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Forensic implementation of soil bacterial DNA profiling is limited by the potential for temporal mismatch of DNA profiles, e.g. after storage or seasonal changes. We compared profiles of samples retrieved at one location over 14 years after air-drying, freeze-drying and –80 °C freezing storage. Sample mismatch in freeze-dried and air-dried samples was significant after two years and continued to increase yearly, whereas profiles after –80 °C freezing remained unchanged for many years. In an attempt to mitigate inter-seasonal temporal mismatches, e.g. when months pass between crime and seizure of evidence, soils sampled in winter and summer were exposed to artificial 'summer' and 'winter' conditions, respectively, and their DNA profiles were compared. Differences were small between soil types, larger between seasons and largest between 'natural' and 'artificial' seasons. Understanding sources of temporal variations is critical for storage of forensics samples and for developing mitigation procedures that could help overcome these time-induced limitations. [ABSTRACT FROM AUTHOR]

This study aimed at testing the application of nano-composites of micelle-montmorillonite for removal of bacteria and parasites from water. The suitability of these complexes for effi cient adsorption of microorganisms was expected on account of their large surface areas, large excess of positive charge, and existence of large hydrophobic domains. Tests included removal from water of bacteria: Gram negative (Escherichia coli K-12), Gram positive (Bacillus megaterium), and a protozoan parasite, Cryptosporidium parvum. Micelles of the organic cations Benzyldimethylhexadecylammonium (BDMHDA), or Octadecyltrimethylammonium complexed with the clay-mineral montmorillonite were shown to reduce by 3-6 orders of magnitude the numbers of microorganisms in water as tested in suspension and by filters (20cm in length) packed with the complexes mixed with excess sand (100:1, w/w). Respiration tests demonstrated that E. coli K-12 cells adsorbed to micelle (BDMHDA)-montmorillonite complex lost their viability. Kinetics of filtration of E. coli by two filters in series was adequately simulated by a model which considers convection, adsorption. and desorption. Filtration of E. coli K-12 cells demonstrated that they stayed adsorbed and inactivated by the complex within the column filter without re-growth in water. These results suggest that filters including micelle-montmorillonite composites can secure the safety of drinking water in case of threatening increases in the number of pathogenic microorganisms in the water. [ABSTRACT FROM AUTHOR]