The influence of external factors on bacteriophages—review

The ability of bacteriophages to survive under unfavorable conditions is highly diversified. We summarize the influence of different external physical and chemical factors, such as temperature, acidity, and ions, on phage persistence. The relationships between a phage’s morphology and its survival abilities suggested by some authors are also discussed. A better understanding of the complex problem of phage sensitivity to external factors may be useful not only for those interested in pharmaceutical and agricultural applications of bacteriophages, but also for others working with phages

Role of Collector Alternating Charged Patches on Transport of <i>Cryptosporidium parvum</i> Oocysts in a Patchwise Charged Heterogeneous Micromodel

The role of collector surface charge heterogeneity on transport of <i>Cryptosporidium parvum</i> oocyst and carboxylate microsphere in 2-dimensional micromodels was studied. The cylindrical silica collectors within the micromodels were coated with 0, 10, 20, 50, and 100% Fe₂O₃ patches. The experimental values of average removal efficiencies (η) of the Fe₂O₃ patches and on the entire collectors were determined. In the presence of significant (>3500 kT) Derjaguin–Landau–Verwey–Overbeek (DLVO) energy barrier between the microspheres and the silica collectors at pH 5.8 and 8.1, η determined for Fe₂O₃ patches on the heterogeneous collectors were significantly less (<i>p</i> < 0.05, <i>t</i> test) than those obtained for collectors coated entirely with Fe₂O₃. However, η calculated for Fe₂O₃ patches for microspheres at pH 4.4 and for oocysts at pH 5.8 and 8.1, where the DLVO energy barrier was relatively small (ca. 200–360 kT), were significantly greater (<i>p</i> < 0.05, <i>t</i> test) than those for the collectors coated entirely with Fe₂O₃. The dependence of η for Fe₂O₃ patches on the DLVO energy barrier indicated the importance of periodic favorable and unfavorable electrostatic interactions between colloids and collectors with alternating Fe₂O₃ and silica patches. Differences between experimentally determined overall η for charged heterogeneous collectors and those predicted by a patchwise geochemical heterogeneous model were observed. These differences can be explained by the model’s lack of consideration for the spatial distribution of charge heterogeneity on the collector surface