1.2: Microbiology in Historical Context Flashcards
(28 cards)
what was Robert Hooke first to do?
*He was the first to describe microbes
what microscope did robert hooke use? what was the maximum magnification?
used a compound microscope (2 lenses to magnify), which allowed magnification up to 30x.
what did Robert Hooke use his microscope to observe?
- Cells in cork
- Bread mold filaments
- Beginning of cell theory - all living things are composed of cells
what was the first discovered microbe by robert hooke
bread mold filaments
what did Antoni van Leeuwenhoek do
- Built microscopes that magnified specimen by 50-300x
- observed single celled micoorganisms
- discovered first bacteria
what did Antoni van Leeuwenhoek call single celled microorganisms?
animalcules
what did Louis Pasteur study and discover?
He studied wine and beer production and was hired to figure out why beer and wine were spoiling. He discovered how alchohol was produced: yeast convert sugar to alcohol. And called it “La vie sans air” aka what we call fermentation. Found the reason for spoiling was that bacteria can sour wine by converting alcohols to acid.
what was the method that Louis Pasteur developed to gently heat to kill unwanted bacteria?
Pasteurization
(used for dairy to make milk last longer)
how did Louis pasteur find that spontaneous generation doesn’t happen, what method did this lead to?
- prepared meat infusions inside of long swan-necked flasks
- boiled the infusion to sterilize it (to destroy any existing microbes so he knew no microbes would be present)
- as long as the flask remains upright, dust and microbes cannot enter and the infusion remains sterile
- led to the development of method for controlling growth of microorganisms (aseptic technique).
what did robert koch study? What did he establish from this?
- studied anthrax -responsible for epidemics in livestock
- he isolated bacteria from the carcass of a diseased animal - Bacillus anthracis
- injected healthy animals with the bacterium
- the healthy animals became ill with anthrax
- then he re-isolated the B. anthracis from the test subjects and showed it was the same as the original bacteria.
- with this he established a set of criteria for relating a specific microbe to a disease
what was the criteria robert koch established for relating a specific microbe to a disease?
- Koch’s postulates
what are the 4 steps of koch’s postulates
- the suspected pathogen must be present in all cases of disease and absent from healthy animals
- the suspected pathogen must be grown in pure culture
- cells from a pure culture of the suspected pathogen must cause disease in a healthy animal
- the suspected pathogen must be re-isolated and shown to be the same as the original
what was the simple way koch realized could be used to obtain pure cultures
using solid media
what was the first solid media that worked made up of? melting and solidifying point?
Broth medium solidified with agar
* agar contains a polysaccharide derived from marine algae that most microorganisms can’t eat
* melts at ~97 C and solidifies at 43 C.
what does a typical petri plate contain? what is each component for
- nutrient broth medium -so the bacteria have something to eat
- 1.5% agar-just there to make it solid
what are the 3 techniques for isolating pure cultures
- the streak plate technique
- the spread plate technique
- the pour plate technique
Describe the process of the streak plate technique
- One edge of a plate is inoculated with a concentrated sample of bacteria
- sample is diluted by streaking it across the surface of the plate, to deposit individual cells on the plate (separate from other cells)
- plate is incubated
- individual cells grow to form colonies
What’s a colony?
- A mass of cells that (ideally) arose from one single cell
-can be used to create a pure culture
(all identical through asexual reproduction)
Describe the process of the spread plate technique
- Sample is diluted before plating
- Diluted sample can be spread over the surface of the plate with a sterile spreader
- Separate cells grow into colonies on the surface of the plate
Describe the process of the pour plate technique
- After the sample is diluted, it is mixed with molten agar (~45 C)
- Colonies form embedded inside the plate
What is the standard plate count technique used for?
- technique used for estimating the concentration of bacteria in a population.
what’s bacterial titre
-the concentration of bacteria in a population.
what’s the formula for bacterial titre? (standard plate count technique)
titre = # colonies/ (volume x dilution)
what units is titre expressed in?
- cfu/ml
