Jenny Jay

Performance of forty-one microbial source tracking methods: a twenty-seven lab evaluation study.

The last decade has seen development of numerous new microbial source tracking (MST) methodologies, but many of these have been tested in just a few laboratories with a limited number of fecal samples. This method evaluation study examined the specificity and sensitivity of 41 MST methodologies by analyzing data generated in 27 laboratories. MST methodologies that targeted human, cow, ruminant, dog, gull, pig, horse, and sheep were tested against sewage, septage, human, cow, dog, deer, pig, chicken, pigeon, gull, horse, and goose fecal samples. Each laboratory received 64 blind samples containing a single source (singletons) or two sources (doubletons), as well as diluted singleton samples to assess method sensitivity. Laboratories utilized their own protocols when performing the methods and data were deposited in a central database before samples were unblinded. Between one and seven laboratories tested each method. The most sensitive and specific assays, based on an analysis of presence/absence of each marker in target and non-target fecal samples, were HF183 endpoint and HF183SYBR (human), CF193 and Rum2Bac (ruminant), CowM2 and CowM3 (cow), BacCan (dog), Gull2SYBR and LeeSeaGull (gull), PF163 and pigmtDNA (pig), HoF597 (horse), PhyloChip (pig, horse, chicken, deer), Universal 16S TRFLP (deer), and Bacteroidales 16S TRFLP (pig, horse, chicken, deer); all had sensitivity and specificity higher than 80% in all or the majority of laboratories. When the abundance of MST markers in target and non-target fecal samples was examined, some assays that performed well in the binary analysis were found to not be sensitive enough as median concentrations fell below a minimum abundance criterion (set at 50 copies per colony forming units of enterococci) in target fecal samples. Similarly, some assays that cross-reacted with non-target fecal sources in the binary analysis were found to perform well in a quantitative analysis because the cross-reaction occurred at very low levels. Based on a quantitative analysis, the best performing methods were HF183Taqman and BacH (human), Rum2Bac and BacR (ruminant), LeeSeaGull (gull), and Pig2Bac (pig); no cow or dog-specific assay met the quantitative specificity and sensitivity criteria. Some of the best performing assays in the study were run by just one laboratory so further testing of assay portability is needed. While this study evaluated the marker performance in defined samples, further field testing as well as development of frameworks for fecal source allocation and risk assessment are needed.

Performance of human fecal anaerobe-associated PCR-based assays in a multi-laboratory method evaluation study.

A number of PCR-based methods for detecting human fecal material in environmental waters have been developed over the past decade, but these methods have rarely received independent comparative testing in large multi-laboratory studies. Here, we evaluated ten of these methods (BacH, BacHum-UCD, Bacteroides thetaiotaomicron (BtH), BsteriF1, gyrB, HF183 endpoint, HF183 SYBR, HF183 Taqman(®), HumM2, and Methanobrevibacter smithii nifH (Mnif)) using 64 blind samples prepared in one laboratory. The blind samples contained either one or two fecal sources from human, wastewater or non-human sources. The assay results were assessed for presence/absence of the human markers and also quantitatively while varying the following: 1) classification of samples that were detected but not quantifiable (DNQ) as positive or negative; 2) reference fecal sample concentration unit of measure (such as culturable indicator bacteria, wet mass, total DNA, etc); and 3) human fecal source type (stool, sewage or septage). Assay performance using presence/absence metrics was found to depend on the classification of DNQ samples. The assays that performed best quantitatively varied based on the fecal concentration unit of measure and laboratory protocol. All methods were consistently more sensitive to human stools compared to sewage or septage in both the presence/absence and quantitative analysis. Overall, HF183 Taqman(®) was found to be the most effective marker of human fecal contamination in this California-based study.

Designing Wireless Sensor Networks as a Shared Resource for Sustainable Development

Wireless sensor networks (WSNs) are a relatively new and rapidly developing technology; they have a wide range of applications including environmental monitoring, agriculture, and public health. Shared technology is a common usage model for technology adoption in developing countries. WSNs have great potential to be utilized as a shared resource due to their on-board processing and ad-hoc networking capabilities, however their deployment as a shared resource requires that the technical community first address several challenges. The main challenges include enabling sensor portability: (1) the frequent movement of sensors within and between deployments, and rapidly deployable systems; (2) systems that are quick and simple to deploy. We first discuss the feasibility of using sensor networks as a shared resource, and then describe our research in addressing the various technical challenges that arise in enabling such sensor portability and rapid deployment. We also outline our experiences in developing and deploying water quality monitoring wireless sensor networks in Bangladesh and California

Pilot- and bench-scale testing of faecal indicator bacteria survival in marine beach sand near point sources

Aim:  Factors affecting faecal indicator bacteria (FIB) and pathogen survival/persistence in sand remain largely unstudied. This work elucidates how biological and physical factors affect die‐off in beach sand following sewage spills.

Growth, CO2 consumption and H2 production of Anabaena variabilis ATCC 29413‐U under different irradiances and CO2 concentrations

Aims:  The objective of this study is to develop kinetic models based on batch experiments describing the growth, CO2 consumption, and H2 production of Anabaena variabilis ATCC 29413‐UTM as functions of irradiance and CO2 concentration.

Persistence and Remobilization of Arsenic in Massachusetts (USA) Lakes Treated With Arsenical Herbicides

Abstract From 1953 to 1969 the Commonwealth of Massachusetts funded a program to evaluate the effectiveness of sodium arsenite for treating algae and macrophytes in lakes. It is well known that arsenic (As) is persistent in the environment; however, little work has been done to determine its long-term fate in the treated lakes. Once sodium arsenite is added to lakes, As typically precipitates and accumulates in bottom sediments, but under certain conditions As in surface sediments can be remobilized to the water column under certain conditions. The goals of this study were to determine whether residual As is present in elevated concentrations in the surface sediments (top 0–15 cm) of treated lakes, and whether As is being significantly remobilized. Eleven lakes were studied: five were known to have been treated with sodium arsenite; three were suspected of having been treated; and three untreated lakes were used for reference. Surface sediment grab samples were collected at multiple locations in each lake and analyzed for total As. In addition, water samples were collected along a vertical transect at the deepest point in each lake and analyzed for total As. In three of the five treated lakes and one of the lakes suspected of having been treated, sediment As concentrations were >100 mg/kg, or about four-fold higher than background. Analysis of the water samples showed that As was being remobilized from sediments of both the treated and untreated lakes where reducing conditions existed. The highest concentrations of dissolved As were measured in the bottom waters of treated lakes at levels >100 μg/L, which is about 50-fold higher than background. Elevated As levels in the sediments of treated lakes could have implications for lake management.

Photobiological Hydrogen Production in a Flat Panel Photobioreactor Using Different Nutrient Media

This study reports a factor 5.5 increase in hydrogen production of Anabaena variabilis ATCC 29413 using Allen-Arnon medium compared with BG-11 and BG-110 media. The results were obtained with a flat panel photobioreactor made of acrylic and operated in two stages at 30°C. Stage 1 aims at converting carbon dioxide into biomass by photosynthesis while Stage 2 aims at producing hydrogen. During Stage 1, the photobioreactor is irradiated with 65 μmol/m2 /s of light and sparged with a mixture of air and carbon dioxide. During Stage 2, irradiance is increased to 150 μmol/m2 /s and the photobioreactor is sparged with pure argon. The parameters continuously monitored are (1) the cyanobacteria concentration, (2) the pH, (3) the dissolved oxygen concentration, (4) the nitrate and (5) the ammonia concentrations in the medium, and (6) the hydrogen concentration in the effluent gas. The three media BG-11, BG-110 , and Allen-Arnon are tested under otherwise similar conditions. The light to biomass energy conversion efficiency varied between 5.5 and 10.5% and was similar for all media. The cyanobacteria concentrations during Stage 2 were 1.10 and 1.17 kg dry cell/m3 with BG-11 and Allen-Arnon media, respectively, while it could not exceed 0.76 kg dry cell/m3 with medium BG-110 . The average specific hydrogen production rates were about 1 and 0.9 L/kg dry cell/h in media BG-11 and BG-110 , respectively. In contrast, it was about 5.6 L/kg dry cell/h in Allen-Arnon medium. The maximum light to hydrogen energy conversion efficiencies achieved were 0.26%, 0.16%, and 1.32% for BG-11, BG-110 , and Allen-Arnon media, respectively. The larger specific hydrogen production rates, efficiencies, and cyanobacteria concentrations achieved using Allen-Arnon medium are attributed to the presence of vanadium, and higher concentrations of molybdenum, magnesium, calcium, sodium, and potassium in the medium.© 2007 ASME

Growth CO2 Consumption, and H2 Production of Anabaena Variabilis ATCC 29413-U Under Different Irradiances and CO2 Concentrations

AIMS The objective of this study is to develop kinetic models based on batch experiments describing the growth, CO(2) consumption, and H(2) production of Anabaena variabilis ATCC 29413-U(TM) as functions of irradiance and CO(2) concentration. METHODS AND RESULTS A parametric experimental study is performed for irradiances from 1120 to 16100 lux and for initial CO(2) mole fractions from 0.03 to 0.20 in argon at pH 7.0 +/- 0.4 with nitrate in the medium. Kinetic models are successfully developed based on the Monod model and on a novel scaling analysis employing the CO(2) consumption half-time as the time scale. CONCLUSIONS Monod models predict the growth, CO(2) consumption and O(2) production within 30%. Moreover, the CO(2) consumption half-time is an appropriate time scale for analysing all experimental data. In addition, the optimum initial CO(2) mole fraction is 0.05 for maximum growth and CO(2) consumption rates. Finally, the saturation irradiance is determined to be 5170 lux for CO(2) consumption and growth whereas, the maximum H(2) production rate occurs around 10,000 lux. SIGNIFICANCE AND IMPACT OF THE STUDY The study presents kinetic models predicting the growth, CO(2) consumption and H(2) production of A. variabilis. The experimental and scaling analysis methods can be generalized to other micro-organisms.