Limits...
Relationship between Organic Carbon and Opportunistic Pathogens in Simulated Glass Water Heaters.

Williams K, Pruden A, Falkinham JO, Edwards M, Williams K, Pruden A, Iii JO, Edwards M - Pathogens (2015)

Bottom Line: R2 > 0.89).R2 = 0.82 to 0.97, for 2 out of 4 time points) and over a limited TOC range (0-1000 µg/L), no other correlations were identified between other OPPPs and added TOC.These results suggest that reducing organic carbon in distributed water is not adequate as a sole strategy for controlling OPPPs, although it may have promise in conjunction with other approaches.

View Article: PubMed Central - PubMed

Affiliation: Via Department of Civil and Environmental Engineering, Virginia Tech, 401 Durham Hall, Blacksburg, VA 24060, USA. kwilli@vt.edu.

ABSTRACT
Controlling organic carbon levels in municipal water has been hypothesized to limit downstream growth of bacteria and opportunistic pathogens in premise plumbing (OPPPs). Here, the relationships between influent organic carbon (0-15,000 µg ozonated fulvic acid /L) and the number of total bacteria [16S rRNA genes and heterotrophic plate counts (HPCs)] and a wide range of OPPPs (gene copy numbers of Acanthamoeba polyphaga, Vermamoeba vermiformis, Legionella pneumophila, and Mycobacterium avium) were examined in the bulk water of 120-mL simulated glass water heaters (SGWHs). The SGWHs were operated at 32-37 °C, which is representative of conditions encountered at the bottom of electric water heaters, with water changes of 80% three times per week to simulate low use. This design presented advantages of controlled and replicated (triplicate) conditions and avoided other potential limitations to OPPP growth in order to isolate the variable of organic carbon. Over seventeen months, strong correlations were observed between total organic carbon (TOC) and both 16S rRNA gene copy numbers and HPC counts (avg. R2 > 0.89). Although M. avium gene copies were occasionally correlated with TOC (avg. R2 = 0.82 to 0.97, for 2 out of 4 time points) and over a limited TOC range (0-1000 µg/L), no other correlations were identified between other OPPPs and added TOC. These results suggest that reducing organic carbon in distributed water is not adequate as a sole strategy for controlling OPPPs, although it may have promise in conjunction with other approaches.

No MeSH data available.


Related in: MedlinePlus

Comparison of L. pneumophila and V. vermiformis under 7-day stagnation (Experiment A3). The dashed line represents initial inoculated SGWH concentration.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4493478&req=5

pathogens-04-00355-f003: Comparison of L. pneumophila and V. vermiformis under 7-day stagnation (Experiment A3). The dashed line represents initial inoculated SGWH concentration.

Mentions: As a result of the findings above, Experiment A3 modifications were implemented to further encourage L. pneumophila amplification. All SGWHs were inoculated with V. vermiformis at the beginning of Experiment A3 to provide an alternative host potentially better suited to the synthetic tap water. V. vermiformis was also found to have naturally colonized the A2 SGWHs at low concentrations upon the addition of GAC-treated Blacksburg, VA tap water. In the A3 Experiment, V. vermiformis rapidly increased in gene copy number by 1 log unit higher than the initial concentration (Figure 3). The concentrations peaked around two weeks after the inoculation of the SGWHs with no added TOC. Lower concentrations of added TOC appeared to encourage the growth of this protozoan as opposed to values above 5 µg/L. However, at no point were V. vermiformis numbers correlated with added organic matter (linearized plots of qPCR vs. added TOC resulted in R2 values of −0.175 (p = 0.862) on day 0, −0.462 (p = 0.004) on day 7, and −0.368 (p = 0.207) on day 21 after the start of Experiment A3).


Relationship between Organic Carbon and Opportunistic Pathogens in Simulated Glass Water Heaters.

Williams K, Pruden A, Falkinham JO, Edwards M, Williams K, Pruden A, Iii JO, Edwards M - Pathogens (2015)

Comparison of L. pneumophila and V. vermiformis under 7-day stagnation (Experiment A3). The dashed line represents initial inoculated SGWH concentration.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493478&req=5

pathogens-04-00355-f003: Comparison of L. pneumophila and V. vermiformis under 7-day stagnation (Experiment A3). The dashed line represents initial inoculated SGWH concentration.
Mentions: As a result of the findings above, Experiment A3 modifications were implemented to further encourage L. pneumophila amplification. All SGWHs were inoculated with V. vermiformis at the beginning of Experiment A3 to provide an alternative host potentially better suited to the synthetic tap water. V. vermiformis was also found to have naturally colonized the A2 SGWHs at low concentrations upon the addition of GAC-treated Blacksburg, VA tap water. In the A3 Experiment, V. vermiformis rapidly increased in gene copy number by 1 log unit higher than the initial concentration (Figure 3). The concentrations peaked around two weeks after the inoculation of the SGWHs with no added TOC. Lower concentrations of added TOC appeared to encourage the growth of this protozoan as opposed to values above 5 µg/L. However, at no point were V. vermiformis numbers correlated with added organic matter (linearized plots of qPCR vs. added TOC resulted in R2 values of −0.175 (p = 0.862) on day 0, −0.462 (p = 0.004) on day 7, and −0.368 (p = 0.207) on day 21 after the start of Experiment A3).

Bottom Line: R2 > 0.89).R2 = 0.82 to 0.97, for 2 out of 4 time points) and over a limited TOC range (0-1000 µg/L), no other correlations were identified between other OPPPs and added TOC.These results suggest that reducing organic carbon in distributed water is not adequate as a sole strategy for controlling OPPPs, although it may have promise in conjunction with other approaches.

View Article: PubMed Central - PubMed

Affiliation: Via Department of Civil and Environmental Engineering, Virginia Tech, 401 Durham Hall, Blacksburg, VA 24060, USA. kwilli@vt.edu.

ABSTRACT
Controlling organic carbon levels in municipal water has been hypothesized to limit downstream growth of bacteria and opportunistic pathogens in premise plumbing (OPPPs). Here, the relationships between influent organic carbon (0-15,000 µg ozonated fulvic acid /L) and the number of total bacteria [16S rRNA genes and heterotrophic plate counts (HPCs)] and a wide range of OPPPs (gene copy numbers of Acanthamoeba polyphaga, Vermamoeba vermiformis, Legionella pneumophila, and Mycobacterium avium) were examined in the bulk water of 120-mL simulated glass water heaters (SGWHs). The SGWHs were operated at 32-37 °C, which is representative of conditions encountered at the bottom of electric water heaters, with water changes of 80% three times per week to simulate low use. This design presented advantages of controlled and replicated (triplicate) conditions and avoided other potential limitations to OPPP growth in order to isolate the variable of organic carbon. Over seventeen months, strong correlations were observed between total organic carbon (TOC) and both 16S rRNA gene copy numbers and HPC counts (avg. R2 > 0.89). Although M. avium gene copies were occasionally correlated with TOC (avg. R2 = 0.82 to 0.97, for 2 out of 4 time points) and over a limited TOC range (0-1000 µg/L), no other correlations were identified between other OPPPs and added TOC. These results suggest that reducing organic carbon in distributed water is not adequate as a sole strategy for controlling OPPPs, although it may have promise in conjunction with other approaches.

No MeSH data available.


Related in: MedlinePlus