State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100039, China.
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
J Hazard Mater. 2024 Apr 15;468:133786. doi: 10.1016/j.jhazmat.2024.133786. Epub 2024 Feb 14.
Despite that nitrogen (N) and phosphorus (P) play critical roles in the lifecycle of microalgae, how N and P further affect the distribution of bacteria and antibiotic resistance genes (ARGs) in the phycosphere is still poorly understood. In this study, the effects of N and P on the distribution of ARGs in the phycosphere of Auxenochlorella pyrenoidosa were investigated. Results showed that the growth and chlorophyll synthesis of microalgae were inhibited when N or P was limited, regardless of the N/P ratios, but the extracellular polymeric substances content and nitrate assimilation efficiency were enhanced in contrast. Metagenomic sequencing revealed that N or P limitation resulted in the recruitment of specific bacteria that highly contribute to the nitrate metabolism in the phycosphere. Besides, N or P limitation promoted the propagation of phycosphere ARGs, primarily through horizontal gene transfer mediated by mobile genetic elements. The enrichment of specific bacteria induced by changes in the algal physiology also contributed to the ARGs proliferation under nutrient limitation. Our results demonstrated that the reduction of algal cells caused by nutrient limitation could promote the propagation of ARGs, which provides new insights into the occurrence and spread of ARGs in the phycosphere.
尽管氮（N）和磷（P）在微藻的生命周期中起着关键作用，但 N 和 P 如何进一步影响藻际中细菌和抗生素抗性基因（ARGs）的分布仍知之甚少。在这项研究中，研究了 N 和 P 对小球藻藻际中 ARGs 分布的影响。结果表明，无论 N/P 比如何，当 N 或 P 受到限制时，微藻的生长和叶绿素合成都会受到抑制，但细胞外聚合物含量和硝酸盐同化效率会增强。宏基因组测序显示，N 或 P 的限制导致了特定细菌的招募，这些细菌对藻际中的硝酸盐代谢有很大的贡献。此外，N 或 P 的限制促进了藻际 ARGs 的传播，主要是通过移动遗传元件介导的水平基因转移。藻类生理变化引起的特定细菌的富集也有助于营养限制下 ARGs 的增殖。我们的研究结果表明，营养限制导致的藻类细胞减少会促进 ARGs 的传播，这为藻际中 ARGs 的发生和传播提供了新的见解。
