纳米Fe3O4对生菜生长及土壤细菌群落结构的影响

纳米Fe₃O₄的广泛应用增加了其暴露到农田环境的可能性,因此亟待研究纳米Fe₃O₄对农业生态环境的影响.本研究采用盆栽试验方式,研究不同浓度纳米Fe₃O₄颗粒(1、10、100 mg·kg^-1)对生菜生长及土壤细菌群落的影响,并与相应浓度的普通Fe₃O₄处理进行对比.通过测定植物光合速率常数、植株Fe含量来评价植物生长;采用高通量测序技术研究土壤细菌群落结构及组成.结果表明: 不同浓度纳米Fe₃O₄的影响不同.低浓度纳米Fe₃O₄能提高植物生物量,增强植物叶片光合速率,增加土壤中黄单胞菌目的相对丰度,降低蓝细菌、鞘脂杆菌纲的相对丰度,但对群落多样性指数影响不显著.高浓度纳米Fe₃O₄抑制作物生长,提高植株中Fe积累及土壤电导率,降低细菌群落系统发育多样性,降低黄单胞菌目、鞘脂杆菌纲相对丰度,增加蓝细菌相对丰度.此外,一些土壤功能微生物对纳米Fe₃O₄及普通Fe₃O₄处理的响应也存在差异,说明不同粒径及浓度的Fe₃O₄均会对土壤微生物群落产生影响,并可能影响地上部分植物性状.因此,在评估纳米颗粒的生物学效应时需较多关注土壤微生物.

Influence of Fe3O4 nanoparticles on lettuce (Lactuca sativa L.)growth and soil bacterial community structure.

With extensive application of Fe₃O₄ nanoparticles in a variety of fields, the possibility of their exposure to agricultural environment is growing. This raises the concerns on their effects on environment. In this investigation, we carried out a pot experiment to investigate the impacts of diffe-rent concentrations of Fe₃O₄ nanoparticles (1, 10, 100 mg·kg^-1), as well as their counterparts, bulk Fe₃O₄ particles, on the lettuce growth and the soil bacterial community. We not only measured the net photosynthetic rate of plant leaves, the Fe content in plant, but also determined the soil bacterial community structure and components using the high throughput technique. Results showed that responses of the plant and bacterial community varied with the increase of Fe₃O₄ nanoparticles concentration. At the low concentration, Fe₃O₄ nanoparticles stimulated plant growth, accompanied by the increased abundance of Xanthomonadales and the decreased abundance of Cyanobacteria and Sphingobacteria, but no significant changes were observed for the bacterial alpha diversity indices. At the high concentration, Fe₃O₄ nanoparticles could not only suppress plant growth, increase Fe content in plant tissue and soil electronic conductivity, but also decrease the phylogenetic diversity of bacterial community, reduce the abundances of Xanthomonadales and Sphingobacteria, and increase the proportion of Cyanobacteria. Moreover, the responses of some functional guilds in soil bacterial community varied between the Fe₃O₄ nanoparticle treatment and the bulk counterpart. This indicated that the size and the concentration of Fe₃O₄ were the factors influencing soil bacterial community, which would potentially impact the plant development. Therefore, more attention should be focused on soil microbes when evaluating the biological effects of nanoparticles.