The Host Modulates Transcriptional Profile and Phenotypic Heterogeneity in Symbionts
Host-microbe interactions are virtually bidirectional, benefiting both the host and microbial sides. It is becoming increasingly recognized the influence of the microbe on many aspects of host physiology and diseases, but whether/how the host affects their symbionts is poorly characterized. Here, we reported that the host acts as a critical factor to shape the lifestyle of their symbionts in the Drosophila and bacteria model system. First, we observe that Drosophila larvae play a pivotal role in competing with pathogenic symbionts in the co-existing niche. More specifically, host larvae antagonize symbionts by deconstructing the surface slick, preventing outgrowth and antagonizing the pathogenicity of S. marcescens. Furthermore, Drosophila larvae cause the shift in the transcriptomic profile of S. marcescens, characterized with the upregulated expression of genes related to bacterial proliferation and growth and the downregulated expression of genes related to bacterial pathogenicity. More importantly, advances in bacterial single-cell RNA sequencing provide opportunities to reveal transcriptional variation, including toxic factors, across individual cells and a subpopulation clustering of isogenic bacterial populations. Finally, we found that AMPs from larvae recapitulated the response of S. marcescens to the presence of Drosophila larvae. Altogether, these findings provide an insight into the pivotal roles of the host in influencing the potential pathogens' lifecycle switching from commensalism to pathogenicity, opening the door to a better understanding of the ecological relationships between the host and microbe. Overall design: First, the single cultivation and heat shock group was detected to test single-cell bacteria sequencing technology. And then the Larvae, Force and control groups  was detected. Single cell transcription profiling was compared between the Larvae, Force and control groups to explore the influence of host on serratia marcescens.