84 125.07
16:1 n-7 38.34 37.10 3.00 17.25 16.08 120.62
18:0 2.31 0.68 1.11 2.44 2.00 11.70
18:1 n-9 22.15 30.14 2.03 12.94 1.60 98.89
18:2 n-6 2.78 3.83 1.03 4.81 4.08 22.19
18:3 n-6 0.28 0.18 0.14 0.34 0.11 0.41
18:3 n-3 0.54 0.37 0.81 4.59 3.42 3.19
20:4 n-6 2.73 5.26 1.14 5.34 2.03 10.52
20:5 n-3 18.65 28.06 2.22 14.72 15.71 55.56
22:5 n-3 0.22 0.08 0.22 0.66 0.32 1.70
22:6 n-3 0.04 0.06 .36 0.50 0.47 6.89
Σn-6 7.50 10.12 3.47 14.81 10.03 50.48
Σn-3 20.38 28.98 4.89 22.91 23.18 71.59
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9. Discussion
• Lipid content will increase under N depleted
condition and CO2 enriched condition.
• Change in ratio of short chain FA: long chain FA
from exponential to stationary phase
• PUFA conc. higher in stationary phase and non-aerated
cultures.
• Higher phosphate conc. Increase PUFA content.
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10. • Nannochloropsis biomass is an interesting
alternative to fish oil produced from fatty fish,
which is widely used for medical purpose in order
to reduce the risk of myocardial illnesses of man
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Conclusion

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Thank You