The impact of industrial-scale cartridge filtration on the native microbial communities from groundwater

Groundwater is a major source for bottled water, which is increasingly consumed all over the world. Some categories of bottled water can be subjected to treatments such as disinfection prior to bottling. In the current study, we present the quantitative impact of industrial-scale micro-filtration (0.22 μm pore size) on native microbial communities of groundwater and evaluate subsequent microbial growth after bottling. Two separate groundwater aquifers were tested. Flow-cytometric total cell concentration (TCC) and total adenosine tri-phosphate (ATP) analysis were used to quantify microbial abundance. The TCC of the native microbial community in both aquifers was in the range of 103–104 cells/ml. Up to 10% of the native microbial community was able to pass through the cartridge filtration units installed at both aquifers. In addition, all samples (either with or without 0.22 μm filtration) showed significant growth after bottling and storage, reaching average final concentrations of 1–3 × 105 cells/ml. However, less growth was observed in carbon-free glassware than in standard polyethylene terephthalate (PET) bottles. Furthermore, our results showed that filtration and bottling can alter the microbial community patterns as observed with flow cytometry. The current study established that industrial-scale micro-filtration cannot serve as an absolute barrier for the native microbial community and provided significant insight to the impact of filtration and bottling on microbial concentrations in bottled water.