ABSTRACT: The bryozoan Bugula neritina hosts an uncultured gammaproteobacterial symbiont, ‘Candidatus Endobugula sertula’ (E. sertula), which also produces the defensive compounds known as bryostatins. These compounds are unpalatable and protect the larvae from predation. Recent studies have shown that the symbiont can be present or absent in B. neritina colonies. The factors determining the symbiotic state of the host are unknown and may include abiotic or biotic variables, including other members of the B. neritina microbiome, which are poorly studied. Here, we explored the relationships between host genotype, environmental factors, E. sertula frequency, and microbiome composition in 141 B. neritina colonies collected from the east coast of North America. We found that latitude, temperature, and host genotype did not correlate with symbiont frequency, but they did impact the overall microbiome composition of B. neritina. Furthermore, we found that symbiont frequency predicts the composition of the non-symbiont microbiome. We hypothesize that chemical or ecological interactions mediated by E. sertula determine the presence or absence of other microbial taxa, which are additionally impacted by environmental factors and host biology.

中文翻译：

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共生体频率预测模型苔藓细菌共生模型中的微生物组组成

摘要：苔藓虫Bugula neritina拥有一种未经培养的γ-变形细菌共生菌' Candidatus Endobugula sertula'（E. sertula），它还产生防御性化合物，称为苔藓抑素。这些化合物难吃，可防止幼虫被捕食。最近的研究表明，共生菌可以存在于或不存在于奈氏芽孢杆菌菌落中。决定宿主共生状态的因素尚不明确，可能包括非生物或生物变量，包括对B. neritina微生物组其他成员的研究不足。在这里，我们探讨了宿主基因型，环境因素，小肠埃希氏菌之间的关系。从北美东海岸采集的141个B. neritina菌落的频率和微生物组组成。我们发现纬度，温度和宿主基因型与共生体频率不相关，但是它们确实影响了芥蓝的整体微生物组组成。此外，我们发现共生体频率预测非共生微生物组的组成。我们假设，由大肠埃希氏菌介导的化学或生态相互作用决定了其他微生物类群的存在与否，另外还受到环境因素和宿主生物学的影响。