摘要

    目标
由于有限的研究和数据，嗜热细菌中抗生素抗性基因（ARGs）的发生和表达机制仍然未知。在这项研究中，已经通过功能性宏基因组学方法对嗜热细菌中的ARGs和金属耐受基因进行了比较分析。

方法
Il弹枪宏基因组序列数据是使用Illumina HiSeq 4000生成的。使用非冗余抗性基因作为参考，使用可从ARDB（抗生素抗性基因数据库）协会获得的ardbAnno V.1.0脚本，从PROKKA预测的基因鉴定了假定的ARG。通过使用BacMetScan V.1.0鉴定了推定的金属抗性基因（MRG）。使用Illumina HiSeq 4000测序技术和双端测序模块对细菌分离株进行全基因组测序。

结果
元基因组学分析显示在锡金的两个温泉中，细菌，放线菌，硬毛菌和拟杆菌的优势显着。发现对于嗜热细菌，通过shot弹枪基因测序进行的ARG分析为阴性。然而，几乎没有检测到基因，但它们显示了与嗜温细菌的最大相似性。同时，在温泉分离株的元基因组序列中也检测到了MRG。在嗜热性地芽孢杆菌的参考基因组序列中通过全基因组测序研究的MRG的检测和ARG的缺失也传达了相同的信息。

结论
通过宏基因组学对锡金温泉中可培养和不可培养细菌中的ARGs和MRGs（重金属抗性基因）的研究表明，MRGs比ARGs优先选择。在这些环境中，缺少ARG也不支持ARG和MRG的共选。对于在抗生素基因上具有金属抗性的这种进化选择，可能对于在地质陨石坑中生存可能是必要的，该陨石坑具有来自地球沉积物而不是抗生素的大量不同金属。此外，取决于嗜热环境中ARG的敏感性，选择可以是环境驱动的，因为它减少了水平基因转移的机会。 
Mùbiāo

    Objectives
Mechanisms of occurrence and expression of antibiotic resistance genes (ARGs) in thermophilic bacteria are still unknown owing to limited research and data. In this research, comparative profiling of ARGs and metal tolerance genes among thermophilic bacteria has been done by functional metagenomic methods.

Methods
Shotgun metagenomic sequence data were generated using Illumina HiSeq 4000. Putative ARGs from the PROKKA predicted genes were identified with the ardbAnno V.1.0 script available from the ARDB (Antibiotic Resistance Genes Database) consortium using the non-redundant resistance genes as a reference. Putative metal resistance genes (MRGs) were identified by using BacMetScan V.1.0. The whole-genome sequencing for bacterial isolates was performed using Illumina HiSeq 4000 sequencing technology with a paired-end sequencing module.

Results
Metagenomic analysis showed the dominance of Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes in two hot springs of Sikkim. ARG analysis through shotgun gene sequencing was found to be negative in the case of thermophilic bacteria. However, few genes were detected but they showed maximum similarity with mesophilic bacteria. Concurrently, MRGs were also detected in the metagenome sequence of isolates from hot springs. Detection of MRGs and absence of ARGs investigated by whole-genome sequencing in the reference genome sequence of thermophilic Geobacillus also conveyed the same message.

Conclusion
The study of ARGs and MRGs (Heavy metal resistance gene) among culturable and non-culturable bacteria from the hot springs of Sikkim via metagenomics showed a preferential selection of MRGs over ARGs. The absence of ARGs also does not support the co-selection of ARGs and MRGs in these environments. This evolutionary selection of metal resistance over antibiotic genes may have been necessary to survive in the geological craters which have an abundance of different metals from earth sediments rather than antibiotics. Furthermore, the selection could be environment driven depending on the susceptibility of ARGs in a thermophilic environments as it reduces the chances of horizontal gene transfer.

    https://www.sciencedirect.com/science/article/pii/S2213716520300904