ENH 222 Lecture Notes - Lecture 5: Turbidity, Petri Dish

• School: Ryerson University
• Department: Environmental Health
• Course: ENH 222
• Professor: Corrine Ong

Document Summary

Divide vi binary fission-therefor they"re all clones (mutations allow for genetic variability) They divide quickly so every 3 hours is a new generation (to put that in perspective, human generations are about 30 years!) Since binary fision goes from 1(gen 0)-2(gen 1)-4(gen 4)-8(gen 3)- It"s the same as saying 2^(generation: grows/reproduce exponentially. Dilute a sample by taking a bit of the highly concentrated sample in 9 ml of another, and another, and another . 25-250 is ideal because its easily countable and there wont be a competition for nutrients. Filtering water is done using membranes with very small openings/pores. Diluting a sample and seeing which grow/ how many do. The three diluting result numbers have been found to be the mpn corresponding to the results. You count how many in grid and then divide by the volume in that grid. For organisms that cannot grow as colonies so its hard to count them.