Welcome to our suite of NUI Galway Microbiology teaching videos. We hope that they will guide you in performing your experiments in a scientific and safe manner.

In this video we demonstrate membrane filtration, a method used in testing the quality of water samples.

A river water sample is filtered through a membrane with a 0.45 µm pore size (smaller than typical bacteria) and bacteria are collected on the surface. The membrane filter is incubated on selective and differential media to grow and count the bacteria in the sample.