期刊
JOURNAL OF ENVIRONMENTAL MANAGEMENT
卷 297, 期 -, 页码 -出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jenvman.2021.113315
关键词
Antibiotic resistome; Metal resistance genes; Dissolved oxygen levels; Oxidative stress; Metagenome-wide analysis; Human pathogens
资金
- Department of Biotechnology (DBT)
- DBT [BT/IN/Indo-UK/AMR-Envi/05/NT/2020-21]
Bacterial communities face oxidative stress when exposed to antibiotics, metals, and varying levels of dissolved oxygen in different environments. This stress increases the co-selection of antibiotic resistance genes (ARGs) and metal resistance genes (MRGs). The genetic linkage between ARGs and MRGs provides evidence for the selection of ARGs under high concentrations of heavy metals.
The bacterial communities are challenged with oxidative stress during their exposure to bactericidal antibiotics, metals, and different levels of dissolved oxygen (DO) encountered in diverse environmental habitats. The frequency of antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) co-selection is increased by selective pressure posed by oxidative stress. Hence, study of resistance acquisition is important from an evolutionary perspective. To understand the dependence of oxidative stress on the dissemination of ARGs and MRGs through a pathogenic bacterial population, 12 metagenomes belonging to gut, water and soil habitats were evaluated. The metagenome-wide analysis showed the chicken gut to pose the most diverse pool of ARGs (30.4 ppm) and pathogenic bacteria (Simpson diversity = 0.98). The most common types of resistances found in all the environmental samples were efflux pumps (13.22 ppm) and genes conferring resistance to vancomycin (12.4 ppm), tetracycline (12.1 ppm), or beta-lactam (9.4 ppm) antibiotics. Additionally, limiting DO level in soil was observed to increase the abundance of excision nucleases (uvrA and uvrB), DNA polymerase (polA), catalases (katG), and other oxidative stress response genes (OSGs). This was further evident from major variations occurred in antibiotic efflux genes due to the effect of DO concentration on two human pathogens, namely Salmonella enterica and Shigella sonnei found in all the selected habitats. In conclusion, the microbial community, when challenged with oxidative stress caused by environmental variations in oxygen level, tends to accumulate higher amounts of ARGs with increased dissemination potential through triggering non-lethal mutagenesis. Furthermore, the genetic linkage or co-occurrence of ARGs and MRGs provides evidence for selecting ARGs under high concentrations of heavy metals.
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