Evaluating the costs and benefits of marsh-management strategies while accounting for uncertain sea-level rise and ecosystem response.

Prioritization of marsh-management strategies is a difficult task as it requires a manager to evaluate the relative benefits of each strategy given uncertainty in future sea-level rise and in dynamic marsh response. A modeling framework to evaluate the costs and benefits of management strategies while accounting for both of these uncertainties has been developed. The base data for the tool are high-resolution uncertainty-analysis results from the SLAMM (Sea-Level Affecting Marshes Model) under different adaptive-management strategies. These results are combined with an ecosystem-valuation assessment from stakeholders. The SLAMM results and stakeholder values are linked together using "utility functions" that characterize the relationship between stakeholder values and geometric metrics such as "marsh area," marsh edge," or "marsh width." The expected-value of each site's ecosystem benefits can then be calculated and compared using estimated costs for each strategy. Estimates of optimal marsh-management strategies may then be produced, maximizing the "ecosystem benefits per estimated costs" ratio.

Comparison of hollow-fiber ultrafiltration to the USEPA VIRADEL technique and USEPA method 1623.

Hollow-fiber ultrafiltration (UF) is a technique that is increasingly viewed as an effective alternative for simultaneously recovering diverse microbes (e.g., viruses, bacteria, parasites) from large volumes of drinking water. The USEPA has organism-specific methods, including Method 1623 for Cryptosporidium and Giardia and the virus adsorption-elution (VIRADEL) technique using 1MDS electropositive filters. In this study, we directly compare the performance of a previously published UF method to that of the USEPA Method 1623 (for recovering Cryptosporidium parvum and Giardia intestinalis) and the 1MDS VIRADEL method (for bacteriophages and echovirus) using 100-L dechlorinated tap water samples. The UF method produced significantly higher recoveries of C. parvum versus Method 1623 (83% mean recovery for UF versus 46% mean recovery for Method 1623), while recoveries for G. intestinalis were similar for both methods. Results of the virus method comparison showed the UF method (including secondary concentration using microconcentrators) to be very effective for the recovery of echovirus 1, bacteriophage MS2, and bacteriophage phi X174, with mean recovery efficiencies of 58, 100, and 77%, respectively. The VIRADEL technique (including secondary concentration by organic flocculation) recovered significantly less echovirus 1, and the bacteriophages could not be quantified by the method due to phage inactivation and/or assay inhibition. The results of this study demonstrate that the UF technique can be as effective, or more effective, than established USEPA methods for recovery of viruses and protozoan parasites from 100-L tap water samples.

Ultrafiltration-based techniques for rapid and simultaneous concentration of multiple microbe classes from 100-L tap water samples.

This study focused on ultrafiltration as a technique for simultaneously concentrating and recovering viruses, bacteria and parasites in 100-L drinking water samples. A chemical dispersant, sodium polyphosphate, and Tween 80 were used to increase microbial recovery efficiencies. Secondary concentration was performed to reduce sample volumes to 3-5 mL for analysis using tissue culture, microscopy, and real-time PCR and RT-PCR. At seeding levels of 100-1000 (CFU, PFU, oocysts, or particles), a "high-flux" ultrafiltration procedure was found to achieve mean recoveries of 51-94% of simultaneously seeded MS2 bacteriophage, echovirus 1, Salmonella enterica subsp. enterica serovar Typhimurium, Bacillus atrophaeus subsp. globigii endospores, Cryptosporidium parvum oocysts, and 4.5-mum microspheres. When 4-7% of the final sample concentrate volume was assayed using real-time PCR and RT-PCR, overall method sensitivities were <100 C. parvum oocysts, <240 PFU echovirus 1, <100 CFU Salmonella and approximately 160 CFU B. atrophaeus spores in 100-L drinking water samples. The "high-flux" ultrafiltration procedure required approximately 2 h, including time required for backflushing. Secondary concentration procedures required an additional 1-3 h, while nucleic acid extraction and real-time PCR procedures required an additional 2-2.5 h. Thus, this study demonstrated that efficient recovery and sensitive detection of diverse microbes in 100-L drinking water samples could be achieved within 5-8 h using ultrafiltration, rapid secondary processing techniques, and real-time PCR.

Evaluation of 1MDS electropositive microfilters for simultaneous recovery of multiple microbe classes from tap water.

The 1MDS electropositive microfilter was designed specifically for virus capture and recovery from water, but its electrostatic properties raise the possibility that 1MDS filters can also effectively capture bacteria and parasites present in water samples. This filter is recommended by United States Environmental Protection Agency (USEPA) for recovering human enteric viruses from water matrices through the Virus Adsorption-Elution (VIRADEL) technique. If bacteria and parasites can also be concentrated and recovered using 1MDS filters, this sampling technique would have greater utility and cost-effectiveness for microbial water quality testing. In this study, both 142-mm flat and 25.4-cm cartridge 1MDS filters (Cuno) were tested to determine their effectiveness for recovery of MS2 and phi X174 bacteriophage, Salmonella enterica (serovar Typhimurium), Bacillus globigii endospores, and Cryptosporidium parvum oocysts from a tap water matrix. By amending the USEPA standard beef extract/glycine eluent with a surfactant (Tween 80) and dispersant (sodium polyphosphate) and varying the pH and temperature, multiple eluent conditions were compared in order to identify an optimum eluent for all organisms. While viruses, bacteria, and parasites are effectively retained by the 1MDS filter, elution efficiencies and associated recovery efficiencies varied for each organism.

Culture-based MEMS device to track Gordonia in activated sludge.

Previously, we reported on the use of microelectromechanical systems (MEMS) fabrication technologies to develop paraffin surfaces for miniaturization of culture-based detection and rapid quantification of Mycolata in environmental samples. In the current study, the novel culture-based biochip was calibrated with a broad range of pure cultures of Mycolata including Gordonia spp. isolated from activated sludge foam. The biochip successfully recovered Gordonia amarae spiked into a sample of mixed liquor collected from a municipal activated sludge system. Comparisons of these results with molecular biology-based assays including 16S rRNA-targeted fluorescence in situ hybridization (FISH) and antibody staining demonstrated that the biochip provides a more rapid and user-friendly platform for reliable identification and quantification of Mycolata in full-scale municipal activated sludge sewage treatment plants. The results of this work successfully demonstrate an alternative platform technology for inexpensive monitoring of environmental microorganisms using existing expertise by potential users in the area of bacterial cultivation.

Development of a rapid method for simultaneous recovery of diverse microbes in drinking water by ultrafiltration with sodium polyphosphate and surfactants.

The ability to simultaneously concentrate diverse microbes is an important consideration for sample collection methods that are used for emergency response and environmental monitoring when drinking water may be contaminated with an array of unknown microbes. This study focused on developing a concentration method using ultrafilters and different combinations of a chemical dispersant (sodium polyphosphate [NaPP]) and surfactants. Tap water samples were seeded with bacteriophage MS2, Escherichia coli, Enterococcus faecalis, Cryptosporidium parvum, 4.5-microm microspheres, Salmonella enterica serovar Typhimurium, Bacillus globigii endospores, and echovirus 1. Ten-liter tap water samples were concentrated to approximately 250 ml in 12 to 42 min, depending on the experimental condition. Initial experiments indicated that pretreating filters with fetal bovine serum or NaPP resulted in an increase in microbe recovery. The addition of NaPP to the tap water samples resulted in significantly higher microbe and microsphere recovery efficiencies. Backflushing of the ultrafilter was found to significantly improve recovery efficiencies. The effectiveness of backflushing was improved further with the addition of Tween 80 to the backflush solution. The ultrafiltration method developed in this study, incorporating the use of NaPP pretreatment and surfactant solution backflushing, was found to recover MS2, C. parvum, microspheres, and several bacterial species with mean recovery efficiencies of 70 to 93%. The mean recovery efficiency for echovirus 1 (49%) was the lowest of the microbes studied for this method. This research demonstrates that ultrafiltration can be effective for recovering diverse microbes simultaneously in tap water and that chemical dispersants and surfactants can be beneficial for improving microbial recovery using this technique.

Developing rapid detection of mycobacteria using microwaves.

In this paper, we describe the development of a culture-based biochip device for rapid detection of mycobacteria in environmental samples. Individual biochips rely upon the unique paraffinophilic nature of mycobacteria to rapidly and selectively adhere to the surface of the device. We used prototype biochips to experimentally demonstrate the concept of rapid and selective detection of mycobacteria by testing pure cultures and using epifluorescence microscopy to visualize microorganisms on the surface. As an alternative, rapid approach for identifying the biomass on the biochip surface, we used microwaves in the 10 to 26 GHz frequency range. The results of this study indicate that different microorganisms are responsible for specific shifts in resonance frequencies of a microwave cavity. By combing the semi-selective paraffin surface of the biochip with the microorganism-specific response to the microwaves, we have developed an improved analytical system with the potential to rapidly identify and enumerate mycobacteria in environmental samples in as little as 2 h.