Control system for soil microbes detrimental to trees using metabolites derived from algal bloom-causing...

Algal blooms, primarily caused by cyanobacteria such as Microcystis aeruginosa, disrupt aquatic ecosystems while also holding potential as a source of bioactive compounds. This study investigated microbial and metabolite changes during the occurrence and mitigation stages of algal blooms based on samples collected from Daecheong Lake in July (algal bloom season) and September (mitigation season) 2024. Using 16S rRNA sequencing, LC/MS-QTOF, and GC/MS, we identified a dynamic shift in microbial communities, with M. aeruginosa dominating during blooms and Flavobacterium fontis increasing post-mitigation. The metabolomic analysis highlighted unique fatty acid profiles, including linoleic acid and gamma-linolenic acid, which showed antimicrobial activity, particularly against plant pathogens such as Bacillus cereus. Algal supernatants significantly enhanced seed germination in crops like Cucumis sativus and Cucurbita moschata, attributed to growth-promoting metabolites such as stigmatellin Y, palmitic acid methyl ester, and phytohormone precursors. However, higher concentrations exhibited inhibitory effects, suggesting the need for optimal dosing. Antimicrobial assays revealed moderate inhibition of pathogens, indicating potential for natural biocontrol applications. This study highlights the dual role of algal blooms as both ecological challenges and valuable resources, laying the groundwork for their utilization in sustainable agriculture, biotechnology, and the development of natural antimicrobials. In particular, the potential of algae-derived substances to promote plant growth and inhibit pathogens has been confirmed through experimental analysis, providing a scientific basis for future practical applications in related fields. Based on this, further research is essential to improve extraction methods, evaluate ecological impacts, and expand production scale for practical application.