Dynamic Successions and Interactions of Phyllospheric Microorganisms in Response to Nh3 Exposure

Phyllosphere and numerous phyllospheric microorganisms present huge potential for air pollution mitigation. Despite research to investigate the microbial compositions in the phyllosphere, the successions and interactions of phyllospheric microorganisms under ammonia gas (NH 3 ) stress remain poorly understood. Herein, we performed 16S, the internal transcribed spacer (ITS) profiling and a quantitative microbial element cycling (QMEC) method to reveal successions, co-occurrence, and N-cycling functions changes of phyllospheric bacteria and fungi during the NH 3 exposure. The input NH 3 mainly elevated ammonium (NH 4 + -N) and thus total nitrogen (TN) level. The exposure decreased fungal concentration with a higher homogeneity while enhanced bacterial concentration with a noticeable richness drop in the phyllosphere. Both short-term (2-week) and long-term (2, 4, 6-week) exposure induced significant changes in microbial compositions. Bacterial genera ( Nocardioides, Pseudonocardia ) and fungal genera ( Alternaria , Acremonium ) dominated throughout the exposure. Intensive microbial interactions compared to that in the natural phyllosphere were observed via network analysis. Our results showed that N-cycling functional genes were largely stimulated by the exposure and might in turn contribute to NH 3 pollution buffer and alleviation via microbial metabolism. This study extended the knowledge on microbial responses to NH 3 exposure in the phyllosphere, and enlightened phylloremediation on NH 3 through microbial role