Chapter 10 - Comparative investigation of fungal and bacterial manganese biomining mechanisms

Abstract

Manganese biomining is a newly evolving area of research consisting of multiple studies and developments about new discoveries of numerous bioleaching microorganisms. Extraction of metal contents in trace amounts from unconventional resources with the use of microorganisms is called bioleaching. Low-grade ores, mining wastes, electronic wastes, domestic wastes and sludge wastes retrieved from different industries possess collectively a huge amount of manganese remains in trace concentrations. Improper disposal of these into the environment causes high risks of heavy metal poisoning of natural resources. Multiple bacterial and fungal species have been proven to contribute in the biomining processes, manganese dissolution and extraction. Bacterial biomining mostly utilizes the methodology of redoxolysis to oxidize or reduce the metal into its pure form with the use of bacterial enzymes. Fungal bioleaching of manganese involves organic acids secreted by fungal species which help in solubilization of manganese metal from the wastes. These refining technologies of manganese biomining enhance the toxic-free removal of mining by-products into the natural environment. This chapter elaborates on the different mechanisms used by bacterium and fungus for the degradation and recovery of manganese. The progress and recent developments are showcased in the chapter highlighting the environment-friendly management of manganese wastes by biomining. This chapter also introduces a native microorganism that was isolated from the mining sites and has the ability to solubilize the manganese, which will further extract the metals from the ores. Therefore, it was used in the leaching mechanism of low-grade manganese ore. The chapter discusses various fungal species which perform under diverse conditions and different parameters (pH, temperature, substrate, incubation time) to aid in the recovery of metals.