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