TECHNICAL REPORTS 2468 Concentrating diverse microbes in a time and cost effective manner is an essential component in water quality monitoring of recreational beaches. Historically, detection of bacteria and viruses requires two different capture methods to detect both types of organisms in a given water sample. Te purpose of this present study was to evaluate a newly devised dual layered filtration system, which was developed to simultaneously concentrate both viruses and bacteria in one step from marine waters. An apparatus was designed to accommodate two 90-mm diam., 0.45μm pore size membranes in series, one on top of the other. Te top polyvinylidene fluoride (PVDF) membrane was used to filter bacteria by physical straining while the bottom HA membrane retained viruses through adsorption. Results indicated that the dual layer filtration system recovered 83 ± 14% of the test bacteria (Enterococcus fecalis) and 81 ± 28% of the test virus (MS2 coliphage) on the top and bottom membranes, respectively. Tis research demonstrates the potential of using a dual layered filtration system for the simultaneous concentration of both bacteria and viruses on separate filters from recreational beach waters. Tis system is relatively simple to use, inexpensive, and has the potential to be suitable for routine monitoring. Tis study serves as a proof of concept for the technique. Additional experiments are needed to evaluate the system on a variety of different bacteria and viruses as well as on water with different physical and chemical parameters. Simultaneous Concentration of Enterococci and Coliphage from Marine Waters using a Dual Layer Filtration System A. M. Abdelzaher and H. M. Solo-Gabriele* University of Miami C. J. Palmer University of Florida T. M. Scott BCS Laboratories I ndicator microorganisms are currently used by regulatory agencies to assess beach water quality. Although they may be useful in most cases for establishing the quality of water, indicator microbes are not necessarily protective of human health (Colford et al., 2007). Tus, there is a need to expand current methods used to assess water quality and this expansion can include direct measurements for pathogens. One of the main obstacles in establishing programs for pathogen monitoring is concentrating water samples for the pathogens of interest as they are usually found in low concentrations (Griffin et al., 2003). Ideally the concentration method should isolate the three main classes of pathogens (bacteria, protozoa, and viruses) simultaneously using one standardized technique. Moreover, given the dilute quantities of these pathogens, regulatory and research laboratories need to have the ability to concentrate volumes larger than the traditionally recommended 100 mL to allow for detection. Te two main approaches currently used to concentrate bacte- ria, protozoa, and viruses are size exclusion and membrane adsorp- tion. Techniques based on the size-exclusion approach have shown promising results in simultaneously concentrating all three classes of organisms (Hill et al., 2005, 2007; Paul et al., 1991, 1996). Sev- eral types of filters may be used in this approach including hollow fiber and tangential flow filters. Tese filters may be blocked with a solution such as calf serum or sodium polyphosphate to limit the amount of microbes that will attach to the membrane (Hill et al., 2005). Terefore microbes as well as all other particles above the pore size of the membranes continue to circulate until the volume decreases to <100 mL. Following this initial concentration a sec- ondary concentration usually takes place to further decrease the volume to <1 mL, an amount that can be analyzed by molecular methods, that is, methods based on amplifying and simultaneously quantifying targeted DNA/RNA molecules. Te advantage of this approach is that large volumes of up to 100 L can be concentrated using this method (Hill et al., 2007) and all classes of microbes are concentrated since they are larger than the pore size used. Te dis- advantage of this approach is that membranes may clog premature- Abbreviations: CFU, colony forming units; PFU, plaque forming units; PVDF, polyvinylidene fuoride; qPCR, quantitative polymerase chain reaction. A.M. Abdelzaher, H.M. Solo-Gabriele, C.J. Palmer, and T.M. Scott, Univ. of Miami, Oceans and Human Health Center, Key Biscayne, FL 33149. A.M. Abdelzaher and H.M. Solo- Gabriele, Dep. of Civil, Architectural, and Environmental Engineering, Univ. of Miami, Coral Gables, FL 33146-0630. C.J. Palmer, Dep. of Infectious Disease and Pathology, Univ. of Florida, Gainesville, FL 32608. T.M. Scott, BCS Labs., Miami, FL 33155. Copyright © 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including pho- tocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Published in J. Environ. Qual. 38:2468–2473 (2009). doi:10.2134/jeq2008.0488 Published online 28 Sept. 2009. Received 21 Nov. 2008. *Corresponding author (hmsolo@miami.edu). © ASA, CSSA, SSSA 677 S. Segoe Rd., Madison, WI 53711 USA SHORT COMMUNICATIONS Published November, 2009