Temporal dynamics of antibiotic resistant bacteria and antibiotic resistance genes in activated sludge upon exposure to starvation

Zhenping Tang; Yu Zhang; Siqi Zhang; Yuanyuan Gao; Yi Duan; Taotao Zeng; Shuai Zhou

doi:10.1016/j.scitotenv.2022.156594

Temporal dynamics of antibiotic resistant bacteria and antibiotic resistance genes in activated sludge upon exposure to starvation

Sci Total Environ. 2022 Sep 20:840:156594. doi: 10.1016/j.scitotenv.2022.156594. Epub 2022 Jun 8.

Authors

Zhenping Tang¹, Yu Zhang², Siqi Zhang², Yuanyuan Gao³, Yi Duan⁴, Taotao Zeng⁴, Shuai Zhou⁵

Affiliations

¹ Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang 421001, China; Hunan Province Key Laboratory of Rare Metal Minerals Exploitation and Geological Disposal of Wastes, University of South China, Hengyang 421001, China.
² School of Civil Engineering, University of South China, Hengyang 421001, China.
³ Hunan Province Key Laboratory of Rare Metal Minerals Exploitation and Geological Disposal of Wastes, University of South China, Hengyang 421001, China.
⁴ Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang 421001, China; School of Civil Engineering, University of South China, Hengyang 421001, China.
⁵ Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang 421001, China; Hunan Province Key Laboratory of Rare Metal Minerals Exploitation and Geological Disposal of Wastes, University of South China, Hengyang 421001, China; School of Civil Engineering, University of South China, Hengyang 421001, China. Electronic address: zs402606665@126.com.

PMID: 35690205
DOI: 10.1016/j.scitotenv.2022.156594

Abstract

The activated sludge represents a huge reservoir for antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Owing to the wastewater fluctuation, annual maintenance and storage requirement, the activated sludge in wastewater treatment plants (WWTPs) may suffer from substrate deficiency (i.e., starvation). Whereas the starvation has been confirmed to regulate the antibiotic resistance in numerous pure bacteria, its impacts on the antibiotic resistance in activated sludge remain unclear. Here, the dynamics of sulfonamide and tetracycline ARB and corresponding ARGs in three forms including intracellular ARGs (iARGs), adsorbed extracellular ARGs (aeARGs) and free extracellular ARGs (feARGs) in activated sludge upon exposure to starvation were investigated. The results showed that, among the different electron donors (i.e., carbon, nitrogen and phosphate), carbon starvation could effectively reduce the absolute abundance of ARB and aeARGs by up to 1.68 lgs and 2.62 lgs, respectively, and released a small amount of feARGs in wastewater with the maximum value of 1.1 × 10⁵ copies/mL due to the high degree of sludge cell lysis and DNA adsorption/degradation. For the different acceptor conditions (that is, alternating anaerobic-aerobic, anaerobic, anoxic and aerobic), the anaerobic-aerobic starvation obviously mitigated the absolute abundance of ARB, aeARGs and iARGs by 0.71 lgs, 3.41 lgs and 1.35 lgs, respectively, via the substantial sludge cell lysis and DNA degradation. These findings demonstrated the response patterns and mechanisms of bacterial resistance in activated sludge to starvation stress, and thus provide clues to control the risk of antibiotic resistance in WWTPs by the starvation strategy.

Keywords: Activated sludge; Antibiotic resistance genes (ARGs); Antibiotic resistant bacteria (ARB); Electron donors/acceptors; Kinetics; Starvation.

MeSH terms

Angiotensin Receptor Antagonists
Angiotensin-Converting Enzyme Inhibitors
Anti-Bacterial Agents / pharmacology
Bacteria / genetics
Carbon
DNA
Drug Resistance, Microbial / genetics
Genes, Bacterial
Sewage* / microbiology
Wastewater* / microbiology

Substances

Angiotensin Receptor Antagonists
Angiotensin-Converting Enzyme Inhibitors
Anti-Bacterial Agents
Sewage
Waste Water
Carbon
DNA