scholarly journals Selective survival of Escherichia coli phylotypes in freshwater beach sand

Author(s):  
Natalie A. Rumball ◽  
HannahRose C. Mayer ◽  
Sandra L. McLellan

Escherichia coli is used as an indicator of fecal pollution at beaches despite evidence of long-term survival in sand. This work investigated the basis for survival of E. coli through field microcosm experiments and phylotypic characterization of more than >1400 E. coli isolated from sand, sewage, and gulls, enabling identification of long-surviving populations and environmental drivers of their persistence. Microcosms containing populations of E. coli from each source (n=176) were buried in the backshore of Lake Michigan for 45 & 96 days under several different nutrient treatments, including unaltered native sand, sterile autoclaved sand and baked nutrient depleted sand. Availability of carbon and nitrogen and competition with the indigenous community were major factors that influenced E. coli survival. E. coli Clermont phylotypes B1 and A were the most dominant phylotypes surviving seasonally (>6 weeks), regardless of source and nutrient treatment, whereas cryptic clade and D/E phylotypes survived over winter (>300 days). Autoclaved sand, presumably supplying nutrients through increased availability, promoted growth and the presence of the indigenous microbial community reduced this effect. Screening of 849 sand E. coli from four freshwater beaches demonstrated that B1, but also D/E, were the most common phylotypes recovered. Analysis by qPCR for the Gull2, Lachno3 and HB human markers demonstrated only 25% of the samples had evidence of gull waste and none of the samples had evidence of human waste. These findings suggest prevalence of E. coli in the sand could be attributed more to long term surviving populations than to new fecal pollution. IMPORTANCE Fecal pollution monitoring still relies upon the enumeration of E. coli, despite the fact that this organism can survive for prolonged periods and has been shown to be easily transported from sand into surrounding waters through waves and runoff, thus no longer represents recent fecal pollution events. Here, we experimentally demonstrate that regardless of host source, certain genetically distinct subgroups, or phylotypes, survive longer than others under conditions typical of Great Lakes beach sites. We found nutrients were a major driver of survival and could actually promote growth, and the presence of native microorganisms modulated these effects. These insights into the dynamics and drivers of survival will improve the interpretation of E. coli measurements at beaches and inform strategies that could focus on reducing nutrient inputs to beaches or maintaining a robust natural microbiome in beach sand.

2003 ◽  
Vol 69 (8) ◽  
pp. 4549-4555 ◽  
Author(s):  
Muruleedhara Byappanahalli ◽  
Melanie Fowler ◽  
Dawn Shively ◽  
Richard Whitman

ABSTRACT Dunes Creek, a small Lake Michigan coastal stream that drains sandy aquifers and wetlands of Indiana Dunes, has chronically elevated Escherichia coli levels along the bathing beach near its outfall. This study sought to understand the sources of E. coli in Dunes Creek's central branch. A systematic survey of random and fixed sampling points of water and sediment was conducted over 3 years. E. coli concentrations in Dunes Creek and beach water were significantly correlated. Weekly monitoring at 14 stations during 1999 and 2000 indicated chronic loading of E. coli throughout the stream. Significant correlations between E. coli numbers in stream water and stream sediment, submerged sediment and margin, and margin and 1 m from shore were found. Median E. coli counts were highest in stream sediments, followed by bank sediments, sediments along spring margins, stream water, and isolated pools; in forest soils, E. coli counts were more variable and relatively lower. Sediment moisture was significantly correlated with E. coli counts. Direct fecal input inadequately explains the widespread and consistent occurrence of E. coli in the Dunes Creek watershed; long-term survival or multiplication or both seem likely. The authors conclude that (i) E. coli is ubiquitous and persistent throughout the Dunes Creek basin, (ii) E. coli occurrence and distribution in riparian sediments help account for the continuous loading of the bacteria in Dunes Creek, and (iii) ditching of the stream, increased drainage, and subsequent loss of wetlands may account for the chronically high E. coli levels observed.


2003 ◽  
Vol 69 (9) ◽  
pp. 5555-5562 ◽  
Author(s):  
Richard L. Whitman ◽  
Meredith B. Nevers

ABSTRACT Swimming advisories due to excessive Escherichia coli concentrations are common at 63rd Street Beach, Chicago, Ill. An intensive study was undertaken to characterize the source and fate of E. coli in beach water and sand at the beach. From April through September 2000, water and sand samples were collected daily or twice daily at two depths on three consecutive days per week (water samples, n = 1,747; sand samples, n = 858); hydrometeorological conditions and bird and bather distributions were also recorded. E. coli concentrations in sand and water were significantly correlated, with the highest concentration being found in foreshore sand, followed by those in submerged sediment and water of increasing depth. Gull contributions to E. coli densities in sand and water were most apparent on the day following gull activity in a given area. E. coli recolonized newly placed foreshore sand within 2 weeks. Analysis of variance, correlation, cluster analyses, concentration gradients, temporal-spatial distribution, demographic patterns, and DNA fingerprinting suggest that E. coli may be able to sustain population density in temperate beach sand during summer months without external inputs. This research presents evidence that foreshore beach sand (i) plays a major role in bacterial lake water quality, (ii) is an important non-point source of E. coli to lake water rather than a net sink, (iii) may be environmentally, and perhaps hygienically, problematic, and (iv) is possibly capable of supporting an autochthonous, high density of indicator bacteria for sustained periods, independent of lake, human, or animal input.


2003 ◽  
Vol 69 (8) ◽  
pp. 4714-4719 ◽  
Author(s):  
Richard L. Whitman ◽  
Dawn A. Shively ◽  
Heather Pawlik ◽  
Meredith B. Nevers ◽  
Muruleedhara N. Byappanahalli

ABSTRACT Each summer, the nuisance green alga Cladophora (mostly Cladophora glomerata) amasses along Lake Michigan beaches, creating nearshore anoxia and unsightly, malodorous mats that can attract problem animals and detract from visitor enjoyment. Traditionally, elevated counts of Escherichia coli are presumed to indicate the presence of sewage, mostly derived from nearby point sources. The relationship between fecal indicator bacteria and Cladophora remains essentially unstudied. This investigation describes the local and regional density of Escherichia coli and enterococci in Cladophora mats along beaches in the four states (Wisconsin, Illinois, Indiana, and Michigan) bordering Lake Michigan. Samples of Cladophora strands collected from 10 beaches (n = 41) were assayed for concentrations of E. coli and enterococci during the summer of 2002. Both E. coli and enterococci were ubiquitous (up to 97% occurrence), with overall log mean densities (± standard errors) of 5.3 (± 4.8) and 4.8 (± 4.5) per g (dry weight). E. coli and enterococci were strongly correlated in southern Lake Michigan beaches (P < 0.001, R 2 = 0.73, n = 17) but not in northern beaches (P = 0.892, n = 16). Both E. coli and enterococci survived for over 6 months in sun-dried Cladophora mats stored at 4°C; the residual bacteria in the dried alga readily grew upon rehydration. These findings suggest that Cladophora amassing along the beaches of Lake Michigan may be an important environmental source of indicator bacteria and call into question the reliability of E. coli and enterococci as indicators of water quality for freshwater recreational beaches.


2009 ◽  
Vol 191 (11) ◽  
pp. 3712-3716 ◽  
Author(s):  
Vyacheslav Palchevskiy ◽  
Steven E. Finkel

ABSTRACT Nutritional competence is the ability of bacterial cells to utilize exogenous double-stranded DNA molecules as a nutrient source. We previously identified several genes in Escherichia coli that are important for this process and proposed a model, based on models of natural competence and transformation in bacteria, where it is assumed that single-stranded DNA (ssDNA) is degraded following entry into the cytoplasm. Since E. coli has several exonucleases, we determined whether they play a role in the long-term survival and the catabolism of DNA as a nutrient. We show here that mutants lacking either ExoI, ExoVII, ExoX, or RecJ are viable during all phases of the bacterial life cycle yet cannot compete with wild-type cells during long-term stationary-phase incubation. We also show that nuclease mutants, alone or in combination, are defective in DNA catabolism, with the exception of the ExoX− single mutant. The ExoX− mutant consumes double-stranded DNA better than wild-type cells, possibly implying the presence of two pathways in E. coli for the processing of ssDNA as it enters the cytoplasm.


2021 ◽  
Author(s):  
Andrea Di Cesare ◽  
Francesco Riva ◽  
Noemi Colinas ◽  
Giulia Borgomaneiro ◽  
Sara Borin ◽  
...  

This study shows that Escherichia coli can be temporarily enriched in zooplankton in natural conditions and that these bacteria can belong to different phylogroups and sequence types including environmental as well as clinical and animal isolates. We isolated 10 E. coli strains and sequenced the genomes of two of them. Phylogenetically the two isolates were closer to strains isolated from poultry meat than with freshwater E. coli, albeit their genomes were smaller than those from poultry. After isolation and fluorescent protein tagging of strains ED1 and ED157 we show that Daphnia sp. can take up these strains and release them alive again, thus forming a temporary host for E. coli. In a chemostat experiment we show that the association does not prolong the bacterial long-term survival, but that at low abundances it does also not significantly reduce the bacterial numbers. We demonstrate that E. coli does not belong to the core microbiota of Daphnia, suffers from competition by the natural microbiota of Daphnia, but can profit from its carapax to survive in water. All in all, this study suggests that the association of E. coli to Daphnia is only temporary but that the cells are viable therein and this might allow encounters with other bacteria for genetic exchange and potential genomic adaptations to the freshwater environment.


2010 ◽  
Vol 76 (24) ◽  
pp. 7925-7930 ◽  
Author(s):  
Evan D. Pepper ◽  
Michael J. Farrell ◽  
Gary Nord ◽  
Steven E. Finkel

ABSTRACT Glycation, or nonenzymatic glycosylation, is a chemical reaction between reactive carbonyl-containing compounds and biomolecules containing free amino groups. Carbonyl-containing compounds include reducing sugars such as glucose or fructose, carbohydrate-derived compounds such as methylglyoxal and glyoxal, and nonsugars such as polyunsaturated fatty acids. The latter group includes molecules such as proteins, DNA, and amino lipids. Glycation-induced damage to these biomolecules has been shown to be a contributing factor in human disorders such as Alzheimer's disease, atherosclerosis, and cataracts and in diabetic complications. Glycation also affects Escherichia coli under standard laboratory conditions, leading to a decline in bacterial population density and long-term survival. Here we have shown that as E. coli aged in batch culture, the amount of carboxymethyl lysine, an advanced glycation end product, accumulated over time and that this accumulation was affected by the addition of glucose to the culture medium. The addition of excess glucose or methylglyoxal to the culture medium resulted in a dose-dependent loss of cell viability. We have also demonstrated that glyoxylase enzyme GloA plays a role in cell survival during glycation stress. In addition, we have provided evidence that carnosine, folic acid, and aminoguanidine inhibit glycation in prokaryotes. These agents may also prove to be beneficial to eukaryotes since the chemical processes of glycation are similar in these two domains of life.


2006 ◽  
Vol 72 (11) ◽  
pp. 7301-7310 ◽  
Author(s):  
Richard L. Whitman ◽  
Meredith B. Nevers ◽  
Muruleedhara N. Byappanahalli

ABSTRACT Recent research has highlighted the occurrence of Escherichia coli in natural habitats not directly influenced by sewage inputs. Most studies on E. coli in recreational water typically focus on discernible sources (e.g., effluent discharge and runoff) and fall short of integrating riparian, nearshore, onshore, and outfall sources. An integrated “beachshed” approach that links E. coli inputs and interactions would be helpful to understand the difference between background loading and sewage pollution; to develop more accurate predictive models; and to understand the differences between potential, net, and apparent culturable E. coli. The objective of this study was to examine the interrelatedness of E. coli occurrence from various coastal watershed components along southern Lake Michigan. The study shows that once established in forest soil, E. coli can persist throughout the year, potentially acting as a continuous non-point source of E. coli to nearby streams. Year-round background stream loading of E. coli can influence beach water quality. E. coli is present in highly variable counts in beach sand to depths just below the water table and to distances at least 5 m inland from the shore, providing a large potential area of input to beach water. In summary, E. coli in the fluvial-lacustrine system may be stored in forest soils, sediments surrounding springs, bank seeps, stream margins and pools, foreshore sand, and surface groundwater. While rainfall events may increase E. coli counts in the foreshore sand and lake water, concentrations quickly decline to prerain concentrations. Onshore winds cause an increase in E. coli in shallow nearshore water, likely resulting from resuspension of E. coli-laden beach sand. When examining indicator bacteria source, flux, and context, the entire “beachshed” as a dynamic interacting system should be considered.


Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2151-2158 ◽  
Author(s):  
Wade M. Hicks ◽  
Matthew V. Kotlajich ◽  
Jonathan E. Visick

The l-isoaspartyl protein carboxyl methyltransferase (pcm) can stimulate repair of isoaspartyl residues arising spontaneously in proteins to normal l-aspartyl residues. PCM is needed in Escherichia coli for maximal long-term survival when exposed to oxidative stress, osmotic stress, repeated heat stress or methanol. The effect of pH on a pcm mutant during long-term stationary phase was examined. PCM was not required for long-term survival of E. coli subjected to pH stress alone; however, PCM-deficient cells showed impaired resistance to paraquat and methanol only at elevated pH. The mutant also showed stress-survival phenotypes in minimal medium buffered to pH 9·0. Accumulation of isoaspartyl residues was accelerated at pH 8·0 or 9·0 in vivo, though PCM-deficient cells did not show higher levels of damage. However, the pcm mutant displayed an extended lag phase in recovering from stationary phase at pH 9·0. Protein repair by PCM thus plays a key role in long-term stress survival only at alkaline pH in E. coli, and it may function primarily to repair damage in cells that are recovering from nutrient limitation and in those cells that are able to divide during long-term stationary phase.


2003 ◽  
Vol 69 (6) ◽  
pp. 3359-3367 ◽  
Author(s):  
Jennifer M. Ritchie ◽  
Graeme R. Campbell ◽  
Jill Shepherd ◽  
Yvonne Beaton ◽  
Davey Jones ◽  
...  

ABSTRACT A chromosomally lux-marked (Tn5 luxCDABE) strain of nontoxigenic Escherichia coli O157:H7 was constructed by transposon mutagenesis and shown to have retained the O157, H7, and intimin phenotypes. The survival characteristics of this strain in the experiments performed (soil at −5, −100, and −1,500 kPa matric potential and artificial groundwater) were indistinguishable from the wild-type strain. Evaluation of potential luminescence was found to be a rapid, cheap, and quantitative measure of viable E. coli O157:H7 Tn5 luxCDABE populations in environmental samples. In the survival studies, bioluminescence of the starved populations of E. coli O157:H7 Tn5 luxCDABE could be reactivated to the original levels of light emission, suggesting that these populations remain viable and potentially infective to humans. The attributes of the construct offer a cheap and low-risk substitute to the use of verocytotoxin-producing E. coli O157:H7 in long-term survival studies.


2006 ◽  
Vol 188 (11) ◽  
pp. 3902-3910 ◽  
Author(s):  
Vyacheslav Palchevskiy ◽  
Steven E. Finkel

ABSTRACT Natural genetic competence is the ability of cells to take up extracellular DNA and is an important mechanism for horizontal gene transfer. Another potential benefit of natural competence is that exogenous DNA can serve as a nutrient source for starving bacteria because the ability to “eat” DNA is necessary for competitive survival in environments containing limited nutrients. We show here that eight Escherichia coli genes, identified as homologs of com genes in Haemophilus influenzae and Neisseria gonorrhoeae, are necessary for the use of extracellular DNA as the sole source of carbon and energy. These genes also confer a competitive advantage to E. coli during long-term stationary-phase incubation. We also show that homologs of these genes are found throughout the proteobacteria, suggesting that the use of DNA as a nutrient may be a widespread phenomenon.


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