Lab 4
Name and Course Section: Avital Gershtein, Section 701 Title: Aseptic Technique & culturing Microbes - Lab # 4
Purpose: The purpose of this experiment is to Learn and employ aseptic technique, to become familiar with basic requirements of microbial growth, to learn the basic forms of culture media, and to become familiar with methods used to control microbial growth.
Bacteria
Growth pattern after 24 hours
Growth pattern after 48 hours
L. acidophilus in liquid MRS broth No growth Amount of sediment grew over the marked line
S. epidermis in liquid nutrient broth No growth Pellicle formed
Procedure: After setting up the incubator, I aseptically transferred S. epidermidis and L. acidophilus. to generate liquid broth cultures. After waiting for 24-48 to observe growth, I recorded my observations. Then, I prepared wet mount slides and direct staining slides of both S. epidermidis and L. acidophilus. to observe them microscopically using oil immersion lens. When I was done, I stored them in the refrigerator for future use.
Observations/ Data Tables:
Bacteria
40x
100x
L. acidophilus (wet mount)
Unclear
Round cells
L. acidophilus (direct stain)
Small circles
Large blue/purple round cells
S. epidermidis (wet mount)
Unclear
Very small dots
S. epidermidis (direct stain)
Small dots
Dots clumped into one group
Results/Analysis: Gained knowledge about culture media and how to distinguish various types of microbial growth. I also learn about variable conditions that are required for microbial growth, including oxygen levels and temperature.
Questions:
A. What is the difference between a bactericidal and bacteriostatic agent? What is the difference between sterilization and disinfection? Bactericidal refers to killing bacteria and bacteriostatic inhibits the growth of bacterial cells. Sterilization completes destruction of all microorganisms including spores and disinfecting kills microorganisms through chemical agent.
B. List five microbial killing methods, how
Purpose: The purpose of this experiment is to Learn and employ aseptic technique, to become familiar with basic requirements of microbial growth, to learn the basic forms of culture media, and to become familiar with methods used to control microbial growth.
Bacteria
Growth pattern after 24 hours
Growth pattern after 48 hours
L. acidophilus in liquid MRS broth No growth Amount of sediment grew over the marked line
S. epidermis in liquid nutrient broth No growth Pellicle formed
Procedure: After setting up the incubator, I aseptically transferred S. epidermidis and L. acidophilus. to generate liquid broth cultures. After waiting for 24-48 to observe growth, I recorded my observations. Then, I prepared wet mount slides and direct staining slides of both S. epidermidis and L. acidophilus. to observe them microscopically using oil immersion lens. When I was done, I stored them in the refrigerator for future use.
Observations/ Data Tables:
Bacteria
40x
100x
L. acidophilus (wet mount)
Unclear
Round cells
L. acidophilus (direct stain)
Small circles
Large blue/purple round cells
S. epidermidis (wet mount)
Unclear
Very small dots
S. epidermidis (direct stain)
Small dots
Dots clumped into one group
Results/Analysis: Gained knowledge about culture media and how to distinguish various types of microbial growth. I also learn about variable conditions that are required for microbial growth, including oxygen levels and temperature.
Questions:
A. What is the difference between a bactericidal and bacteriostatic agent? What is the difference between sterilization and disinfection? Bactericidal refers to killing bacteria and bacteriostatic inhibits the growth of bacterial cells. Sterilization completes destruction of all microorganisms including spores and disinfecting kills microorganisms through chemical agent.
B. List five microbial killing methods, how