Wastewater Microbiology Blogiology

Lab 5:  Enumeration of Microorganisms (Photo: Cafe Press) Introduction     The purpose of this lab will ultimately be to familiarize ourselves with counting microorganism colonies.  In the process, we will learn another plating method called spread plating and learn our strengths and weaknesses using these techniques.     The total viable count is based upon the ability of a microorganism placed in a nutrient environment to grow.  While individual microorganisms cannot be seen with the naked eye, they can grow in colonies which are visible to any plain Jane.  Counting the colonies gives an indication of the number of viable colony forming units (CFU) present in the original sample.  However, the appropriate growth medium must be chosen first to get to the counting phase.  This part is crucial because the accuracy will be best if the chosen medium is as similar as possible to the sample environment.     Plate counting is the oldest technique in the book, so why teach an old do

Lab 4:  Using the Spectrophotometer to Measure the Rate of Bacterial Cell Division: A Bacterial Population Growth Curve (Photo:Miamioh) Introduction     The purpose of this lab will ultimately be to observe the growth of an Escherichia coli population in its lag phase, its exponential growth phase and its stationary phase.  Each group will measure the turbidity of different E. coli samples all taken at different times to get a wide range of measurements that will then construct a growth graph.  The biggest issue will most likely be the counting of the hemocytometerns that contain the E. coli .     While it is different for every bacteria, E. coli has a doubling time as short as 20 minutes. However, once they are placed in a growth medium (in this case LB broth), they will take some getting used to their environment. This period of adjustment is called the lag phase and will seen as the initial flatline on the growth curve graph.  Once the cells microorganisms are comfortable,

Lab 3: Streak Plate, Culture Transfer Instruments and Techniques, Isolation and Maintenance of Pure Culture (Photo: Pinterest) Introduction     The purpose of this lab will ultimately be to grow a pure culture of  Escherichia coli, place a colony inside LB broth and freeze a stock all to be used in later labs.  However, this will be complicated by the fact that microorganisms do not grow in neat, pure populations.  A pure culture must be isolated first from a mixed community.  The first of such ways would be to grow a sample onto selective media so that the media's components only allow the growth of limited or one type of microorganisms. ( A selective media is a specialized concoction of specific elements that provide for the growth and success of limited microorganisms.  The list of ingredients of selective media differs from non-selective media in that it is much longer and more complex. )  After  this is done, a single, specific colony can be removed and either plate