BIOL240 Lecture Notes - Lecture 19: Petri Dish, Microbiological Culture, Turbidity
15 Mar 2019
School
Department
Course
Professor
Document Summary
When you move between quadrants, you are diluting it because you move first into the previous quadrant then continue to finish streaking the current quadrant: heat handle of inoculating loop also when sterilizing it but not too much. You can see colonies in the agar too. Advantage is you can have many more colonies occurring before overlapping so you can count easily. Problem is many bacteria may die due to high temp. of agar. Quantifying microbes: direct counts, viable cell counts, turbidity measurements. Direct count: you can use normal light microscopes but you need specialized slides (petroff-hausser counting chamber) to aid in counting, the chamber has hills and valleys. Place suspension on hill and put cover slide on top. Viable cell count: serial dilutions and cfus. Anything above is tntc: units are cfu/ml, only take averages between 25 250 cfu per plate.
