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Diatoms are one of the primitive forms of eukaryotic existence. They are unicellular, photosynthetic algae which exists in sea water, fresh water and in normal soil. They belong to class Bacillariophyceae. Due to their abundance and critical role in the food web, they can be referred as ‘production factories’ of the marine world. Examples for diatoms are Cyclotella, Skeletonema, Thalassiosira etc. They form biofilmic layer on water surfaces, these biofilms are rich in carbohydrates. They also play a key role in fixing the Carbon dioxide in the atmosphere.

Cell walls of diatoms are made up of two silicate cylindrical outer and inner valves, called epivalve and hypotheca respectively. Frustules are composed of silica as well as organic compounds like silaffins (protein with silica affinity) and polyamines. After the death of diatoms, decomposition of the internal organelles occurs leaving the glass skeletons (frustules) behind. These remaining of diatoms are called diatomites. Based on the molecular weight of frustules, they are further divided into α-frustulin, β-frustulin, γ-frustulin, δ-frustulin and ε-frustulin.

Frustules can be used for various industrial purposes as Filter materials, Mineral fillers, Biosensors, Biomineralization process, Production of Insulation materials and Abrasives. Several research works are ongoing on the chemical nature of frustules due to its morphological characteristics like porosity, inertness and silicate finishing. Nanotechnology is another area where the silicate frustules inspire due to its nanostructure, self assembling property and uniqueness. Thalassiosira pseudonana was the first diatom to be sequenced. Scientists have predicted T. pseudonana to be the next break through in computer chips. Researches have proven that diatoms, Nitzschia obtusa and Navicula minima acts as bioaccumulator, which accumulated trace amounts of gold.

Biomass production of diatoms benefits health industry in many ways: Diatoms like Phaeodactylum tricornutum and Skeletonema costatum are natural producers of Eicosapentaenoic Acid: type of poly unsaturated omega 3 fatty acid. PUFA s are in demand because of its role in healthcare as it reduces cardiovascular diseases and mental disorders. Arachidonic acid: type of poly unsaturated omega 6 fatty acid, they acts as precursors for Prostaglandins. Acetyl Co A- Carboxylase: An enzyme which is required for the synthesis of Triglycerides, which can be converted into glycerol and monoesters and thus biodiesel production. Fatty acid metabolism in peroxisomes and mitochondria. Integration of urea cycle into Nitrogen metabolism. Amino acids like Aspartic acid, Isoleucine play major role in cosmetic industry. It was thought earlier that they had therapeutical values like Vitamins present. Anyhow, no studies were made to support this hypothesis. It also acts as a forensic investigation tool. The morphology of frustules sheds light on different delivering mechanisms in Genetic engineering.

Its applications are extended to textile industry as decolouring agents. These organisms can be exploited by using the carbohydrates for ethanol production, chlorophyll carotenoid proteins for methane production and natural oils for biodiesel production. Bioremediation property – they are heavy metal resistant hence can be used for bioremediation, researches have shown that Arsenic toxicity were bioremedified using these diatoms. Extensive studies and researches have to be conducted to explore the unseen potentials of diatoms.