Adenovirus, MS2 and PhiX174 interactions with drinking water biofilms developed on PVC, cement and cast iron

Abstract

Biofilms colonizing pipe surfaces of drinking water distribution systems could provide habitat and shelter for pathogenic viruses present in the water phase. This study aims (i) to develop a method to detect viral particles present in a drinking water biofilm and (ii) to study viral interactions with drinking water biofilms. A pilot scale system was used to develop drinking water biofilms on 3 materials (7 cm(2) discs): PVC, cast iron and cement. Biofilms were inoculated with viral model including MS2, PhiX174 or adenovirus. Five techniques were tested to recover virus from biofilms. The most efficient uses beef extract and glycine at pH = 9. After sonication and centrifugation, the pH of the supernatant is neutralized prior to viral analysis. The calculated recovery rates varied from 29.3 to 74.6% depending on the virus (MS2 or PhiX174) and the material. Applying this protocol, the interactions of virus models (MS2 and adenovirus) with drinking water biofilms were compared. Our results show that adsorption of viruses to biofilms depends on their isoelectric points, the disc material and the hydrodynamic conditions. Applying hydrodynamic conditions similar to those existing in drinking water networks resulted in a viral adsorption corresponding to less than 1% of the initial viral load.

Impact of sewer biofilms on fate of SARS-CoV-2 RNA and wastewater surveillance

“…In this study, we identified two roles of biofilms in mediating the fate of SARS-CoV-2 RNA in sewers: firstly, biofilms could facilitate RNA biodegradation, which might cause RNA signal loss over long HRTs; secondly, biofilms form a reservoir for viral RNA, protecting virus fragments from being washed off during hydraulic changes, and subsequently releasing RNA fragments back to surrounding wastewater. This suggested that the fate of SARS-CoV-2 RNA in sewers was a dynamic equilibrium between adsorption, decay, desorption and detachment of RNA associated with biofilms, similar to findings of previous studies for other bacterial and viral indicators 8,21 . According to observations in this study, the adsorption and accumulation of SARS-CoV-2 RNA onto biofilms played a dominant role, particularly with respect to degradation, leading to the persistence of RNA in a sewer section after several wastewater replacements.…”

Roles of ionic strength and biofilm roughness on adhesion kinetics of Escherichia coli onto groundwater biofilm grown on PVC surfaces

“…While previous studies have convincingly presented the evidence that biofilms can harbor pathogens (Flemming and Wingender, 2010; Altman et al, 2009; Helmi et al, 2010, 2008; Kumar and Anand, 1998), systematic studies to identify the physical and chemical factors controlling pathogen attachment to biofilm are rare. For example, Escherichia coli and fluorescent polystyrene beads have been found to attach more to biofilms grown from tap water on glass slides than to the surface of clean glass slides (Paris et al, 2009).…”

The effect of chlorination and hydrodynamic shear stress on the persistence of bacteriophages associated with drinking water biofilms

“…An eluting protocol was then carried out as previously described (Helmi et al . ). Briefly, each coupon was immersed in 20 ml of elution buffer containing beef extract (1%) and glycine (50 mmol l −1 ) adjusted to pH 9; probe sonication was carried out twice on ice for 1 min at 20–25 W (Vibra‐cell).…”