Microbial cooperation improves bioleaching recovery rates

Abstract

Whilst bioleaching is primarily used to recover minerals from low-grade ores, the increasing demand for Rare Earth elements combined with supply chain concerns is opening up new avenues of extraction from mine tailings, waste products and recyclable materials. Exploration of new, novel and economically viable techniques are required to manage the coming shortage and volatility of global markets with more environmentally sound alternatives to traditional mining operations holding the key.The exploitation of microbes in the industrial application of bioleaching has been underway since the 1950s 1 due to their ability to mobilise minerals from ore bodies, with either heap leaching implemented for the recovery of Cu, Zn, Ni 2 or stirred tank reactors for U or Au 3 . With fewer discoveries of large high grade mineral deposits occurring 4 it is anticipated that demand for raw minerals will outstrip reserves for not only these elements, but also for Rare Earth Elements (REEs). REEs are fundamental components of mobile phones, lasers, electric batteries and superconductors 5 .With dwindling supplies of high grade REE stocks, ever increasing demand for new technologies and a push for the mining industry to 'go green', the processing of lower grade ores, recycling of electronic waste and treatment of discarded mining by-products using bioleaching applications is proving attractive. Due to this the use and application of bioleaching techniques is expanding as they are more cost efficient, less energy intensive and employ more ecofriendly techniques 2 .REEs (15 elements with atomic numbers ranging from 57 to 71) 6 are located amid carbonates, placer deposits, pegmatites and marine phosphates 7 . However, current bioleaching applications utilise the autotrophic oxidation of ferrous and reduced sulphur compounds for mineral release and subsequent recovery, which are found in low amounts in REE ore bodies. Nevertheless, studies of REE mineral extraction from phosphate ores by bioleaching are in their infancy [8][9][10] . These bioleaching activities utilise acidophilic and For example, the fungal species Penicillium tricolor was shown to leach 30-70% of available REEs from red mud 9 compared to Bacillus megaterium, which leached less than 1% from monazite 11 .Industrial operations with ferrous and sulphide ores often involve two or more species due to the leaching chemistry requirements, size of the processes and the inability to maintain sterility. It has been shown that mixed acidophilic populations increase recovery rates of copper 12 compared to pure cultures. Our research initially conducted with pure cultures 13 (Figure 1) demonstrated low recovery rates of REEs from a concentrated Western Australian monazite, whereas when bioleaching was performed using nonsterile ore complete with the native population and an introduced PSM (Figure 2), REE leaching rates increased tenfold with some species 14 . These leaching rates were much greater than those recorded with either pure cultures or the native consortia alone.Under the M...

Secondary lanthanide phosphate mineralisation in weathering profiles of I-, S- and A-type granites

“…Understanding of microbially-mediated REE-bearing phosphate mineral weathering may inform the development of new biomining strategies for extraction of REEs from low grade mine tailings (Zhuang et al , 2015; Corbett et al , 2018; Corbett and Watkin, 2018). As sequestration of phosphate into secondary REE phases can limit P bioavailability in agricultural soils, the current study motivates investigation of microbial processes that can dissolve REE/P-bearing minerals.…”

Reduced interactivity during microbial community degradation leads to the extinction of Tricholomas matsutake

“…As interactivity within the soil microbial community decreased during degradation, T. matsutake lost cooperative interactions (Figure 4c) that may have been capable of enhancing the rates of certain ecological processes (Corbett & Watkin, 2018;Cui et al, 2019), stimulating energy conservation by individual members (Malik et al, 2018), and even allowing the coexistence of certain species (Cai et al, 2020). The loss of cooperation increases the cost of survival for that species.…”

Reduced interactivity during microbial community degradation lead to the extinction of Tricholomas matsutake

“…As interactivity within the soil microbial community decreased during degradation, T.matsutakelost cooperative interactions (Fig. 3C) that may have been capable of enhancing the rates of certain ecological processes (Corbett & Watkin, 2018, Cui et al , 2019, stimulating energy conservation by individual members (Malik et al , 2018), and even allowing the coexistence of certain species (Cai et al , 2020). The loss of cooperation increases the cost of survival for that species.…”