Unlocking the bacterial contact-dependent antibacterial activity to engineer a biocontrol alliance of two species from natural incompatibility to artificial compatibility

Plant growth-promoting rhizobacteria(PGPR)contain various biocontrol bacteria with broad-spectrum antimicrobial activity,and their single species has been extensively applied to control crop diseases.The development of complex biocontrol community by mixing two or more PGPR members together is a promising strategy to enlarge the efficacy and scope of biocontrol.However,an effective method to assess the natural compatibility of PGPR members has not yet been established to date.Here,we developed such a tool by using the bacterial contactdependent antibacterial activity(CDAA)as a probe.We showed that the CDAA events are common in two-species interactions in the four selected representative PGPRs,represented by the incompatible interaction of Lysobacter enzymogenes strain OH11(OH11)and Lysobacter antibioticus strain OH13(OH13).We further showed that the CDAA between OH11 and OH13 is jointly controlled by a contact-dependent killing device,called the type IV secretion system(T4SS).By deleting the respective T4SS synthesis genes,the T4SS in both strains was co-inactivated and this step unlocked their natural CDAA,resulting in an engineered,compatible mutant alliance that co-displayed antibacterial and antifungal activity.Therefore,this study reveals that releasing bacterial CDAA is effective to rationally engineer the biocontrol community.

New avenues for systematically inferring cellcell communication:through single-cell transcriptomics data

For multicellular organisms,cell-cell communication is essential to numerous biological processes.Drawing upon the latest development of single-cell RNA-sequencing(scRNA-seq),high-resolution transcriptomic data have deepened our understanding of cellular phenotype heterogeneity and composition of complex tissues,which enables systematic cell-cell communication studies at a single-cell level.We first summarize a common workflow of cell-cell communication study using scRNA-seq data,which often includes data preparation,construction of communication networks,and result validation.Two common strategies taken to uncover cell-cell communications are reviewed,e.g.,physically vicinal structure-based and ligand-receptor interaction-based one.To conclude,challenges and current applications of cell-cell communication studies at a single-cell resolution are discussed in details and future perspectives are proposed.