Different organs of a host represent distinct microenvironments resulting in the establishment of multiple discrete bacterial communities within a host. These discrete bacterial communities can also vary according to geographical location. For the Pacific oyster, Crassostrea gigas, the factors governing bacterial diversity and abundance of different oyster microenvironments are poorly understood. In this study, the factors shaping bacterial abundance, diversity and composition associated with the C. gigas mantle, gill, adductor muscle and digestive gland were characterised using 16S (V3-V4) rRNA amplicon sequencing across six discrete estuaries. Both location and tissue-type, with tissue-type being the stronger determinant, were factors driving bacterial community composition. Bacterial communities from wave-dominated estuaries had similar compositions and higher bacterial abundance despite being geographically distant from one another, possibly indicating that functional estuarine morphology characteristics are a factor shaping the oyster bacterial community. Despite the bacterial community heterogeneity, examinations of the core bacterial community identified Spirochaetaceae bacteria as conserved across all sites and samples. Whereas members of the Vulcaniibacterium, Spirochaetaceae and Margulisbacteria, and Polynucleobacter were regionally conserved members of the digestive gland, gill and mantle bacterial communities, respectively. This indicates that baseline bacterial community profiles for specific locations are necessary when investigating bacterial communities in oyster health.

中文翻译：

---

太平洋牡蛎细菌群落的区域和牡蛎微环境尺度异质性

宿主的不同器官代表不同的微环境，导致宿主内建立了多个离散的细菌群落。这些离散的细菌群落也可以根据地理位置而变化。对于太平洋牡蛎Crassostrea gigas，控制细菌多样性和不同牡蛎微环境丰度的因素了解得很少。在这项研究中，影响与C. gigas相关的细菌丰度，多样性和组成的因素使用跨六个离散河口的16S（V3-V4）rRNA扩增子序列对地幔，g，内收肌和消化腺进行表征。位置和组织类型，其中组织类型是更强的决定因素，都是驱动细菌群落组成的因素。尽管在地理位置上彼此相距遥远，但波浪主导河口的细菌群落具有相似的成分和较高的细菌丰度，这可能表明功能性河口形态特征是影响牡蛎细菌群落的一个因素。尽管细菌群落具有异质性，但对核心细菌群落的检查发现螺旋藻科细菌在所有位点和样品中都是保守的。鉴于Vulcaniibacterium的成员，螺旋藻科和Margulisbacteria以及多核杆菌分别是消化腺，g和地幔细菌群落的区域保守成员。这表明在调查牡蛎健康中的细菌群落时，特定位置的基线细菌群落概况是必要的。