Membrane filtration is a simple way of concentrating microorganisms from a liquid sample.
Quantitative enrichment of large, filterable volumes on nutrient agar plates
Membrane filters with pore sizes of 0.65 µm retain yeasts from the liquid sample, which are then incubated aerobically on agar nutrient media. The filtrate is collected in a receiving container and then discarded. The colonies that have grown are then counted and analysed under a microscope.