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At least 181 records · Page 10Linked to original sources
USGS2000

Microbiological and chemical quality of ground water used as a source of public supply in southern Missouri — Phase II, April–July, 1998

The protection of public health through quality public ground-water systems is the responsibility of the U. S. Environmental Protection Agency and the State of Missouri, through the Missouri Department of Natural Resources, Public Drinking Water Program. Approximately 95 percent of the public-water supplies in Missouri use ground water as their source of drinking water through more than 3,700 public wells. Karst terrain, intensive agricultural operations, extensive numbers of on-site sewage systems, and poor well construction can lead to chemical and microbiological contamination of the contributing aquifers. Sitespecific studies and routine regulatory monitoring have produced information on the overall quality and potability of the State's public-drinking-water supplies, but little is known about the presence of viruses. The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, sampled 109 public-water supplies to characterize the physical, chemical, bacterial, and viral conditions in southern Missouri. During April to July 1998, these wells were sampled for nutrients, total organic carbon, optical brighteners, indicator bacteria, enteric viruses, and ribonucleic acid and somatic coli phages. These constituents indicate possible surface contamination of the sampled aquifer. Selection of the wells to be sampled depended on the age of the well (pre-1970), land use, geohydrology, and well construction. None of the physical or chemical constituents measured or analyzed exceeded Missouri's Drinking Water Standards set by the Public Drinking Water Program of the Missouri Department of Natural Resources. The majority of ammonia plus organic nitrogen, nitrite, and phosphorus concentrations were below the laboratory's minimum reporting levels. There were a greater number of detects above the minimum reporting level with respect to the nitrite plus nitrate, ammonia, orthophosphate, and total organic carbon concentrations. Analyses included comparing and contrasting the data by grouping according to well age and construction, karst type, geohydrology, soil type, and land use. There was little variation in well construction between selected wells. The results indicated several groupings of similar and dissimilar concentrations, most expected because of hydrological, physical, or land use differences. Dissolved oxygen values indicated distinct variation in the different groupings. There were significant differences in dissolved oxygen values between the secondary and non-karst areas, the Ozark confined and Ozark unconfined geohydrologic groups, and between agricultural and other land uses. In groupings by soil and geohydrology, the Missouri bootheel region differed with respect to ammonia, total organic carbon, and phosphorus when compared with the other groups. Less than 10 percent of the wells sampled tested positive for bacterial contamination. E. coli was the most frequently detected bacterium. The public wells at Monett and West Plains, Missouri, had plates with colonies too numerous to count for all three indicator bacteria. Further analyses by rRNA (ribosomal RiboNucleic Acid) hybridization techniques detennined that much of the bacteria present were from ruminant and human sources. No enteric viruses were detected in the 109 samples. Both ribonucleic acid and somatic coliphage were detected at two wells. One additional well had ribonucleic acid coliphage and another had somatic coliphage for a total of four wells with coliphage selects.

Missouri↗
USGS2013

Dryland soil microbial communities display spatial biogeographic patterns associated with soil depth and soil parent material

Biological soil crusts (biocrusts) are common to drylands worldwide. We employed replicated, spatially nested sampling and 16S rRNA gene sequencing to describe the soil microbial communities in three soils derived from different parent material (sandstone, shale, and gypsum). For each soil type, two depths (biocrusts, 0–1 cm; below-crust soils, 2–5 cm) and two horizontal spatial scales (15 cm and 5 m) were sampled. In all three soils, Cyanobacteria and Proteobacteria demonstrated significantly higher relative abundance in the biocrusts, while Chloroflexi and Archaea were significantly enriched in the below-crust soils. Biomass and diversity of the communities in biocrusts or below-crust soils did not differ with soil type. However, biocrusts on gypsum soil harbored significantly larger populations of Actinobacteria and Proteobacteria and lower populations of Cyanobacteria. Numerically dominant operational taxonomic units (OTU; 97% sequence identity) in the biocrusts were conserved across the soil types, whereas two dominant OTUs in the below-crust sand and shale soils were not identified in the gypsum soil. The uniformity with which small-scale vertical community differences are maintained across larger horizontal spatial scales and soil types is a feature of dryland ecosystems that should be considered when designing management plans and determining the response of biocrusts to environmental disturbances.

Utah↗
USGS2006

Quantity-activity relationship of denitrifying bacteria and environmental scaling in streams of a forested watershed

The spatial variability of subreach denitrification rates in streams was evaluated with respect to controlling environmental conditions, molecular examination of denitrifying bacteria, and dimensional analysis. Denitrification activities ranged from 0 and 800 ng-N gsed-1 d-1 with large variations observed within short distances (<50 m) along stream reaches. A log-normal probability distribution described the range in denitrification activities and was used to define low (16% of the probability distributibn), medium (68%), and high (16%) denitrification potential groups. Denitrifying bacteria were quantified using a competitive polymerase chain reaction (cPCR) technique that amplified the nirK gene that encodes for nitrite reductase. Results showed a range of nirK quantities from 103 to 107 gene-copy-number gsed.-1 A nonparametric statistical test showed no significant difference in nirK quantifies among stream reaches, but revealed that samples with a high denitrification potential had significantly higher nirK quantities. Denitrification activity was positively correlated with nirK quantities with scatter in the data that can be attributed to varying environmental conditions along stream reaches. Dimensional analysis was used to evaluate denitrification activities according to environmental variables that describe fluid-flow properties, nitrate and organic material quantities, and dissolved oxygen flux. Buckingham's pi theorem was used to generate dimensionless groupings and field data were used to determine scaling parameters. The resulting expressions between dimensionless NO3- flux and dimensionless groupings of environmental variables showed consistent scaling, which indicates that the subreach variability in denitrification rates can be predicted by the controlling physical, chemical, and microbiological conditions. Copyright 2006 by the American Geophysical Union.

Journal of Geophysical Research G: Biogeosciences↗
USGS2015

Biological and geochemical data along Indian Point, Vermilion Bay, Louisiana

Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center collected shallow sediment cores and surface samples from a coastal salt marsh environment next to Vermilion Bay in southwest Louisiana in January 2013. The sampling was part of a larger USGS study to gather data for assessing environmental changes over the past 150 years. The objective of the study was to expand upon the historical context of sea level and storms affecting coastal systems and how these systems might change under persistent or varying conditions. The data from this report add to a regional environmental change database that aids with the continuing effort to understand the evolution of coastal systems. This report serves as an archive for sedimentological, radiochemical, and microbiological data derived from the sediment cores. Data are available for January 2013. Downloadable data are available as Excel spreadsheets and as JPEG files. Additional files include ArcGIS shapefiles of the sampling sites, detailed results of sediment analyses, and formal Federal Geographic Data Committee metadata. Acknowledgments The authors thank Nancy DeWitt, B.J. Reynolds, Christopher Reich (USGS, St. Petersburg Coastal and Marine Science Center), for help with sample collection and processing; Michael Ball, Sarai Piazza, and Gregory Steyer (USGS, Coastal Restoration Assessment Branch) for assistance accessing CRMS Site 541; and Darrell Anders and Phillip Turnipseed (USGS National Wetlands Research Center) for technical support while in the field. We would also like to thank Caitlyn Reynolds and Nicholas Zaremba for their pre-release commentary and peer review. Information Statement This publication was prepared by an agency of the United States Government. Although these data were processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency

Louisiana↗
USGS2011

Distribution of Fecal Indicator Bacteria along the Malibu, California, Coastline

Each year, over 550 million people visit California's public beaches. To protect beach-goers from exposure to waterborne disease, California state law requires water-quality monitoring for fecal indicator bacteria (FIB), such as enterococci and Escherichia coli (E. coli), at beaches having more than 50,000 yearly visitors. FIB are used to assess the microbiological quality of water because, although not typically disease causing, they are correlated with the occurrence of certain waterborne diseases. Tests show that FIB concentrations occasionally exceed U.S. Environmental Protection Agency (USEPA) public health standards for recreational water in Malibu Lagoon and at several Malibu beaches (Regional Water Quality Control Board, 2009). Scientists from the U.S. Geological Survey's (USGS) California Water Science Center are doing a study to identify the distribution and sources of FIB in coastal Malibu waters (fig. 1). The study methods were similar to those used in a study of FIB contamination on beaches in the Santa Barbara, California, area (Izbicki and others, 2009). This report describes the study approach and presents preliminary results used to evaluate the distribution and source of FIB in the Malibu area. Results of this study will help decision-makers address human health issues associated with FIB contamination in Malibu, and the methods used in this study can be used in other coastal areas affected by FIB contamination.

Open-File Report↗
USGS2002

Microbial transformation of elements: The case of arsenic and selenium

Microbial activity is responsible for the transformation of at least one third of the elements in the periodic table. These transformations are the result of assimilatory, dissimilatory, or detoxification processes and form the cornerstones of many biogeochemical cycles. Arsenic and selenium are two elements whose roles in microbial ecology have only recently been recognized. Known as "essential toxins", they are required in trace amounts for growth and metabolism but are toxic at elevated concentrations. Arsenic is used as an osmolite in some marine organisms while selenium is required as selenocysteine (i.e. the twenty-first amino acid) or as a ligand to metal in some enzymes (e.g. FeNiSe hydrogenase). Arsenic resistance involves a small-molecular-weight arsenate reductase (ArsC). The use of arsenic and selenium oxyanions for energy is widespread in prokaryotes with representative organisms from the Crenarchaeota, thermophilic bacteria, low and high G+C gram-positive bacteria, and Proteobacteria. Recent studies have shown that both elements are actively cycled and play a significant role in carbon mineralization in certain environments. The occurrence of multiple mechanisms involving different enzymes for arsenic and selenium transformation indicates several different evolutionary pathways (e.g. convergence and lateral gene transfer) and underscores the environmental significance and selective impact in microbial evolution of these two elements.

International Microbiology↗
USGS1984

Water quality of a stream-aquifer system, southern Franklin County, Ohio

The chemical quality of the water resources in the Scioto River valley south of Columbus, Ohio, was evaluated on the basis of data collected from 74 wells and 4 surface-water sites. A very hard calcium bicarbonate water that is high in dissolved solids is characteristic of the aquifer. Mean pH of the ground water is 7.3, and bicaerbonate concentrations range from 238 to 530 milligrams per liter. Concentrations of dissolved iron in water samples (0.01 to 3.9 milligrams per liter) frequently exceed the drinking water standard of 0.3 milligrams per liter established by the Ohio Environmental Protection Agency. The chemical quality of local streams closely resembles the ground-water quality, except for higher concentrations of sodium, chloride, and sulfate in the surface water. Microbiological testing of ground water for fecal bacteria indicated concentrations ranging from 1 to 2,400 colonies per 100 milliliters. The higher concentrations were observed in one well on the Scioto River flood plain after a flood event. Mass-balance calculations of the chemical data indicate that pH is buffered primarily by the carbonate system. Data for pH, calculated Eh, and concentrations of ferrous iron and reduced sulfur show that areas of different chemical environments exist within the aquifer. A reaction model of an induced-infiltration radial collector system indicates the amount of mass transfer (chemical reactions that occur as ground water and surface water mix) is small, and that the mixing ratio between ground and surface waters is four to one.

Water-Resources Investigations Report↗
USGS2016

Optimization of a sample processing protocol for recovery of Bacillus anthracis spores from soil

Following a release of Bacillus anthracis spores into the environment, there is a potential for lasting environmental contamination in soils. There is a need for detection protocols for B. anthracis in environmental matrices. However, identification of B. anthracis within a soil is a difficult task. Processing soil samples helps to remove debris, chemical components, and biological impurities that can interfere with microbiological detection. This study aimed to optimize a previously used indirect processing protocol, which included a series of washing and centrifugation steps. Optimization of the protocol included: identifying an ideal extraction diluent, variation in the number of wash steps, variation in the initial centrifugation speed, sonication and shaking mechanisms. The optimized protocol was demonstrated at two laboratories in order to evaluate the recovery of spores from loamy and sandy soils. The new protocol demonstrated an improved limit of detection for loamy and sandy soils over the non-optimized protocol with an approximate matrix limit of detection at 14 spores/g of soil. There were no significant differences overall between the two laboratories for either soil type, suggesting that the processing protocol will be robust enough to use at multiple laboratories while achieving comparable recoveries.

Journal of Microbiological Methods↗
USGS2018

Collection methods and quality assessment for Escherichia coli, water quality, and microbial source tracking data within Tumacácori National Historical Park and the upper Santa Cruz River, Arizona, 2015-16

Tumacácori National Historical Park protects the culturally important Mission, San José de Tumacácori, while also managing a portion of the ecologically diverse riparian corridor of the Santa Cruz River. This report describes the methods and quality assurance procedures used in the collection of water samples for the analysis of Escherichia coli ( E. coli ), microbial source tracking markers, suspended sediment, water-quality parameters, turbidity, and the data collection for discharge and stage; the process for data review and approval is also described. Finally, this report provides a quantitative assessment of the quality of the E. coli , microbial source tracking, and suspended sediment data. The data-quality assessment revealed that bias attributed to field and laboratory contamination was minimal, with E. coli detections in only 3 out of 33 field blank samples analyzed. Concentrations in the field blanks were several orders of magnitude lower than environmental concentrations. The microbial source tracking (MST) field blank was below the detection limit for all MST markers analyzed. Laboratory blanks for E. coli at the USGS Arizona Water Science Center and laboratory blanks for MST markers at the USGS Ohio Water Microbiology Laboratory were all below the detection limit. Irreplicate data for E. coli and suspended sediment indicated that bias was not introduced to the data by combining samples collected using discrete sampling methods with samples collected using automatic sampling methods. The split and sequential E. coli replicate data showed consistent analytical variability and a single equation was developed to explain the variability of E. coli concentrations. An additional analysis of analytical variability for E. coli indicated analytical variability around 18 percent relative standard deviation and no trend was observed in the concentration during the processing and analysis of multiple split-replicates. Two replicate samples were collected for MST and individual markers were compared for a base flow and flood sample. For the markers found in common between the two types of samples, the relative standard deviation for the base flow sample was more than 3 times greater than the markers in the flood sample. Sequential suspended sediment replicates had a relative standard deviation of about 1.3 percent, indicating that environmental and analytical variability was minimal. A holding time review and laboratory study analysis supported the extended holding times required for this investigation. Most concentrations for flood and base-flow samples were within the theoretical variability specified in the most probable number approach suggesting that extended hold times did not overly influence the final concentrations reported.

Arizona↗
USGS2009

Biomineralization associated with microbial reduction of Fe 3+ and oxidation of Fe 2+ in solid minerals

Iron-reducing and oxidizing microorganisms gain energy through reduction or oxidation of iron, and by doing so play an important role in the geochemical cycling of iron. This study was undertaken to investigate mineral transformations associated with microbial reduction of Fe 3+ and oxidation of Fe 2+ in solid minerals. A fluid sample from the 2450 m depth of the Chinese Continental Scientific Drilling project was collected, and Fe 3+ -reducing and Fe 2+ -oxidizing microorganisms were enriched. The enrichment cultures displayed reduction of Fe 3+ in nontronite and ferric citrate, and oxidation of Fe 2+ in vivianite, siderite, and monosulfide (FeS). Additional experiments verified that the iron reduction and oxidation was biological. Oxidation of FeS resulted in the formation of goethite, lepidocrocite, and ferrihydrite as products. Although our molecular microbiological analyses detected Thermoan-aerobacter ethanolicus as a predominant organism in the enrichment culture, Fe 3+ reduction and Fe 2+ oxidation may be accomplished by a consortia of organisms. Our results have important environmental and ecological implications for iron redox cycling in solid minerals in natural environments, where iron mineral transformations may be related to the mobility and solubility of inorganic and organic contaminants.

American Mineralogist↗
USGS2021

Outside the box: Working with wildlife in biocontainment

Research with captive wildlife in Animal Biosafety Level 2 (ABSL2) and 3 (ABSL3) facilities is becoming increasingly necessary as emerging and re-emerging diseases involving wildlife have increasing impacts on human, animal, and environmental health. Utilizing wildlife species in a research facility often requires outside the box thinking with specialized knowledge, practices, facilities, and equipment. The USGS National Wildlife Health Center (NWHC) houses an ABSL3 facility dedicated to understanding wildlife diseases and developing tools to mitigate their impacts on animal and human health. This review presents considerations for utilizing captive wildlife for infectious disease studies, including, husbandry, animal welfare, veterinary care, and biosafety. Examples are drawn from primary literature review and collective 40-year experience of the NWHC. Working with wildlife in ABSL2 and ABSL3 facilities differs from laboratory animals in that typical laboratory housing systems, husbandry practices, and biosafety practices are not designed for work with wildlife. This requires thoughtful adaptation of standard equipment and practices, invention of customized solutions and development of appropriate enrichment plans using the natural history of the species and the microbiological characteristics of introduced and native pathogens. Ultimately, this task requires critical risk assessment, understanding of the physical and psychological needs of diverse species, creativity, innovation, and flexibility. Finally, continual reassessment and improvement are imperative in this constantly changing specialty area of infectious disease and environmental hazard research.

ILAR Journal↗
USGS2009

Results From a Microbial Source-Tracking Study at Villa Angela Beach, Cleveland, Ohio, 2007

During the 2007 recreational season at Villa Angela Beach in Cleveland, Ohio, scientists with the U.S. Geological Survey (USGS) and the Northeast Ohio Regional Sewer District (NEORSD) found high Escherichia coli (E. coli) concentrations that were not easily explained by results obtained to date in ongoing investigations of recreational water quality at the beach. To help understand the sources behind these elevated E. coli concentrations, the USGS and NEORSD sampled beach-area water for Bacteroides DNA markers. Bacteroides are a group of enteric bacteria that are being used in microbial source tracking, in hope that host-associated DNA markers could be used to indicate potential sources of E. coli in the Villa Angela environment. The USGS Ohio Water Microbiology Laboratory analyzed a total of 13 source samples (sewage and waterfowl feces) and 33 beach-area water and sand samples for three Bacteroides DNA markers. This report lists the results of those analyses, along with environmental conditions at Villa Angela on the dates that samples were collected.

Open-File Report↗
USGS2025

Potential water-quality and hydrology stressors on freshwater mussels with development of environmental DNA assays for selected mussels and macroinvertebrates in Big Darby Creek Basin, Ohio, 2020–22

The richness and abundance of freshwater mussels in the Big Darby Creek Basin has declined in recent decades, according to survey results published by the Ohio Biological Survey. In October 2016, a major mussel die-off of undetermined cause reportedly affected over 50 miles of Big Darby Creek; however, fishes and other wildlife were not noticeably impacted. Pollution, habitat destruction, climate change, and hydrologic modification have all been theorized as potential reasons for the widespread declines in freshwater mussel populations in North America. To better understand potential stressors to mussels and other aquatic organisms in the Big Darby Creek Basin, the U.S. Geological Survey, in cooperation with the Ohio Water Development Authority, evaluated water quality and temporal changes in hydrology at selected locations. In addition, environmental deoxyribonucleic acid (eDNA) quantitative polymerase chain reaction (qPCR) assays were developed to detect the presence of selected mussels and macroinvertebrates using stream water. Time-weighted average concentrations of pesticides, organic wastewater compounds (OWCs), and polycyclic aromatic hydrocarbons (PAHs) were determined for selected locations within the Big Darby Creek Basin. Passive samplers designed to mimic the respiratory exposure of aquatic organisms and the bioconcentration of organic contaminants into their fatty tissues were deployed three times annually at three sites within the Big Darby Creek Basin in 2020 and 2021. Analyses were done for 204 pesticide compounds, 38 OWCs, and 33 PAHs. Of the 204 pesticide compounds, 70 were detected in at least one sample; 30 were detected in all samples. Herbicides and herbicide degradates were the pesticides most frequently detected and also had some of the highest concentrations of the pesticides detected in this study. Three herbicides (atrazine, ametryn, and metribuzin) were detected in at least 88 percent of samples and two fungicides (azoxystrobin and propiconazole) were detected in all samples. Of the 38 OWCs, 24 were detected in at least one sample; however, only one ( N , N -diethyltoluamide [DEET]) was detected in all samples. Of the 33 PAHs, 29 were detected in at least one sample; 12 were detected in all samples. A continuous water-quality monitor was operated seasonally on Big Darby Creek above Georgesville, Ohio, from 2020 to 2022. Dissolved oxygen concentrations generally followed a daily cycle, peaking in early evening and troughing around sunrise. There were occasional 24-hour swings in dissolved oxygen concentration that had a range exceeding 10 milligrams per liter. However, dissolved oxygen concentrations never fell below Ohio’s aquatic life criteria for warmwater habitats (outside of mixing zones) of 4.0 milligrams per liter as an instantaneous minimum and 5.0 milligrams per liter as a minimum 24-hour average. The Ohio water-quality criteria for temperatures are 29.4 degrees Celsius as an instantaneous maximum and 27.8 degrees Celsius as a 24-hour average maximum. In 2020, there were 10 days when the maximum instantaneous value for temperature was exceeded and 3 consecutive days when the maximum 24-hour average temperature was exceeded. Streamflow time-series data from three gaging stations within the Big Darby Creek Basin were evaluated for trends in annual flow statistics and daily nonexceedance probabilities over time. In general, the evaluation of streamflow conditions at the Big Darby Creek gage (with 97 years of record) indicated that streamflow changed between water years 1922 and 2021. During that time span, flows in general increased, the number of high-flow pulses became more frequent, and low-flow pulses and extreme low-flow periods became less frequent. The only strong indication of trends over time in annual flow statistics for the relatively short records for the other two gages (on Little Darby Creek, with 25 years of record, and Hellbranch Run, with 29 years of record) was that as time went on, reversals between rising and falling periods became more frequent. The U.S. Geological Survey Ohio Water Microbiology Laboratory developed eDNA qPCR assays to detect Epioblasma rangiana (northern riffleshell mussels), Chimarra obscura (a species of caddisfly), Maccaffertium pulchellum (a species of mayfly), and optimized a preexisting eDNA qPCR assay to detect for Ptychobranchus fasciolaris (kidneyshell mussels). The assays were validated by using environmental sampling methods. Assay sensitivity was established by determining the limits of detection and quantification. Water samples were collected at 12 sites in the Big Darby Creek Basin between 2020 and 2022 and analyzed for eDNA with the qPCR assays developed for this study.

Ohio↗
USGS2011

Vulnerability of high-latitude soil organic carbon in North America to disturbance

This synthesis addresses the vulnerability of the North American high-latitude soil organic carbon (SOC) pool to climate change. Disturbances caused by climate warming in arctic, subarctic, and boreal environments can result in significant redistribution of C among major reservoirs with potential global impacts. We divide the current northern high-latitude SOC pools into (1) near-surface soils where SOC is affected by seasonal freeze-thaw processes and changes in moisture status, and (2) deeper permafrost and peatland strata down to several tens of meters depth where SOC is usually not affected by short-term changes. We address key factors (permafrost, vegetation, hydrology, paleoenvironmental history) and processes (C input, storage, decomposition, and output) responsible for the formation of the large high-latitude SOC pool in North America and highlight how climate-related disturbances could alter this pool's character and size. Press disturbances of relatively slow but persistent nature such as top-down thawing of permafrost, and changes in hydrology, microbiological communities, pedological processes, and vegetation types, as well as pulse disturbances of relatively rapid and local nature such as wildfires and thermokarst, could substantially impact SOC stocks. Ongoing climate warming in the North American high-latitude region could result in crossing environmental thresholds, thereby accelerating press disturbances and increasingly triggering pulse disturbances and eventually affecting the C source/sink net character of northern high-latitude soils. Finally, we assess postdisturbance feedbacks, models, and predictions for the northern high-latitude SOC pool, and discuss data and research gaps to be addressed by future research.

Journal of Geophysical Research G: Biogeosciences↗
USGS2005

Identification of amoebae implicated in the life cycle of Pfiesteria and Pfiesteria-like dinoflagellates

This study was undertaken to assess whether amoebae commonly found in mesohaline environments are in fact stages in the life cycles of Pfiesteria and Pfiesteria-like dinoflagellates. Primary isolations of amoebae and dinoflagellates were made from water and sediment samples from five tributaries of the Chesapeake Bay. Additional amoebae were also cloned from bioassay aquaria where fish mortality was attributed to Pfiesteria . Electron microscopy and small subunit (SSU) rRNA gene sequence analysis of these isolates clearly demonstrated that the commonly depicted amoeboid form of Pfiesteria is very likely a species of Korotnevella and is unrelated to Pfiesteria or Pfiesteria -like dinoflagellates. We have determined that the Pfiesteria and Pfiesteria -like dinoflagellates examined in this study undergo a typical homothallic life cycle without amoeboid stages. Furthermore, we have demonstrated that cloned amoebae sharing morphological characteristics described for stages in the life cycle of Pfiesteria do not transform into dinozoites. The strict clonal isolation and cultivation techniques used in this study substantially support the conclusion that the amoebae and some of the flagellates depicted in the life cycle of Pfiesteria are environmental contaminants of the Pfiesteria culture system and that the Ambush Predator Hypothesis needs to be rigorously reevaluated.

Maryland, Virginia↗
USGS2017

Environmental Escherichia coli : Ecology and public health implications - A review

Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae . The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through feces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent fecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extra-intestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a fecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics provide the diversity and complexity of E. coli strains in various environments, affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments in regards to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia . The impact of environmental E. coli on water quality and public health is also discussed.

Journal of Applied Microbiology↗