Lecture 1 Flashcards
What is microbiology?
Study of organisms too small to see with the naked eye
(bacteria, archaea, fungi, protozoa)
(some can be seen with the naked eye)
What are the 3 main domains of life according to Whittaker?
Monera: archaea and bacteria
Protista: eukaryotes
Crown taxa: very little of total diversity
What are microbes?
Bacteria: very small 1-6um in size
Archaea: none pathogenic
Fungi
Protists: very diverse, most eukaryotes
Where are microorganisms found?
Everywhere where temperature is less than 140 degrees
How many microbial cells are there estimated to be on Earth?
4-6 X 10 ^30 cells
Why are there so many microbes?
Rapid growth rate
Many chances of speciation through random mutation
Long evolutionary history
Every available niche is occupied with them
How long ago was the estimate for multi-cellular organisms?
6-7 million years ago
Through what 3 ways are nutritional categories based on?
Energy, electron donor and cell carbon
What is a phototroph?
Gets energy from light
What is a chemotroph?
Energy from chemical bonds
What is an organotroph?
Organic compounds as e- donors
What is a lithotroph?
Inorganic compounds as e- donors
What are autotrophs?
CO2 as carbon source
What are heterotrophs?
Organic carbon as carbon source
What are prototrophs?
Synthesise all their own cellular components
(including ALL amino acids, nucleotides, vitamins)
What is fastidious bacteria?
Need organic components, such as vitamins
Need organic components
(Humans)
What are the primary nutrients of all organisms to survive?
Macronutrients: C, H, O, N, S, P, K, Mg, Na, Ca, Fe
Micronutrients: B, Cr, Co, Cu, Fe, Zn
What is the carbon and energy source in E. Coli?
Glucose
How is bacteria grown?
Asexual reproduction by binary fission
Cells double in size and split into 2
Exponential growth as 1 cells becomes 2, becomes 4
What limits bacterial growth?
The environment
Cells too close together stop growing = carrying capacity
How do microbes grow?
Assimilating and cell division
- Lag phase: adapting to new conditions
- Log phase: exponential growth
- Stationary phase: limitation by nutrients, build up of waste that inhibits growth
- Death
How are the growth of microbes measured?
Cell number
Optical density
Fresh/ dry weight
Protein
DNA
How can microbes be counted using total viable count?
Count colony forming units
Plate serial dilutions onto solidified media
Based on how dilute the sample is calculate total viable count
What is the problem with the identification of microorganisms?
Limited morphological diversity
Most microbes look similar down a microscope
Must use range of methods for identification
What are ways of identifying microorganisms?
Microscopy and staining
Growth on selective media
Testing substrate spectrum supporting growth
Testing of enzyme activities
What is selective media when growing colonies of organisms?
Allows the growth of only some types of organisms
What is differential media when growing colonies of organisms?
Allows the identification of organisms based on growth and appearance on that medium
Identify based on colour, shape etc.
How can enzymes be tested using ApiZym?
- Culture of organism grown
- Cells resuspended in a buffer
- Test wells are inoculated
- Resulting colour in test strip is compared against database
