Seaweed in biology

Updated: Mar 14

Without algae-extracted polysaccharides (phycocolloids) no modern biology!

Enter a biology laboratory and you will for sure find a bottle containing a white powder labeled agar or agarose. Yes, the polysaccharide extracted from red seaweed is a critical element of biology research and microbial diagnostic. So much that when the red seaweed harvest is poor, and the agar price raises it impacts many laboratories around the world.

Agar is routinely used to grow bacteria and agarose for cell culture and for DNA separation.

Ultrapure Agarose from Invitrogen. One of the purest forms of agarose that you can find for the purification of DNA.

Microbiology culture

Today, microbial infections are treated fairly well thanks to our ability to culture bacteria in the laboratory. This tremendous milestone has led to many technological breakthroughs including the discovery of antibiotics.

This would not have been possible without the contribution of the wife of one of Robert Koch's students: Angelina Hesse.

Robert Koch, better known as the father of microbiology discover the origin of tuberculosis. He was able to make this discovery by developing with his students all the techniques that we still use today to culture bacteria. The Petri Dish: Julius Petri one of Koch's students who invented the design which allow to culture bacteria in a sterile manner.

On what bacteria are growing in the Petri dish? The red-seaweed-extracted polysaccharide agar.

A plastic Petri dish filled with agar to culture bacteria. This one is used to check the sterility of surfaces by squizzing the agar onto a desk or laboratory bench.

In the infancy of microbiology, bacteria were cultivated in liquid. But this technique was unreliable and is time-consuming. A solid support technique was developed in Robert Koch's laboratory. In the beginning, they were using gelatin to create soft but solid support to grow bacteria. But many bacteria can digest gelatin and so after a few days, the gelatin was degrading and unstable at 37°C, the temperature at which bacteria are cultured. But replacing gelating with agar gel already used at that time in the Asian cuisine as a gelling agent provided a stable solid media that couldn't be digested by bacteria.

After several days of incubation, the pathogens present on the surface are growing on the plate. here we can see three different bacteria colonies and one fungus. Well, I better clean my desk !

Today the agar plate technique developed in Koch's laboratory has not evolved much. New media have appeared which are mixed with the agar gel to form a media that can selectively grow a certain type of bacteria. But the principle is still the same over 140 years later.

To read more about this topic:

Cambau E, Drancourt M. Steps towards the discovery of Mycobacterium tuberculosis by Robert Koch, 1882. Clin Microbiol Infect. 2014 Mar;20(3):196-201. doi: 10.1111/1469-0691.12555. PMID: 24450600.


The work of a second Nobel prize awardee has led to the use of seaweed-extracted polysaccharides in biology laboratories. Arne Tiselius developed in the 1940s a technique to separate protein based on their size and electric charge: electrophoresis. Molecules are loaded in a hydrogel. A current is applied between both ends of the gel that forces the proteins to travel through the hydrogel pores. Decades later, the technique was adapted to DNA purification. Using agarose, one of the two polysaccharides composing agar, DNA and mRNA strands can be separated based on their size.

An electrophorsis set up. A current generator is used to apply a current at both end of agarose hydrogel to forces molecules through the hydrogel's pores.

To read more about this topic:

Jeppson, J O; Laurell, C B; Franzén, B (1979). Agarose gel electrophoresis. Clinical Chemistry, 25(4), 629–638. doi:10.1093/clinchem/25.4.629

3D cell culture and bioprinting

For now almost a century we are able to grow mammalian cells in the laboratory. These cells are cultures either in solution or on glass or plastic slides. But we are not flat, so cells cultures on these flat surfaces are not experiencing the same environment as in our 3D organs. What did scientists do to culture cells in 3D? Well, look at what materials they had on their bench and picked up agarose. Cells can be grown on agarose that reproduces the natural 3D environment. With the emergence of tissue engineering and the development of 3D bioprinting, agarose is still being used to create objects that resemble anatomies of the human body using agarose.

3D bioprinting of agarose (transparent) hydrogel with a blood vessel replicate (in blue).

To read more about this topic:

Check our publications here and here

Phycocolloids like agar and agarose have plaid a major role in the establishment of our current bioengineering techniques. Without these hydrogels extracted from seaweeds, we wouldn't have antibiotics or DNA sequencing techniques. But we believe that this is not the last act that seaweed has to play in bioengineering. Let's see what seaweed-extracted hydrogels are capable of helping us create artificial organs.

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