Question

Which mineral is immobilized by mycorrhizal fungi?

Answer 1

Biosolubilization of Mineral Insoluble phosphates by Immobilized Fungi (Aspergillus Niger) in Fluidized Bed Bioreactor

Answer 2

Nitrogen will remain immobilized within fungi.  

As fungi internalize nitrogen and phosphorous, they become unavailable for other plants.  

The only way, nitrogen is available for other plants when absorbed by fungi is when their tissues senesce and are decomposed and are consumed by other organisms or until it is secreted out in a form of ammonium.