Bioprospecting for and the applications of halophilic acidophiles in bioleaching operations

Abstract

The economic recovery of metals from sulfide ores has become a topic of increasing interest due to the escalating demand for critical minerals and the reducing grade of available ores. Bioleaching is the use of acidophilic iron and sulfur-oxidising microorganisms to facilitate the extraction of base metals from primary sulfide ores and tailings. One significant issue limiting the use of bioleaching is the availability of freshwater due to the sensitivity of these microbes to chloride. The use of saline tolerant acidophilic iron-and-sulfur oxidising microorganisms will go a long way to addressing this issue. There are three possible means of sourcing suitable microorganisms; adaptation, genetic engineering and bioprospecting, with bioprospecting showing the greatest possibilities. Bioprospecting in search of native organisms for bioleaching operations has led researchers to numerous locations around the world and the isolation of iron-and sulfuroxidising acidophiles that are capable of tolerating high levels of salinity has been of particular interest in these investigations.

Microbes of biotechnological importance in acidic saline lakes in the Yilgarn Craton, Western Australia

“…Additionally, acidophiles are notorious for being highly sensitive to chloride ions, possibly another biological barrier to the evolution of haloacidophiles ( Suzuki et al, 1999 ; Baker-Austin and Dopson, 2007 ). Previous research involving the biology of acidic saline environments has been motivated by isolating iron- and sulfur-oxidizing bacteria that have potential in saline biomining operations as well as understanding the biological basis of acid and saline polyextremophiles ( Simmons and Norris, 2002 ; Zammit et al, 2009 ; O’Dell et al, 2018 ; Chen and Schlömann, 2023 ; Corbett and Watkin, 2023 ). Using haloacidophilic iron- and sulfur-oxidizing microbes for bioleaching operations has the possibility to reduce the cost of biomining as seawater may be able to replace reverse osmosis water currently used to irrigate these processes ( Rohwerder et al, 2003 ; Rea et al, 2015 ; Johnson and Schippers, 2017 ).…”