Investigating the effects of aluminum exposure on the cell wall of the marine diatom Phaeodactylum tricornutum

Marine diatoms exhibit varying responses to aluminum (Al) in seawater, influenced by their cell wall composition and structure, yet the mechanisms driving this relationship remain poorly understood. Herein, this study aimed to elucidate how Al interacts with the cell wall of the model diatom Phaeodactylum tricornutum and impacts its physiological and ecological behaviors. To achieve this, novel multidisciplinary approaches that combine X-ray photoelectron spectroscopy, non-invasive micro-test technology, and atomic force microscopy were employed. The results showed that the presence of 100 nM Al in the cultural medium did not have a significant impact on the cell growth of P. tricornutum. However, with an increase in Al concentration to 2 μM, there was a notable decrease in cell growth. Al exposure altered cell wall functional groups, siliceous components, and nitrogen adsorption potential, alongside inducing nanoscale morphological changes, including increased surface roughness and modulus. These structural modifications correlated with reduced copepod grazing and accelerated sinking rates, suggesting that Al-cell wall interactions critically modulate diatom ecological dynamics. This work provides integrated evidence linking Al-induced cell wall remodeling to broader ecological consequences in marine diatoms, advancing understanding of trace metal impacts on phytoplankton ecology.