The response mechanisms of kelp Macrocystis pyrifera holobiont to elevated temperature and CO2 concentration

The kelp Macrocystis pyrifera, a crucial component of marine ecosystems, is significantly impacted by climate change and environmental stresses. Macrocystis pyrifera and its associated bacteria form a holistic functional unit (holobiont), yet the regulatory roles of bacteria in stress responses and acclimation are often overlooked. This study investigates the diversity of M. pyrifera associated bacteria and their chemical interactions under high temperature and elevated CO2 conditions. Our findings indicate that high temperatures significantly reduce associated bacterial diversity, while elevated CO2 does not alter community structure. Key microbial biomarkers identified include Pseudomonas, Sulfitobacter, and Olleya. However, it is unknown how they function in M. pyrifera. In metabolite analysis, we identified 18 metabolites with significant differences. These metabolites included phospholipids, antibacterial compounds, signaling molecules, and various compounds of unclear function. The changes in these compounds are probably connected to how M. pyrifera respond to climate change. These results will enrich the baseline data related to the chemical interactions between the microbiota and M. pyrifera and provide clues for predicting the resilience of M. pyrifera to future climate change.