Surface chemical composition of diatoms

Area of Science:

• Marine biology
• Biochemistry
• Materials science

Background:

• Diatoms possess intricate cell walls crucial for their structure and function.
• Phaeodactylum tricornutum exhibits unique morphotypes with varying cell wall compositions.
• Understanding diatom cell surface chemistry is vital for ecological and biotechnological applications.

Purpose of the Study:

• To investigate the surface chemical composition of Phaeodactylum tricornutum morphotypes.
• To compare the elemental and biochemical makeup of P. tricornutum with Thalassiosira pseudonana.
• To elucidate the role of silica and polysaccharides in diatom cell wall structure.

Main Methods:

• X-ray photoelectron spectroscopy (XPS) was employed for surface elemental analysis.
• Comparison of P. tricornutum morphotypes (fusiform, triradiate) with T. pseudonana.
• Analysis of silicon speciation (condensed silica, weakly polymerized silicate) and other biomolecules.

Main Results:

• T. pseudonana showed high silicon concentration, primarily condensed silica (SiO2).
• P. tricornutum morphotypes contained less silicon, predominantly weakly polymerized silicate.
• Polysaccharides were abundant in P. tricornutum cell walls, replacing silica structurally; lipids and sulfate groups were also detected.

Conclusions:

• P. tricornutum's cell wall structure relies more on polysaccharides than silica.
• Distinct silicon speciation and biochemical profiles exist between P. tricornutum and T. pseudonana.
• XPS provides valuable insights into the complex surface chemistry of diatoms.