Physiological and transcriptomic analyses reveal mechanistic insight into the adaption of marine Bacillus subtilis C01 to alumina nanoparticles

An increasing number of studies have investigated the effects of nanoparticles (NPs) on microbial systems; however, few existing reports have focused on the defense mechanisms of bacteria against NPs. Whether secondary metabolism biosynthesis is a response to NP stress and contributes to the adaption of bacteria to NPs is unclear. Here, a significant induction in the surfactin production and biofilm formation were detected by adding Al(2)O(3) NPs to the B. subtilis fermentation broth. Physiological analysis showed that Al(2)O(3) NP stress could also affect the cell and colony morphogenesis and inhibit the motility and sporulation. Exogenously adding commercial surfactin restored the swarming motility. Additionally, a suite of toxicity assays analyzing membrane damage, cellular ROS generation, electron transport activity and membrane potential was used to determine the molecular mechanisms of toxicity of Al(2)O(3) NPs. Furthermore, whole transcriptomic analysis was used to elucidate the mechanisms of B. subtilis adaption to Al(2)O(3) NPs. These results revealed several mechanisms by which marine B. subtilis C01 adapt to Al(2)O(3) NPs. Additionally, this study broadens the applications of nanomaterials and describes the important effects on secondary metabolism and multicellularity regulation by using Al(2)O(3) NPs or other nano-products.