Point-of-use Unit Based on Gravity Ultrafiltration Removes Waterborne Gastrointestinal Pathogens from Untreated Water Sources in Rural Communities.

OBJECTIVE: In developing countries, rural communities often face the lack of potable water infrastructure and must rely on untreated sources for drinking, which are often contaminated with waterborne pathogens. The use of home water treatment devices is seen as one means of reducing the risk of exposure to waterborne pathogens. The aim of this study was to evaluate the microbiological and physicochemical performance of a simple in-home point-of-use device based on gravity ultrafiltration through an ultrafilter membrane. METHODS: Twenty-five randomly selected households from 2 rural communities in Culiacán, Mexico, were enrolled. Water samples were collected before and after treatment and during storage for a period of 8 weeks. Heterotrophic bacteria, total coliforms, fecal coliforms, Escherichia coli, and Giardia spp were quantified, as well as various physicochemical parameters. RESULTS: All of the untreated water samples contained high levels of indicator bacteria, but none were detected in the treated water fulfilling the requirements set by the Mexican Norm (NOM-127-SSA1-1994) and the World Health Organization guidelines for drinking water. However, indicator bacteria (fecal coliforms and E coli) were detected in every sample from water stored 24 hours after treatment. CONCLUSION: This study demonstrated that point-of-use filters using gravity-fed ultrafilters are a low-cost, effective water treatment technology for water of poor microbial quality. However, further identification of the sources and mechanisms by which water is contaminated when stored after treatment will help with designing and implementing better strategies for keeping water safe for domestic use.

Effects of forespore-specific overexpression of apurinic/apyrimidinic endonuclease Nfo on the DNA-damage resistance properties of Bacillus subtilis spores.

The effects of overexpression of the apurinic/apyrimidinic DNA endonuclease Nfo on wet and dry heat and UV-C (254 nm) resistance of Bacillus subtilis spores with or without alpha/beta-type small, acid-soluble spore proteins (SASP) were determined. Results revealed that overexpression of Nfo > or =50-fold in spores increased the wet heat resistance of exoA nfo B. subtilis spores (termed alpha(-)beta(-)) that lack most alpha/beta-type SASP, but had no effect on these spores' UV-C resistance. Nfo overexpression also increased these spores' dry heat resistance, and to levels slightly greater than that of wild-type spores. These results are consistent: (1) with wet and dry heat (but not UV-C) generating abasic sites in alpha(-)beta(-) spore DNA; (2) with dry heat generating some of these lesions in spores that retain alpha/beta-type SASP; and (3) indicate that Nfo can repair these abasic lesions following spore germination.