Bacteriophage therapy for membrane biofouling in membrane bioreactors and antibiotic-resistant bacterial biofilms

Bacteriophage-mediated approaches for biofilm control

Biofilms are complex microbial communities in which planktonic and dormant bacteria are enveloped in extracellular polymeric substances (EPS) such as exopolysaccharides, proteins, lipids, and DNA. These multicellular structures present resistance to conventional antimicrobial treatments, including antibiotics. The formation of biofilms raises considerable concern in healthcare settings, biofilms can exacerbate infections in patients and compromise the integrity of medical devices employed during treatment. Similarly, certain bacterial species contribute to bulking, foaming, and biofilm development in water environments such as wastewater treatment plants, water reservoirs, and aquaculture facilities. Additionally, food production facilities provide ideal conditions for establishing bacterial biofilms, which can serve as reservoirs for foodborne pathogens. Efforts to combat antibiotic resistance involve exploring various strategies, including bacteriophage therapy. Research has been conducted on the effects of phages and their individual proteins to assess their potential for biofilm removal. However, challenges persist, prompting the examination of refined approaches such as drug-phage combination therapies, phage cocktails, and genetically modified phages for clinical applications. This review aims to highlight the progress regarding bacteriophage-based approaches for biofilm eradication in different settings.

Biofilm formation in food industries: Challenges and control strategies for food safety

Various pathogens have the ability to grow on food matrices and instruments. This grow may reach to form biofilms. Bacterial biofilms are community of microorganisms embedded in extracellular polymeric substances (EPSs) containing lipids, DNA, proteins, and polysaccharides. These EPSs provide a tolerance and favorable living condition for microorganisms. Biofilm formations could not only contribute a risk for food safety but also have negative impacts on healthcare sector. Once biofilms form, they reveal resistances to traditional detergents and disinfectants, leading to cross-contamination. Inhibition of biofilms formation and abolition of mature biofilms is the main target for controlling of biofilm hazards in the food industry. Some novel eco-friendly technologies such as ultrasound, ultraviolet, cold plasma, magnetic nanoparticles, different chemicals additives as vitamins, D-amino acids, enzymes, antimicrobial peptides, and many other inhibitors provide a significant value on biofilm inhibition. These anti-biofilm agents represent promising tools for food industries and researchers to interfere with different phases of biofilms including adherence, quorum sensing molecules, and cell-to-cell communication. This perspective review highlights the biofilm formation mechanisms, issues associated with biofilms, environmental factors influencing bacterial biofilm development, and recent strategies employed to control biofilm-forming bacteria in the food industry. Further studies are still needed to explore the effects of biofilm regulation in food industries and exploit more regulation strategies for improving the quality and decreasing economic losses.

Phage phylogeny, molecular signaling, and auxiliary antimicrobial resistance in aerobic and anaerobic membrane bioreactors

Phage emit communication signals that inform their lytic and lysogenic life cycles. However, little is known regarding the abundance and diversity of the genes associated with phage communication systems in wastewater treatment microbial communities. This study focused on phage communities within two distinct biochemical wastewater environments, specifically aerobic membrane bioreactors (AeMBRs) and anaerobic membrane bioreactors (AnMBRs) exposed to varying antibiotic concentrations. Metagenomic data from the bench-scale systems were analyzed to explore phage phylogeny, life cycles, and genetic capacity for antimicrobial resistance and quorum sensing. Two dominant phage families, Schitoviridae and Peduoviridae, exhibited redox-dependent dynamics. Schitoviridae prevailed in anaerobic conditions, while Peduoviridae dominated in aerobic conditions. Notably, the abundance of lytic and lysogenic proteins varied across conditions, suggesting the coexistence of both life cycles. Furthermore, the presence of antibiotic resistance genes (ARGs) within viral contigs highlighted the potential for phage to transfer ARGs in AeMBRs. Finally, quorum sensing genes in the virome of AeMBRs indicated possible molecular signaling between phage and bacteria. Overall, this study provides insights into the dynamics of viral communities across varied redox conditions in MBRs. These findings shed light on phage life cycles, and auxiliary genetic capacity such as antibiotic resistance and bacterial quorum sensing within wastewater treatment microbial communities.

Application of bacteriophages in biopolymer-based functional food packaging films

Recently, food spoilage caused by pathogens has been increasing. Therefore, applying control strategies is essential. Bacteriophages can potentially reduce this problem due to their host specificity, ability to inhibit bacterial growth, and extend the shelf life of food. When bacteriophages are applied directly to food, their antibacterial activity is lost. In this regard, bacteriophage-loaded biopolymers offer an excellent option to improve food safety by extending their shelf life. Applying bacteriophages in food preservation requires comprehensive and structured information on their isolation, culturing, storage, and encapsulation in biopolymers for active food packaging applications. This review focuses on using bacteriophages in food packaging and preservation. It discusses the methods for phage application on food, their use for polymer formulation and functionalization, and their effect in enhancing food matrix properties to obtain maximum antibacterial activity in food model systems.

Bacteriophages: Vectors of or weapons against the transmission of antibiotic resistance genes in hospital wastewater systems?

Antimicrobial resistance poses a serious threat to human health and is responsible for the death of millions of people annually. Hospital wastewater is an important hotspot for antibiotic-resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). However, little is known about the relationship between phages and ARGs in hospital wastewater systems (HWS). In the present study, the viral diversity of 12 HWSs using data from public metagenomic databases was investigated. Viruses were widely found in both the influent and effluent of each HWS. A total of 45 unique ARGs were carried by 85 viral contigs, which accounted for only 0.14% of the total viral populations, implying that ARGs were not commonly present in phages. Three efflux pump genes were identified as shared between phages and bacterial genomes. However, the predominant types of ARGs in HWS such as aminoglycoside- and beta-lactam-resistance genes were rarely found in phages. Based on CRISPR spacer and tRNA matches, interactions between 171 viral contigs and 60 antibiotic-resistant genomes were predicted, including interactions involving phages and vancomycin-resistant Enterococcus_B faecium or beta-lactam-resistant Klebsiella pneumoniae. More than half (56.1%) of these viral contigs indicated lytic and none of them carried ARGs. As the vOTUs in this study had few ARGs and were primarily lytic, HWS may be a valuable source for phage discovery. Future studies will be able to experimentally validate these sequence-based results to confirm the suitability of HWS phages for pathogen control measures in wastewater.

Bacteriophage-based biocontrol technology to enhance the efficiency of wastewater treatment and reduce targeted bacterial biofilms

Wastewater treatment is an essential process for public health and a sustainable ecosystem. Inadequate wastewater treatment can lead to the release of organic and inorganic pollutants and pathogenic bacteria into the receiving waters which could be further utilized for recreation purposes. The interaction between bacteriophage and bacteria in a wastewater treatment plant plays a major role in maintaining the treatment process. Phage therapy has been proposed as an alternative to conventional treatment methods as bacteriophages can be used on specific targets and leave useful bacteria unharmed. The bacterial species, which are responsible for bulking, foaming, and biofilm formation in a wastewater treatment plant (WWTP) have been identified and their respective phages are isolated to control their growth. Phages with lytic life cycles are preferred to lysogenic. Lytic phages can kill the specific target as they lyse the cell, infect most of the hosts, and have an immediate effect on controlling problems caused by bacteria in a WWTP. The bacteriophages such as T7, SPI1, GTE7, PhaxI, MAG1, MAG2, ϕPh_Se01, ϕPh_Se02, and Bxb1 have been investigated for the removal of bacterial biofilms from wastewater. Novel experimental setups have improved the efficiency of phage therapy in small-scale and pilot-scale experiments. Much more in-depth knowledge of the microbial community and their interaction would help promote the usage of phage therapy in large-scale wastewater treatments. This paper has covered the recent advancements in phage therapy as an effective biocontrol of pathogenic bacteria in the wastewater treatment process and has looked at certain shortcomings that have to be improved.

A Klebsiella pneumoniae NDM-1+ bacteriophage: Adaptive polyvalence and disruption of heterogenous biofilms

Bacteriophage KL-2146 is a lytic virus isolated to infect Klebsiella pneumoniae BAA2146, a pathogen carrying the broad range antibiotic resistance gene New Delhi metallo-betalactamase-1 (NDM-1). Upon complete characterization, the virus is shown to belong to the Drexlerviridae family and is a member of the Webervirus genus located within the (formerly) T1-like cluster of phages. Its double-stranded (dsDNA) genome is 47,844 bp long and is predicted to have 74 protein-coding sequences (CDS). After challenging a variety of K. pneumoniae strains with phage KL-2146, grown on the NDM-1 positive strain BAA-2146, polyvalence was shown for a single antibiotic-sensitive strain, K. pneumoniae 13,883, with a very low initial infection efficiency in liquid culture. However, after one or more cycles of infection in K. pneumoniae 13,883, nearly 100% infection efficiency was achieved, while infection efficiency toward its original host, K. pneumoniae BAA-2146, was decreased. This change in host specificity is reversible upon re-infection of the NDM-1 positive strain (BAA-2146) using phages grown on the NDM-1 negative strain (13883). In biofilm infectivity experiments, the polyvalent nature of KL-2146 was demonstrated with the killing of both the multidrug-resistant K. pneumoniae BAA-2146 and drug-sensitive 13,883 in a multi-strain biofilm. The ability to infect an alternate, antibiotic-sensitive strain makes KL-2146 a useful model for studying phages infecting the NDM-1+ strain, K. pneumoniae BAA-2146. GRAPHICAL ABSTRACT.

Bacteriophages in wastewater treatment: can they be an approach to optimize biological treatment processes?

In this paper, we explore the applications of bacteriophages and the advantages of using these viruses to control undesirable organisms in wastewater treatment plants. Based on this, this paper reviewed the literature on the subject by performing a bibliometric and scientometric analysis of articles published in peer-reviewed journals through 2021. We obtained 806 publications, of which 40% were published in the last 5 years, demonstrating an increase in interest in the subject. These articles analyzed, bacteriophages in treatment plants were strongly linked to bacteria such as Escherichia coli and related to disinfection, inactivation, sewage, and wastewater, in addition, biocontrol studies have gained prominence in recent years, particularly due to the resistance of microorganisms to antibiotics. Studies have shown that bacteriophages have great potential for application in treatment systems to control unwanted processes and act as valuable economic and environmental tools to improve the efficiency of various treatment technologies. Although these viruses have already been studied in various applications to optimize treatment plant processes, technology transfer remains a challenge due to the limitations of the technique-such as physicochemical factors related to the environment-and the complexity of biological systems. The research focusing on application strategies in conjunction with molecular biology techniques can expand this study area, enabling the discovery of new bacteriophages.

Genome characterization of the novel lytic genome sequence of the phage YUEEL01 of the Myoviridae family

Antimicrobial resistance is a global concern because of its rapid emergence in the environment and the associated high risk to human and animal health. Municipal wastewater, including urban, hospital, and pharmaceutical effluent, is the primary source of contamination by antibiotics and antibiotic-resistant bacteria (ARB). Biological processes are commonly used for wastewater treatment. Biologically based strategies are a promising approach to effective integrated ARB control because they focus on antibiotic resistance. An effective bacteriophage against multi-drug resistance (MDR) microbes in municipal wastewater was.

Bacteriophages: A weapon against mixed-species biofilms in the food processing environment

Mixed-species biofilms represent the most frequent actual lifestyles of microorganisms in food processing environments, and they are usually more resistant to control methods than single-species biofilms. The persistence of biofilms formed by foodborne pathogens is believed to cause serious human diseases. These challenges have encouraged researchers to search for novel, natural methods that are more effective towards mixed-species biofilms. Recently, the use of bacteriophages to control mixed-species biofilms have grown significantly in the food industry as an alternative to conventional methods. This review highlights a comprehensive introduction of mixed-species biofilms formed by foodborne pathogens and their enhanced resistance to anti-biofilm removal strategies. Additionally, several methods for controlling mixed-species biofilms briefly focused on applying bacteriophages in the food industry have also been discussed. This article concludes by suggesting that using bacteriophage, combined with other 'green' methods, could effectively control mixed-species biofilms in the food industry.

Molecular Insight into AC Electric Field Enhanced Removal of Protein Aggregates from a Material Surface

Biofouling, caused by unwanted accumulation of the biological molecules on the material surface, is a common problem when medical devices are planted in the human body. Application of an electric field was first suggested in the 1960s along with many other approaches to deactivate the biofouling process. There are experiments showing a higher efficiency in reducing the biofouling using the alternating current (AC) compared to the direct current (DC). Here, using molecular dynamics (MD) simulations, we compared the binding stability of a single protein molecule on a graphene surface with either an AC or a DC field was applied. We first showed that the protein molecule, initially attached to the graphene surface, will spontaneously be desorbed by the applied AC electric field, while it remains intact under the DC field of the same voltage. We then revealed that the desorption of the protein by the AC electric field is kinetically controlled. As the orientation of the protein changed alongside the reversing electric field, the protein-graphene interface would be destabilized the most if the AC frequency was close to that of the relaxation of the protein dipole moment (i.e., resonance).

UV and bacteriophages as a chemical-free approach for cleaning membranes from anaerobic bioreactors

Anaerobic membrane bioreactor (AnMBR) for wastewater treatment has attracted much interest due to its efficacy in providing high-quality effluent with minimal energy costs. However, membrane biofouling represents the main bottleneck for AnMBR because it diminishes flux and necessitates frequent replacement of membranes. In this study, we assessed the feasibility of combining bacteriophages and UV-C irradiation to provide a chemical-free approach to remove biofoulants on the membrane. The combination of bacteriophage and UV-C resulted in better log cells removal and ca. 2× higher extracellular polymeric substance (EPS) concentration reduction in mature biofoulants compared to either UV-C or bacteriophage alone. The cleaning mechanism behind this combined approach is by 1) reducing the relative abundance of Acinetobacter spp. and selected bacteria (e.g., Paludibacter, Pseudomonas, Cloacibacterium, and gram-positive Firmicutes) associated with the membrane biofilm and 2) forming cavities in the biofilm to maintain water flux through the membrane. When the combined treatment was further compared with the common chemical cleaning procedure, a similar reduction on the cell numbers was observed (1.4 log). However, the combined treatment was less effective in removing EPS compared with chemical cleaning. These results suggest that the combination of UV-C and bacteriophage have an additive effect in biofouling reduction, representing a potential chemical-free method to remove reversible biofoulants on membrane fitted to an AnMBR.

Bacteriophages as tools for biofilm biocontrol in different fields

Microbial biofilms are difficult to control due to the limited accessibility that antimicrobial drugs and chemicals have to the entrapped inner cells. The extracellular matrix, binds water, contributes to altered cell physiology within biofilms and act as a barrier for most antiproliferative molecules. Thus, new strategies need to be developed to overcome biofilm vitality. In this review, based on 223 documents, the advantages, recommendations, and limitations of using bacteriophages as 'biofilm predators' are presented. The plausibility of using phages (bacteriophages and mycoviruses) to control biofilms grown in different environments is also discussed. The topics covered here include recent historical experiences in biofilm control/eradication using phages in medicine, dentistry, veterinary, and food industries, the pros and cons of their use, and the development of microbial resistance/immunity to such viruses.

Enhanced mutualistic symbiosis between soil phages and bacteria with elevated chromium-induced environmental stress

BACKGROUND

Microbe-virus interactions have broad implications on the composition, function, and evolution of microbiomes. Elucidating the effects of environmental stresses on these interactions is critical to identify the ecological function of viral communities and understand microbiome environmental adaptation. Heavy metal-contaminated soils represent a relevant ecosystem to study the interplay between microbes, viruses, and environmental stressors.

RESULTS

Metagenomic analysis revealed that Cr pollution adversely altered the abundance, diversity, and composition of viral and bacterial communities. Host-phage linkage based on CRISPR indicated that, in soils with high Cr contamination, the abundance of phages associated with heavy metal-tolerant hosts increased, as did the relative abundance of phages with broad host ranges (identified as host-phage linkages across genera), which would facilitate transfection and broader distribution of heavy metal resistance genes in the bacterial community. Examining variations along the pollutant gradient, enhanced mutualistic phage-bacterium interactions were observed in the face of greater environmental stresses. Specifically, the fractions of lysogens in bacterial communities (identified by integrase genes within bacterial genomes and prophage induction assay by mitomycin-C) were positively correlated with Cr contamination levels. Furthermore, viral genomic analysis demonstrated that lysogenic phages under higher Cr-induced stresses carried more auxiliary metabolic genes regulating microbial heavy metal detoxification.

CONCLUSION

With the intensification of Cr-induced environmental stresses, the composition, replication strategy, and ecological function of the phage community all evolve alongside the bacterial community to adapt to extreme habitats. These result in a transformation of the phage-bacterium interaction from parasitism to mutualism in extreme environments and underscore the influential role of phages in bacterial adaptation to pollution-related stress and in related biogeochemical processes. Video Abstract.

Regenerating heavily biofouled dissolved oxygen sensors using bacterial viruses

Bacterial biofilms are aggregates of bacterial cells embedded in a self-produced extracellular polymeric matrix. Biofilm formation has always been considered a major challenge for sensors used in underwater measurements, and is a primary source of measurement error, especially when it comes to long-term in situ monitoring. We demonstrate the utility of lytic bacteriophages (bacterial viruses) as a non-invasive strategy for removing bacterial biofilms formed on the gas permeable membrane of electrochemical dissolved oxygen sensors. Our results show that a 4 day Pseudomonas aeruginosa biofilm with a fully developed matrix significantly affected the sensor signal and response time, decreasing the signal by 32% and increasing the response time by 94%. In addition, measurements with the biofouled membrane had a very low signal to nose ratio compared to a clean sensor membrane. A single dose of overnight phage treatment effectively removed the biofilm (as indicated by scanning electron micrographs and fluorescence images of the membrane), without the need for repeated treatments. Furthermore, the sensor signal that had plummeted by 32% for a fully biofouled membrane, was returned to the original value (7.96 ± 0.27 mg L⁻¹) after phage treatment and the signal to noise ratio (calculated as the ratio of mean to standard deviation) increased 8 folds for a phage-treated membrane compared to a biofouled membrane. Our data indicate near complete regeneration and signal recovery for the dissolved oxygen sensor, making the biofouled sensor reusable without the use of harsh chemicals that could destroy the fragile sensor membrane.

Lytic bacteriophages can be utilized as a non-invasive method for removing bacterial biofilms formed on the surface of gas permeable membranes of dissolved oxygen sensors.

Bacteriophages in water pollution control: Advantages and limitations

Wastewater is a breeding ground for many pathogens, which may pose a threat to human health through various water transmission pathways. Therefore, a simple and effective method is urgently required to monitor and treat wastewater. As bacterial viruses, bacteriophages (phages) are the most widely distributed and abundant organisms in the biosphere. Owing to their capacity to specifically infect bacterial hosts, they have recently been used as novel tools in water pollution control. The purpose of this review is to summarize and evaluate the roles of phages in monitoring pathogens, tracking pollution sources, treating pathogenic bacteria, infecting bloom-forming cyanobacteria, and controlling bulking sludge and biofilm pollution in wastewater treatment systems. We also discuss the limitations of phage usage in water pollution control, including phage-mediated horizontal gene transfer, the evolution of bacterial resistance, and phage concentration decrease. This review provides an integrated outlook on the use of phages in water pollution control.

Pyophage cocktail for the biocontrol of membrane fouling and its effect in aerobic microbial biofilm community during the treatment of antibiotics

Membrane bioreactor systems face an inevitable challenge that is biofouling, which not only hinders the operation of the system, but also poses an environmental and medical concern caused by the increased antibiotic resistance in bacterial biofilms. This study investigates the disruption of membrane fouling using bacteriophage cocktail (Pyophage) in an aerobic membrane bioreactor for treatment of wastewater containing high non-lethal concentration of erythromycin, tetracycline and sulfamethoxazole, while also considering the effect of the cocktail on performance. The results indicate that Pyophage cocktail contributes significantly to the decrease (45%) in transmembrane pressure while also suppressing biofilm-producing bacteria compared to the control reactors. It also reconstructed biodegradation mechanism of antibiotics especially increasing the relative abundance of gram-negative bacteria by enhancement the removal rate of erythromycin and sulfamethoxazole from the aerobic system to 99%.

Hormetic Promotion of Biofilm Growth by Polyvalent Bacteriophages at Low Concentrations

Interactions between bacteriophages (phages) and biofilms are poorly understood despite their broad ecological and water quality implications. Here, we report that biofilm exposure to lytic polyvalent phages at low concentrations (i.e., 10²-10⁴ phages/mL) can counterintuitively promote biofilm growth and densification (corroborated by confocal laser scanning microscopy (CLSM)). Such exposure hormetically upregulated quorum sensing genes (by 4.1- to 24.9-fold), polysaccharide production genes (by 3.7- to 9.3-fold), and curli synthesis genes (by 4.5- to 6.5-fold) in the biofilm-dwelling bacterial hosts (i.e., Escherichia coli and Pseudomonas aeruginosa) relative to unexposed controls. Accordingly, the biofilm matrix increased its polysaccharide and extracellular DNA content relative to unexposed controls (by 41.8 ± 2.3 and 81.4 ± 2.2%, respectively), which decreased biofilm permeability and increased structural integrity. This contributed to enhanced resistance to disinfection with chlorine (bacteria half-lives were 6.08 ± 0.05 vs 3.91 ± 0.03 min for unexposed controls) and to subsequent phage infection (biomass removal was 18.2 ± 1.2 vs 32.3 ± 1.2% for unexposed controls), apparently by mitigating diffusion of these antibacterial agents through the biofilm. Overall, low concentrations of phages reaching a biofilm may result in unintended biofilm stimulation, which might accelerate biofouling, biocorrosion, or other biofilm-related water quality problems.

Evaluating the effect of silver nanoparticles on bacteriophage lytic infection cycle-a mechanistic understanding

Bacteriophages and engineered nano-material (AgNPS) interactions is a relatively unexplored area of research. To answer the fundamental question whether bacteriophage lytic growth cycle is affected by the presence of AgNPs, laboratory experiments were performed with phages of Klebsiella pneumoniae, Delftia tsuruhatensis, Salmonella typhimurium, and Shigella flexneri using silver nanoparticles (AgNPs) with coating materials. One-step growth curves of bacteriophages indicated that the presence of these nanoparticles, and the associated ions of silver, produced pronounced effects on the lytic infection of certain bacteriophages. Effects included 96% reductions in post-infection phage yield in terms of plaque forming units (PFUs) after phages were incubated with silver nanoparticles and 28%-43% reductions from the presence of Ag⁺ alone. However, when Klebsiella pneumonia phage KL and Salmonella typhimurium phage Det7 were exposed to silver nanoparticles coated with poly-N-vinyl-2 pyrrolidone (PVP), an increase in final phage yield by as much as 250% was observed compared with the same phage not incubated with nanoparticles. A proposed mechanism, observed by transmission electron microscopy and verified using synthetic biology by which the nanoparticle binding phenotype can be produced, is that the binding of metal nanomaterial to phage virions results in potentially inhibitory effects. This binding was found to be dependent on the presence of exposed positively charged C-terminal amino-acid residues on the phage capsid surface, implied at first by amino-acid sequence comparisons between capsid proteins of the different phages used in this study. This was then proven experimentally using targeted DNA editing methods to fuse positive charged amino-acid residues to the coat protein C-terminus of non-binding phage. This induced the AgNP binding phenotype, as observed by TEM, DLS size measurements, and growth curve data that show the mutant constructs to be functionally inhibited after exposure to AgNPs. This research sets up a first platform for further research in the unexplored area of phage and AgNP interactions and provides useful findings.

Biofouling and me: My Stockholm syndrome with biofilms

Biofouling is the undesired deposition and growth of microorganisms on surfaces, forming biofilms. The definition is subjective and operational: not every biofilm causes biofouling - only if a given a subjective "threshold of interference" is exceeded, biofilms cause technical or medical problems. These range from the formation of slime layers on ship hulls or in pipelines, which increase friction resistance, to separation membranes, on which biofilms increase hydraulic resistance, to heat exchangers where they interfere with heat transport to contamination of treated water by eroded biofilm cells which may comprise hygienically relevant microorganisms, and, most dangerous, to biofilms on implants and catheters which can cause persistent infections. The largest fraction of anti-fouling research, usually in short-term experiments, is focused on prevention or limiting primary microbial adhesion. Intuitively, this appears only logical, but turns out mostly hopeless. This is because in technical systems with open access for microorganisms, all surfaces are colonized sooner or later which explains the very limited success of that research. As a result, the use of biocides remains the major tool to fight persistent biofilms. However, this is costly in terms of biocides, it stresses working materials, causes off-time and environmental damage and it usually leaves large parts of biofilms in place, ready for regrowth. In order to really solve biofouling problems, it is necessary to learn how to live with biofilms and mitigate their detrimental effects. This requires rather an integrated strategy than aiming to invent "one-shot" solutions. In this context, it helps to understand the biofilm way of life as a natural phenomenon. Biofilms are the oldest, most successful and most widely distributed form of life on earth, existing even in extreme environments and being highly resilient. Microorganisms in biofilms live in a self-produced matrix of extracellular polymeric substances (EPS) which allows them to develop emerging properties such as enhanced nutrient acquisition, synergistic microconsortia, enhanced tolerance to biocides and antibiotics, intense intercellular communication and cooperation. Transiently immobilized, biofilm organisms turn their matrix into an external digestion system by retaining complexed exoenzymes in the matrix. Biofilms grow even on traces of any biodegradable material, therefore, an effective anti-fouling strategy comprises to keep the system low in nutrients (good housekeeping), employing low-fouling, easy-to-clean surfaces, monitoring of biofilm development, allowing for early intervention, and acknowledging that cleaning can be more important than trying to kill biofilms, because cleaning does not cut the nutrient supply of survivors and dead biomass serves as an additional carbon source for "cannibalizing" survivors, supporting rapid after growth. An integrated concept is presented as the result of a long journey of the author through biofouling problems.

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

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.

Mini-review: efficacy of lytic bacteriophages on multispecies biofilms

There is potential for phages to prevent and control bacterial biofilms, but few studies have examined the effect of phages on the multispecies biofilms that characterize most bacterial infections. This paper reviews the mechanism of action of phages, the evidence supporting the view that phage therapy will be effective against bacterial targets and the opposite viewpoint, phage application approaches, and the comparative advantage of phage therapy in multispecies biofilms. The few reports measuring the actions of lytic phages against multispecies biofilms are also reviewed. The authors are cautiously optimistic about the application of phages against their targets when in multispecies biofilms because some lysis mechanisms do not require species specificity.

Bacteriophages To Sensitize a Pathogenic New Delhi Metallo β-Lactamase-Positive Escherichia coli to Solar Disinfection

Bacteriophages active against a New Delhi metallo beta lactamase (NDM)-positive E. coli PI-7 were isolated from municipal wastewater and tested for their lytic effect against the bacterial host. Bacteriophages were highly specific to E. coli PI-7 when tested for host-range. After determining host-specificity, bacteriophages were tested for their ability to sensitize E. coli PI-7 to solar irradiation. Solar irradiation coupled with bacteriophages successfully reduced the length of the lag-phase for E. coli PI-7 from 4 h to 2 h in buffer solution. The reduction of lag-phase length was also observed in filtered wastewater effluent and chlorinated effluent. Previously, we found through gene expression analysis that cell wall, oxidative stress, and DNA repair functions played a large role in protecting E. coli PI-7 against solar damage. Here, gene expression analysis of bacteriophage-supplemented solar-irradiated E. coli PI-7 revealed downregulation of cell wall functions. Downregulation of functions implicated in scavenging and detoxifying reactive oxygen species, as well as DNA repair genes, was also observed in bacteriophage-supplemented solar-irradiated E. coli PI-7. Moreover, solar irradiation activates recA, which can induce lytic activity of bacteriophages. Overall, the combined treatment led to gene responses that appeared to make E. coli PI-7 more susceptible to solar disinfection and bacteriophage infection. Our findings suggest that bacteriophages show good potential to be used as a biocontrol tool to complement solar irradiation in mitigating the persistence of antibiotic-resistant bacteria in reuse waters.

Bacterial Endospores as Phage Genome Carriers and Protective Shells

Bacterial endospores can serve as phage genome protection shells against various environmental stresses to enhance microbial control applications. The genomes of polyvalent lytic Bacillus phages PBSC1 and PBSC2, which infect both B. subtilis subsp. subtilis and B. cereus NRS 248, were incorporated into B. subtilis endospores (without integration into the host chromosome). When PBSC1 and PBSC2 were released from germinating endospores, they significantly inhibited the growth of the targeted opportunistic pathogen B. cereus Optimal endospore entrapment was achieved when phages were introduced to the fast-sporulating prespores at a multiplicity of infection of 1. Longer endospore maturation (48 h versus 24 h) increased both spore yield and efficiency of entrapment. Compared with free phages, spore-protected phage genomes showed significantly higher resistance toward high temperatures (60 to 80°C), extreme pH (pH 2 or pH 12), and copper ions (0.1 to 10 mg/liter). Endospore germination is inducible by low concentrations of l-alanine or by a germinant mixture (l-asparagine, d-glucose, d-fructose, and K+) to trigger the expression, assembly, and consequent release of phage particles within 60 to 90 min. Overall, the superior resiliency of polyvalent phages protected by endospores might enable nonrefrigerated phage storage and enhance phage applications after exposure to adverse environmental conditions.IMPORTANCE Bacteriophages are being considered for the control of multidrug-resistant and other problematic bacteria in environmental systems. However, the efficacy of phage-based microbial control is limited by infectivity loss during phage delivery and/or storage. Here, we exploit the pseudolysogenic state of phages, which involves incorporation of their genome into bacterial endospores (without integration into the host chromosome), to enhance survival in unfavorable environments. We isolated polyvalent (broad-host-range) phages that efficiently infect both benign and opportunistically pathogenic Bacillus strains and encapsulated the phage genomes in B. subtilis endospores to significantly improve resistance to various environmental stressors. Encapsulation by spores also significantly enhanced phage genome viability during storage. We also show that endospore germination can be induced on demand with nutrient germinants that trigger the release of active phages. Overall, we demonstrate that encapsulation of polyvalent phage genomes into benign endospores holds great promise for broadening the scope and efficacy of phage biocontrol.

Bacteriophage Infectivity Against Pseudomonas aeruginosa in Saline Conditions

Pseudomonas aeruginosa is a ubiquitous member of marine biofilm, and reduces thiosulfate to produce toxic hydrogen sulfide gas. In this study, lytic bacteriophages were isolated and applied to inhibit the growth of P. aeruginosa in planktonic mode at different temperature, pH, and salinity. Bacteriophages showed optimal infectivity at a multiplicity of infection of 10 in saline conditions, and demonstrated lytic abilities over all tested temperature (25, 30, 37, and 45°C) and pH 6–9. Planktonic P. aeruginosa exhibited significantly longer lag phase and lower specific growth rates upon exposure to bacteriophages. Bacteriophages were subsequently applied to P. aeruginosa-enriched biofilm and were determined to lower the relative abundance of Pseudomonas-related taxa from 0.17 to 5.58% in controls to 0.01–0.61% in treated microbial communities. The relative abundance of Alphaproteobacteria, Pseudoalteromonas, and Planococcaceae decreased, possibly due to the phage-induced disruption of the biofilm matrix. Lastly, when applied to mitigate biofouling of ultrafiltration membranes, bacteriophages were determined to reduce the transmembrane pressure increase by 18% when utilized alone, and by 49% when used in combination with citric acid. The combined treatment was more effective compared with the citric acid treatment alone, which reported ca. 30% transmembrane pressure reduction. Collectively, the findings demonstrated that bacteriophages can be used as a biocidal agent to mitigate undesirable P. aeruginosa-associated problems in seawater applications.

Bacteriophage Clinical Use as Antibacterial "Drugs": Utility and Precedent

For phage therapy-the treatment of bacterial infections using bacterial viruses-a key issue is the conflict between apparent ease of clinical application, on the one hand, and on the other hand, numerous difficulties that can be associated with undertaking preclinical development. These conflicts between achieving efficacy in the real world versus rigorously understanding that efficacy should not be surprising because equivalent conflicts have been observed in applied biology for millennia: exploiting the inherent, holistic tendencies of useful systems, e.g., of dairy cows, inevitably is easier than modeling those systems or maintaining effectiveness while reducing such systems to isolated parts. Trial and error alone, in other words, can be a powerful means toward technological development. Undertaking trial and error-based programs, especially in the clinic, nonetheless is highly dependent on those technologies possessing both inherent safety and intrinsic tendencies toward effectiveness, but in this modern era we tend to forget that ideally there would exist antibacterials which could be thus developed, that is, with tendencies toward both safety and effectiveness, and which are even relatively inexpensive. Consequently, we tend to demand rigor as well as expense of development even to the point of potentially squandering such utility, were it to exist. In this review I lay out evidence that in phage therapy such potential, in fact, does exist. Advancement of phage therapy unquestionably requires effective regulation as well as rigorous demonstration of efficacy, but after nearly 100 years of clinical practice, perhaps not as much emphasis on strictly laboratory-based proof of principle.

Bacteriophage Isolated from Sewage Eliminates and Prevents the Establishment of Escherichia Coli Biofilm

Purpose: Biofilm growth exerts a negative impact on industry and health, necessitating the development of strategies to control. The objective of this work was study the lytic activity of the phage isolated from the sewage network in the formation and degradation of Escherichia coli biofilms.

Methods: E. coli cultures were incubated in 96-well polystyrene microplates under controlled conditions to evaluate the biofilm formation. The E. coli cultures and established biofilms were treated with the suspensions of the vB_EcoM-UFV017 (EcoM017) bacteriophage obtained from sewage for 24 hours. The E. coli bacterial density was measured using absorbance at 600 nm and the biofilms were measured by crystal violet staining. Polystyrene coupons were used as support for Scanning Electron Microscopy and Confocal Microscopy to evaluate biofilm formation.

Results: The E. coli strains formed biofilms in polystyrene microplates after 48 hours’ incubation. The highest EcoM017 phage titer, in the prevention and degradation experiments, reduced the bacterial growth and the quantity of biofilm formed by E. coli in 90.0% and 87.5%, respectively. The minimum dose capable of reducing the biofilms of this bacterium was 10¹ PFU/mL after 24 hours. The preformed E. coli biofilm mass was reduced 79% post exposure to the phage in the degradation assay. Microscopic analysis confirmed the results obtained in the plates assays.

Conclusion: The EcoM017 phage prevented biofilm formation and degraded the E. coli-established ones. The EcoM017 phage isolated from sewage can reduce bacterial attachment and lyse the E. coli associated biofilm cells, offering biotechnological potential applicability for this phage.

Complete genome sequence of lytic bacteriophage RG-2014 that infects the multidrug resistant bacterium Delftia tsuruhatensis ARB-1

A lytic bacteriophage RG-2014 infecting a biofilm forming multidrug resistant bacterium Delftia tsuruhatensis strain ARB-1 as its host was isolated from a full-scale municipal wastewater treatment plant. Lytic phage RG-2014 was isolated for developing phage based therapeutic approaches against Delftia tsuruhatensis strain ARB-1. The strain ARB-1 belongs to the Comamonadaceae family of the Betaproteobacteria class. RG-2014 was characterized for its type, burst size, latent and eclipse time periods of 150 ± 9 PFU/cell, 10-min, <5-min, respectively. The phage was found to be a dsDNA virus belonging to the Podoviridae family. It has an isometric icosahedrally shaped capsid with a diameter of 85 nm. The complete genome of the isolated phage was sequenced and determined to be 73.8 kbp in length with a G + C content of 59.9%. Significant similarities in gene homology and order were observed between Delftia phage RG-2014 and the E. coli phage N4 indicating that it is a member of the N4-like phage group.

Suppression of Enteric Bacteria by Bacteriophages: Importance of Phage Polyvalence in the Presence of Soil Bacteria

Bacteriophages are widely recognized for their importance in microbial ecology and bacterial control. However, little is known about how phage polyvalence (i.e., broad host range) affects bacterial suppression and interspecies competition in environments harboring enteric pathogens and soil bacteria. Here we compare the efficacy of polyvalent phage PEf1 versus coliphage T4 in suppressing a model enteric bacterium (E. coli K-12) in mixtures with soil bacteria (Pseudomonas putida F1 and Bacillus subtilis 168). Although T4 was more effective than PEf1 in infecting E. coli K-12 in pure cultures, PEf1 was 20-fold more effective in suppressing E. coli under simulated multispecies biofilm conditions because polyvalence enhanced PEf1 propagation in P. putida. In contrast, soil bacteria do not propagate coliphages and hindered T4 diffusion through the biofilm. Similar tests were also conducted under planktonic conditions to discern how interspecies competition contributes to E. coli suppression without the confounding effects of restricted phage diffusion. Significant synergistic suppression was observed by the combined effects of phages plus competing bacteria. T4 was slightly more effective in suppressing E. coli in these planktonic mixed cultures, even though PEf1 reached higher concentrations by reproducing also in P. putida (7.2 ± 0.4 vs 6.0 ± 1.0 log₁₀PFU/mL). Apparently, enhanced suppression by higher PEf1 propagation was offset by P. putida lysis, which decreased stress from interspecies competition relative to incubations with T4. In similar planktonic tests with more competing soil bacteria species, P. putida lysis was less critical in mitigating interspecies competition and PEf1 eliminated E. coli faster than T4 (36 vs 42 h). Overall, this study shows that polyvalent phages can propagate in soil bacteria and significantly enhance suppression of co-occurring enteric species.

Advances in the treatment of problematic industrial biofilms

In nature, microorganisms tend to form biofilms that consist of extracellular polymeric substances with embedded sessile cells. Biofilms, especially mixed-culture synergistic biofilm consortia, are notoriously difficult to treat. They employ various defense mechanisms against attacks from antimicrobial agents. Problematic industrial biofilms cause biofouling as well as biocorrosion, also known as microbiologically influenced corrosion. Biocides are often used to treat biofilms together with scrubbing or pigging. Unfortunately, chemical treatments suppress vulnerable microbial species while allowing resistant species to take over. Repeated treatment cycles are typically needed in biofilm mitigation. This leads to biocide dosage escalation, causing environmental problems, higher costs and sometimes operational problems such as scale formation. New treatment methods are being developed such as enhanced biocide treatment and bacteriophage treatment. Special materials such as antibacterial stainless steels are also being created to combat biofilms. This review discussed some of the advances made in the fight against problematic industrial biofilms.

Insights of Phage-Host Interaction in Hypersaline Ecosystem through Metagenomics Analyses

Bacteriophages, as the most abundant biological entities on Earth, place significant predation pressure on their hosts. This pressure plays a critical role in the evolution, diversity, and abundance of bacteria. In addition, phages modulate the genetic diversity of prokaryotic communities through the transfer of auxiliary metabolic genes. Various studies have been conducted in diverse ecosystems to understand phage-host interactions and their effects on prokaryote metabolism and community composition. However, hypersaline environments remain among the least studied ecosystems and the interaction between the phages and prokaryotes in these habitats is poorly understood. This study begins to fill this knowledge gap by analyzing bacteriophage-host interactions in the Great Salt Lake, the largest prehistoric hypersaline lake in the Western Hemisphere. Our metagenomics analyses allowed us to comprehensively identify the bacterial and phage communities with Proteobacteria, Firmicutes, and Bacteroidetes as the most dominant bacterial species and Siphoviridae, Myoviridae, and Podoviridae as the most dominant viral families found in the metagenomic sequences. We also characterized interactions between the phage and prokaryotic communities of Great Salt Lake and determined how these interactions possibly influence the community diversity, structure, and biogeochemical cycles. In addition, presence of prophages and their interaction with the prokaryotic host was studied and showed the possibility of prophage induction and subsequent infection of prokaryotic community present in the Great Salt Lake environment under different environmental stress factors. We found that carbon cycle was the most susceptible nutrient cycling pathways to prophage induction in the presence of environmental stresses. This study gives an enhanced snapshot of phage and prokaryote abundance and diversity as well as their interactions in a hypersaline complex ecosystem, which can pave the way for further research studies.

Microbial community analysis of bulk sludge/cake layers and biofouling-causing microbial consortia in a full-scale aerobic membrane bioreactor

Pyrosequencing was used to investigate biofouling-causing microbial consortia at the community level in bulk sludge and cake layers within a full-scale membrane bioreactor (MBR). The analysis revealed Chao's estimates of total operational taxonomic units (OTUs) of 1726, 1806, and 1362 for bulk sludge, cake outer layer, and cake inner layer, respectively. The bulk sludge and cake outer layer OTUs clustered together, whereas the cake inner layer OTUs formed a separate group, indicating that environmental conditions affected the microbial community composition within the MBR. Bacteroidetes, Proteobacteria, and Chloroflexi were the dominant phyla in both the bulk sludge and the cake layers. Comparison at the genus level showed twelve distinct genera in the cake layers that were absent in bulk sludge. Twenty distinct genera were recorded in the inner cake layer. Those genera are likely the microbial colonization pioneers in full-scale membrane bioreactors.

Methane dependent denitrification- from ecosystem to laboratory-scale enrichment for engineering applications

Managing nitrogen and carbon cycles in engineered and natural ecosystems is an environmental challenge. In this manuscript, we report a process which connects these two cycles with immense ecological and engineering significance. Sediments, collected from Jordan River in Salt Lake City, Utah were used as seed to start a laboratory-scale denitrification coupled to anaerobic methane oxidation (n-DAMO) reactor fed with methane (CH4) and nitrite (NO2(-)). Methane (CH4)-dependent denitrification in sediments of a nutrient-impaired river was found to be in the range of 40 nmol kg(-1) d(-1) to 70 nmol kg(-1) d(-1). Post 19 months of operation of the lab scale reactor, the n-DAMO reactor achieved nitrite removal rate of 2.88 mmol L(-1) d(-1). Enrichment of n-DAMO prokaryotes was evident from the increase in 16S rRNA gene copy number of bacteria belonging to the NC10 phylum in the reactor, corroborating with increase in the oxidation rates of CH4 coupled with NO2(-)-N removal from 21 μM to 190 μM of CH4 d(-1). Based on stable isotope experiments by other researchers, nitric oxide dismutase (nod) functional gene was hypothesized to be responsible for splitting nitric oxide to nitrogen and oxygen and this internally generated oxygen is utilized by n-DAMO prokaryotes to oxidize methane gas. Primers targeting the unique nitric oxide dismutase (nod) gene were developed and tested on the enrichment culture for the first time. This revealed that n-DAMO organisms are closely related yet distinct from, the M. oxyfera which had been enriched in earlier studies. The results emphasize tremendous future promise to use these novel organisms for wastewater treatment purposes, especially to take advantage of the dissolved methane present in anaerobic digester effluents.

Biofilm control with natural and genetically-modified phages

Bacteriophages, as the most dominant and diverse entities in the universe, have the potential to be one of the most promising therapeutic agents. The emergence of multidrug-resistant bacteria and the antibiotic crisis in the last few decades have resulted in a renewed interest in phage therapy. Furthermore, bacteriophages, with the capacity to rapidly infect and overcome bacterial resistance, have demonstrated a sustainable approach against bacterial pathogens-particularly in biofilm. Biofilm, as complex microbial communities located at interphases embedded in a matrix of bacterial extracellular polysaccharide substances (EPS), is involved in health issues such as infections associated with the use of biomaterials and chronic infections by multidrug resistant bacteria, as well as industrial issues such as biofilm formation on stainless steel surfaces in food industry and membrane biofouling in water and wastewater treatment processes. In this paper, the most recent studies on the potential of phage therapy using natural and genetically-modified lytic phages and their associated enzymes in fighting biofilm development in various fields including engineering, industry, and medical applications are reviewed. Phage-mediated prevention approaches as an indirect phage therapy strategy are also explored in this review. In addition, the limitations of these approaches and suggestions to overcome these constraints are discussed to enhance the efficiency of phage therapy process. Finally, future perspectives and directions for further research towards a better understanding of phage therapy to control biofilm are recommended.

Isolation of Polyvalent Bacteriophages by Sequential Multiple-Host Approaches

Many studies on phage biology are based on isolation methods that may inadvertently select for narrow-host-range phages. Consequently, broad-host-range phages, whose ecological significance is largely unexplored, are consistently overlooked. To enhance research on such polyvalent phages, we developed two sequential multihost isolation methods and tested both culture-dependent and culture-independent phage libraries for broad infectivity. Lytic phages isolated from activated sludge were capable of interspecies or even interorder infectivity without a significant reduction in the efficiency of plating (0.45 to 1.15). Two polyvalent phages (PX1 of the Podoviridae family and PEf1 of the Siphoviridae family) were characterized in terms of adsorption rate (3.54 × 10(-10) to 8.53 × 10(-10) ml/min), latent time (40 to 55 min), and burst size (45 to 99 PFU/cell), using different hosts. These phages were enriched with a nonpathogenic host (Pseudomonas putida F1 or Escherichia coli K-12) and subsequently used to infect model problematic bacteria. By using a multiplicity of infection of 10 in bacterial challenge tests, >60% lethality was observed for Pseudomonas aeruginosa relative to uninfected controls. The corresponding lethality for Pseudomonas syringae was ∼ 50%. Overall, this work suggests that polyvalent phages may be readily isolated from the environment by using different sequential hosts, and this approach should facilitate the study of their ecological significance as well as enable novel applications.

Microbiological study of bacteriophage induction in the presence of chemical stress factors in enhanced biological phosphorus removal (EBPR)

Polyphosphate accumulating organisms (PAOs) are responsible for carrying the enhanced biological phosphorus removal (EBPR). Although the EBPR process is well studied, the failure of EBPR performance at both laboratory and full-scale plants has revealed a lack of knowledge about the ecological and microbiological aspects of EBPR processes. Bacteriophages are viruses that infect bacteria as their sole host. Bacteriophage infection of polyphosphate accumulating organisms (PAOs) has not been considered as a main contributor to biological phosphorus removal upsets. This study examined the effects of different stress factors on the dynamics of bacteriophages and the corresponding effects on the phosphorus removal performance in a lab-scale EBPR system. The results showed that copper (heavy metal), cyanide (toxic chemical), and ciprofloxacin (antibiotic), as three different anthropogenic stress factors, can induce phages integrated onto bacterial genomes (i.e. prophages) in an enriched EBPR sequencing batch reactor, resulting in a decrease in the polyphosphate kinase gene ppk1 clades copy number, phosphorus accumulation capacity, and phosphorus removal performance. This study opens opportunities for further research on the effects of bacteriophages in nutrient cycles both in controlled systems such as wastewater treatment plants and natural ecosystems.

Ecology of Anti-Biofilm Agents II: Bacteriophage Exploitation and Biocontrol of Biofilm Bacteria

Bacteriophages are the viruses of bacteria. In the guise of phage therapy they have been used for decades to successfully treat what are probable biofilm-containing chronic bacterial infections. More recently, phage treatment or biocontrol of biofilm bacteria has been brought back to the laboratory for more rigorous assessment as well as towards the use of phages to combat environmental biofilms, ones other than those directly associated with bacterial infections. Considered in a companion article is the inherent ecological utility of bacteriophages versus antibiotics as anti-biofilm agents. Discussed here is a model for phage ecological interaction with bacteria as they may occur across biofilm-containing ecosystems. Specifically, to the extent that individual bacterial types are not highly abundant within biofilm-containing environments, then phage exploitation of those bacteria may represent a "Feast-or-famine" existence in which infection of highly localized concentrations of phage-sensitive bacteria alternate with treacherous searches by the resulting phage progeny virions for new concentrations of phage-sensitive bacteria to infect. An updated synopsis of the literature concerning laboratory testing of phage use to combat bacterial biofilms is then provided along with tips on how "Ecologically" such phage-mediated biofilm control can be modified to more reliably achieve anti-biofilm efficacy.