磺胺甲吧恶唑对罗非鱼养殖水体细菌群落的影响

Effect of Sulfamethoxazole on Water Bacterial Community Structure in Tilapia(Oreochromis niloticus)Culture Pond

以SCT 1084-2006《磺胺类药物水产养殖使用规范》为依据,制作无(NS)、低(LS)、中(MS)和高(HS)剂量磺胺甲啊恶唑(SMZ)的饲料,通过8周的养殖试验(前4周投喂SMZ饲料,后4周投喂无SMZ饲料)、16S高通量测序技术和生物信息学分析来研究养殖过程中不同剂量SMZ的使用对养殖水体细菌群落结构的影响。第2、4、6和8周时运用16S rRNA和生物信息学测定分析水体微生物多样性。研究显示:(1)不同剂量SMZ投喂下对养殖水体细菌的生物多样性有不同程度的降低影响,中、高剂量效果显著,停止投喂SMZ饲料后显著性差异消失、差异程度降低;(2)不同剂量SMZ投喂时均改变了细菌群落结构,其中NS群落和LS群落差异弱于与MS和HS群落的差异,这种差异在停药4周后仍存在;(3)SMZ的抑菌和细菌耐药作用显著改变水体菌群从门至属的物种组成,SMZ主要诱导了变形菌门下β-变形菌纲中的某些参与氮循环相关的细菌(如:Candidatus_Branchiomonas和12up),同时抑制了一些致病菌(如:拟杆菌门的黄杆菌等);(4)SMZ对水体细菌群落的改变在一定程度上改变其功能分配和抑制其功能强度。研究结果表明,不同剂量饲料拌喂SMZ不仅会在不同程度上显著改变养殖水体细菌群落结构且有一定的延续性;此外,在SMZ的选择压力下一些与脱氮相关的菌成为明显的优势种,可能会对养殖池塘的氮循环有潜在的影响。

Based on the Specification for the Application of Sulfonamides in Aquaculture(SCT 1084-2006), blank group(NS), low(LS, 0.67 g/kg), medium(MS, 6.67 g/kg) and high(HS, 33.33 g/kg) doses of sulfamethoxazole(SMZ) fodder were made. The effects of different doses of SMZ on the bacterial community structure of aquaculture water were studied through a8 weeks of culture experiment(the first 4 weeks were SMZ diet and the last 4 weeks were no SMZ feed), 16 S high-throughput sequencing technology and bioinformatics analysis. Bacterial diversity in water was determined at week 2, 4, 6 and 8 weeks using 16 S rRNA and bioinformatics. The results showed that bacterial species abundance and diversity of cultured water decreased in accordance with SMZ doses. Thus, MS and HS effect was significantly remarked. However, after SMZ feed was stopped, the significant difference disappeared and the degrees of difference decreased. The bacterial community structure changed when SMZ were fed at different doses, the variance between NS community and LS community is weaker than that between NS and MS community and NS and HS community. Moreover, this difference was observed after 4 weeks of drug withdrawal. The bacteriostatic and bacterial resistance of SMZ have significantly changed the species composition of water bacteria from phylum to genus. SMZ mainly induces some bacteria related to nitrogen cycle in the β-proteobacteria of proteobacteria(e.g., Candidatus_Branchiomonas and 12 up), and prevented some pathogenic bacteria(e.g., flavobacterium of bacteroides). The alteration in SMZ bacterial community to some extent changed their efficient distribution and inhibited their functional strength. Based on the study, different doses of SMZ mixed with feed could not only significantly change the community structure of bacteria in the aquaculture water, but also have some continuous effect. In addition, under the selective pressure of SMZ, some bacteria related to denitrification became obvious dominant species, which may have a potential impact on the nitrogen cycle in aquaculture water.