Brändle, K.

Friedrich, F.

Jungfer, C.

Obst, U.

Schwartz, T.

Varela Villarreal, J.

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KIT – University of the State of Baden-Wuerttemberg andNational Research Center of the Helmholtz AssociationJungfer, C., Varela Villarreal, J., Brändle, K., Friedrich, F., Obst, U., Schwartz, T. Does copper material induce VBNC state in drinking water biofilm bacteria?Institute of Functional Interfaces (IFG)Microbiology of Natural and Technical Surfaces DepartmentE-mail: christina.jungfer@kit.eduBiofilms from drinking water pipelines are a possible niche for all kinds of bacteria, including pathogens, and may be responsible for contamination of drinking water systems. In general, a clear understanding of survival, regeneration and regrowth of bacteria in biofilms is of considerable value.To get a deeper look in this problem, drinking water biofilms from different waterworks (K, M, F, S) were investigated in a modular pilot scale using different pipe materials including copper. Three months old biofilms were investigated with molecular biological and microscopy methods.Copper couponsCopper pipesHigh TOTAL CELL COUNTS (104 up to 106cells/cm2) were detected without disinfection and after UV disinfection. After chemical disinfection treatment 103 up to 104cells/cm2 were observed.But low METABOLIC ACTIVITIES and no or low numbers of CULTIVABLE CELLS (cfu) were found in these biofilms indicating a high number of VBNC. Similar results were detected with other materials (data not shown).When stress and vitality markers on RNA level were investigated with GENE EXPRESSION ANALYSIS, a distinct recA induction, which is responsible for the dark repair, was found in biofilms from copper material after UV disinfection.When copper was used as pipe material, remarkable results and differences to other materials were found in biofilms.The use of ENVIRONMENTAL SCANNING ELECTRON MICROSCOPE(ESEM) gave us a clear picture of intact cells and mushroom-like biofilmstructures on the copper surface. LIVE/DEAD STAINING verified clearly the presence of cells with intact cell membranes.The presence of natural bacterial communities on copper pipelines were verified under real drinking water conditions after applying modern detection methods.These results clearly showed that copper surface did not prevent biofilmformation defying the bacteriostatic copper properties theory. After three months in drinking water an intact biofilm was found on copper material with populations diverse to other materials. Though almost no cultivable bacteria were found, a clear gene expression activity was detectedAll these results indicate the presence of VBNC bacteria on copper.Population analysis by PCR-DGGE showed a significant shift in bacterial populations when copper material was used after the different disinfection treatments. In general a decrease in band number was observed. UV disinfection/oxidation: up-regulation of recA-mediated dark repair in natural biofilms. ClO2 and Cl2 disinfection: no recA expression. copper: highest recA induction in biofilms.WW = waterworks; c = coupons; p = pipes; ↑ = recAinduction; ↔ = recA ground expression; n.d.: recAnot detected; NTU= nephelometric turbidity unit.BACKGROUND AND EXPERIMENTAL APPROACHRESULTSCONCLUSIONSDrinking waterBIOFILM DEVICES, EACH FITTED WITH 15 SLIDESPIPES WITH DIFFERENT MATERIALS, 5 M LENGTHPIPE BIOFILMS SLIDE BIOFILMSEFFLUENTBIOFILM PILOT SCALEstainless steel (St)copper (Cu)polyvinyl chloride (PVC)polyethylene (PE)disinfectionINFLUENTssAt stainless steel surfaces no clear biofilm pictures were observed with theESEM microscopy (data not shown).Pearson correlation (Opt:0.50%) [0.0%-100.0%]MVV Strecken 210080604073 .666.880.575.45091.427.7MVV Strecken 2MVV Vergl St R1MVV Vergl St R2Mvv Vergl PVC R1MVV Vergl PE R2MVV Vergl PVC R2MVV Vergl PE R1MVV Vergl Cu R1MVV Vergl Cu R2MVV Vergl St R1MVV Vergl St R2Mvv Vergl PVC R1MVV Vergl PE R2MVV Vergl P C R2MVV Vergl PE R1MVV Vergl Cu R1MVV Vergl Cu R2WW M (untreated): pipe biofilmsss p1ss p2PVC p1PE p2PVC p2PE p1Cu p1Cu p2PCR: Polymerase Chain Reaction; DGGE: Denaturating Gradient Gel Electrophoresis.Live/Dead stainingTotal Cell Count (DAPI)1,0E+001,0E+011,0E+021,0E+031,0E+041,0E+051,0E+061,0E+07untr. Cuntr. PUV CUV PClO2 Stag. C1ClO2 Stag. C2ClO2 CClO2 PCl2 Ctreatments/ biofilm carriercells/cm2Metabolic Activities (CTC) / Cultiable Cells (cfu)0,0E+001,0E+022,0E+023,0E+024,0E+025,0E+026,0E+02untr. Cuntr. PUV CUV PClO2 Stag. C1ClO2 Stag. C2ClO2 CClO2 P Cl2 Ctreatments/ biofilm carriercells/cm2CTCcfu 2dTreatments: untr.: untreated; UV: UV disinfection; ClO2: chlorine dioxide disinfection; Cl2: chlorine disinfection; Stag.: stagnation. Biofilm carrier: c: coupons; p: pipescThis work was funded by a grant of the BMBF.

Does copper material induce VBNC state in drinking water biofilm bacteria?

https://publikationen.bibliothek.kit.edu/220084192/3815865

Does copper material induce VBNC state in drinking water biofilm bacteria?

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