Deciphering distribution and migration of soil antibiotic resistance genes in different latitude regions of Antarctica by metagenomics

Abstract:

[Objective] Antarctic environments are extremely diverse and affected by human activities in varying degrees. The aim of this study is to explore distribution and migration of soil antibiotic resistant genes (ARGs) in different latitude regions of Antarctica.[Methods] We selected soil metagenomic data from Antarctic high (HLG) and low latitude regions (LLG) and surrounding regions of feedlot. Metagenomic reads was assembled using software MetaWRAP. ARGs, plasmids and integrative and conjugative elements (ICEs) were annotated using CARD (The Comprehensive Antibiotic Resistance Database), PlasFlow and ICEberg, respectively. [Results] In the Antarctic soils, Proteobacteria, Actinomycetes, Bacteroidetes and Firmicutes were the dominant phyla. Belonging to 25 ARG types, 406 ARGs were found, among which multidrug, tetracycline and aminoglycoside resistance genes dominated. The NMDS analysis showed that the characteristics of ARGs in Antarctic soils were significantly different from those in agricultural soils nearby feedlot (ANOSIM, P=0.001). The proportion of ARGs in all ORFs in the Antarctic HLG was 0.28%, lower than that in the LLG (1.93%, P<0.01). Different ARGs present different latitude-region resistance patterns. Therein, nitroimidazole, aminoglycoside, glycopeptide and macrolide resistance genes were mainly distributed in the HLG, while tetracycline and sulfonamide resistance genes were mainly distributed in the LLG (P<0.05). The migration analysis of ARGs in Antarctic soils showed that 17% of the detected ARGs were carried by plasmids. In addition, 163 ICEs carrying ARGs, belonging to 14 ARG types (e.g., multidrug, peptide and tetracycline resistance genes), were found. These ICEs carrying ARGs were extensively distributed among α-, β- and γ-proteobacteria. [Conclusion] The differences in microbial communities and ARGs between the Antarctic high and low latitude areas occurred, plasmids and ICEs facilitated migration of nature ARGs. This study provided a certain data basis for understanding the natural antibiotic resistance from the pre-antibiotic era.