Genetic diversity of dissolved free extracellular DNA compared to intracellular DNA in wastewater treatment plants

IF 8.2 1区环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES Science of the Total Environment Pub Date : 2025-03-05 DOI:10.1016/j.scitotenv.2025.178989

Soichiro Tamai , Miki Okuno , Yoshitoshi Ogura , Yoshihiro Suzuki

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Abstract

Dissolved free extracellular DNA (free-exDNA) coexists with intracellular DNA (inDNA) in aquatic environments. Free-exDNA can be taken up by bacteria through transformation, and wastewater treatment plants (WWTPs) are positioned as potential hot spots for genetic contamination. However, studies comparing the composition of free-exDNA and inDNA is limited. This study employed colloidal adsorption and foam concentration method to recover free-exDNA from different WWTP stages and compared its diversity with inDNA via metagenomic analysis. Free-exDNA concentrations were observed to increase after chlorination. Genetic analysis revealed a higher abundance of specific genes following chlorination, suggesting that free-exDNA in effluent originated from bacterial death in secondary treated water. This result indicates that free-exDNA, which increases due to chlorination, is subsequently released into the catchment. Additionally, several high-risk antibiotic-resistance genes (ARGs) were detected that colocalized with mobile genetic elements. These ARGs were expected to have a high potential for gene transfer via transformation, and the risk was highlighted. Overall, these findings deepen our understanding of horizontal gene transfer risks in WWTPs.

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来源期刊

Science of the Total Environment 环境科学-环境科学

CiteScore

17.60

自引率

10.20%

发文量

8726

审稿时长

2.4 months

期刊介绍： The Science of the Total Environment is an international journal dedicated to scientific research on the environment and its interaction with humanity. It covers a wide range of disciplines and seeks to publish innovative, hypothesis-driven, and impactful research that explores the entire environment, including the atmosphere, lithosphere, hydrosphere, biosphere, and anthroposphere. The journal's updated Aims & Scope emphasizes the importance of interdisciplinary environmental research with broad impact. Priority is given to studies that advance fundamental understanding and explore the interconnectedness of multiple environmental spheres. Field studies are preferred, while laboratory experiments must demonstrate significant methodological advancements or mechanistic insights with direct relevance to the environment.