Bacteriophages In Water Research Articles

Interaction between functionalized multiwalled carbon nanotubes and MS2 bacteriophages in water

Fate and transport of carbon nanomaterials can be strongly dependent on the interaction with secondary particulates in the aquatic systems. Bio-particulates in water, e.g., viruses with charged and hydrophobic surface moieties, may profoundly influence the interfacial behavior and hence the environmental fate of nanomaterials (and vice versa). This study systematically evaluates the interfacial interaction of acid-functionalized multiwalled carbon nanotubes (MWNTs) with MS2 bacteriophages, or heteroaggregation behavior of these particulates, under mono- and di-valent cations and with Suwannee River humic acid (SRHA). Results indicate that the highest concentration of MS2 (i.e., MWNT:MS2 of 100:1) renders exceptional stability of MWNTs, even in high salinity conditions. However, at lower MS2 concentrations (i.e., MWNT:MS2 of 1000:1 and 10,000:1), the suppression of MWNT heteroaggregation rate is not as significant. The observed enhanced stability is likely caused by the preferential attachment of the MS2 capsids onto MWNT surfaces, which is mediated by electrostatic attraction (between negatively charged oxygen-containing moieties on MWNTs and positively charged amino acid residues on MS2 surfaces) and/or by MS2 capsids with positive hydropathy index (indicating strong hydrophobicity). Presence of SRHA also shows stability enhancement; however, at lower MS2 concentrations, SRHA dominated the heteroaggregation behavior. These results implicate that preferential interaction between virus capsids (i.e., MS2 and may be other waterborne viruses) and carbonaceous nanomaterials may influence environmental transport of both in aquatic environments.

Somatic and F-specific bacteriophages in waters of the small, municipal Rusałka Lake in Szczecin

Investigations of bacteriophages showed that in the environment are mostly in water, but in small municipal lakes sporadically been studied. Previous studies of bacteriophages in the aqueous environment related to the determination of the quantity and diversity and use them as indicators of water pollution. In the last study probably of the most important are the F-specific and somatic bacteriophages specific to E. coli. In our study examined them in a small municipal lake in Szczecin (Poland) in context of occurrence of F-specific and somatic bacteriophages specific to E. coli with used of SAL method. We proved that count of bacteriophages in this water tank is lower in context of different waters, but the relation between the amounts of this viruses and environments condition (air and water temperature) were similar to results observed in waters of seas, rivers and lakes.

Isolation of bacteriophages from air using vacuum filtration technique: an improved and novel method.

Development of a simple and economical air sampler for isolation and enrichment of bacteriophages from air samples. A vacuum filtration unit with simple modifications was used for isolation of bacteriophages from air sampled in the lavatory. Air was sampled at the rate of 62lmin-1 by bubbling into Mcllvaine buffer for 30min, which was used as bacteriophage solution for enrichment and plaque assessment against individual hosts. Alternatively, the aforementioned phage solution was enriched using a host consortium before plaque assessment. Phages were isolated in the range of 1-12PFU per ml by the first method, whereas enrichment with host consortium gave phages around 10- to 1000-folds higher in number. Combining with established enrichment method, an improvement of about 10 times in phage isolation efficiency was attained. The method is very useful for studying the natural bacteriophages of air, requiring only a basic microbiological laboratory setup making it simple and economical. This study brings out a simple, economical air sampler for assessing air bacteriophages that can be employed by any microbial laboratory. Although various methods are available for studying bacteriophages in water and soil, very limited are available for air. To the best of our knowledge, the method developed in this study is unique in its design and concept for studying bacteriophages in air. The sampler is sterilizable by autoclaving and maintains a healthy rate of airflow provided by conventional vacuum pumps. The use of a nonspecific 'trapping solution' allows for the qualitative and quantitative study of air bacteriophages.

Novel Bacteroides host strains for detection of human- and animal-specific bacteriophages in water

Bacteriophages active against specific Bacteroides host strains were shown to be suitable for detection of human faecal pollution. However, the practical application of this finding is limited because some specific host strains were restricted to certain geographic regions. In this study, novel Bacteroides host strains were isolated that discriminate human and animal faecal pollution in Switzerland. Two strains specific for bacteriophages present in human faecal contamination and three strains specific for bacteriophages indicating animal faecal contamination were evaluated. Bacteriophages infecting human strains were exclusively found in human wastewater, whereas animal strains detected bacteriophages only in animal waste. The newly isolated host strains could be used to determine the source of surface and spring water faecal contamination in field situations. Applying the newly isolated host Bacteroides thetaiotaomicron ARABA 84 for detection of bacteriophages allowed the detection of human faecal contamination in spring water.

Ceramic media amended with metal oxide for the capture of viruses in drinking water

Ceramic materials that can adsorb and/or inactivate viruses in water may find widespread application in low‐tech drinking‐water treatment technologies in developing countries, where porous ceramic filters and ceramic granular media filters are increasingly promoted for that purpose. We examined the adsorption and subsequent inactivation of bacteriophages MS2 and ϕX‐174 on five ceramic media in batch adsorption studies to determine media suitability for use in a ceramic water filter application. The media examined were a kaolinitic ceramic medium and four kaolinitic ceramic media amended with iron or aluminium oxides that had been incorporated into the kaolinitic clays before firing. Batch adsorption tests indicate increased sorption and inactivation of surrogate viruses by media amended with Fe and Al oxide, with FeOOH‐amended ceramic inactivating all bacteriophages up to 8 log10. Unmodified ceramic was a poor adsorbent of bacteriophages at less than 1 log10 adsorption‐inactivation and high recovery of sorbed phages. These studies suggest that contact with ceramic media, modified with electropositive Fe or Al oxides, can reduce bacteriophages in waters to a greater extent than unmodified ceramic.

Detection and characterization of F+ RNA bacteriophages in water and shellfish: Application of a multiplex real-time reverse transcription PCR

Genotyping of F+ RNA bacteriophages has been used to distinguish between human and animal contributions to contaminated water and food. There are four genetically distinct genogroups of F+ RNA bacteriophages. Genogroups I and IV predominate in animal wastes and genogroups II and III in wastes of human origin. In this study, a multiplex real-time RT-PCR-based method was developed to detect and genotype F+ RNA bacteriophages. The assay was shown to be broadly reactive against a wide spectrum of F+ RNA bacteriophage strains, including MS2, GA, Qβ, MX1, SP and FI, and was able to detect and genotype F+ RNA bacteriophages in shellfish and river water. The assay is highly sensitive, with detection limits <10 PFU/reaction and <10 copies/reaction of the target sequences carried in plasmids, respectively. The applications of this assay include F+ RNA semi-quantitation and microbial source tracking.

Enumeration of bacteriophages in water by different laboratories of the European Union in two interlaboratory comparison studies

As part of a European project on bacteriophages in bathing waters two interlaboratory comparison studies were carried out (May 1997 and March 1998). During these studies phage reference materials as well as naturally polluted standard samples were analysed in 16 European laboratories. Three groups of bacteriophages were tested using standardised methods: somatic coliphages, F-specific RNA-phages and phages of Bacteroides fragilis. Many of the participating laboratories applied one or more of the phage methods for the first time, after a one-week training session in a central laboratory. Nevertheless, the values of repeatability ( r = 1.35–1.38 calculated on log 10-scale) and reproducibility ( R = 1.52–2.04 calculated on log 10-scale) when analysing phage reference materials were close to the theoretical optimum for a Poisson distribution. When analysing the naturally polluted samples more variation in results within and between laboratories was found ( r = 1.63–2.34; R = 3.10–5.72), in comparison with the results obtained with the pure phage reference materials.

Inactivation of bacteriophages in water by means of non-ionizing (uv-253.7 nm) and ionizing (gamma) radiation: a comparative approach

The inactivation behaviour of the bacteriophages PHI X 174 (ssDNA virus), MS2 (ssRNA virus) and B40-8 (dsDNA) toward non-ionizing (UV-253.7 nm) as well as to ionizing radiation (gamma radiation) was studied in order to evaluate their potential as viral indicators for water disinfection by irradiation. Previous findings of the high UV-253.7 nm resistance of MS2 were confirmed whereas an unexpected high sensitivity to gamma radiation compared to the two other phages was found. On the other hand, PHI X 174 revealed an enhanced UV sensitivity but a high resistance to ionizing radiation. B40-8 had an intermediate position between the other two bacteriophages relative to both types of radiation. As expected, the data of E. coli reconfirmed the unreliability of fecal indicator bacteria for the purpose of predicting responses of viruses to water treatment. In UV disinfection the influence of water matrix may be adequately controlled by considering the UV (253.7 nm) absorption of the water whereas so far no such parameter has existed for the influence of the water quality on ionizing irradiation with respect to the scavenger concentration.

Effect of dissolved oxygen on the inactivation of bacteriophages in water by gamma radiation: Important role of $$H\dot O_2 $$ radicalsradicals

The inactivation of bacteriophages by γ-radiation was studied in 0.1M Na phosphate buffer and in deionized water in the presence and absence of dissolved oxygen. From the results obtained it is possible to make conclusion that\(H\dot O_2 \) radicals /which are formed in radiolysis of water in the presence of oxygen/ have a marked inactivating effect on bacteriophages, but in the simultaneous presence of\(\dot OH\) radicals an inactivation takes place between them.

Comparison of positively charged membrane filters and their use in concentrating bacteriophages in water

Virus adsorption-elution studies and physical measurements were performed on four electro-positive membrane filters (Virosorb 1MDS, Posidyne N66, Zeta plus C-30 and Seitz S). The relative hydrophobicity of the membrane filters was determined by measuring the contact angle of carbon tetrachloride with the filters and by measuring the rate of rise of hexadecane and water in the filters. Viruses adsorbed to the least hydrophobic filter (Virosorb 1MDS) could be eluted by using a solution of salt (NaCI or NaEDTA) alone to disrupt electrostatic interactions between the viruses and the filter. Solutions containing both salt and detergent were required to elute virus adsorbed to two of the more hydrophobic filters (Posidyne N66 and Zeta plus C-30), indicating that both electrostatic and hydrophobic interactions were responsible for viral adsorption to these filters. A two-step procedure for recovering bacteriophages from water was developed that employed different filters for each step. Virosorb 1MDS was used to adsorb indigenous phage in water samples. Adsorbed virus could be recovered by treating the filter with a solution of 1.0 M NaCl. Phages in this solution could be further concentrated by a second adsorption-elution step that used Seitz S filters.

A novel technique for the enumeration of bacteriophage from water

A novel method has been developed for concentrating and enumerating bacteriophages in water. Host bacterial cells are added to water samples to adsorb phage and then the infected bacteria are collected by centrifugation at 4000 rev./min for 30 min. The pellets are resuspended in small volumes and assayed for phages using the agar-overlay method. This procedure was more successful than three established techniques in recovering Bacillus phages from seeded samples of tap water. It also gave efficient recovery of phages from samples of river, lake and sea-water.