Laboratory Experiments in Microbiology-Exercise 3
are procedures used to avoid introducing unwanted microbes and to prevent spreading microbes where they are not wanted.
What are aseptic techniques?
Who successfully transferred Bacillus anthracis and Mycobacterium tuberculosis between diseased animals and laboratory media?
is a Nichrome wire held with and insulated handle.
It is used for transferring bacteria between library media and microscope slides.
What is an inoculating loop?
Heating or flaming - in in flame until the loop is red hot
The inoculating loop is sterilized by?
broth (liquid) such as infusions and blood
What were the first bacteria cultures grown in?
potato starch, coagulated egg white and meat
What were the first solids used to grow cultures?
What did Robert Koch use?
Who suggested agar to Koch?
both- in the hottest part of the flame
Do you sterilize an inoculating loop before or after the transfer of bacteria?
chemically defined medium
What do you call a medium whose exact chemical composition is known?
media for which the exact chemical composition varies slightly from batch to batch
What is a complex media?
protein in the form of meat extracts and partially digested proteins called peptones.
Organic carbon, energy, nitrogen sources are usually supplied by ____________________ and________.
liquid complex medium-when agar is added it becomes a solid medium called nutrient agar
Nutrient broth is?
marine red algae
liquefies at 100*C
What is agar?
Media must be sterilized after preparation true or false?
steam sterilization or autoclaving
process by which it is steamed under pressure heated to 121*C at 15 pounds of pressure (psi)
for 15 minutes
What is the most common method of sterilizing culture media that are heat stable?
upside down with the agar at the top otherwise moisture will form
How do you store a sample in a petri dish?
that microbes will be intentionally introduced onto nutrient agar and into nutrient broth
What does inoculated mean?
What do you call the time that bacteria are inoculated into culture media and they increase?
When liquid media becomes turbid it is__________.
a population of cells that arises from a single bacterial cell.
What is a colony?
A colony may arise from a group of the same microbes attached to one another.
A colony-forming unit is?
1. clear no bacteria
3. pellicle and turbid- cloudy and a film
5. sediment- bottom
Bacterial growth in broth
too numerous to count
What is TNTC?
Liquid-nutrient broth/ loop or needle
solid- agar slant- loop or needle zig-zag when inserting bacteria
semi-solid (agar deeps) needle/stab streak
You use a loop or needle with?
peptones or meat extracts
What are bacteria using for nutrients in nutrient agar?
They thrive in oxygen and oxygen is richer at the top
Why do some bacteria go to top?
to determine motility and to culture bacteria that require a lower core of oxygen
Purpose of agar deeps?