Fungicide azoxystrobin induced changes on the soil microbiome

Abstract Azoxystrobin is a widely used systemic fungicide in the Northeast of China, but it is unclear how azoxystrobin impacts the soil microbiome. Thus, we studied the impact of azoxystrobin on the microbial community structure and function in Chinese Spodosols. Field soil that had never been exposed to azoxystrobin was amended in laboratory batch experiments with 0 mg kg-1, 2 mg kg-1, 25 mg kg-1 and 50 mg kg-1 of azoxystrobin. Four soil enzymes (urease, invertase, phosphatase and catalase) were monitored to assess the impact of azoxystrobin on carbon, nitrogen and phosphorus cycling as well as the microbial activity. The results show that the urease, invertase, and phosphatase (hydrolytic enzymes) activities was inhibited by as little as 2 mg kg−1 of azoxystrobin after 35 days, whereas the catalase (oxidoreductase enzyme) activity was promoted by the same concentration in most cases. Biolog Ecoplate analysis indicated that the utilization of different carbon sources was inhibited by azoxystrobin. 16S rRNA sequencing showed the bacterial operational taxonomic unit richness and the Shannon index decreased with increasing azoxystrobin concentration. Relative abundances of Sphingomonas decreased while Amycolatopsis and Sphingomonas increased by addition of increasing levels of azoxystrobin. In conclusion, azoxystrobin application to Spodosols leads to reduced urease, invertase, and phosphatase activities, which can impact nutrient cycling and carbon utilization. Furthermore, azoxystrobin application changed the microbiome community structure.