Measuring microbial growth through membrane filtration is an effective technique used to quantify viable cells in liquid cultures, particularly when the cell count is low. This method involves passing a known volume of liquid culture through a membrane filter, which contains extremely small pores that are smaller than the cells themselves. As the liquid is filtered, the cells become trapped in the membrane, allowing for subsequent analysis.
After filtration, the membrane filter is placed onto an agar plate and incubated, promoting the growth of colonies from the trapped viable cells. Each colony that forms corresponds to a colony-forming unit (CFU), which represents an individual viable cell from the original culture. This process not only allows for the counting of living cells but also provides insights into the overall health and viability of the microbial population.
The setup for membrane filtration typically includes a filter apparatus where the liquid culture is poured onto the membrane filter. A vacuum is applied to facilitate the passage of the liquid through the filter, ensuring that the cells remain on the surface. Once the filtration is complete, the membrane can be transferred to a petri dish containing solid growth media, where microbial growth can be observed and quantified.
This technique is particularly useful in various microbiological applications, including water quality testing and food safety assessments, where understanding the number of viable microorganisms is crucial. As you continue to explore this topic, you will gain practical experience in applying these concepts to real-world scenarios.
