Accumulation of DNA in the exopolymeric matrix of activated sludge and bacterial cultures

Palmgren, Rikke; Nielsen, Per Halkjær

doi:10.1016/0273-1223(96)00650-6

Cited by 21 publications

(2 citation statements)

References 20 publications

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“…More significantly, it is demonstrated that this process occurs during early exponential phase growth when DNA concentrations in the supernatant are low (\0.1 lg ml -1 ). Though DNA has been reported to be a component of the extracellular polymers of activated sludge flocs, little is known about its origins and structural role in this context (Palmgren and Nielsen 1996). This study indicates the accumulation of nucleic acids might prove essential in the floc formation process.…”

Section: Discussionmentioning

confidence: 91%

Extracellular DNA and Type IV pili mediate surface attachment by Acidovorax temperans

Heijstra

Pichler

Liang

et al. 2009

Antonie van Leeuwenhoek

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Extracellular DNA can play a structural role in the microbial environment. Here evidence is presented that an environmental isolate of Acidovorax temperans utilises extracellular DNA for intercellular and cell-surface attachment and that Type IV pili and electrostatic interactions play a role in this interaction. Preliminary attempts to isolate and purify extracellular polysaccharides from A. temperans strain CB2 yielded significant amounts of DNA raising the question of whether this molecule was present as a structural component in the extracellular matrix. The role of DNA in attachment was indicated by experiments in which the addition of DNase to liquid medium inhibited the attachment of Acidovorax to glass wool. A Tn5 insertional mutant, lacking Type IV pili, was unable to initiate attachment. Addition of DNase caused rapid detachment of bound cells, but no detachment occurred when proteinase, RNase or inactivated DNase were used. Addition of MgCl(2) also caused significant detachment, supporting the possible mechanistic role of electrostatic interactions in the attachment process. Although attachment was apparent in early to mid-log phase growth, surprisingly DNA was not detected in the culture supernatant until late stationary phase and coincided with an appreciable loss of cell viability. This suggests that during log-phase growth attachment is mediated by eDNA that is released in low quantities and/or is highly localised within the extracellular matrix and also that stationary phase DNA release through widespread cell lysis may be a separate and unrelated event.

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Section: Discussionmentioning

confidence: 91%

Extracellular DNA and Type IV pili mediate surface attachment by Acidovorax temperans

Heijstra

Pichler

Liang

et al. 2009

Antonie van Leeuwenhoek

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“…eDNA was recently proved to be a major structural component in the biofilm matrix and found to play various roles for biofilm development including enhancement of adhesion [44] and cohesion of biofilm [45], as well as exchange of genetic information [4]. Palmgren and Nielsen [46] found eDNA could accumulate in the EPS matrix of activated sludge as well as pure cultures of P. putida . Andrews et al [47] also found that the intensities of nucleic acids related to Raman peaks were significantly greater in biofilm cells compared with suspended cells.…”

Section: Discussionmentioning

confidence: 99%

Surface-enhanced Raman scattering (SERS) revealing chemical variation during biofilm formation: from initial attachment to mature biofilm

2012

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Surface-enhanced Raman scattering (SERS) has recently been proved to be a promising technique for characterizing the chemical composition of the biofilm matrix. In the present study, to fully understand the chemical variations during biofilm formation, SERS based on silver colloidal nanoparticles was applied to evaluate the chemical components in the matrix of biofilm at different growth phases, including initial attached bacteria, colonies, and mature biofilm. Meanwhile, atomic force microscopy was also applied to study the changes of biofilm morphology. Three model bacteria, including Escherichia coli, Pseudomonas putida, and Bacillus subtilis, were used to cultivate biofilms. The results showed that the content of carbohydrates, proteins, and nucleic acids in the biofilm matrix increased significantly along with the biofilm growth of the three bacteria judging from the intensities and appearance probabilities of related marker peaks in the SERS spectra. The content of lipids, however, only increased in the Gram-negative biofilms (E. coli and P. putida) rather than the Gram-positive biofilm (B. subtilis). Our findings strongly suggest the SERS has significant potential for studying chemical variations during biofilm formation.FigureAchieving surface-enhanced Raman scattering by coating silver nanoparticles on biofilm surface.

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Gene Exchange in Biofilms

Wuertz

2003

Encyclopedia of Environmental Microbiology

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Accumulation of DNA in the exopolymeric matrix of activated sludge and bacterial cultures

Cited by 21 publications

References 20 publications

Extracellular DNA and Type IV pili mediate surface attachment by Acidovorax temperans

Extracellular DNA and Type IV pili mediate surface attachment by Acidovorax temperans

Surface-enhanced Raman scattering (SERS) revealing chemical variation during biofilm formation: from initial attachment to mature biofilm

Gene Exchange in Biofilms

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