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Fts proteins
- Filamentous temperature-senesitive proteins
- FtsZ - Ring around centre
- ZipA - Connects FtsZ to membrane
- FtsA - Recruits other cytoplasmic proteins
- FtsK - Mediates separation of chromosomes
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Min proteins
Facilitate location of FtsZ
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MreB
- Prokaryotic shape determining factor
- - Simple cytoskeleton (Bacteria and Archaea)
- - Not found in coccus
- - Loacalizes peptidoglycan synthesis
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Crescentin
- Shape-determining protein produced by vibrio-shaped cells of Caulobacter crescentus
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- Found on concave surfaces
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Epicentre of cell wall growth
- Cocci - From FtsZ ring
- Rod-shapes - From points along length
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Bactoprenol
- Carrier molecule that plays a major role in insertion of peptidoglycan precursors
- - Nonpolar, easy membrane passage
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Generation time equation
- g = t/n
- t = duration of exp. growth
- n = No. of generations during exponential growth period
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Typical growth curve
- 1. Slow growth at first while numbers increase
- 2. Exponential growth while nutrients are present
- 3. Stabilized growth as nutrients become limiting and waste builds up
- 4. Death
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Effects of too high or too low temperatures for a cell
- Too low - Membrane gelling, slow transport
- Too high - Protein denaturation, membrane collapse, thermal lysis
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Cold extremophiles
- Psychrophiles - Very cold temperature optima
- Psychrotolerant - Organisms that can grow at 0°C, though their optimum is somewhat higher
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Cold climate adaptations
- More α helices than β sheets
- More polar and less nonpolar residues
- Decreased interactions between protein domains
- Antifreeze proteins
- Accumulation of compatible solutes
- Upregulation of peptidoglycan synthesis
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Hot extremophiles
- Thermophiles - Growth optima between 45°C and 80°C
- Hyperthermophiles - Optima greater than 80°C
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Extreme-hot climate adaptations
- Heat tolerant protein folding
- Increased ionic bonds between acidic and basic residues
- Di-inositol phosphate, diglycerol phosphate
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Bacterial adaptation to high heat
Membranes rich in saturated fatty acids
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Archeal adaptation to high heat
Lipid monolayer rather than bilayer
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Neutrophiles, Acidophiles and Alkaliphiles
- Neutrophiles - pH 6-8
- Acidophiles - pH <6; sensitive membranes
- Alkaliphiles - pH >9; Na+ motive force (not H+)
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Internal pH of Acidophiles and Alkaliphiles
Still ~neutral with some variation (4.6-9.5)
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Types of salt loving bacteria
Halotolerant (0%-5% NaCl), halophile (5%-7% NaCl), extreme halophile (>15% NaCl)
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Mechanism of resisting high salt concentration
Compatible solutes
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Oxygen tolerant bacteria types
Aerobes, facultative organisms (take it or leave it), microaerophiles (only small amounts), aerotolerant (live with it, but don't use it)
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Sterillization
Killing or removal of all viable organisms
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Inhibition (cleaning)
Limiting microbial growth
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Deconatimination
Treatment of an object to make it safe to handle
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Disinfection
Removes all pathogens, but not necessarily all microorganisms
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Pasteurization
Controlled heat to reduce microbial load in heat-sensitive liquids
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Bacteriostatic, bacteriocidal, bacteriolytic
- -static; Inhibits growth only
- -cidal; Kills only viable cells
- -lytic; Kills eveything
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