Community structure of β-Proteobacterial ammonia-oxidizing bacteria in prawn farm sediment

To examine the community structure of β-Proteobacterial ammonia-oxidizing bacteria (AOB) in prawn farm sediment, the 16S rRNA gene library was constructed with β-Proteobacterial AOB-specific primers. The library was screened by PCR-restriction fragment length polymorphism (RFLP) analysis and clones with unique RFLP patterns were sequenced. Two groups of β-Proteobacterial AOB, the Nitrosomonas and the Nitrosospira, were detected. The Nitrosomonas occupied an absolute dominant position, accounting for more than 90% of total clones in the clone library, while the Nitrosospira accounting for 5.48%. Nitrosomonas-affiliated clones were grouped into the N. marina and the N. sp. Nm143 clusters, and Nitrosospira-affiliated clones were grouped into the Nitrosospira cluster 1. No other clusters of β-Proteobacterial AOB were found. The results enriched our knowledge of AOB diversity in the prawn farm sediment and provided important foundational data for further functional studies of these microbes in mariculture environments.