Response of peanut plant and soil N-fixing bacterial communities to conventional and biodegradable microplastics

• Published in: Journal of hazardous materials Vol. 459; p. 132142
• Main Authors: Wang, Quanlong, Feng, Xueying, Liu, Yingying, Li, Wenguang, Cui, Wenzhi, Sun, Yuhuan, Zhang, Shuwu, Wang, Fayuan, Xing, Baoshan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.10.2023
• Subjects: agroecosystems; bacterial communities; biodegradability; Biodegradable microplastics; community structure; dose response; microplastics; nitrogen content; Nitrogen uptake; Nitrogen-fixing bacteria; nodulation; Peanut; peanuts; phytomass; phytotoxicity; plant height; pollution; polyethylene; polylactic acid; polystyrenes; soil; Soil available nitrogen; urease; Peanut; Nitrogen-fixing bacteria; Nitrogen uptake; Biodegradable microplastics; Soil available nitrogen
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.132142

Microplastics (MPs) occur and distribute widely in agroecosystems, posing a potential threat to soil−plant systems. However, little is known about their effects on legumes and N-fixing microbes. Here, we explored the effects of high-density polyethylene (HDPE), polystyrene (PS), and polylactic acid (PLA) on the growth of peanuts and soil N-fixing bacterial communities. All MPs treatments showed no phytotoxic effects on plant biomass, and PS and PLA even increased plant height, especially at the high dose. All MPs changed soil NO3−-N and NH4+-N contents and the activities of urease and FDAse. Particularly, high-dose PLA decreased soil NO3−-N content by 97% and increased soil urease activity by 104%. In most cases, MPs negatively affected plant N content, and high-dose PLA had the most pronounced effects. All MPs especially PLA changed soil N-fixing bacterial community structure. Symbiotic N-fixer Rhizoboales were greatly enriched by high-dose PLA, accompanied by the emergence of root nodulation, which may represent an adaptive strategy for peanuts to overcome N deficiency caused by PLA MPs pollution. Our findings indicate that MPs can change peanut−N fixing bacteria systems in a type- and dose-dependent manner, and biodegradable MPs may have more profound consequences for N biogeochemical cycling than traditional MPs. [Display omitted] •High-dose PLA MPs greatly decreased soil NO3−-N and NH4+-N contents.•All MPs showed no phytotoxicity and PS and PLA increased plant height.•PLA MPs stimulated Rhizobia and nodulation to compensate soil N deficiency.•MPs showed type- and dose-dependent effects on N-fixing bacterial communities.•PLA MPs caused more profound effects on soil N cycling than HDPE and PS MPs.