Going Viral: Emerging Opportunities for Phage-Based Bacterial Control in Water Treatment and Reuse

Abstract

CONSPECTUS:Water security to protect human lives and support sustainable development is one of the greatest global challenges of this century. While a myriad of water pollutants can impact public health, the greatest threat arises from pathogenic bacteria that can be harbored in different components of water treatment, distribution, and reuse systems. Bacterial biofilms can also promote water infrastructure corrosion and biofouling, which substantially increase the cost and complexity of many critical operations. Conventional disinfection and microbial control approaches are often insufficient to keep up with the increasing complexity and renewed relevance of this pressing challenge. For example, common disinfectants cannot easily penetrate and eradicate biofilms, and are also relatively ineffective against resistant microorganisms. The use of chemical disinfectants is also curtailed by regulations aimed at minimizing the formation of harmful disinfection byproducts. Furthermore, disinfectants cannot be used to kill problematic bacteria in biological treatment processes without upsetting system performance. This underscores the need for novel, more precise, and more sustainable microbial control technologies. Bacteriophages (phages), which are viruses that exclusively infect bacteria, are the most abundant (and perhaps the most underutilized) biological resource on Earth, and hold great promise for targeting problematic bacteria. Although phages should not replace broad-spectrum disinfectants in drinking water treatment, they offer great potential for applications where selective targeting of problematic bacteria is warranted and antimicrobial chemicals are either relatively ineffective or their use would result in unintended detrimental consequences. Promising applications for phage-based biocontrol include selectively suppressing bulking and foaming bacteria that hinder activated sludge clarification, mitigating proliferation of antibiotic resistant strains in biological wastewater treatment systems where broad-spectrum antimicrobials would impair pollutant biodegradation, and complementing biofilm eradication efforts to delay corrosion and biofouling. Phages could also mitigate harmful cyanobacteria blooms that produce toxins in source waters, and could also serve as substitutes for the prophylactic use of antibiotics and biocides in animal agriculture to reduce their discharge to source waters and the associated selective pressure for resistant bacteria. Here, we consider the phage life cycle and its implications for bacterial control, and elaborate on the biochemical basis of such potential application niches in the water supply and reuse cycle. We also discuss potential technological barriers for phage-based bacterial control and suggest strategies and research needs to overcome them.

Bacteriophages in water pollution control: Advantages and limitations

“…These agents not only harm some benign bacteria but also cause antibiotic resistance in some pathogenic bacteria (Deng et al, 2018). Therefore, antibacterial agents are becoming increasingly ineffective, and the wastewater treatment process employing them has an unpredictable impact (Mathieu et al, 2019). More precise and efficient methods need to be developed and used in water pollution control.…”

“…As a biological control method, phage therapy employing lytic phages has made breakthrough progress in agronomy, pharmacy, medicine, and other fields (Doss et al, 2017). Inspired by these studies, more researchers are opting to use phages to solve the problem of water pollution (Mathieu et al, 2019). Compared with other wastewater treatment methods, phage usage has the following advantages: (1) Specificity: Unlike antibacterial agents, phages are highly specific for their host and do not damage beneficial bacteria.…”

“…As safe, efficient, and low-cost biological control agents, phages can be used to treat specific pathogenic bacteria in sewage. Phage-based technology also reduces the use of chemical reagents (Mathieu et al, 2019). Isolation of specific phages for specific pathogens is important.…”

“…To alleviate this disparity, effective treatment and reuse of wastewater are becoming increasingly important. The existence of pathogenic bacteria and viral pathogens in wastewater poses a threat to human health and has become a major public health issue (Mathieu et al, 2019). Residual antibiotics may be discharged into wastewater from hospitals without treatment, creating selection pressure on the microorganisms in the water and accelerating the development of antibioticresistance genes (ARGs) (Rodriguez-Mozaz et al, 2015).…”

Characterization of Novel Lytic Bacteriophages of Achromobacter marplantensis Isolated from a Pneumonia Patient

“…Bacteriophages are an important natural predator against bacteria in the ecosystem, and may be utilised to treat human infections [ 22 , 23 ] as well as to modulate the microbiota during bioremediation in a range of environments including wastewater, activated sludge and contaminated soil [ 24 , 25 , 26 ]. There have been published reports of bacteriophages lytic against A. xylosoxidans [ 27 , 28 , 29 , 30 ], including their use in clinical therapy against A. xylosoxidans lung infection in CF patients [ 31 ].…”