Dynamic patterns of quorum sensing signals in phycospheric microbes during a marine algal bloom.

In the marine environment, the interactions among various species based on chemical signals play critical roles in influencing microbial structure and function. Quorum sensing (QS), the well-known signal-dependent communication autoinducer, is an important regulator in complex microbial communities. Here, we explored the QS gene profiles of phycosphere bacteria during a microcosmic phytoplankton bloom using metagenomic sequence data. More than fifteen subtypes of QS systems and 211,980 non-redundant amino acid sequences were collected and classified for constructing a hierarchical quorum-sensing database. The abundance of the various QS subtypes varied at different bloom stages and showed a strong correlation with phycosphere microorganisms. This suggested that QS is involved in regulating the phycosphere microbial succession during an algal bloom. A neutral community model revealed that the QS functional gene community assemblies were driven by stochastic processes. Co-occurrence model analysis showed that the QS gene networks of phycospheric microbes had similar topological structure and functional composition, which is a potential cornerstone for maintaining signal communication and population stabilization among microorganisms. Overall, QS systems have a strong relationship with the development of algal blooms and participate in regulating algal-associated microbial communities as chemical signals. This research reveals the chemical and ecological behavior of algal symbiotic bacteria and expands the current understanding of microbial dynamics in marine algal blooms.