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| Mechanisms of extracellular polymeric substances-mediated copper and cadmium tolerance in Pantoea dispersa |
| Received:May 14, 2025 |
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| KeyWord:Cu2+;Cd2+;extracellular polymeric substances;Pantoea dispersa MSC14;physiological response;transcriptomics |
| Author Name | Affiliation | E-mail | | SONG Yuxin | School of Environment and Energy, South China University of Technology, Guangzhou 510006, China | | | YUAN Meng | School of Environment and Energy, South China University of Technology, Guangzhou 510006, China | | | CHEN Guotao | School of Environment and Energy, South China University of Technology, Guangzhou 510006, China | | | XIE Guanghong | School of Environment and Energy, South China University of Technology, Guangzhou 510006, China | | | ZHU Chongling | School of Environment and Energy, South China University of Technology, Guangzhou 510006, China | | | CUI Tangbing | School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China | | | REN Yuan | School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Guangzhou 510006, China
The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions, Guangzhou 510006, China | ceyren@scut.edu.cn |
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| Abstract: |
| To explore the survival strategies of microorganisms in response to heavy metal stress, clarify the functions of extracellular polymeric substances（EPS）in the heavy metal tolerance of microorganisms, and reveal the differences in tolerance mechanisms to different heavy metals, this study measured the EPS production of Pantoea dispersa MSC14 and revealed the role of EPS in the tolerance mechanisms by comparing the changes in physiological indicators before and after EPS removal. Furthermore, transcriptomics elucidated the different tolerance mechanisms between Cu2+ and Cd2+. The results showed that strain MSC14 still exhibited considerable metabolic activity under 300 mg · L-1 Cu2+ and Cd2+. Meanwhile, the content of EPS increased significantly. Under Cu2+ stress, the contents of polysaccharides and proteins increased to 19.0-fold and 9.3-fold respectively at the highest, while under Cd2+ stress, they increased by 5.8-fold and 7.8-fold respectively at the highest. The extracellular adsorption by strain MSC14 was significantly higher than intracellular accumulation. After removing EPS, the total accumulation decreased by 49.8%-52.0% and 40.0%-68.6% respectively, while the degree of oxidative stress was aggravated. KEGG pathway analysis indicated that Cu2+ induced nitrogen metabolism, facilitating the reduction of Cu2+ to Cu+, while Cd2+ enhanced small molecule synthesis and transport. This suggested that Cd2+ improved tolerance through intracellular precipitation and efflux. In summary, EPS serves as an important barrier for strain MSC14 to tolerate Cu2+ and Cd2+. Meanwhile, the strain has developed distinct specific tolerance strategies for Cu2+ and Cd2+ |
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