Light but mighty: researchers find the key for a resistant alga

23-04-2020

Jania sp, a coralline red alga, has a helical structure, which makes it extremely resistant to stress, researchers led by the Technion- Israel Institute of Technology have found, using three different beamlines at the ESRF. They publish their results in Advanced Science today.

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Jania sp. is an articulated, coralline red alga with biomineralized tissue, living in the shallow waters of oceans and seas around the world and sustaining an enormous amount of stress due to the waves of the sea. Its skeleton is made of high magnesium calcite and it is very light weight, which brings its weight down while remaining very strong.

“Jania had already been studied before, but not with synchrotron X-rays, so we decided to do it to find out what made it such a sturdy alga”, explains Boaz Pokroy, corresponding author and professor at the Technion- Israel Institute of Technology. The goal was to investigate the structure of these algae at various length scales, from the nano to the macroscale.

The team, made up of scientists from the Technion, as well as the Charité University in Berlin and the ESRF, went to different beamlines at the ESRF to find answers. They solved the crystal structure and determined the effect of the magnesium on the structure. Then they went to the beamline ID16B, where they used the technique of X-ray nanotomography. “And that is when the story got a twist: we found that the structure is helical, which had never been seen before”, says Pokroy.

“We found that the helix shape of the structure makes the alga 20% more compliant to stand the bending forces it is submitted to”, adds Pokroy.

 

The experiments on ID19 and ID22, where they used X-ray microtomography and X-ray powder diffraction, showed that Jania’s stem has a micron-sized open cells, similar to wood, but made of mineral, with a structure of 64% of porosity. They also found that the closer to the alga’s surface, the mineralization on cell walls is thicker than near its inner part, “probably to better sustain the stress applied on its outer surface by the waves”, explains Pokroy. On ID19, scientist Alexander Rack, co-author of the study, explains: “Using high sensitivity microtomography on ID19, our collaborators have been able to understand how nature creates complex morphologies.”

“These findings are of great importance in deepening the understanding of nature’s designs, and it is potentially relevant for the development of new low-weight, high-compliance structures”, adds Pokroy. One example that could benefit from this research is concrete. This material is very brittle and does not stand bending forces, and so today manufacturers add steel into it. If it could adopt a helical open-cells structure, it could bring down the weight and make it more flexible and resistant.

For the ESRF, this collaboration with the Technion team has proved very successful: "At ID16B we are very proud of having this long-standing collaboration on biomineral materials, with very interesting scientific results and several high-impact factor publications", says Julie Villanova, scientist at ID16B and also co-author of the paper.

Reference:

Bianco-Stein N, et al, Advanced Science, 21 April 2020. https://doi.org/10.1002/advs.202000108

Text and video by Montserrat Capellas Espuny.

Top image: Jania sp algae on a beach. Credits: Wild Singapore.