Factors Influencing the Persistence of Fecal <i>Bacteroides</i> in Stream Water

Bell, Alyssa; Layton, Alice C.; McKay, Larry D.; Williams, Dan; Gentry, Randall W.; Sayler, Gary S.

doi:10.2134/jeq2008.0258

Cited by 66 publications

(74 citation statements)

References 28 publications

(47 reference statements)

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“…Temperature, on the other hand, had a positive effect on decay rates. This pattern is consistent across all studies examining temperature effects, with the exception that Bell et al (8) noticed a decrease in decay rates between 30 and 35°C, although temperatures around 35°C are not likely to occur often in most natural waters. In our study, in 10°C microcosms, Bacteroidales always persisted longer than in higher-temperature microcosms at any salinity (Fig.…”

Section: Discussionsupporting

confidence: 75%

“…The effects of temperature on Bacteroidales survival have been investigated (8,29), and a general positive relationship between temperature and decay rates has been found, as expected. Several studies have also examined the persistence of Bacteroidales in the presence or absence of light (4,39,40), which have had mixed results.…”

supporting

confidence: 64%

“…(approximately equivalent to 10 copies per PCR); therefore, this value can be viewed as the limit of detection with the (8). d Temperature effect adjusted by using the original decay rates of log 10 copies day Ϫ1 before conversion to ln(C T /C 0 ) with temperature-dependent data presented by Okabe and Shimazu in Table 1 sample volumes and reaction conditions used, consistent with the limit of detection reported for this assay (15).…”

supporting

confidence: 59%

“…It is possible that increased salinity may have inhibited or killed predators in the microcosm design of this study and that of other studies, causing the decrease in decay rates relatied to decreased predation activity, which has been shown to significantly impact Bacteroides marker persistence (23). Using filtered and unfiltered surface waters, the differential survival or persistence due to predation or other biological actions has been shown previously to affect Bacteroidales (8). In the study by Okabe and Shimazu (29), the use of unfiltered seawater increased persistence of Bacteroidales markers in higher-salinity samples, and this was indirectly attributed to salinity controls on predation.…”

Section: Discussionmentioning

confidence: 81%

“…When decay rate estimates from this study and other studies were next adjusted for microcosm conditions (temperature and salinity), good agreement was observed between rate estimates in most cases. The study with the lowest dark freshwater decay rate used an inoculum coming from a single healthy horse (8). The study with the highest dark freshwater decay rates had inocula coming from either strictly human feces from a mixture of eight individuals or strictly cow feces from 10 patties (39).…”

Section: Discussionmentioning

confidence: 99%

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Fecal Bacteroidales Diversity and Decay in Response to Variations in Temperature and Salinity

Schulz

Childers

2011

Appl Environ Microbiol

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Bacteroidales are attractive as water quality indicators because of their potential to discern sources of fecal pollution, and it is presumed that these bacteria do not multiply outside their host organisms. The persistence of a fecal Bacteroidales marker was monitored over 14 days in river water microcosms that varied in temperature from 10°C to 30°C and salinity from 0‰ to 30‰ by quantitative PCR (qPCR). Decay rates were estimated and compared to the results of other studies examining the survival and persistence of Bacteroidales markers by converting decay rates from other studies to a common decay rate unit. The log-linear decay rates estimated in this work ranged from ؊0.18 to ؊1.31 ln(C T /C 0 ) day ؊1 , where C T is the threshold cycle and C 0 is the concentration of cells at time zero, which is comparable to findings in previous studies. Salinity had a positive effect on Bacteroidales marker persistence, while decay was more rapid at higher temperatures. Comparison of 16S rRNA gene clone libraries generated from microcosm samples indicated that most of the operational taxonomic unit (OTU) and phylogenetic diversity was found within samples and not between samples, indicating at least qualitatively that diverse lineages persist and likely have similar survival characteristics under most of the conditions examined. It was noted that the samples at higher salinities also had the smallest amount of diversity between samples as well as the lowest decay rates. This research also highlights the need for a repository of raw survival and persistence data if more sophisticated models of decay are to be employed and compared between different studies.Fecal pollution has negative impacts from both environmental and economic perspectives. The presence of traditional fecal indicator bacteria (FIB), namely, Escherichia coli and Enterococcus, is the standard by which the extent of fecal contamination and potential health hazard is currently assessed for recreational waters. Determining the presence of FIB is a relatively easy task, but determining the source(s) is a considerably more complex problem. Molecular methods based on the identification of 16S rRNA gene markers of fecal Bacteroidales have been successfully applied to delineate the sources of fecal pollution based on differences in host species intestinal community compositions (9,20,34). Determination of the mere presence of different sources of fecal pollution by using host-specific Bacteroidales markers was a significant advance for water quality analysis. The next problem that presented itself was quantifying the relative contributions of fecal pollution from respective sources. Since the first Bacteroidales hostspecific molecular marker detection systems were published, studies have followed describing quantitative PCR (qPCR) methods for quantifying the abundance of specific markers (15,21,25,28) in natural samples. Although enumeration of the specific markers is currently possible, it is clear that host-specific marker quantities in natural waters do not d...

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Section: Discussionsupporting

confidence: 75%

supporting

confidence: 64%

supporting

confidence: 59%

Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

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Fecal Bacteroidales Diversity and Decay in Response to Variations in Temperature and Salinity

Schulz

Childers

2011

Appl Environ Microbiol

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Water Quality Changes Shortly After Low‐Head Dam Removal Examined With Cultural and Microbial Source Tracking Methods

Bohrerova

Park

Halloran

et al. 2016

River Research & Apps

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Short-term effects of low head dam removal on water quality of urbanized stream were evaluated, focusing on fecal pollution indicators. Composite river samples were analyzed for Escherichia coli concentrations, nitrates, phosphates, turbidity and human-specific marker (HF183) and antibiotic resistance marker (tetQ) before and after dam removal during dry weather conditions. The sampled Olentangy River water in summer before the dam removal showed poor water quality with mean E. coli concentration of 439 colony forming unit (CFU)/100 mL, mean turbidity of 10 NTU and mean nutrient concentrations of 0.61 and 0.41 mg/L for nitrate and phosphate, respectively. Surprisingly, even one month after the dam removal, E. coli numbers doubled and nitrate concentration tripled compared to pre-removal concentrations. Although the detected HF183 concentrations were below the quantifiable levels, they did not correlate with E. coli concentrations, suggesting E. coli from other than human fecal origin. The correlation between turbidity and E. coli during dry weather further suggests E. coli accumulation in impoundment sediments and release once dam was removed. These short-term effects of dam removal on water quality should be further evaluated, especially if recreation and other beneficial uses of water in the area are expected. *Significant correlations Figure 2. Plot of average water temperature (°C) with standard deviation (bars) at the four sampling dates (n = 8 per point); all showed significantly different water temperatures WATER QUALITY AFTER LOW-HEAD DAM REMOVAL IN AN URBAN RIVER

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Identification of fecal contamination sources of groundwater in rural areas of Vhembe District Municipality, Limpopo Province, South Africa

Sekgobela,

Murei,

Khabo‐Mmekoa

et al. 2023

Water Environment Research

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Groundwater is a valuable source of drinking water worldwide, recognized as an improved drinking water source. However, on‐site sanitation systems may put groundwater at risk of fecal contamination. In the present study, two approaches were used to ascertain the sources of fecal contamination in groundwater used by communities of the Vhembe District Municipality. Overall, 87.5% of boreholes (n = 70) in the wet and 72.5% in the dry season were contaminated with Escherichia coli, and septic tank (n = 18) wastewaters displayed up to 104 cfu/mL E. coli. Host‐specific Bacteroidales quantitative polymerase chain reaction (qPCR) assays established the presence of human (BacHum and HF183) and animal (Cytb, BacCan, and Pig‐2Bac) genetic markers in groundwater from 15.7% of boreholes (wet) and 10% of boreholes (dry). No strong associations were founded between culturable E. coli counts and the presence/absence of marker genes for all the markers except for Cytb marker, which showed a weak significant correlation (r = 0.217; p = <0.01) between E. coli and the Cytb marker under dry seasonal conditions. Human markers and Cytb were present in the household septic tank wastewater samples. Significant differences in marker genes distribution in wastewater were observed using the Chi‐squared test: HF183 (p = <0.001) and BacHum (p = <0.001). Overall, no association was recorded between markers in groundwater and in wastewater for 18 households' septic tanks. A combined culturable E. coli and host‐specific Bacteroidales qPCR assays remain an appropriate approach for the identification of fecal contamination of groundwater.Practitioner Points Households primarily used private boreholes for drinking water, as a primary source. Most households used on‐site sanitation systems, including ventilated improved pit latrines and flush toilets connected to septic tanks. Escherichia coli was detected in groundwater, and the sources of fecal contamination were humans and animals (pigs, dogs, and chickens). The presence of human and animal markers in groundwater suggests that humans and animals are liable for fecal contamination. Fecal contamination in drinking water sources poses a significant concern due to pathogenic microorganisms posing potential human health risks.

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Factors Influencing the Persistence of Fecal Bacteroides in Stream Water

Cited by 66 publications

References 28 publications

Fecal Bacteroidales Diversity and Decay in Response to Variations in Temperature and Salinity

Fecal Bacteroidales Diversity and Decay in Response to Variations in Temperature and Salinity

Water Quality Changes Shortly After Low‐Head Dam Removal Examined With Cultural and Microbial Source Tracking Methods

Identification of fecal contamination sources of groundwater in rural areas of Vhembe District Municipality, Limpopo Province, South Africa

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