Effects of Sample Holding Time on Concentrations of Microorganisms in Water Samples

Selvakumar, Ariamalar; Borst, Michael; Boner, Mark; Mallon, Phil

doi:10.2175/106143004x141591

Cited by 23 publications

(24 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Contradictory results regarding the holding of E. coli for 48 h have been found by earlier studies (Pope et al 2003;Selvakumar et al 2004). No previous investigations have had the power to analyze a 72 h holding time.…”

Section: Discussionmentioning

confidence: 76%

“…Traditional statistical methods (employed by the majority of holding time literature (Dutka and El-Shaarawi 1980;McDaniels et al 1985;Pope et al 2003;Selvakumar et al 2004;Aulenbach 2010)) prove significant differences between means of groups by rejecting the null hypothesis (equivalent means) in favour of an alternate hypothesis (the means are different) (Streiner 2003). However, in these methods, failing to disprove the null (an insignificant result) is not equivalent to proving the null hypothesis is true (Mascha and Sessler 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, there is limited and inconsistent scientific evidence supporting these policies, none of which is specific to groundwater samples. Previous studies have investigated surface water (lakes and rivers, often those receiving municipal or agricultural waste) (Standridge and Lesar 1977;Dutka and El-Shaarawi 1980;Pope et al 2003;Aulenbach 2010), municipal and industrial effluent (Standridge and Lesar 1977;Dutka and El-Shaarawi 1980;Selvakumar et al 2004), stormwater (Selvakumar et al 2004), and water from within municipal distribution systems (McDaniels et al 1985). Survival rates were variable for different fecal indicator bacteria (FIB), with total coliforms often decreasing shortly after collection (Mendez Novelo et al 2010), whereas fecal coliforms generally survived longer, possibly up to 62 h (Aulenbach 2010).…”

mentioning

confidence: 99%

“…Survival rates were variable for different fecal indicator bacteria (FIB), with total coliforms often decreasing shortly after collection (Mendez Novelo et al 2010), whereas fecal coliforms generally survived longer, possibly up to 62 h (Aulenbach 2010). Some studies observed significant decreases in Escherichia coli (E. coli) density by 18Á24 h (Selvakumar et al 2004, Aulenbach 2010, while other studies suggested that up to 48 h was acceptable (Pope et al 2003). Notably, across all of these studies, there was very little power to analyze holding times greater than 48 h.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Evaluating appropriate maximum holding times for private well water samples

Maier¹,

Krolik

Fan

et al. 2015

Environ. Health Rev.

View full text Add to dashboard Cite

Privately maintained groundwater wells are often located at a great distance from laboratories, creating a barrier to bacteriological testing (a necessity for determining drinking water potability). Extending the acceptable holding time between testing and collection could potentially diminish this barrier. Using seven Escherichia coli strains isolated from private well waters, the acceptability of Ontario's current allowable sample maximum holding time (48 h) was compared with time of collection. Additionally, the acceptability of extending the holding time from 48 h to 72 h was investigated. All analyses were performed using noninferiority statistical approaches to determine if later holding times had no meaningful difference in bacterial growth (determined by colony forming unit enumeration). All strains did not statistically decrease below the acceptable 10% difference during the two time periods. However, variations in the survival rates of isolates were observed, suggesting that a risk management approach should be employed when determining maximum holding times.

show abstract

Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Evaluating appropriate maximum holding times for private well water samples

Maier¹,

Krolik

Fan

et al. 2015

Environ. Health Rev.

View full text Add to dashboard Cite

show abstract

“…Refrigeration at 4°C slows substrate uptake and metabolism by many microorganisms without causing cell death [26], and is a common technique for mitigating distortion of environmental and wastewater samples during short-term storage [24,34,37]; however, the effectiveness of refrigeration for preserving oil fieldproduced water samples has not been documented. To the authors' knowledge, no published studies exist that examine the effects of storage on the anaerobic microbial communities relevant to oil field sampling in general or nitrate amendment studies in particular.…”

Section: Introductionmentioning

confidence: 99%

Storage of oil field-produced waters alters their chemical and microbiological characteristics

Hulecki

Foght

Fedorak

2010

J Ind Microbiol Biotechnol

View full text Add to dashboard Cite

Many oil fields are in remote locations, and the time required for shipment of produced water samples for microbiological examination may be lengthy. No studies have reported on how storage of oil field waters can change their characteristics. Produced water samples from three Alberta oil fields were collected in sterile, industry-approved 4-l epoxy-lined steel cans, sealed with minimal headspace and stored under anoxic conditions for 14 days at either 4 degrees C or room temperature (ca. 21 degrees C). Storage resulted in significant changes in water chemistry, microbial number estimates and/or community response to amendment with nitrate. During room-temperature storage, activity and growth of sulfate-reducing bacteria (and, to a lesser extent, fermenters and methanogens) in the samples led to significant changes in sulfide, acetate and propionate concentrations as well as a significant increase in most probable number estimates, particularly of sulfate-reducing bacteria. Sulfide production during room-temperature storage was likely to be responsible for the altered response to nitrate amendment observed in microcosms containing sulfidogenic samples. Refrigerated storage suppressed sulfate reduction and growth of sulfate-reducing bacteria. However, declines in sulfide concentrations were observed in two of the three samples stored at 4 degrees C, suggesting abiotic losses of sulfide. In one of the samples stored at room temperature, nitrate amendment led to ammonification. These results demonstrate that storage of oil field water samples for 14 days, such as might occur because of lengthy transport times or delays before analysis in the laboratory, can affect microbial numbers and activity as well as water sample chemistry.

show abstract