目的：建立肠道微生物共存网络，探究抑郁症（MDD）患者肠道微生物与健康对照（HC）的不同。方 法：招募MDD患者和HC组受试者，各35例，收集临床症状进行评估，并采集粪便样本进行宏基因组测序，计 算微生物物种之间的相关性，构建肠道微生物共存网络，分析组间网络拓扑属性差异以及关键节点的改 变。结果：对2组使用同种方法构建的肠道微生物共存网络的分析提示，MDD组肠道群落微生态发生变化， 网络中平均度和连接性下降，种间相互作用减少，微生态关键成员改变。HC网络的模块中心节点是Ruminococcus flavefaciens，连接节点是 Clostridium CAG 389 和 Lachnospiraceae bacterium A2；被识别为 MDD 网 络模块中心节点的是 uncultured Blautia sp, Bacteroides mediterraneensis 和 Parabacteroides distasonis。Ruminococcus flavefaciens和Clostridium CAG 389丰度与临床抑郁和焦虑量表得分之间存在显著相关。 结论： MDD人群的肠道微生物共存网络和健康人群不同。共存网络分析有必要在肠道微生物相关研究中进一步 推广和发展，以期获得更多纯丰度以外的发现。

The co-occurrence network was established to explore the differences between the gut microbiome of patients with major depressive disorder (MDD) and healthy controls (HCs). Methods: Thirty-five MDD patients and 35 HCs were recruited, and their stool samples were collected for sequencing. Correlations between microbial species were calculated to construct the co-occurrence network of gut microbiome. Differences in network topology attributes and key nodes between groups were analyzed. Results: The analysis of gut microbiome co-occurrence networks showed that the microecology of the gut community was changed in MDD group. The decreased average degree and connectance of the network indicated the decreased interspecific interaction. Key members of the microecology were also found changed. The module hub for HC was Ruminococcus flavefaciens, and the connectors were Clostridium CAG 389 and Lachnospiraceae bacterium A2. The uncultured Blautia sp, Bacteroides mediterranensis and Parabolides distasonis were identified as the module hubs for MDD. Besides, the abundance of Ruminococcus flavefaciens and Clostridium CAG 389 both showed a significant correlation between clinical depression and anxiety scale scores. Conclusion: The co-occurrence network of gut microbiome in patients with MDD is different from healthy controls. To obtain more findings beyond pure abundance, co-occurrence network analysis needs to be further promoted and developed in researches related to gut microbiome.