氨氮与亚硝酸盐对吉富罗非鱼肠道菌群的影响

氨氮和亚硝酸盐是蛋白质的代谢副产物，水体中高浓度的氨氮和亚硝酸盐会显著抑制罗非鱼的免疫力。肠道微生物与鱼类的免疫息息相关，然而氨氮和亚硝酸盐是否影响罗非鱼的肠道微生物仍不清楚。本研究采用基于16S rDNA基因序列的高通量测序，研究了氨氮和亚硝酸盐对吉富罗非鱼肠道菌群的影响。结果表明，罗非鱼肠道微生物群落主要以变形菌门和放线菌门为主。氨氮和亚硝酸盐不改变罗非鱼肠道菌群的alpha多样性，但显著改变物种组成，其中Aurantimicrobium菌属在两种处理下比例显著降低。原核类群功能注释(FAPROTAX)分析表明，氨氮和亚硝酸盐胁迫导致的差异ASVs主要涉及化能异养、好氧化能异养、硝酸盐还原、脂肪族非甲烷烃降解、芳香烃降解和芳香族化合物降解。本研究通过了解氨氮和亚硝酸盐对罗非鱼肠道微生物的影响，为研究肠道微生物对罗非鱼免疫的影响奠定基础。

Effects of Ammonia Nitrogen and Nitrite on Intestinal Flora of Genetically Improved Farmed Tilapia

Ammonia nitrogen and nitrite are metabolic byproducts of protein, and their high concentration of ammonia nitrogen and nitrite in water environment significantly inhibit the immunity of tilapia. While the relationship between intestinal flora and fish immunity is well-established, the effects of ammonia nitrogen and nitrite on tilapia''s intestinal flora remain unclear. In this study, high throughput sequencing based on 16S rDNA gene sequence was used to study the effects of ammonia nitrogen and nitrite on intestinal microflora of tilapia. The results showed that the main intestinal microbial communities of tilapia were Proteobacteria and Actinobacteria. Ammonia nitrogen and nitrite did not change the alpha diversity of tilapia intestinal microflora, but significantly changed species composition, in which the proportion of Aurantimicrobium decreased significantly under both treatments. Prokaryotic group functional annotation (FAPROTAX) analysis showed that the different ASVs caused by ammonia nitrogen and nitrite stress were mainly related to chemoheterotrophy, aerobic chemoheterotrophy, nitrate reduction, aliphatic non methane hydrocarbon degradation, aromatic hydrocarbon degradation and aromatic compound degradation. By understanding the effects of ammonia nitrogen and nitrite on tilapia intestinal tract microorganisms, this study laid a foundation for the effects of intestinal microorganisms on tilapia immunity.