Single-cell ionomes of terrestrial cryosphere algae.

Area of Science:

• Environmental microbiology
• Plant science
• Biogeochemistry

Background:

• Algae from the Viridiplantae lineage inhabit glaciers and snow patches globally.
• These cryosphere algae are adapted to extreme conditions like freezing temperatures, high light, and oligotrophic environments.
• The cellular nutrient balancing strategies of cryosphere algae remain largely unknown.

Purpose of the Study:

• To investigate the single-cell ionomes of cryosphere chlorophyte algae.
• To compare the ionomes of cryosphere algae with mesophile chlorophyte algae.
• To understand nutrient homeostasis in algae adapted to extreme cold environments.

Main Methods:

• Single-cell inductively coupled plasma-mass spectrometry (SC-ICP-MS) was used to quantify ionomes.
• Cryosphere algae (Microglena sp., Raphidonema sempervirens, Deuterostichococcus sp.) and mesophile algae (Acutodesmus obliquus, Chlamydomonas reinhardtii) were analyzed.
• Results were validated using mass spectrometric analyses of digested cultures.

Main Results:

• Cryosphere algae showed lower single-cell Phosphorus, Magnesium, and Calcium per cell biovolume compared to mesophiles, suggesting slower metabolism.
• Under phosphorus starvation, Raphidonema sempervirens maintained its ionome, while Microglena sp. showed a P and Mg loss and Cu increase, indicating polyphosphate hydrolysis.
• Algal ionomes differ significantly between cryosphere and mesophile species.

Conclusions:

• Cryosphere algae possess unique nutrient homeostasis mechanisms for survival in extreme cold.
• Single-cell ionome analysis provides critical insights into algal adaptation to oligotrophic and freezing conditions.
• Understanding cryosphere algal nutrient strategies is vital for predicting ecosystem responses to climate change.