巢湖完全氨氧化细菌的丰度、群落结构及其影响因素研究

完全氨氧化过程（complete ammonia oxidation， comammox）的发现使研究者们对硝化作用和氮循环都有了新的认识.本研究选取巢湖冬夏季表层（0~10 cm）沉积物样品，运用高通量测序、实时定量PCR等分子生物学技术对comammox细菌的丰度和群落结构进行研究.结果表明：基于amoA基因的comammox细菌的丰度为（5.20±0.72）×10⁶~（4.06±1.23）×10⁷ copies·g^-1；氨氧化古菌的丰度为（5.39±1.01）×10⁵~（1.60±0.18）×10⁷ copies·g^-1；氨氧化细菌的丰度为（6.16±1.57）×10⁵~（4.30±0.19）×10⁶ copies·g^-1.comammox细菌的绝对丰度显著高于氨氧化古菌和氨氧化细菌.多样性分析表明冬季巢湖表层沉积物中的comammox细菌的物种多样性大于夏季.其中Candidatus Nitrospira nitrificans、Candidatus Nitrospira nitrosa和Candidatus Nitrospira inopinata的相对丰度最高占比分别为78.72%、49.80%和6.28%，且夏季样点中Candidatus Nitrospira inopinata的相对丰度显著高于冬季样点.主坐标分析（Principle Coordinate Analysis， PcoA）结果表明，comammox细菌的群落结构具有明显的时间异质性.理化因子中，NH₄⁺和NO₃^-与comammox细菌的丰度呈负相关关系.本研究在一定程度上揭示了comammox细菌的丰度、群落组成、多样性及其与理化因子的关系.

Research on abundance, community structure and influencing factors of complete ammonia oxidizing (comammox) bacteria in Chaohu Lake

The discovery of complete ammonia oxidation (comammox) has given us new insights into nitrification and nitrogen cycling. In this study, the abundance and community structure of comammox bacteria of the surface sediment samples which were selected (0~10 cm) from the Chaohu Lake in winter and summer were studied by high-throughput sequencing and Real-time quantitative PCR (qPCR). Results showed that the abundance of comammox bacteria based on amoA gene ranging from (5.20±0.72)×10⁶ to (4.06±1.23)×10⁷ copies·g^-1; while ammonia-oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) ranged from (5.39±1.01)×10⁵ to (1.60±0.18)×10⁷ copies·g^-1 and (6.16±1.57)×10⁵ to (4.30±0.19)×10⁶ copies·g^-1, respectively. It was obviously the absolute abundance of comammox was significantly higher than AOA and AOB in the surface sediments of the Chaohu Lake. Moreover, the diversity analysis indicated that the species diversity of comammox bacteria in winter was greater than that in summer. The highest relative abundances of Candidatus Nitrospira nitrificans, Candidatus Nitrospira nitrosa and Candidatus Nitrospira inopinata were 78.72%, 49.80% and 6.28%, respectively, and the relative abundance of Candidatus Nitrospira inopinata was higher in summer than that in winter. Furthermore, the community structure of comammox bacteria showed an obviously temporal heterogeneity confirmed by Principle Coordinate Analysis (PCoA). Additionally, NH₄⁺ and NO₃^- were negatively correlated with the abundance of comammox. To some extent, our findings revealed the abundance, community composition, diversity of comammox bacteria and their relationships with physical and chemical factors.