Microbiology Lecture 4 Flashcards
Define aseptic technique.
Ensure cultures are inoculated without contamination of unwanted microbes.
What is the first important step in aseptic technique?
Flame the loop to sterilise it.
What is the microbe loop made of and why?
Nichrome wire, as it is durable against repeated heating and cooling.
At what angle are the loops held against the flame, and why?
At a downward angle, to prevent any possible liquids from running downward to the hand.
How does a bunsen burner create an area of sterility?
Heats the air around the flame, preventing airborne microbes contaminating.
What is the problem with boiling the media to sterilise it before culturing? How can this be addressed? What is done with heat sensitive materials?
Boiling will kill microbes, but not endospores. Autoclaving is performed. If heat sensitive, is instead filtered to be made sterile, and added to cooled media.
Define chemoorganotroph.
microorganism requiring organic compounds for energy.
How can the requirements of a microorganism be determined?
Begin with minimal media, then sequentially supplement with nutrients to isolate requirements.
Describe nutrient media. Is this kind of media well defined?
Has a source of carbon, such as sugar, or complex like yeast extract/peptones.
Poorly defined as the source of nutrients can differ significantly.
Define peptone.
Oligopeptides obtained by boiling organic mass like blood, bones, and meat.
What is the problem with using gelatine as a media?
Isnt solid at 37 the grease.
Where is agar gel obtained from?
Red algae.
How is agar media prepared?
Dissolved in boiling water, and sets around 45C.
What temperature does agar melt after it has set?
98C.
What x% solution does agar form a strong gel?
1%.
