Microorganisms Role in Recycling Minerals (AQA A Level Biology): Revision Note

The role of microorganisms in mineral cycling

• Microorganisms play a vital role in recycling chemical elements, such as phosphorus and nitrogen, in ecosystems; examples include:

  • saprobionts in decomposition

  • mycorrhizae in plant roots

Saprobionts

• Saprobionts are:

organisms that decompose dead and waste organic matter

• Examples include fungi and bacteria

• Decomposition by saprobionts releases chemical elements, such as phosphorus and nitrogen, from within dead and waste material

• The process of decomposition by saprobionts is as follows:

  1. enzymes are secreted onto a food source

  2. extracellular digestion occurs

  3. nutrients are absorbed

• Importantly, not all of the products of extracellular digestion are absorbed by saprobionts; some mineral ions remain in the soil where they can be absorbed by plants

Mycorrhizae

• Mycorrhizae are:

symbiotic relationships between fungi and the roots of plants

• Fungi form long, thin filaments known as hyphae, which connect with plant roots

• The hyphae effectively increase the surface area of the root systems of the plants, increasing absorption of water and inorganic ions

• In return the fungi receive carbon compounds, e.g. glucose, from the plant