(Solution) SCIE1046 Activity 5.1 Bacterial Growth Curves Experiment with bacterial growth

COURSE  

SCIE1046: Fundamental of Microbiology with Lab

  1. About the Lab

Learning Objectives:

  • Use given data to plot a growth curve on a semi-logarithmic scale.
  • Recognize the different phases of bacterial growth (lag, exponential, stationary, decline).
  • Learn how the growth rate can be calculated from a growth curve.

Estimated Length: 45 to 55 minutes

 

MAKE THE CONNECTION

The background information in section 2 was adapted from the following Microbiology lecture course Tutorials:
4.1.1 Bacterial Growth
4.2.1 Sterilization, Disinfectants, and Antiseptics

 

  1. Background Information

The following background information will be helpful as you prepare for the simulation.

2a. Introduction to Controlling Microbial Growth

There are many reasons why it can be useful to control microbial growth. For example, we clean a dinner table before eating or clean a surface before preparing food on it. A doctor needs to reduce the risk of a pathogen spreading from one patient to the next. Surgical instruments need to be especially clean to prevent infections after surgery.

The ways used to control microbial growth differ depending on the context. In this lesson, the focus is on microbes on surfaces. For example, one way to reduce the spread of disease is by cleaning the inanimate objects (fomites) on which microbes may be left by one person and picked up by another. In other lessons, you will learn about the ways in which medications are used to control pathogens inside the human body.

 

TERM TO KNOW

This glossary term is important to know and will help you during the Activity.

Fomite

An inanimate object that may harbor microbes, potentially allowing them to spread to someone else and cause disease.

2b. Exponents and Scientific Notation

Microbiologists use exponential notation in many situations. For instance, exponential notation is used to describe the number of microbes in a population when the numbers are very large. Very large numbers can be cumbersome to write and difficult to express. Using exponential or scientific notation allows the microbiologist to express the number as a power of 10. A power of 10 is as many number 10s as indicated by the exponent multiplied together. An exponent is a symbol written above and to the right of a mathematical expression to indicate the operation of raising to a power. For example, in 103, 3 is the exponent.

IN CONTEXT

If we were quantifying the number of specific microbes in a sample, we might end up with a number such as 6,580,000,000. This number can be written as an exponent in scientific notation by writing . 6.58 is referred to as the coefficient and is always a number between 1 and 9. The 9 in 109 is the exponent and is representative of the number of spaces from the decimal point.

The exponent can be positive or negative depending on which direction the coefficient is moving from the decimal point……