Abstract:
The study of the soil resistome is important in understanding the evolution of antibiotic resistance and its dissemination
between the clinic and the environment. However, very little is known about the soil resistome, especially of those from
deserts. Here, we characterize the bacterial communities, using targeted sequencing of the 16S rRNA genes, and both the
resistome and the mobilome in Namib Desert soils, using shotgun metagenomics. We detected a variety of antibiotic resistance
genes (ARGs) that conferred resistance to antibiotics such as elfamycin, rifampicin, and fluoroquinolones, metal/biocide
resistance genes (MRGs/BRGs) conferring resistance to metals such as arsenic and copper, and mobile genetic elements
(MGEs) such as the ColE1-like plasmid. The presence of metal/biocide resistance genes in close proximity to ARGs indicated
a potential for co-selection of resistance to antibiotics and metals/biocides. The co-existence of MGEs and horizontally
acquired ARGs most likely contributed to a decoupling between bacterial community composition and ARG profiles. Overall,
this study indicates that soil bacterial communities in Namib Desert soils host a diversity of resistance elements and that
horizontal gene transfer, rather than host phylogeny, plays an essential role in their dynamics.
