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| Properties of ball-milled biochar and its toxic effects on E. coli and S. aureus |
| Received:December 23, 2018 |
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| KeyWord:ball-milled biochar;toxicity;Escherichia coli;Staphylococcus aureus;ROS |
| Author Name | Affiliation | E-mail | | GUO Sai-sai | College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | | | LIU Xiao-mei | College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | | | CHEN Hong-kun | State Key Lab of Petroleum Pollution Control, CNPC Research Institute of Safety & Environmental Technology, Beijing 102206, China | | | ZHUANG Zhi-cheng | College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | | | WANG Yi-zhi | Tianjin Tianmai Energy Saving Equipment Co., Ltd., Tianjin 300112, China | | | TANG Jing-chun | College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Tianjin 300071, China | tangjch@nankai.edu.cn |
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| Abstract: |
| Ball milling is effective in changing the particle size distribution of biochar(BC); however, it can cause toxic effects during the utilization of biochar. Therefore, it is essential to analyze the microbial toxicity of ball-milled biochar(BM). In this study, element analyses, BET, SEM, and FTIR detection were conducted to characterize the properties of wheat straw biochar prepared at 500℃ and BM. The effects of different concentrations of BC(0, 10, 20, 50, 100 mg·L-1, and 200 mg·L-1)on the ROS content and survival rate of bacteria were studied to confirm the effects of BC and BM on Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923, respectively. The results showed that the specific surface area of BC was 98 m2·g-1, and the surface area of BM increased to 309 m2·g-1. Ball milling could lead to an increase in the oxygen-containing functional groups in biochar. In the 0.9% NaCl solution, when mixed with 10 mg·L-1 BM, the survival rate of S. aureus was 90.1%, and the survival rate of E. coli was 98.2%. The survival rate of S. aureus decreased to 23.5%, and the survival rate of E. coli remained at 91.8%, when the concentration of BM was increased to 200 mg·L-1. However, in the LB medium, the survival rate of S. aureus increased to 58.1% when the concentration of BM was 200 mg·L-1. Under the same conditions, the toxicity of BM on microorganisms was significantly higher than that of general BC, which might be related to the differences in particle size. The toxicity of BM on S. aureus was significantly higher than that on the gram-negative bacteria, E. coli, which may be related to the extracellular polymeric substances(EPSs)produced by E. coli. By adding N-acetyl cysteine(NAC), an ROS eliminating agent, we found that oxidative damage was the main cause of cell death in S. aureus, and other factors such as mechanical damage of BM nanoparticles in cells might also be the basis of the toxic effects caused by BM. As this study concludes that BM shows toxic effects on microorganisms, it is necessary to consider environmental effects when BM is being used. |
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