Global transcriptional and translational regulation of Sphingomonas melonis TY in response to hyperosmotic stress

Hyperosmotic stress is one of the most ubiquitous stress factors in microbial habitats and impairs the efficiency of bacteria performing vital biochemical tasks. Sphingomonas serves as a 'superstar' of plant defense and pollutant degradation, and is widely existed in the environment. However, it is still unclear that how Sphingomonas sp. survives under hyperosmotic stress conditions. In this study, multiomics profiling analysis was conducted with S. melonis TY under hyperosmotic conditions to investigate the intracellular hyperosmotic responses. The transcriptome and proteome revealed that sensing systems, including most membrane protein coding genes were upregulated, genes related to two-component systems were tiered adjusted to reset the whole system, other stress response regulators such as sigma-70 were also significantly tiered upregulated. In addition, transport systems together with compatible solute biosynthesis related genes were significantly upregulated to accumulate intracellular nutrients and compatible solutes. When treated with hyperosmotic stress, redox-stress response systems were triggered and mechanosensitive channels together with ion transporters were induced to maintain cellular ion homeostasis. In addition, cellular concentration of c-di-guanosine monophosphate synthetase (c-di-GMP) was reduced, followed by negative influences on genes involved in flagellar assembly and chemotaxis pathways, leading to severe damage to the athletic ability of S. melonis TY, and causing detachments of biofilms. Briefly, this research revealed a comprehensive response mechanism of S. melonis TY exposure to hyperosmotic stress, and emphasized that flagellar assembly and biofilm formation were vulnerable to hyperosmotic conditions. Importance. Sphingomonas, a genus with versatile functions survives extensively, lauded for its prominent role in plant protection and environmental remediation. Current evidence shows that hyperosmotic stress as a ubiquitous environmental factor, usually threatens the survival of microbes and thus impairs the efficiency of their environmental functions. Thus, it is essential to explore the cellular responses to hyperosmotic stress. Hence, this research will greatly enhance our understanding of the global transcriptional and translational regulation of S. melonis TY in response to hyperosmotic stress, leading to broader perspectives on the impacts of stressful environments.