摘要

      三氯生（TCS）是一种广谱抗菌剂，广泛应用于各种消费品中。虽然它最近在美国被禁止用于洗手液，但它仍然是一种畅销牙膏的关键成分。TCS是一种疏水性的微污染物，在厌氧消化条件下难以降解，从而导致生物固体中TCS浓度较高。本研究的目的是利用鸟枪基因组学研究TCS对实验室厌氧消化池抗生素抗性和潜在交叉保护的影响。据推测，亚基因组学将揭示抗生素耐药基因（ARGs）的选择，这是以前在纯培养研究或混合培养研究中没有发现的，使用靶向qPCR。在本研究中，四种不同水平的TCS被连续喂入三倍于实验室规模的厌氧消化池，以评估TCS水平对抗生素耐药基因谱（resistome）的影响。对抗生素/金属耐药基因数据库（BacMet）的爆破基因组分析表明，ARG的多样性和丰度随TCS浓度梯度的变化而变化。在TCS浓度最高的消化池中，细菌多样性和消化功能丧失，而已知的抗TCS基因FabV在TCS浓度极高的环境中增加。其他一些已知的ARG或金属抗性基因，包括corA和arsB，也随着TCS浓度的增加而增加。利用种子数据库对其它功能基因进行分析，发现包括不同类型转运体和转座子在内的潜在抗性关键基因增加。这些结果表明，即使在维持功能（即产甲烷量）的情况下，抗菌剂也能改变厌氧消化池中多种抗性基因的丰度。这项研究还表明，利用生物固体土地可以将富集的ARG释放到环境中。

      Triclosan (TCS) is a broad-spectrum antimicrobial used in a variety of consumer products. While it was recently banned from hand soaps in the US, it is still a key ingredient in a top-selling toothpaste. TCS is a hydrophobic micropollutant that is recalcitrant under anaerobic digestion thereby resulting in high TCS concentrations in biosolids. The objective of this study was to determine the impact of TCS on the antibiotic resistome and potential cross-protection in lab-scale anaerobic digesters using shotgun metagenomics. It was hypothesized that metagenomics would reveal selection for antibiotic resistance genes (ARGs) not previously found in pure culture studies or mixed-culture studies using targeted qPCR. In this study, four different levels of TCS were continuously fed to triplicate lab-scale anaerobic digesters to assess the effect of TCS levels on the antibiotic resistance gene profiles (resistome). Blasting metagenomic reads against antibiotic/metal resistance gene database (BacMet) revealed that ARG diversity and abundance changed along the TCS concentration gradient. While loss of bacterial diversity and digester function were observed in the digester treated with the highest TCS concentration, FabV, which is a known TCS resistance gene, increased in this extremely high TCS environment. The abundance of several other known ARG or metal resistance genes (MRGs), including corA and arsB, also increased as the concentrations of TCS increased. Analysis of other functional genes using SEED database revealed the increase of potentially key genes for resistance including different types of transporters and transposons. These results indicate that antimicrobials can alter the abundance of multiple resistance genes in anaerobic digesters even when function (i.e. methane production) is maintained. This study also suggests that enriched ARGs could be released into environments with biosolids land application.

       https://www.sciencedirect.com/science/article/pii/S0269749118316403?via%3Dihub