[1] Surface and subsurface soil samples analyzed for this investigation were collected from the hyperarid Yungay region in the Atacama Desert, Chile. This report details the bacterial diversity derived from DNA and PLFA extracted directly from these extremely desiccated soils. Actinobacteria, Proteobacteria, Firmicutes and TM7 division bacteria were detected. Ninety-four percent of the 16S rRNA genes cloned from these soils belong to the Actinobacteria phylum, and the majority of these were most closely related to the genus Frankia. A 24-hour water activity (a w ) time course showed a diurnal cycle that peaked at 0.52 in the early predawn hours, and ranged from 0.01-0.08 during the day. All measured water activity values were below the levels required for microbial growth or enzyme activity. Total organic carbon (TOC) concentrations were above the limit of detection and below the limit of quantification (i.e., 200 mg/g < TOC < 1000 mg/g), and phospholipid fatty acid (PLFA) concentrations ranged from 2 Â 10 5 to 7 Â 10 6 cell equivalents per gram of soil. Soil extracts analyzed for culturable biomass yielded mostly no growth on R2A media; the highest single extract yielded 47 colony forming units (CFU) per gram of soil.Citation: Connon, S.

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A fully automated anthrax smoke detector (ASD) has been developed and tested. The ASD is intended to serve as a cost effective front-end monitor for anthrax surveillance systems. The principle of operation is based on measuring airborne endospore concentrations, where a sharp concentration increase signals an anthrax attack. The ASD features an air sampler, a thermal lysis unit, a syringe pump, a time-gated spectrometer, and endospore detection chemistry comprised of dipicolinic acid (DPA)-triggered terbium ion (Tb(3+)) luminescence. Anthrax attacks were simulated using aerosolized Bacillus atrophaeus spores in fumed silica, and corresponding Tb-DPA intensities were monitored as a function of time and correlated to the number of airborne endospores collected. A concentration dependence of 10(2)-10(6) spores/mg of fumed silica yielded a dynamic range of 4 orders of magnitude and a limit of detection of 16 spores/L when 250 L of air were sampled. Simulated attacks were detected in less than 15 min.

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