摘要

我们以前的研究表明，在芬兰波罗的海北部渔场下面的沉积物中局部富集了特定的抗生素抗性基因( ARGs )，即使来自抗生素的选择压力可以忽略不计。我们认为不断涌入的养殖鱼粪可能是养殖场沉积物中富含ARGs来源。本研究分析了来自波罗的海养殖场的20条鱼的肠道内容物中抗生素耐药性的组成。采用高通量WaferGen qPCR阵列和364个引物组来检测和定量ARGs、移动遗传元件( MGE )和16S rRNA基因。尽管qPCR引物组的选择相当广泛，但在肠内容物中仅检测到28个基因。检测到的基因是编码磺胺类药物( sul1 )、甲氧苄啶( dfrA1 )、四环素[tet（32），tetM，tetO，tetW]、氨基糖苷类( aadA 1、aadA 2 )、氯霉素( catA 1 )和外排泵耐药基因( emrB、matA、mefA、msrA )。检测到的基因还包括1类整合子相关基因( int1，qacEΔ1 )和转座酶( tnpA )。重要的是，大多数检测到的基因都是在农场沉积物中富集的相同基因。这一研究初步表明，尽管农场缺乏同时期的抗生素处理，但养殖鱼类的粪便有助于农场沉积物中ARG的富集。我们观察到个体养殖鱼类的肠道内容物有其自身的抗性成分。我们结果还显示转座酶和Tet基因的总相对丰度呈显著相关( p = 0.001，R2 = 0.71 )。此外，我们还分析了养殖鱼类的粘膜皮肤和鳃丝的耐药性，但仅检测到一个多药耐药基因( emrB )。据我们所知，这是第一项用独立于培养的方法报道养殖鱼类抗药性的研究。确定ARG的可能来源，特别是活化的ARG，对于控制鱼类养殖设施中ARG的发生和扩散以及降低ARG从农场扩散到周围环境的风险至关重要。

Our previous studies showed that particular antibiotic resistance genes (ARGs) were enriched locally in sediments below fish farms in the Northern Baltic Sea, Finland, even when the selection pressure from antibiotics was negligible. We assumed that a constant influx of farmed fish feces could be the plausible source of the ARGs enriched in the farm sediments. In the present study, we analyzed the composition of the antibiotic resistome from the intestinal contents of 20 fish from the Baltic Sea farms. We used a high-throughput method, WaferGen qPCR array with 364 primer sets to detect and quantify ARGs, mobile genetic elements (MGE), and the 16S rRNA gene. Despite a considerably wide selection of qPCR primer sets, only 28 genes were detected in the intestinal contents. The detected genes were ARGs encoding resistance to sulfonamide (sul1), trimethoprim (dfrA1), tetracycline [tet(32), tetM, tetO, tetW], aminoglycoside (aadA1, aadA2), chloramphenicol (catA1), and efflux-pumps resistance genes (emrB, matA, mefA, msrA). The detected genes also included class 1 integron-associated genes (intI1, qacEΔ1) and transposases (tnpA). Importantly, most of the detected genes were the same genes enriched in the farm sediments. This preliminary study suggests that feces from farmed fish contribute to the ARG enrichment in farm sediments despite the lack of contemporaneous antibiotic treatments at the farms. We observed that the intestinal contents of individual farmed fish had their own resistome compositions. Our result also showed that the total relative abundances of transposases and tet genes were significantly correlated (p = 0.001, R2 = 0.71). In addition, we analyzed the mucosal skin and gill filament resistomes of the farmed fish but only one multidrug-efflux resistance gene (emrB) was detected. To our knowledge, this is the first study reporting the resistome of farmed fish using a culture-independent method. Determining the possible sources of ARGs, especially mobilized ARGs, is essential for controlling the occurrence and spread of ARGs at fish farming facilities and for lowering the risk of ARG spread from the farms to surrounding environments.

https://www.frontiersin.org/articles/10.3389/fmicb.2016.02137/full