I have taken a water sample from point that pass trough two new water cartridge with filter 0.45 & 0.2 micron, so it's seem to be sterile !
and filtrated it with 0.45 Millipore filter, after incubation I found the sample is very crowded with colonies, knowing that the source is very crowded also with bacteria.
Does the high load of bacteria can pass throw the filter cartridges ?
AND WHY PASS throw the cartridge but not in the (0.45 Millipore filter)?
Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli passed through a 0.45-µm pore size filter within 48–96 h. Pseudomonas aeruginosa, Serratia marcescens, and Listeria monocytogenes passed through a 0.3-µm pore size filter.
Article Membrane filter (pore size, 0.22â0.45 μm; thickness, 150 ...
abstract
Bacteria growing on MF-Millipore filters (thickness, 150 micro m) passed through the underlying membrane by their infiltration activity. Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli passed through a 0.45- micro m pore size filter within 48-96 h. Pseudomonas aeruginosa, Serratia marcescens, and Listeria monocytogenes passed through a 0.3- micro m pore size filter. P. aeruginosa passed through a 0.22- micro m pore size filter. The membranes which allowed passing-through of bacteria showed normal bubble point values in the integrity test. Studies with isogenic S. marcescens mutants indicated that flagellum-dependent motility or surface-active exolipid were important in the passing-through. P. aeruginosa PAO1 C strain defective in twitching motility was unable to pass through the 0.22- micro m filter. Scanning electron microscopy showed bacteria passing-through the 0.22- micro m filter. Millipore membrane filters having well-defined reticulate structures will be useful in the study of infiltration activity of microbes
Filtration of liquids through 0.2-μm filters is a common and often-used method for the removal of microorganisms from heat-sensitive solutions. Such 0.2 μm filtrations are frequently referred to as ‘sterile filtration’, reflecting the general belief that all living organisms are excluded from the filtrate.
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