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

Dashuai Mu,Zongjun Du,Zhenxing Xu,Guanjun Chen,Xiuxia Yu

doi:10.1038/srep29953

Abstract

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 Al2O3 NPs to the B. subtilis fermentation broth. Physiological analysis showed that Al2O3 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 Al2O3 NPs. Furthermore, whole transcriptomic analysis was used to elucidate the mechanisms of B. subtilis adaption to Al2O3 NPs. These results revealed several mechanisms by which marine B. subtilis C01 adapt to Al2O3 NPs. Additionally, this study broadens the applications of nanomaterials and describes the important effects on secondary metabolism and multicellularity regulation by using Al2O3 NPs or other nano-products.

Highlights

There has been a quantum increase in the use of nanoparticles (NPs) in many spheres of life
The few existing reports on the defense mechanisms of tolerant bacteria against NPs are limited to Mycobacterium smegmatis with Cu-doped TiO2 NPs43, B. subtilis and Pseudomonas putida with nC6044, and Cupriavidus metallidurans CH34 with Al2O3 NPs45 and do not provide mechanistic insights by using full transcriptional analysis
Whether secondary metabolism biosynthesis could respond to NP stress and enhance the adaption of bacteria to NPs was unknown

Summary

Introduction

There has been a quantum increase in the use of nanoparticles (NPs) in many spheres of life. An increasing number of studies have investigated the effects of NPs on microbial systems. Zinc oxide and magnesium oxide NPs were found to exert significant growth inhibitory effects, which were related to membrane damage and oxidative stress responses in Escherichia. It should be mentioned that Al2O3 NPs could attach to the cell wall and travel into the cytoplasm of E. coli, where they exert toxic effects[11,12]. Al2O3 NPs could cause the cell wall damage and lipid peroxidation www.nature.com/scientificreports/. Caused a decrease in cell viability of Bacillus licheniformis[12] These reports mainly focused on the antibacterial properties of NPs, whether or how microorganism adapt to NP stress remains unclear

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Conclusion