Elevated Ozone Changed Soil Microbial Community in a Rice Paddy

Although the environmental impact of ozone (O(3)) has been widely investigated, there have been few studies about the effect of O(3) on underground processes, especially soil microbial communities. This study aimed to investigate O(3) effects on the soil microbial community structure and function in a rice paddy field, China. There were three treatments within open-top chambers: charcoal-filtered air (CF as a check treatment), CF plus 100 nL O(3) L(-1) (O(3)-1), and CF plus 150 nL O(3) L(-1) (O(3)-2). Soil samples were collected in August, September, and October to assess microbial biomass C, community-level physiological profiles (CLPPs), and phospholipid fatty acids (PLFAs) of soil microbes. The results showed that soil microbial biomass under elevated O(3) concentration was statistically significantly decreased compared with the check treatment in October. Soil microbial functional indices including average well color development, richness, and Shannon diversity were significantly decreased by elevated O(3) in September. Principal components analysis of CLPP data showed that elevated O(3) significantly changed the C sources utilization pattern of microbes in September (Principle Component 1,P < 0.05). During all growing stages, elevated O(3) had significant effects on soil microbial composition expressed as PLFA percentage, which indicated that PLFA was more sensitive than CLPP for study of the microbial community. The stress indicators, including the ratio of saturated to unsaturated fatty acids and the ratio of cyclopropyl fatty acids to their precursors, such as cy17:0 to 16:1 omega 7c, also increased under elevated O(3) exposure.