1 - Introduction to Microbiology Flashcards
Three domains
Archaea
Bacteria
Eukarya
Bacteria info
1-6 micrometers long
Mostly very small, can be some that are visible to naked eye
Archaea info
Can be extremophiles - can grow in extreme conditions
No known pathogenic archaea
Fungi info
Eukaryotic microbes
Size varies enormously
Commonly found with spores
Protists info
Very diverse - most eukaryotes are protists
Size range - 1-150 micrometers
Different types of microorganisms
Bacteria
Archaea
Fungi
Protozoa
Significance of microorganisms in global biomass
4-6 x 10^30 microbial cells in earth estimated
Microbial carbon equals that of all plants
Microbial Nitrogen and Phosphorous is 10x that of plant biomass
Bacteria and Archaea:
Major portion of biomass on Earth
Key reservoirs of nutrients for all life
Five kingdoms
Plants
Fungi
Animal
Protists
Bacteria
Distribution/abundance of microorganisms (not in size order)
Cloud water (least abundant
Seawater
Soil
Rivers and lakes
Marine subsurface
Human cells and bacteria in humans (most)
Why so many microorganisms
Rapid growth rate in environment
Many changes of speciation through random mutations
Exchange of genetic material (lateral gene transfer)
Every available niche is occupied by specifically adaptations microbes
A very long evolutionary history (3.8 billion years)
Phototroph def
Converts light energy to chemical, usable energy for organism
Chemotroph def
Utilise energy from chemical bonds, breaking them open to convert energy
Organotroph
Organic compounds as electron donors
Lithotroph
Inorganic compounds as electron donors
Autotrophs
CO2 as a carbon source
Heterotrophs
Organic compound as a carbon source
Photolithoautotroph - example
Cyanobacteria (and plants!)
- light energy used
- water as an electron donor
- CO2 fixation for ATP production
Chemoorganoheterotroph example
E. Coli (and most animals)
- chemical bond energy (O2)
- organic compounds (e.g. sugars) as electron donors
- organic compounds as carbon source - eat other organic compounds
Chemolithoautotroph - example
Thiobacillus spp.
- chemical bond energy
- inorganic compound (reduced sulfur compounds) as electron donor
- Fix CO2
Nutrients required for bacterial growth in the lab
Primary macronutrients:
- Carbon (CO2, or organic Carbon)
- H, O, N, S, P, K, Mg, Na, Ca, Fe
Micronutrients:
- B, Cr, Co, Cu, Fe, Mn, Mo, Ni, Se, W, V, Zn
Phototroph growth in the lab
Synthesise all their own cellular components (including all amino acids, nucleotides, vitamins)
Fastidious bacteria growth in the lab
Need organic components, such as vitamins, in growth medium
Luria broth - complex medium broth makeup
Glucose - 15g
Peptone - 5g
Yeast extract - 5g
KH2PO4 - 2g
- dissolved in distilled water - pH 7
Peptone (hydrolysed protein) and yeast extract are “undefined” chemicals containing cellular material
-most bacteria will grow using this complex growth medium
Defined medium - Thiobacillus thioparus
More complex media - where some microbes need to be grown
- some microbes have to be grown inside eukaryotic cells or in animals, or in other specific environments
E.g. syphilis grown in testicular cells, leprosy agent grown on feet of mice or armadillos
Growth of bacteria
- Asexual reproduction by binary fission or budding
- Cells double in’s size then split in two
- exponential growth - 2, 4, 8 etc.
- incomplete separation produces pairs or larger assemblies of bacteria
Why bacterial growth is limited
Exponential growth of bacteria can produce large numbers
All environments are limited though
- so limit is carrying capacity of medium
- limited by space and availability of nutrients
- most bacteria subject to bacterial growth curve
Bacterial growth curve stages
Lag phase - adapt to new conditions
Log/exponential phase - exponential growth
Stationary phase - limited by nutrients, buildup of toxic waste products - inhibit growth
Death phase - organisms start dying off, and may lyse
Measurements of growth
Cell number
Optical density
Fresh/dry weight (biomass?)
Protein
DNA
Instruments to measure growth of microbes
Haemocytometer
Dilution plating (serial dilutions etc.)
Turbidmetry
typical prokaryotic cell organelles
Cell wall
Cytoplasmic membrane (plasma membrane)
Nucleoid -
cytoplasm
Plasmid
Ribosomes
typical eukaryotic cell organelles
cell wall
cytoplasmic membrane
mitochondrion
nuclear membrane
nucleus
ribosomes
ER - endoplasmic reticulum (rough and smooth)
cytoplasm
golgi complex