不同盐度循环养殖水体微生物群落特征

为探究盐度对拟穴青蟹养殖水体微生物群落结构的影响，深入理解养殖盐度、氮磷环境因子与微生物群落结构的相关关系，采用16S rRNA高通量测序技术分析了盐度为1‰（S1）、3‰（S3）、5‰（S5）、7‰（S7）、9‰（S9）的循环养殖水体中微生物群落特征.结果表明:①水体中微生物包含67门74纲152目281科745属431种，不同盐度的养殖水体中微生物物种数目依次表现为S3 > S1 > S5 > S7 > S9，物种多样性依次表现为S1 > S3 > S7 > S9 > S5，S1和S3的水体优势菌种的地位和作用远高于S5、S7和S9的养殖水体.②五组水样的微生物群落结构总体相似度较低，S1与S3以及S7与S9的水体微生物群落结构最为相似.③变形菌门（Proteobacteria）为养殖水体绝对优势菌门，其相对丰度依次表现为S5 > S7 > S9 > S1 > S3，厚壁菌门（Firmicutes）相对丰度依次表现为S9 > S3 > S5 > S7 > S1，拟杆菌门（Bacteroidetes）相对丰度依次表现为S1 > S7 > S3 > S9 > S5.养殖水体存在大量具有脱氮除磷特性的微生物，较小盐度差会造成脱氮除磷微生物种类和丰度出现显著差异化.④4种营养盐中的ρ（NO₂--N）对水体微生物群落影响最为显著（P < 0.05），ρ（NH₄+-N）、ρ（NO₂--N）、ρ（NO₃--N）、ρ（PO₄3--P）整体与属水平微生物群落呈极显著性正相关（P < 0.01）.研究显示，盐度主要通过影响养殖水体的氮磷营养盐间接改变水体中微生物群落，氮磷环境因子中NO₃--N为主要驱动因子，一个系统中的营养盐因子并不是单独地对养殖水体微生物群落起作用，而是协同发挥作用，共同调节其微生物群落结构. 

Microbial Community Characteristics in Recirculating Aquaculture Waters at Different Salinity Levels

In order to explore the effect of salinity on the microbial community structure in aquaculture water of Scylla paramamosain aquaculture environment, 16S rRNA high-throughput sequencing technique was used to determine the relationships between water nutrients and the microbial communities at different salinity levels of 1‰(S1), 3‰(S3), 5‰(S5), 7‰(S7) and 9‰(S9). The results showed that: (1) There were 67 phyla, 74 classes, 152 orders, 281 families, 745 genera and 431 species of bacterial communities in the aquaculture environment. At different salinity levels, the number of microbial species among different treatment groups was S3 > S1 > S5 > S7 > S9, and the species diversity was S1 > S3 > S7 > S9 > S5. The dominant species in the S1 and S3 treatment groups had much higher influence and function than those in the S5, S7 and S9. (2) Generally, the similarity of microbial community structure among the five treatment groups was relatively low. The microbial community of the S1 and S3 was similar, and the structure in the S7 and of S9 was similar. (3) Proteobacteria was the dominant phylum in the aquaculture environment. The relative abundance of different microbial communities was S5 > S7 > S9 > S1 > S3 for Proteobacteria, S9 > S3 > S5 > S7 > S1 for Firmicutes, and S1 > S7 > S3 > S9 > S5 for Bacteroidetes. There were a large number of nitrogen- or phosphorus-removing bacteria in the aquaculture environment. Small salinity changes could cause significant differences in the composition and relative abundance of nitrogen- or phosphorus-removing bacteria. (4) Nitrate-nitrogen of the four nutrients had the most significant impact on microbial community (P < 0.05), whereas ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen and phosphate had significant positively correlations with the overall and different genera of microbial community (P < 0.01). The results depicted that salinity could alter the nitrogen and phosphorus nutrients in the culture environment, which indirectly changed the microbial community structure. Nitrate-nitrogen was the major determining factor among nitrogen and phosphorus nutrients in the culture environment. The effect of nutrients on the microbial community structure in the culture environment was synergistic, but not independent.