Microbial Ecology

Microbial Ecology

• The study of the interaction of microbes with the biotic and abiotic environments in which they live

  • 1% of all microbial species have been discovered

The Role of Archaea

• Archaea do not cause human diseases

• Extremophiles

  • They thrive in extreme conditions

    • ie high/low temps, extreme pH levels, or high salt concentrations

• Archaea have pseudopeptidoglycan/pseudomurein in their cell walls

  • Lacks D-aminos and muramic acids

  • Ether linkages

• Methanogenic Archaea

  • Strictly anaerobic and produce methane as a byproduct

  • Methanogens are commonly used in sewage treatment plants and can be found in cow rumens full of grass

• Methanogenic vs Methanotrophs

  • Methanogens produce methane as a byproduct

  • Methanotrophs use methane as a source of carbon and energy

• Extremely halophilic archaea

  • live in extremely salty conditions

  • Optimum growth 70-110C

• Acidophilic Archaeans

  • Live in low pH

• Alkaliphilic Archaeans

  • Live in high pH

Microbes and Biogeochemical Cycles

Biogeochemical Cycles

• Chemically and physically change nutrients to form one another

Microbes in the Carbon Cycle

• Microbes convert carbon between various forms

  • CO2 and Methane are greenhouse gases that trap heat in the atmosphere

Microbes in the Nitrogen Cycle

• Microbes participate in many aspects of the nitrogen cycle

  • Nitrification

    • Ammonia (NH3) to Nitrate (NO3-)

  • Denitrification

    • Nitrate(NO3-) into gas (N2), removing useful nitrogen from soil

  • Ammonification

    • Bacteria decay plant and animal waste into ammonia (NH3)

Microbes in the Sulfur Cycle

• Microbes reduce sulfur oxides (SO2,SO3,SO4) into hydrogen sulfide (H2S)

Microbes in the oxygen cycle

• Photosynthetic microbes release oxygen

Microbes in the Phosphorous cycle

• No major role

Water Microbiology

• Microbes process sewage in water treatment plants

  • Primary Treatment

    • Physically removes solid organic materials

    • Followed by anaerobic digestion of sludge

  • Secondary Treatmnet

    • Uses microbes to remove organic materail from liquid sewage

      • Trickling filtration

      • Activated sludge processing

      • Large lagoons

        • Primary treatment physically removes organic compounds, while secondary treatment uses microbes to degrade organic compounds

  • Tertiary Treatment

    • Removes inorganic materials through chemical means

  • Disinfect through chlorination

• Biological Oxygen Demand (BOD)

  • More organic material means greater BOD and more stress on marine life

• Organic material removal reduces BOD

  • 20-30% by primary

  • 90-95% by secondary

• Septic Tanks

  • A holding tank for waste water

  • Not a treatment system

  • Periodic emptying of solid organic material

  • Microbes no role

  • High BOD→ Extremely green grass around tanks

Composting

• the process of decomposing organic material and recycling it as fertilizer

• Adding soil adds microbes which break down organic material

• Composting can reduce solid matter by two thirds in a matter of months

Bioremediation

• Waste management technique using biological agents to degrade pollutants

• Most natural organic compounds can be degraded by microbes

• Synthetic compounds can also be degraded