LNA和HNA细菌在反硝化过程中的迁移特征分析

低核酸（low nucleic acid，LNA）和高核酸（high nucleic acid，HNA）细菌在不同环境条件下表现出不同特性，当前尚不清楚反硝化过程对细菌的影响。为此，通过对不同反硝化条件下游离态的LNA和HNA细菌沿程变化情况及相关细菌群基因测序分析，发现游离菌在反硝化过程中会快速增多，且反硝化速率越大，增速越高。结果显示:反硝化时LNA细菌比HNA细菌更快脱离污泥絮体，只有在反硝化达到一定程度，使絮体结构疏松甚至破碎时HNA细菌才会表现出快速增多，由此推测低核酸（LNA）细菌位于污泥表面或者填充于絮体之间，而高核酸（HNA）细菌是污泥絮体的骨架部分。淀粉在反硝化时会因其网捕作用使游离菌减少，但乙酸钠的反硝化作用比淀粉的网捕作用对游离菌的影响更为显著。同时HNA细菌具有较高的丰度和多样性，是主要功能菌，而LNA细菌对反硝化反应能做出更快的响应，可作为反硝化启动的指示参数。

SHUTTLE CHARACTERISTICS OF LNA AND HNA BACTERIA DURING DENITRIFICATION PROCESS

Low nucleic acid (LNA) and high nucleic acid (HNA) bacteria show different characteristics under different environmental conditions, and the effect of denitrification process on bacteria is still unclear. The variations of free-swimming LNA and HNA bacteria under different denitrification conditions and microbial community were thus investigated in this study, it was found that free-swimming bacteria increased rapidly during the denitrification process, and greater the denitrification rate resulted in a higher increase of free-swimming bacteria. It was evidenced that LNA bacteria moved faster than HNA bacteria at the beginning of the denitrification reaction. HNA bacteria showed a rapid increase, either the denitrification reached a certain level, or the floc structure loose or break, indicating that LNA bacteria was mainly on the surface of flocs and functioned as glue, or filling materials of the pores of flocs. HNA bacteria functioned as a backbone of flocs. When starch was used as the carbon source for denitrification, free-swimming bacteria were reduced due to the bridge-capture of starch. However the denitrification of sodium acetate had a more significant effect on free-swimming bacteria than the bridge-capture of starch. In addition, HNA bacteria had higher abundance and diversity than LNA bacteria, and was found out as the main functional bacteria. LNA bacteria can respond faster to denitrification and be used as a signal for denitrification initiation.