Liu Xiaomei, Wang Xiaolong, Wang RenJun, Guo Saisai, Ahmad Shakeel, Song Yuhao, Gao Peike, Chen Junfeng, Liu Chunchen, Ding Ning
School of Life Sciences, Qufu Normal University, Qufu, Shandong, 273165, China.
Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
Environ Pollut. 2023 Jan 15;317:120680. doi: 10.1016/j.envpol.2022.120680. Epub 2022 Nov 19.
Antibiotic resistance genes (ARGs) have caused widespread concern because of their potential harm to environmental safety and human health. As substitutes for conventional plastics, the toxic effects of short-term degradation products of biodegradable plastics (polylactic acid (PLA) and polyhydroxyalkanoates (PHA)) on bacteria and their impact on ARGs transfer were the focus of this study. After 60 days of degradation, more secondary nanoplastics were released from the biodegradable plastics PLA and PHA than that from the conventional plastics polystyrene (PS). All kinds of nanoplastics, no matter released from biodegradable plastics or conventional plastics, had no significant toxicity to bacteria. Nanoplastic particles from biodegradable plastics could significantly increase the transfer efficiency of ARGs. Although the amount of secondary nanoplastics produced by PHA microplastics was much higher than that of PLA, the transfer frequency after exposure to PLA was much higher, which may be due to the agglomeration of PHA nanoplastics caused by plastic instability in solution. After exposure to the 60 d PLA nanoplastics, the transfer frequency was the highest, which was approximately 28 times higher than that of control. The biodegradable nanoplastics significantly enhanced the expression of the outer membrane pore protein genes ompA and ompC, which could increase cell membrane permeability. The expression levels of trfAp and trbBp were increased by repressed major global regulatory genes korA, korB, and trbA, which eventually led to an increase in conjugative transfer frequency. This study provides important insights into the evaluation of the environmental and health risks caused by secondary nanoplastics released from biodegradable plastics.
抗生素抗性基因（ARGs）因其对环境安全和人类健康的潜在危害而引起了广泛关注。作为传统塑料的替代品，可生物降解塑料（聚乳酸（PLA）和聚羟基脂肪酸酯（PHA））短期降解产物对细菌的毒性作用及其对ARGs转移的影响是本研究的重点。降解60天后，可生物降解塑料PLA和PHA释放的次生纳米塑料比传统塑料聚苯乙烯（PS）更多。各种纳米塑料，无论从可生物降解塑料还是传统塑料中释放出来，对细菌均无明显毒性。可生物降解塑料产生的纳米塑料颗粒可显著提高ARGs的转移效率。虽然PHA微塑料产生的次生纳米塑料数量远高于PLA，但接触PLA后的转移频率要高得多，这可能是由于溶液中塑料不稳定导致PHA纳米塑料团聚所致。接触60天的PLA纳米塑料后，转移频率最高，约为对照的28倍。可生物降解纳米塑料显著增强了外膜孔蛋白基因ompA和ompC的表达，这可能会增加细胞膜通透性。trfAp和trbBp的表达水平因主要全局调控基因korA、korB和trbA的抑制而增加，最终导致接合转移频率增加。本研究为评估可生物降解塑料释放的次生纳米塑料所造成的环境和健康风险提供了重要见解。
