BioProject

Understanding the niches of microbial lineages, is central to microbial ecology. More...

Understanding the niches of microbial lineages, is central to microbial ecology. We observed rapid succession of photosynthetic eukaryote taxa and the associated bacterial and archaeal taxa, by frequent sampling following a massive diatom bloom off southern California, following up over 5 months [to summer stratified conditions]. Chloroplast 16S rRNA sequences characterized phytoplankton, and bacterial 16S analysis was validated with mock communities. Initially, distinct Pseudo-nitzchia strains peaked on successive days, followed by Tetraselmis, Heterosigma, Ostreococcus and multiple haptophytes. The rapid bacterial and archaeal response included large or particle attached communities responding more than the small and free-living communities. Short-lived blooms of Verrucomicrobia and Flavobacteria were in the large fraction, whereas SAR92 and Roseobacter were in the smaller fraction; all these taxa peaked on distinct days. After the initial diatom bloom decline, several OTUs of MGII Archaea bloomed over a week, comprising up about 30% of both the small and large fraction, strongly implicating this poorly-known group with a boom/bust lifestyle associated with phytoplankton blooms. The spring-to-summer bacterial and archaeal succession was better explained statistically by the photosynthetic eukaryote community than environmental parameters. Network analysis identified tightly-correlated individual phytoplankton and bacterial dynamics. In particular, the nitrogen-fixing cyanobacterium (UCYN-A) was strongly correlated with its known symbiont, Braarudosphaera, and also other potential host phytoplankton and bacteria including Flavobacteria. Overall the description of ecological niches and apparent interaction between organisms in this high-temporally resolved time-series provides novel, thorough description and allows for future inspection of the mechanisms controlling these dynamics. Less...