对照处理（PA，0 mg/L）马氏珠母贝肠道的优势菌门为变形菌门（Proteobacteria）、软壁菌门（Tenericutes）和厚壁菌门（Firmicutes），相对丰度分别为40.65%、33.87%和15.75%;两个恩诺沙星处理（PB，5 mg/L;PC，10 mg/L）的优势菌均为变形菌门，相对丰度分别为91.61%和85.00%。在属水平上，PA处理马氏珠母贝肠道的优势菌属为支原体属（Mycoplasma）、微小杆菌属（Exiguobacterium）、柠檬酸细菌属（Citrobacter）和埃希氏菌—志贺氏菌属（Escherichia-Shigella），相对丰度分别为26.33%、12.22%、10.62%和9.66%;PB处理的优势菌属为弧菌属（Vibrio），相对丰度为52.10%;PC处理的优势菌属为弧菌属和发光杆菌属（Photobacterium），相对丰度分别为40.24%和23.43%。操作分类单元（OTU）聚类分析结果表明，3个处理（PA、PB和PC）的共有OUTs为138个，占OTUs总数的54.76%;PB和PC处理的共有OUTs达176个，即这两个处理间具有更高的相似性。【结论】恩诺沙星处理浓度达5 mg/L时即对马氏珠母贝肠道微生物群落产生影响，并使其暴露于弧菌等致病菌的威胁下，因此在马氏珠母贝养殖生产中须谨慎使用恩诺沙星。
关键词： 马氏珠母贝;恩诺沙星;肠道微生物;α多样性;相对丰度;高通量测序
中图分类号： S968.316 文献标志码： A 文章编号：2095-1191（2019）05-1104-07
Abstract：【Objective】The aim of the study was to investigate the possible impact of eofloxacin on Pinctada fucata martensii， find out the changing rule and provide a reference for the optimal treatment of bacterial infection in P. fucata martensii. 【Method】The microbial shifts in the intestine of P. fucata martensii in response to eofloxacin treatments at di-fferent dosages（0， 5， and 10 mg/L） were quantitatively evaluated using 16S rDNA gene sequencing， and the similarities and differences of intestinal microbial community structure among different treatments were compared and analyzed by bioinformatics at the phylum and genus levels. 【Result】A total of 755159 effective sequences were obtained from 9 intestinal contents samples of P. fucata martensii（PA1， PA2， PA3， PB1， PB2， PB3， PC1， PC2 and PC3），belonging to 48 genera and 9 phyla. At the phylum level， the dominant genera of the control （PA， 0 mg/L） was Proteobacteria， Tenericutes and Firmicutes， whose relative abundances were 40.65%，33.87% and 15.75%， respectively. Nevertheless， the dominant phylum in two eofloxacin treatment groups（PB， 5 mg/L; PC， 10 mg/L） were Proteobacteria， the relative abundance of which have reached 91.61% and 85.00% respectively. At the genus level， the dominant phylum of PA treatment were Mycoplasma， Exiguobacterium， Citrobacter， Escherichia-Shigella， the relative abundance of which were 26.33%， 12.22%，10.62% and 9.66%，respectively. Vibrio held the dominant position of PB， and its relative abundance was 52.10%. Vibrio and Photobacterium made up the most share of microbial community of PC， which collectively accounted for 40.24% and 23.43% respectively. OTU cluster analysis showed that there were 138 OTUs in three treatments（PA， PB and PC）， accounting for 54.76% of the total OTUs. 176 OUTs were shared by PB and PC， which meaned that there was a higher similarity between the two treatments. 【Conclusion】Overall， eofloxacin alters the microbial community diversity of P. fucata martensii as the dosage reaches 5 mg/L， and exposes them to the threat of pathogenic bacteria such as Vibrio. Therefore， the use of eofloxacin should be carefully considered in the culture of P. fucata martensii.