Fate of sulfonamide-antibiotic resistance genes in two estuarine
environments with differing anthropogenic influences
Guangshui Na, Zihao Lu, Hui Gao, Ruijing Li, Ziwei Yao and Chuanlin
Huo
Key Laboratory for Ecological Environment in Coastal Areas (SOA),
National Marine Environmental Monitoring Center, Dalian, China.
E-
mail: gsna@nmemc.org.cn
With the growing problem of antibiotic resistance around the world,
antibiotic resistance genes (ARGs) are emerging contaminants found at
elevated levels in inland aquatic environments near regions of agricultural
and urban activity. However, little quantitative data exist on the migration
and attenuation of ARGs in the estuarine ecosystem, which is central to
predicting their fate after release into the aquatic environment. To
determine the prevalence and fate of sulfonamide ARGs (sul-ARGs) in two
estuaries under different effects of anthropogenic activities, we
characterized the occurrence and distribution of the sul-ARGs (sul1, sul2,
and sul3) in Daliaohe and Liaohe river estuaries. In addition, we
characterized environmental contamination in three ways: five types of
antibiotics, concentrations of 11 metals, and the eutrophication index (EI),
against which we explored correlations with sul-ARGs. Results showed
that sul-ARGs were widespread in Daliaohe and Liaohe River estuaries,
although the concentrations of sulfonamides were very low. The
distribution of sul-ARGs was affected by continental-oceanic interaction,
and no significant correlations existed between sul-ARGs and antibiotic
residues. Nevertheless, the trend in change of concentrations of sul-ARGs
differed between the two estuaries. Analysis of the results indicated that
several metals were significantly and positively correlated with sul-ARGs.
Pearson’s correlation coefficients were higher than those determined
between antibiotic residues and sul-ARGs. Meanwhile, the relative
abundance of sul-ARGs was positively correlated with the relative
abundance of int1 which suggested that the propagation of sul-ARGs was
facilitated by class 1 integrons in estuaries.