Effects of environmental variables on abundance of ammonia-oxidizing communities in sediments of Luotian River, China

Ammonia-oxidizing communities play important functional roles in the nitrification. However, environmental stresses can significantly affect this process by controlling the abundant communities of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities. In this study, we examined the abundance variations of ammonia-oxidizing communities using quantitative polymerase chain reaction (qPCR) and terminal-restriction fragment length polymorphism (T-RFLP) in a typical subtropical river, Luotian County, South Dabie Mountains, China. Clone libraries were conducted to evaluate the community structure and abundance of AOA and AOB in sediments. Results showed thatNitrososphaera spandNitrosopumilus spwere the most dominant AOA. The abundance of the AOA and AOB amoA gene ranged from 5.28 × 108gene copies (g-soil−1) to 2.23 × 108gene copies (g-soil−1) and 5.45 × 108gene copies (g-soil−1) to 3.30 × 107gene copies (g-soil−1), respectively. Five environmental variables, namely, ORP, DO, NO${}_{3}^{-}$, Temp, and NH${}_{4}^{+}$ were played a major function in microbial communities of AOA and AOB in sediments. The T-RFLP profiles of AOA showed that 488 and 116 bp T-RFs were dominated. Overall, the results of this study showed that anthropogenic activities andenvironmental stress in rivers can alter the structure and function of microbes in their variable environment.