Chemical interactions between kelp and symbiotic bacteria under elevated CO condition.

UNLABELLED

Kelps are pivotal to temperate coastal ecosystems, providing essential habitat and nutrients for diverse marine life, and significantly enhancing local biodiversity. The impacts of elevated CO levels on kelps may induce far-reaching effects throughout the marine food web, with potential consequences for biodiversity and ecosystem functions. This study considers the kelp and its symbiotic microorganisms as a holistic functional unit (holobiont) to examine their collective response to heightened CO levels. Over a 4 month cultivation from the fertilization of gametes to the development of juvenile sporophytes, our findings reveal that elevated CO levels influence the structure of the symbiotic microbiome, alter metabolic profiles, and reshape microbe-metabolite interactions using 16S rRNA amplicon sequencing and liquid chromatography coupled to mass spectrometry analysis. Notably, , , , , Milano-WF1B-44 and were selected as microbiome biomarkers, which showed significant increases in comparative abundance with elevated CO levels. Stress-response molecules including fatty-acid metabolites, oxylipins, and hormone-like compounds such as methyl jasmonate and prostaglandin F2a emerged as critical metabolomic indicators. We propose that elevated CO puts certain stress on the holobiont, prompting the release of these stress-response molecules. Moreover, these molecules may aid the kelp's adaptation by modulating the microbial community structure, particularly influencing potential pathogenic bacteria, to cope with environmental change. These results will enrich the baseline data related to the chemical interactions between the microbiota and and provide clues for predicting the resilience of kelps to future climate change.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s42995-024-00259-5.