Direct estimation of biofilm density on different pipe material coupons using a specific DNA-probe

Chang, Young-Cheol; Puil, M. Le; Biggerstaff, John; Randall, Andrew A.; Schulte, Alfons; Taylor, James S.

doi:10.1016/j.mcp.2003.07.004

Cited by 32 publications

(14 citation statements)

References 23 publications

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“…Shear rates have been suggested to be important in the development of biofilm community structure (3) and govern the abilities of individual species to immigrate to biofilms and to colonize new surfaces (9,45). Other factors include substratum composition, concentrations of solutes, and nutrient availability (6,19). Our data are in agreement with those of Soini et al (42) and indicated that an increase in the fluid shear rate from approximately 0 to 305 S Ϫ1 reduced the total cell number by only 10-fold (from approximately 2.5 ϫ 10 6 CFU/cm 2 to 1 ϫ 10 5 CFU/cm 2 ).…”

Section: Discussionmentioning

confidence: 99%

Shear Rate Moderates Community Diversity in Freshwater Biofilms

Rickard

McBain

Stead

et al. 2004

Appl Environ Microbiol

149

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The development of freshwater multispecies biofilms at solid-liquid interfaces occurs both in quiescent waters and under conditions of high shear rates. However, the influence of hydrodynamic shear rates on bacterial biofilm diversity is poorly understood. We hypothesized that different shear rates would significantly influence biofilm diversity and alter the relative proportions of coaggregating and autoaggregating community isolates. In order to study this hypothesis, freshwater biofilms were developed at five shear rates (<0.1 to 305 S ؊1 ) in a rotating concentric cylinder reactor fed with untreated potable water. Eubacterial diversity was assessed by denaturing gradient gel electrophoresis (DGGE) and culturing on R2A agar. Fifty morphologically distinct biofilm strains and 16 planktonic strains were isolated by culturing and identified by partial 16S rRNA gene sequencing, and their relatedness was determined by the construction of a neighbor-joining phylogenetic tree. Phylogenetic and DGGE analyses showed an inverse relationship between shear rate and bacterial diversity. An in vitro aggregation assay was used to assess the relative proportions of coaggregating and autoaggregating species from each biofilm. The highest proportion of autoaggregating bacteria was present at high shear rates ( Microorganisms colonize a wide range of environments as spatially organized, taxonomically diverse, multispecies biofilm communities (1,20,44). In potable water distribution systems, many bacterial species, including members of the Proteobacteria, Actinobacteria, low-GϩC-content gram-positive bacteria, and Cytophaga-Flavobacterium-Bacterioides group, readily adhere to surfaces to form multispecies biofilms (29,41). The abilities of these taxonomically diverse organisms to attach to surfaces and codevelop within multispecies biofilms are imperative for their survival and persistence within flowing environments (4,33,44). Few published articles have described the effect of shear on the bacterial composition and diversity of freshwater biofilms. Evidence is emerging, however, that at high fluid velocities with associated high shear rates, multispecies communities are less diverse than those developed at lower shear rates (9,23,35,42). In order to adhere to surfaces or surface-attached cells and subsequently to form biofilms, bacteria in high-velocity flowing systems must overcome shear stress at the fluid-surface interface (7, 11). Attachment is facilitated by the expression of cell surface polymers that alter cell surface properties (3, 15). Properties that enhance attachment include increases in whole-cell hydrophobicity (14) and the abilities to coaggregate (25, 36) and autoaggregate (17). Recently, it was shown, using a simple recirculating tank model (35), that freshwater biofilms formed at high shear rates contained a high proportion of bacterial species that were not detectable in the surrounding fluid phase. In addition, a larger proportion of biofilm strains than of their planktonic counterparts were able to coaggr...

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Section: Discussionmentioning

confidence: 99%

Shear Rate Moderates Community Diversity in Freshwater Biofilms

Rickard

McBain

Stead

et al. 2004

Appl Environ Microbiol

149

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“…Based on this sequence a 15-mer PNA probe (ECOLIFILM) was designed, labeled with cyanine dye Cy3 (excitation, 550 nm; emission, 570 nm), and flanked with solubility enhancers. Cy3 was chosen because it provides sufficient signal intensity, even for bacteria living in oligotrophic environments (30), and its emission is not within the autofluorescence wavelength range of that of pipe materials used for drinking water supply (8).…”

Section: Methodsmentioning

confidence: 99%

Detection of Escherichia coli in Biofilms from Pipe Samples and Coupons in Drinking Water Distribution Networks

Juhna

Birzniece

Larsson

et al. 2007

Appl Environ Microbiol

102

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Fluorescence in situ hybridization (FISH) was used for direct detection of Escherichia coli on pipe surfaces and coupons in drinking water distribution networks. Old cast iron main pipes were removed from water distribution networks in France, England, Portugal, and Latvia, and E. coli was analyzed in the biofilm. In addition, 44 flat coupons made of cast iron, polyvinyl chloride, or stainless steel were placed into and continuously exposed to water on 15 locations of 6 distribution networks in France and Latvia and examined after 1 to 6 months exposure to the drinking water. In order to increase the signal intensity, a peptide nucleic acid (PNA) 15-mer probe was used in the FISH screening for the presence or absence of E. coli on the surface of pipes and coupons, thus reducing occasional problems of autofluorescence and low fluorescence of the labeled bacteria. For comparison, cells were removed from the surfaces and examined with culture-based or enzymatic (detection of ␤-D-glucuronidase) methods. An additional verification was made by using PCR. Culture method indicated presence of E. coli in one of five pipes, whereas all pipes were positive with the FISH methods. E. coli was detected in 56% of the coupons using PNA FISH, but no E. coli was detected using culture or enzymatic methods. PCR analyses confirmed the presence of E. coli in samples that were negative according to culture-based and enzymatic methods. The viability of E. coli cells in the samples was demonstrated by the cell elongation after resuscitation in low-nutrient medium supplemented with pipemidic acid, suggesting that the cells were present in an active but nonculturable state, unable to grow on agar media. E. coli contributed to ca. 0.001 to 0.1% of the total bacterial number in the samples. The presence and number of E. coli did not correlate with any of physical and/or chemical characteristic of the drinking water (e.g., temperature, chlorine, or biodegradable organic matter concentration). We show here that E. coli is present in the biofilms of drinking water networks in Europe. Some of the cells are metabolically active but are often not detected due to limitations of traditionally used culture-based methods, indicating that biofilm should be considered as a reservoir that must be investigated further in order to evaluate the risk for human health.The drinking water supplier has to provide the consumer potable water of a quality identical to that leaving the treatment plant. However, it has been well documented that water that reaches the consumer's tap is often of worse microbiological quality than that which left the plant (29). Therefore, the analyses used for monitoring the hygiene of potable water must be rapid to perform and able to detect the major microbial groups of concern. Escherichia coli is still used as the principle indicator for drinking water pollution monitoring (39) and is even considered a superior indicator (11), since enterotoxic and enterohemorrhagic forms are one of the major causes of water-related outbreaks (29...

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“…The imaging platform allowed acquisition of specific spectral signatures for each pixel of the image and, therefore, allowed separation of the microsphere fluorescent signal from the inherent noise signal of the sample material. Based on previous works (Chang et al, 2003;Biggerstaff et al, 2006;Le Puil et al, 2006), a quantitation protocol was derived by way of AutoDeblur ® (AutoQuant Imaging Inc., Watervliet, NY). Fluorescence areas were quantified for each image to obtain the density of microspheres in each field of view.…”

Section: Microsphere Tracersmentioning

confidence: 99%

Challenges for Coring Deep Permafrost on Earth and Mars

et al. 2008

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A scientific drilling expedition to the High Lake region of Nunavut, Canada, was recently completed with the goals of collecting samples and delineating gradients in salinity, gas composition, pH, pe, and microbial abundance in a 400 m thick permafrost zone and accessing the underlying pristine subpermafrost brine. With a triple-barrel wireline tool and the use of stringent quality assurance and quality control (QA/QC) protocols, 200 m of frozen, Archean, mafic volcanic rock was collected from the lower boundary that separates the permafrost layer and subpermafrost saline water. Hot water was used to remove cuttings and prevent the drill rods from freezing in place. No cryopegs were detected during penetration through the permafrost. Coring stopped at the 535 m depth, and the drill water was bailed from the hole while saline water replaced it. Within 24 hours, the borehole iced closed at 125 m depth due to vapor condensation from atmospheric moisture and, initially, warm water leaking through the casing, which blocked further access. Preliminary data suggest that the recovered cores contain viable anaerobic microorganisms that are not contaminants even though isotopic analyses of the saline borehole water suggests that it is a residue of the drilling brine used to remove the ice from the upper, older portion of the borehole. Any proposed coring mission to Mars that seeks to access subpermafrost brine will not only require borehole stability but also a means by which to generate substantial heating along the borehole string to prevent closure of the borehole from condensation of water vapor generated by drilling.

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Direct estimation of biofilm density on different pipe material coupons using a specific DNA-probe

Cited by 32 publications

References 23 publications

Shear Rate Moderates Community Diversity in Freshwater Biofilms

Shear Rate Moderates Community Diversity in Freshwater Biofilms

Detection of Escherichia coli in Biofilms from Pipe Samples and Coupons in Drinking Water Distribution Networks

Challenges for Coring Deep Permafrost on Earth and Mars

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