DIVERSITY OF LIPIDS IN ALGAE

Aakanksha1, Shilpi Samantray2, Supriya Guruprasad 2 & T.V Ramachandra2

1 Birla Institute of Technology, Ranchi2Energy & Wetland Research Group, Centre for Ecological Sciences, Indian Institute of Science, Bangalore - 560012

Algae are:

• Crytogamous• Ubiquitous • Prokaryotic or Eukaryotic• Photosynthetic • Reproduce asexually sometimes sexually• Planktonic or Benthic

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Algae can be used as the feedstocks for the biodiesel because of its behavior of synthesizing and accumulating large amount of lipids , high growth rates, tolerance to very adverse conditions, production of value adding products.

Algal population can be affected by the environmental factors like seasonal changes, nutrient availability , light penetration etc.

Algae are primarily made up of proteins carbohydrates, fats and lipids in varying proportions.

They can accumulate large amount of protein about 47% of total biomass.

In algae the organic carbon is represented by carbohydrates, polysaccharides , nitrogenous and polyphenolic materials .

The diversity of algal lipids and its ability to modify the lipid composition according to environment made them ubiquitous.

Green algae are the most important oleaginous algae.

Microalgae represent an exceptionally

diverse but highly specialized group of

micro-organisms adapted to various ecological habitats.

ALGAE

Cyanophyta Chlorophyta Cryptophyta Bacillariophyta Haptophyta Dinophyta Eustigmatophyta

CLASSIFICATION OF ALGAE

INTRODUCTION Algae can be classified on the basis of :

Size of the algal cell

Pigment color

Presence of flagella

Life cycle

Stored material

Cell wall composition

Fatty acid Bacillariophyta Eustigmatophyta Chlorophyta Haptophyta Cyanophyta Cryptophyta Dinophyta

C10:0 +

C11:0 +

C12:0 +

C14:0 + + + + + +

C14:1

C14:2 +

C15:0 + + +

C16:0 + + + + + + +

C16:1ω5 +

C16:1ω7 + + + + + + +

C16:1ω9 + + +

C16:2ω4 + + +

C16:2ω7 + + +

C16:3 + +

C17:0 +

C18:0 + + + + + +

C18:1ω7 + + +

C18:1ω9 + + + + + + +

C18:1ω13 +

C18:2ω6 + + + + + +

C18:3ω3 + + + + + + +

C18:3ω6 + + + + + + +

C18:4ω3 + + + + + +

C18:5ω3 + +

C20:0 +

C20:1 +

C20:4ω6 + + +

C20:5ω3 + + + + +

C22:5ω3 + +

C22:6ω3 + +

C24:0 +

CONCLUSION

Algae are known as the potential source of Lipids.

The lipid classes are present in all the algal species are C16:0, C16:1ω7, C18:1ω9, C18:3ω3, C18:3ω6.

They have the ability to produce TAG as a storage lipid under photo-oxidative stress or other adverse environmental conditions.

Chlorophyta, Bacillariophyta and Cyanobacteria are the most favored algae by the researcher for biofuels production due to their high lipid content.

Some of these unsaturated fatty acids that are found in different algal species include: arachidonic acid, eicospentaenoic acid, docasahexaenoic acid, gamma-linolenic acid, and linoleic acid.

TAGs are the Microalgal feedstock of Biodiesel production and PUFAs provides essential fatty acids.

Shift in lipid metabolism from membrane lipid synthesis to the storage of neutral lipids takes place in adverse situation.

Acknowledgement

I want to thank entire EWRG for their valuable suggestions.

Source

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The ability of algae to survive or proliferate over a wide range of environmental conditions is, to a large extent, reflected in the tremendous diversity and sometimes unusual pattern of cellular lipids as well as the ability to modify lipid metabolism efficiently in response to changes in environmental

conditions

Classification of lipids

Polar Lipid Non Polar Lipid

Phospholipid

Sphingolipid

Glycolipid

Sterol

Triacylglycerol

Hydrocarbon

Lipids of algae

Polar lipids are mainly the part of membrane lipids. These are synthesized during normal conditions. They constitute about 5-20% o f the cell.

Membrane lipids are mainly in the form of Glycosylglyserides which resides in chloroplast of the cell and other membrane lipid is phosphoglyserides which resides in the plasma membrane and endoplasmic membrane.

Neutral lipids are synthesized during adverse conditions. These lipids get accumulated in the cytoplasm of the cell in the form of densely packed bodies. Sometimes they can be stored in the inter-thylakoidal space of the chloroplast of some green algae.

Neutral lipids can be TAGs or hydrocarbons. Hydrocarbons constitute about 5% of the total biomass. TAGs are the potential feedstocks for the biodiesel production.

Fatty acids are the building blocks of lipids. Algae contain fatty acid having chain length C16- C18. Fatty acid can be saturated or unsaturated depending on the presence of double bonds between carbon atoms. Saturated and Mono unsaturated fatty acids are dominating in algae.

TAGs constitute about 80% of the total lipids found in algal cell . The TAGs having saturated and mono-unsaturated fatty acids are used for biofuels production.

Algae oils have been found to be very high in unsaturated fatty acid . Some of these fatty acids are found in different algae species include : arachidonic acid , eicospentaenoic acid, docasahexaenoic acid, gamma-linolenic acid and linoleic acid. The PUFAs found in algal species are omega 3, omega 4, omega 5, omega 6, omega 7, omega 9, omega 13. Among these PUFAs omega 3 and omega 6 are essential fatty acids, which acts as nutrient supplement in mariculture.

The dominating fatty acids in bacillariophyta is C16:0,C16:1,C20:5ω3 and C22:6 ω3, in eustigmatophyta C16:0, C18:1, C20:3, and C20:4 ω3, in chlorophyta C16:0, C18:1, C18:2 and C18:3 ω3, in cryptophyta C16:0, C20:1, C18:3 ω3, C18:4, and C20:5, in dinophyta C16:0, C18:5 ω3 and C22:6 ω3, in cyanophyta C16:0, C16:1, C18:1, C18:2 and C18:3 ω3.

Major applications of algal lipids

Algal neutral lipids (TAGs) are the potential source of biofuels

Some PUFAs ( omega 3 and sometimes omega 6) acts as essential fatty acids which provides nutrient supplement .

Factors affecting lipid composition

In algae genetic constituent decides the lipid content and composition in normal growth conditions.

In adverse situation the factors which decides the lipid composition is nutrients, light intensity, temperature, growth phase and physiological conditions.

The nutrient which basically affects the lipid composition is nitrogen, phosphate, silicate. The concentration of silicate affects the Diatom only. Starvation of these nutrients helps in accumulation of neutral lipids.

With increasing temperature saturation of fatty acids starts increasing.

Low light intensity induces the formation of polar lipids.

During stationary phase amount of TAGs increases.

References

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Table : showing the fatty acids present in different algae

Lipids in Algae

C16:0

C18:0

C16:0

C18:1

C18:1

C18:1

C18:1

C16:0

C18:1

C18:1

C18:1

C18:1

C18:2

C18:1

C18:0

C18:1

C16:0

C18:1

C16:0

C16:0

C18:0

C18:0

C18:1

C18:2

C18:0

C16:0

C18:1

C16:1

C18:1

C16:0

C20:1

C18:1

C18:0

C18:1

C18:O

C18:2

C16:1

C16:0

C18:1

C18:2

C16:0

C18:2

C16:0

C16:0

C18:0

C18:2

C18:1

C16:0

C16:1

C16:0

C18:1

C18:1

C18:2

C18:2

C18:1

C14:0

C18:0

C18:1

C16:0

C18:1

C18:1

C16:0

C16:0

C18:2

C18:1

C14:0

C18:0

C18:0

C16:0

C18:2

C16:0

C18:1

C18:1

C18:2

C18:1

C18:1

C18:0

C16:O

C18:1

C16:1

C18:1

C18:1

C16:0

C18:1

C18:1

C18:1

C18:1

C16:0

C16:0

C18:1

C18:0

C18:0

C18:0

C18:1

C16:0

C16:0

C18:1

C18:1

C18:1

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