Bacterial interactions in Nematostella vectensis

The maintenance and resilience of host-associated microbiota during development is a fundamental process influencing the fitness of many organisms. Several host properties were identified as influencing factors on bacterial colonization, including the innate immune system, mucus composition and diet. In contrast, the importance of bacteria-bacteria interactions on host colonization is less understood. Here, we use bacterial abundance data of the marine model organism Nematostella vectensis to reconstruct potential bacteria-bacteria interactions through co-occurrence networks. The analysis indicates that bacteria-bacteria interactions are dynamic during host colonization and change according to the host's developmental stage. To assess the predictive power of inferred interactions, we tested bacterial isolates with predicted cooperative or competitive behavior for their ability to influence bacterial recolonization dynamics. Within three days of recolonization all tested bacterial isolates affected bacterial community structure, while only competitive bacteria increased bacterial diversity. Already one week after recolonization almost no differences in bacterial community structure could be observed between control and treatments. These results show that predicted competitive bacteria can influence community structure for a short period of time, verifying the in silico predictions. However, within one week, the effects of the bacterial isolates are neutralized, indicating a high degree of resilience of the bacterial community.宿主共生微生物群在发育过程中的维持与恢复力，是影响诸多生物体生存适合度的核心过程。已有研究明确宿主的多项属性可作为细菌定殖的影响因素，包括先天免疫系统、黏液组分与饮食结构。与之相对，细菌间互作对宿主定殖的重要性仍有待进一步阐明。本研究利用海洋模式生物星状海葵（Nematostella vectensis）的细菌丰度数据，通过共现网络重构潜在的细菌间互作关系。分析结果显示，细菌间互作在宿主定殖过程中呈动态变化，并随宿主发育阶段发生调整。为评估所推断互作的预测能力，本研究针对具有预测合作或竞争特性的细菌分离株，检验其对细菌重新定殖动态的影响能力。在重新定殖后的三天内，所有受试细菌分离株均会改变细菌群落结构，而仅竞争型细菌可提升细菌群落多样性。在重新定殖一周后，对照组与处理组之间几乎已无法观测到细菌群落结构的差异。上述结果表明，经预测的竞争型细菌可在短期内影响群落结构，验证了计算机模拟（in silico）的推断结果。但在一周内，细菌分离株的干预效果便已被抵消，这表明细菌群落具备极高的恢复弹性。