Lecture 1. Introduction To Microbiology Flashcards
What is microbiology?
Study of organisms too small to see with the naked
eye (bacteria, archaea, fungi, protozoa)
But some can be much larger, define microbiology NOT purely by size
What was Whittaker’s “Five kingdoms’
The crown taxa (plantae, Fungi, animalia), protista and bacteria
Incorrect
What are the actual three domains?
Bacteria, archaea and eukarya
What is the average size of most bacteria?
1-6 μm
What were archaea once thought to be?
Extremophiles only
When was the first non-extreme archaeon isolated?
2004
Are there any known pathogenic archaea?
No
What is the size of the largest fungal colony?
~10,000kg
What are most eukaryotes?
Protists
What is the size range of protists?
1-150μm
What is the distribution of microorganisms in cloud water?
10³-10⁴/ml
What is the distribution of microorganisms in sea water?
10⁶/ml
What is the distribution of microorganisms in soil?
10⁷-10⁹/g
What is the distribution of microorganisms in rivers and lakes?
10⁵-10⁷/ml
What is the distribution of microorganisms in the marine subsurface?
10⁶-10¹¹/ml
What is the distribution of microorganisms in human cells?
10¹³-10¹⁴
What is the distribution of microorganisms in bacterial cells?
10¹⁴
What is the estimated total of microbial cells on earth?
4-6x10³⁰
Why are bacteria and archaea important?
Major portion of biomass on Earth and key reservoirs of nutrients for all life
Why are there so many microorganisms?
Rapid growth rate even in the environment
Many chances of speciation through random mutations
Exchange of genetic material (lateral gene transfer)
Every available niche is occupied by specifically adapted
microbes
A very long evolutionary history (~3.8 billion years)
What does phototroph mean?
Energy from light
What does chemotroph mean?
Energy from chemical bonds
What does organotroph mean?
Organic compounds as e⁻ donors
What does lithotroph mean?
Inorganic compounds as e⁻ donors
What does autotroph mean?
CO₂ as carbon source
What does heterotroph mean?
Organic carbon as carbon source
What are plants and cyanobacteria?
Photolithoautotrophs (Use light energy, water as e⁻ donor, fix carbon dioxide)
What are animals and E. coli?
Chemoorganoheterotroph (Use chemical bond energy (e.g. O₂), organic compounds (e.g. sugars) as e⁻ donor and carbon source)
What is Thiobacillus spp.?
Chemolithoautotroph (Use chemical bond energy, inorganic compound (reduced sulfur compounds) as e⁻ donor, fix carbon dioxide)
What are the primary nutrients required to grow bacteria?
Macronutrients and micronutrients
What are examples of macronutrients?
C (CO₂ or organic C), H, O, N, S, P, K, Mg, Na, Ca, Fe
What are examples of micronutrients?
B, Cr, Co, Cu, Fe, Mn, Mo, Ni, Se, W, V, Zn
What do prototrophs synthesise?
All their own cellular components (including all amino acids, nucleotides, vitamins)
Why are there no complex materials in the defined medium for E. coli?
E. coli can make them all itself
How does bacteria grow?
Asexual reproduction by binary fission or budding
Exponential growth because one cell becomes two
becomes four etc.
Incomplete separation produces pairs or larger assemblies of bacteria
What are the four stages of microbe growth?
Lag phase
Log/exponential phase
Stationary phase
Death phase
What occurs in the lag phase?
Microbes adapting to (new) conditions
What occurs in the log/exponential phase?
Exponential growth in microbes
What occurs in the stationary phase?
Limitation by nutrients, buildup of waste products that inhibit growth
What occurs in the death phase?
Organisms start dying off and may lyse
What is selective media?
Media that allows the growth of only some types of media (used to culture/identify presumed pathogens from clinical specimens)
What is differential media?
Media that allows the identification of organisms
based on growth and appearance on that medium (often based on colour differences)
What is ApiZym?
A common test system, mainly optimised
towards pathogens
