Deciphering bacterial interactions via DSF-regulated public goods in an anammox community

Abstract Background: Bacterial interaction and communication via quorum sensing (QS) received extensively attention, as it can coordinate bacterial behavior and activity through the QS signal molecules in microbial community. Though the exchange of public goods regulated by QS have been explored in pure culture, how signal sense, transmit, and affect the social traits through regulating public goods in complex communities remains unclear. Results: The levels of public goods (e.g. extracellular polymeric substances (EPS) and amino acids) changed significantly when exogenous diffusion signal factor (DSF), a kind of QS molecules, was added. Approaches involving meta-omics and hierarchical signalling network construction give insight into that anammox species ( Jettenia caeni , AMX1) and Proteobacteria -affiliated bacterium (PRO1) can sense and transit DSF signals, thus directly regulating the production and exchange of public goods via the secondary messenger c-di-GMP regulator, Clp. In detail, these two kinds of species can supply more costly amino acids for DSF-Secretor species (like AMX2, CFX1, CFX3, and PRO4) after sensing DSF. Meanwhile, DSF-Secretor species encoded diverse genes involved in hydrolysis of extracellular protein and carbohydrate and genes involved in transportation of peptides and sugars. The exogenous DSF-inducement also leads to the high expression of these genes, which indicated DSF-Secretor species helped anammox bacteria scavenge extracellular detritus. This process can be considered as a feedback of public goods supply by anammox bacteria, as this process contributed to create a suitable environment for anammox bacteria growth. Namely, DSF can bridge bacterial interactions through regulating public goods. Furthermore, the trade-off induces discrepant metabolic loads of different microbial clusters and community succession. It illustrated the potential to artificially alleviate metabolic loads and thus increase proliferation rate for certain bacteria through QS. Conclusions: DSF can bridge interactions of anammox bacteria and DSF-Secretor species through regulating production and exchange of public goods using Clp regulator. Deciphering microbial interactions via QS provides insights for understanding the molecular evolution of QS in microbial community.