Abundance of Class 1 Integron-Integrase and Sulfonamide Resistance Genes in River Water and Sediment Is Affected by Anthropogenic Pressure and Environmental Factors.

Ryszard Koczura,Natalia Łopacinska,Joanna Mokracka,Agata Taraszewska

doi:10.1007/s00248-016-0843-4

Ryszard Koczura, Natalia Łopacinska + Show 2 more

Open Access

https://doi.org/10.1007/s00248-016-0843-4

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Journal: Microbial ecology	Publication Date: Sep 6, 2016
Citations: 105	License type: CC BY 4.0

Affiliation: Adam Mickiewicz University in Poznań

Abstract

In this study, we determined the presence of class 1 integron-integrase gene in culturable heterotrophic bacteria isolated from river water and sediment sampled upstream and downstream of a wastewater treatment plant effluent discharge. Moreover, we quantified intI1 and sulfonamide resistance genes (sul1 and sul2) in the water and sediment using qPCR. There was no correlation between the results from water and sediment samples, which suggests integron-containing bacteria are differentially retained in these two environmental compartments. The discharge of treated wastewater significantly increased the frequency of intI1 among culturable bacteria and the gene copy number in river water, and increased the number of sul1 genes in the sediment. We also observed seasonal differences in the frequency of the class 1 integron-integrase gene among culturable heterotrophs as well as intI1 copy number in water, but not in sediment. The results suggest that the abundance of class 1 integrons in aquatic habitat depends on anthropogenic pressure and environmental factors.Electronic supplementary materialThe online version of this article (doi:10.1007/s00248-016-0843-4) contains supplementary material, which is available to authorized users.

Highlights

Surface waters act as important recipients, reservoirs, and vectors of biotic contaminants like antibiotic-resistant bacteria (ARBs) and antibiotic resistance genes (ARGs) in the environment [1,2,3]
The highest average number of heterotrophic bacteria in the sediment was noted at the downstream site, where it reached 1.1 × 106 CFU g−1, compared with 1.9 × 105 CFU g−1 at the upstream site and 5.0 × 105 CFU g−1 at the city site
We determined the copy number of 16S ribosomal RNA (rRNA) gene, which in the sediment was approximately two orders of magnitude higher than that in water. This reflected the differences in the total number of culturable heterotrophic bacteria and coliforms between water and sediments

Summary

Introduction

Surface waters act as important recipients, reservoirs, and vectors of biotic contaminants like antibiotic-resistant bacteria (ARBs) and antibiotic resistance genes (ARGs) in the environment [1,2,3]. Agricultural and wastewater input of antibiotics, biocides, and heavy metals into surface waters imposes selective pressure enabling the maintenance and amplification of ARBs and enhancing lateral transfer of ARGs in the environment [4, 5]. Over 130 different resistance gene cassettes have been described in the variable regions of class 1 integrons, so far. These integrons are widely distributed among clinical strains, and in environmental isolates, their presence can be associated with increased frequency of virulence genes [8]. Class 1 resistance integrons are located on mobile elements like transposons and plasmids and are involved in spread of antibiotic resistance genes in bacteria by lateral gene transfer [9, 10]

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