What is aseptic technique? Why is it used in microbiology?
-A specific procedure used to prevent unwanted microorganisms from contaminating laboratory procedure personnel and equipment
-to maintain pure cultures
Explain how you would subculture bacteria from a broth culture in a test tube to:
a. an agar slant with an inoculating loop
b. an agar deep with an inoculating needle
c. another broth tube with an inoculating loop
a. dip the inoculating loop in the broth and transfer culture to agar slant by streaking the slant from the bottom to the top with a zigzag pattern.
b. dip the inoculating loop in the broth and transfer culture to agar deep by stabbing the needle in the center of the tube but not all the way to the bottom.
c. dip the inoculating loop in the broth and transfer culture to broth by dipping the loop in the broth and swirling the loop
Describe how you would obtain a pure culture of an organism and maintain it with short term maintenance (1-3 months)
-Transfer the bacteria from center of a single colony to a slant tube with a screw cap
-Incubate overnight at 37 degrees and store in the refrigerator for 1-3 months.
The best way to preserve many stock cultures for long periods of time is through lyophilization (freeze drying). Briefly describe this procedure
-Bacteria culture is suspended in a sterile solution of some protective media such as milk
- transfer to viles quickly freeze in a dry ice/alcohol bath
-dry under vacuum while still frozen and seal the vile
What is the purpose of subculturing?
Obtain a pure culture and to maintain a pure culture
What are some signs of growth in liquid medium?
Torbitity (cloudy), gas bubbles, odor, color change due to pH change