Biofilm responses to ageing and to a high phosphate load in a bench-scale drinking water system.
The effects of ageing and of phosphate load on drinking water biofilms developed on a polycarbonate substratum in the pseudo-equilibrium state have been evaluated. Phosphate was added in an amount higher than the stochiometric nutrient requirements of bacteria, at concentrations commonly applied in a drinking water distribution system for corrosion control. Multiple parameters were monitored: heterotrophic plate counts (HPCs), total direct counts (TDCs) and potential exoproteolytic activity (PEPA) in order to characterise changes in bacterial biofilms. The total carbohydrate, amino acid and phosphate contents of biofilms were analysed to characterise and monitor the biochemical composition of the biofilm.The three enumeration methods showed that a pseudo-equilibrium state was reached after 7 weeks of colonisation after which, the bacterial growth rate in the biofilm was 0.1 log per week on average. Bulk phosphate addition doubled the phosphate in the biofilm, but did not affect the other biological, physiological or chemical parameters measured. Polysaccharides increased in the biofilm with ageing and the dynamics of individual carbohydrate synthesis also varied with the age of the biofilm. Once pseudo-equilibrium, it was found that the total proteins were globally constant, whereas the spectra of some individual amino acids of the proteins had significantly changed.
Batté
Magali
M
NSERC Industrial Chair on Drinking Water, Ecole Polytechnique de Montréal, CP 6079, Succ Centre Ville, Montréal, Canada QC H3C 3A7.
Koudjonou
Boniface
B
Laurent
Patrick
P
Mathieu
Laurence
L
Coallier
Josée
J
Prévost
Michèle
M
D018441:Biofilms; D008962:Models, Theoretical; D010710:Phosphates / Q000378:metabolism*; D011157:Population Dynamics; D013997:Time Factors; D018508:Water Purification; D014881:Water Supply
D010710:Phosphates