Mass spectrometry imaging of Antarctic Ulva and its native microbiome with AP-SMALDI-HRMS

The green alga Ulva (Chlorophyta) hosts bacteria that promote algal growth and development, from germlings to mature plants. These associated bacteria produce bioactive compounds, including thallusin, N-acyl homoserine lactones, and ectoine, which contribute critically to the growth, development, and overall physiological fitness of the algal host.

However, there is limited research on the metabolome of cold-adapted Ulva holobionts, especially those from hard-to-reach regions like Antarctica, and how they respond to environmental changes. This study uses high-resolution mass spectrometry to examine heat induced shifts of osmolytes and zwitter ion in Ulva collected in the Antarctic ecosystem of Potter Cove, King Georg Island. We identified small polar and zwitterionic metabolites, such as cysteinolic acid, ectoine, glutamine, glycerol, and proline, in Ulva tissues analyzed with Ultra-High-Performance Liquid Chromatography coupled with High-resolution Mass Spectrometry (UHPLC-HRMS).