Particle-association lifestyle is a phylogenetically conserved trait in bathypelagic prokaryotes

The free-living (FL) and particle-attached (PA) marine microbial communities have repeatedly been proved to differ in their diversity and composition in the photic ocean and also recently in the bathypelagic ocean at a global scale. However, although high taxonomic ranks have been proved to exhibit preferences for a PA or FL mode of life, it remains poorly understood whether two clear lifestyles do exist and how these are distributed across the prokaryotic phylogeny. We studied the FL and PA prokaryotes in 30 stations distributed worldwide within the bathypelagic oceanic realm using high throughput sequencing of their 16S rDNA. A high proportion of the bathypelagic prokaryotes were mostly found either attached to particles or freely in the surrounding water but rarely in both types of environments. In particular, this trait was deeply conserved through their phylogeny suggesting that the deep-ocean particles and the surrounding water constitute two highly distinct niches and that transi...自由生活（free-living, FL）与颗粒附着（particle-attached, PA）海洋微生物群落，已被多项研究证实在透光层海洋中存在多样性与群落组成的显著差异；近期全球尺度的研究同样在深层带海洋中发现了这一现象。然而，尽管已有研究表明高级分类单元对颗粒附着或自由生活的生活方式具有偏好性，但目前学界仍不甚明确：是否存在两类明确的生活型，以及这些生活型如何在原核生物系统发育树中分布。本研究针对全球范围内30个站位的深层带海洋生境，通过对原核生物16S核糖体DNA（16S rDNA）进行高通量测序，分析了其中的自由生活与颗粒附着原核生物群落。研究发现，绝大多数深层带原核生物要么主要附着于颗粒之上，要么主要自由生活于周围水体中，极少在两类生境中均有分布。尤为关键的是，这一特性在其系统发育过程中高度保守，提示深海颗粒与周围水体实为两个高度分化的生态位，且物种从...