HKU Civil Engineering Team Discovers Import

image: Viral genes shared at six treatment plants in Hong Kong.
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Credit: The University of Hong Kong

Prokaryotic viruses (phages) present in activated sludge (AS), a biological treatment process widely used in sewage treatment plants (WWTPs), act to regulate the composition of the microbial community in activated sludge. Phages are major bacterial predators, through virus-host interactions with key bacterial populations in AS systems, they can influence pollutant removal efficiency. High specificity phages could be used to curb unwanted bacteria, for example, filamentous bacteria associated with unwanted foaming which might disrupt the AS system’s removal efficiency.

Clinically, phage therapy has been shown by other research teams to be effective against the antibiotic resistant superbug Acinetobacter baumannii, and activated sludge in WWTPs is an important source for isolating phages to treat infections in order to save lives.

The research team led by Professor Tong Zhang from the Department of Civil Engineering at the University of Hong Kong (HKU) recently applied a systematic metagenomic pipeline to recover a catalog of approximately 50,000 phages from six sewage treatment plants in Hong Kong. The study reveals the significant and uncharacterized prokaryotic viral diversity in activated sludge, and greatly expands the current catalog of prokaryotic AS viruses to provide a benchmark for the use of phage treatments to control unwanted microorganisms at work stations. purification. The results have been published in a leading scientific journal Nature Communication.

Professor Zhang said, “Prokaryotic viruses are so small that people have neglected their role in WWTP. By discovering the numerous virus-host interactions in the functional microorganisms of wastewater treatment plants, this study highlights the potential roles of phages in the elimination of pollutants and the protection of the environment.

This is the first work on a global scale to explore the connections between functional microorganisms in wastewater treatment plants and prokaryotic viruses. Future work will include analysis of long-term AS phage community dynamics and phage isolation to control unwanted bacteria in wastewater treatment plants.

This work is part of Prof. Zhang’s project supported by the Thematic Research Program (TRS) of the University Grants Committee to Support Research of Strategic Importance.

About the research team
The first author, Dr Yiqiang Chen, holds a doctorate from Professor Zhang. Other scientists contributing to the research include Dr Yulin Wang, postdoctoral fellow in Prof. Zhang’s research group, Dr David Paez-Espino (Joint Genome Institute of US Department of Energy) and Prof. Martin F. Polz (University of Vienna and Massachusetts Institute of Technology).

About Professor Tong Zhang
Professor Tong Zhang headed the Environmental Microbiome Engineering and Biotechnology Laboratory at the Civil Engineering Department of HKU. His research focuses on the “environmental microbiome”. He has done cutting-edge work on the emerging topic of the “Environmental Dimension of Antibiotic Resistance” in the field of the microbiome. You can find more information about Professor Tong Zhang and his research team at:

The research paper “Prokaryotic Viruses Impact Functional Microorganisms in Nutrient Removal and Carbon Cycling in Wastewater Treatment Plants” was published in Nature Communication :

Media inquiries:
Ms. Celia Lee, Faculty of Engineering, HKU (Tel: 3917 8519; Email: [email protected]) or
Mr. Heng Cheng, Faculty of Engineering, HKU (Tel: 3917 1924; E-mail: [email protected])

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