Bacteria and macroalgae share an inseparable relationship, jointly influencing coastal ecosystems. Within macroalgae habitats, Planctomycetota, a group of bacteria notoriously challenging to cultivate, often dominate. However, the mechanisms facilitating their persistence in this environment remain unclear. Here, we successfully isolated a novel Planctomycetota bacterium, Stieleria sp. HD01, from the surface of kelp. We demonstrated that HD01 possesses a robust ability to metabolize fucoidan, which constitutes half of the kelp‐derived organic carbon and exhibits resistance to attack by most microorganisms. Moreover, HD01 can utilize a broad spectrum of other organics, indicating its metabolic versatility and competitive prowess within algal environments. Additionally, HD01 can secrete antagonistic substances against other bacteria, form biofilms, and employ superoxide dismutase and catalase to resist oxidative stress, further consolidating its ecological fitness. Comparative metagenomics analysis suggested that Planctomycetota may have a mutually beneficial relationship with kelp.

中文翻译：

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浮霉菌门细菌在大型藻类栖息地繁衍生息并与大型藻类建立互利关系的适应性特征


细菌和大型藻类有着不可分割的关系，共同影响沿海生态系统。在大型藻类栖息地中，浮霉菌（Planctomycetota）——一组众所周知难以培养的细菌——通常占据主导地位。然而，促进它们在这种环境中持续存在的机制仍不清楚。在这里，我们成功分离出一种新型浮菌门细菌，Stieleria sp。 HD01，取自海带表面。我们证明 HD01 具有强大的代谢岩藻依聚糖的能力，岩藻依聚糖占海带来源的有机碳的一半，并且对大多数微生物的攻击具有抵抗力。此外，HD01 可以利用广泛的其他有机物，表明其在藻类环境中的代谢多功能性和竞争能力。此外，HD01还可以分泌针对其他细菌的拮抗物质，形成生物膜，并利用超氧化物歧化酶和过氧化氢酶来抵抗氧化应激，进一步巩固其生态适应性。比较宏基因组学分析表明浮霉菌可能与海带存在互利关系。