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Identification and algicidal mechanism of extracellular polysaccharides from Sulfitobacter pseudonitzschiae H46: A novel biocontrol agent for Chattonella marina bloom
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DOI：10.1016/j.hal.2026.103088.png)
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Abstract
En 中文
Harmful algal blooms (HABs) pose a significant threat to marine ecosystems and human health. Biological control technologies for mitigating HABs have shown promising application potential due to their environmentally sustainable and highly efficient characteristics. This study investigated the algicidal activity of extra-cellular polysaccharides (EPs) secreted by a phycospherical bacterium Sulfitobacter pseudonitzschiae H46 in lysis of harmful alga Chattonella marina. The composition of EPs and its algicidal mechanisms were also analyzed. The results demonstrated that the metabolites of strain H46 exhibit algicidal activity with species-specificity, particularly against C. marina with an inhibition rate of approximately 75 %. Molecular weight fractionation of the metabolites revealed that the 10-30 kDa fraction is the core active component responsible for algicidal effects. This fraction was confirmed to be bacterial EPs and disrupting the integrity of algal cell membranes thereby causing leakage of intracellular contents and resulting in the lysis of the cell. Fourier transform infrared spectroscopy and high performance liquid chromatography analysis confirmed that the EPs possess typical polysaccharide structural features and are classified as a heteropolysaccharide composed of seven monosaccharide units including mannose, glucuronic acid, galacturonic acid, N-acetylglucosamine, N-acetylgalactosamine, galactose, and fucose. Furthermore, EPs from H46 significantly enhanced the activities of superoxide dismutase, catalase, and peroxidase in C. marina, indicating that EPs activate antioxidant defense mechanisms to mitigate reactive oxygen species-induced cellular damage. This study represents the first report on bacterial EPs with algicidal function via microalgal lysis. The EPs produced by S. pseudonitzschiae H46 show prospective application in serving as a novel biocontrol agent for C. marina blooms.
Keywords:
Extracellular polysaccharides
Algicidal activity
Sulfitobacter pseudonitzschiae
Harmful algal bloom
Chattonella marina
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