MCB 150 Extreme Environments

• Extreme Environments


  Habitats characterized by harsh environmental conditions; conditions beyond the optimal range for human development
• Factors affecting extreme environments


  • Extreme temperature
  • Extreme pH
  • Extreme ionic strength
  • Extreme pressure
  • High radiation
  • Water availability (xeric environments)
  • Nutrient availability (oligotrophic environments)
• Extremophiles


  Organisms that can adapt to extreme environment conditions and can grow optimally in them
• Extremotrophs


  Organisms that can grow in extreme environments but not optimally
• Studying microbial diversity in extreme environments is important for bioremediation and biotechnology
• Hyperthermophilic environment


  Temperature: 80C to 115C; Deep geothermal heated oil-containing stratifications; Shallow coastal and deep-water hot sediments; Hydrothermal vents (with low salinity; bottom of North Sea areas); 4000 m below the sea level
• Thermophilic environment


  Temperature: 50C to 80C; Coal refuse; Hot water tanks; Compost piles
• Psychrophilic environment


  Temperature: below 15C; Polar zones; High mountains; Glaciers; Deep oceans
• Organisms present in temperature extremes


  • Hyperthermophiles: Thermotogales and Aquificales
  • Thermophiles: Photosynthetic bacteria - Chloroflexus and Chromatium; Sulfur oxidizers - Thiobacillus; Sulfate reducers - Desulfovibrio; Gram-neg aerobes - Thermus; Methanogens
  • Psychrophiles: Pseudoalteromonas and Pseudomonas; Methanogenium and Methanococcoides

  
• Challenge for hyperthermophiles and thermophiles


  Maintenance of membrane fluidity and stability
• Adaptation of hyperthermophiles and thermophiles


  Tetraether lipid layer in membrane with saturated isoprenoid chains linked to glycerol or other alcohol; Prominent hydrophobic core, increased electrostatic interactions
• Challenge for psychrophiles


  Low rate of biochemical activity
• Adaptations of psychrophiles


  Cold-active enzymes; Antifreeze proteins
• Hyperthermophiles are consumers of organic matter; Thermophiles are consumers of organic matter; Psychrophiles are involved in pollutant degradation
• Anaerobic environments lack atmospheric oxygen but atomic oxygen that is bound to compounds can still be present
• Anaerobic protozoans found in the rumen of cows


  • Epidinium
  • Entodinium
  • Diplodinium
  • Holotrich ciliates
• Cows benefit from these anaerobic protozoans as they are integral in fiber digestion
• Sites for sample collection


  • Gastrointestinal tract
  • Still waters
  • Deep soil sediments
  • Lake and river sediments
• Sample collection methods


  • Sterile syringe
  • Sterile glass container
• Sample processing methods


  • Polyethylene glove box
  • Anaerobic chambers
  • Oxygen removal
  • Allotment for gas production
• Sample analysis methods


  • Cell number or biomass quantification
  • Spectrometry
  • Assay kits
  • Measuring produced gas
• Thermophilic environments


  Characterized by high temperatures ranging from 50°C to 80°C
• Thermophiles and hyperthermophiles


  • Face the challenge of maintaining membrane fluidity and stability given the extremely high temperatures
  • Adaptation: Formation of a tetraether lipid layer in their membrane, containing saturated isoprenoid chains linked to glycerol or another alcohol
  • Adaptation: Prominent hydrophobic cores and increased electrostatic interactions
• Psychrophilic environments


  Environments with temperatures below 15°C
• Microorganisms found in cold regions


  • Pseudomonas
  • Methanococcoides
• Psychrophiles


  • Adaptation: Cold-active enzymes and antifreeze proteins
  • Function: Act as 'environmental cleaners' for pollutant degradation, specifically petroleum hydrocarbons
• Acidic environments


  pH lower than 5
• Man-made acidic environments


  • Acid mine drainage
  • Biomining activities
  • Mine waste dumps and tailings
• Alkaline environments


  pH above 8
• Alkaline environments from human activities


  • Cement manufacturing
  • Waste treatment processes
• Acidophiles


  Microorganisms that inhabit extremely acidic environments
• Extremely acidophiles


  Have pH optima of 3 or below
• Moderate acidophiles


  Have pH optima of 3-5