Abiotic Effects Flashcards
Abiotic factors
Temperature Pressure Salinity PH Oxygen Radiation Heavy metals and toxic compounds
Abiotic boundaries for earth and other plants
Restraints on earths life is a combination of pressure, PH, temp and salinity
Life has been detected in all regions of the earth
If same criteria are placed on other planets suggests life is possible
Extremophile
Org that grows optimally under 1+ chemical/physical extreme condition
Evolution of earths extremophiles
Most of earths history only microbial life existed
Bacteria and archaea branches ~3.8bya
Prokaryotes more evolved to inhabit varied and extreme abiotic conditions
Present day O2 concs only in place the last few hundred million years
PH nomenclature
hyperacidophile = PH 9 Hyperalkiphile = >PH 11
Temperature nomenclature
Psychrophile =<15C
Mesophile =20-45C
thermophilic =45-80C
Hyperthermophile = >80C
Salinity nomeclature
Non-halophile = <1.2%
Halotolerant = 1.2-2.9%
Halophile = >8.8%
Extreme halophile = >14.5%
Pressure nomeclature
Piezotolerant = 0.1-10MPa Piezophile = 10-50MPa Hyperpiezophile = >50MPa
Water nomenclature
Xerophile = <0.7
Micro environments/niches
Abiotic gradients creating micro niches within microscopic distances
- affected by microbial activities
- what grows where determined by nutrient availability
E.g. in soil aggregate decreasing O2 towards the centre until anoxic = aerobic microorgs on outside and anaerobic in centre
low temperature environments
Antarctic ice sheets Permafrost in tundra Sea ice Glaciers and frozen lakes Deep ocean and sea floor
Describe psychrophily
Ice contains <100nm layers of liquid water
W/ high concentrations solutes
Large enough gaps to support microbial life
Microbial activity measured at -40C in tundra
E.g. sea ice bacterium psychromonas
adaptations to psychrophily
- Proteins/enzymes
- Ahelix and b sheet structures = more flexibly
- polar > hydrophilic AA content - Cytoplasmic membranes
- high content unsaturated and short chain fatty acids
- polyunsaturated fatty acids e.g. unsaturated diether lipids (UDLs) in methanococcoides burtonii - Cold shock proteins
- RNA regulation: prevents inhibitory mRNA secondary structure formation - Cyroprotectants
- glycerol = prevents ice crystals
- extracellular polysaccharide substances (EPS)
High temperature environments
Hydrothermal vents
Hot springs, geysers and fumaroles
Hot mud volcanoes
E.g. hyperthermophile bacteria
Thermotoga maritima
Hyperthermophile adaptations
- stabilising proteins
- hydrophobic cores
- disulphide bonds
- stabilisation by chaperones (assist with protein folding ) - Stabilising DNA
- reverse DNA gyrase = positive supercoils
- DNA binding proteins or archeal histones - Stabilising lipids
- dibiphtynal tetraether lipids in archaea
- bacterial diether lipids = produce membrane that are less permeable so better in extremes
Is there an upper temp limit on life?
People used to think it was 60C
Now we think it is 130C
Have seen life at 122C
Describe Geogemma barossi
Alive at 122C
Archaea in hydrothermal vent
Obligate anaerobe
Iron reducing chemolithotroph = needs iron for energy
Describe thermus aquaticus
Bacterium from hot spring
Optimum temp = 65-70C
Chemotroph
Source of Taq polymerase = no PCR without these
Piezophiles
Pressure increases by 1 mega pascal per kilometre in the oceans so often found underwater
They are often facultative anaerobes belonging to psychrophiles
Hyperthermophile-piezophiles are archaea
Piezophile adaptations
High proportion of unsaturated fatty acids in membranes = prevents gelling at high pressure
Specific outer membrane protiens (OmpH) porins allow molecules to diffuse through membrane
Hyper saline (High salt) environments
Seawater evaporating ponds
Salt lakes
Saline soils
How to halophiles regulate osmolarity
Regulation of turgor pressure
Osmolytes = solutes that increase osmolarity within cell without affect metabolism e.g. glycerol
‘Salt in’ cytoplasm accumulation of K+ as osmolytes
bacteriorhodopsin
Bacteriorhodopsin produced by halobarchaea
Allows growth in absence of water and dissolved O2 as saline environments sry out red/purple colouration as absorbs light at 570nm
1st membrane to have its 3D structure elucidated
7 membrane spanning a-helixes > each with ~25 hydrophobic AA with one molecule of retinol in centre of the protein
- all trans retinol molecules activated by light and protonated
Energy transduction in bacterhodopsin
light mediated ATP synthesis
- Retinal protonated when exposed to light = converted from trans to cis form
- Retinal transfers its H+ to a protein. Protein has conformational change and carries H+ across cell membrane = released into periplasm
- Protons in periplasm re-enter cell via ATP synthase = ATP generated
- De protonated retinal picks up another H+ from cytoplasm
Cycles back
Low PH environments
Sulphur lakes
Acid drainage
Cave ‘snotties’ - bacteria hanging from ceiling
How do acidophiles adapt to high PH sand e.g. of acidophile
E.g. = E.coli
Continuously, actively pump out H+
How do alkaliphiles adapt to high PH sand e.g. of alkaliphiles
E.g. Bacillus firmus
Reduce internal PH
Call walls contain acidic polymers
Na+/H+ antiporters systems and ATPase driven expulsion
Types of anaerobic metabolism
Fermentation
Anaerobic respiration
Fermentation
Same organic compound as e- donor and e- acceptor
ATP formed by substrate level phosphorylation
Anaerobic respiration
Formation of proton motif force (PMF) by oxidative phosphorylation
Involves electron acceptor other than O2
Niche partitioning in marine sediment
As further down becomes more anaerobic and alternative electron acceptor to O2 changes
3 zones:
Oxic = aerobic respiration, fermentation, nitrate reduction
Suboxic = manganese or iron reduction
Anoxic = sulphate reduction or methanogenesis (using carbon dioxide)
