BIOL240 Lecture Notes - Lecture 8: Absorbance, Spectrophotometry, Membrane Technology
29 Jun 2017
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Document Summary
Standard light microscopy used to directly count cells. Bacterial suspension is added onto the surface of a petroff-hausser counting chamber: petroff-hauss er counting chamber = fancy microscope slide engineered to contain a specific array of ridges/valleys in a central etched grid pattern. A cover slip is placed over the cells in the chamber: this compresses the liquid over the grid, and extra fluid flows into the side wells. Method is ideal for quick results, and all materials are reusable (for as many cultures as needed) Counting colonies that form on the plate surface after the pour/spread plate methods: aka counting the colony-forming units (cfus) in the suspension, counting cfus = counting viable cells via indirect measurement. But you must dilute your cell population or else too many colonies will arise: dilution series/serial dilution is tested. Works for cultures with ~10^6 cells (or more: cells in the culture will begin absorbing light at this density.
