Abstract: A relatively solid, stable biomass reaction product is provided produced from microorganisms having metal uptake properties when contacted by an aqueous solution containing metal cations. The biomass reaction product is produced by treating cells thereof with a caustic solution, whereby the biomass reaction product after drying is characterized in the particulate state of having substantially enhanced uptake of metal cations from aqueous solutions as compared to the metal uptake property of the microorganism before treatment. The biomass reaction product in the particulate state is preferably immobilized in an insoluble binder.