Whole-cell biotechnological applications with thermoacidophilic Crenarchaeota:Opportunities and challenges

Abstract

Extremophiles are microorganisms that thrive in harsh environmental conditions where no life exists. These environmental conditions can involve temperature, acidity, salinity, pressure, or radiation that are typically uninhabitable to most microorganisms. The thermoacidophilic Archaea (e.g., Acidianus , Metallosphaera and Sulfolobus) can thrive at high temperatures and low pHs. These organisms are capable of autotrophic, lithotrophic, heterotrophic, chemoheterotrophic, and chemolithoautotrophic lifestyles, and thus can easily be cultivated on many different substrates. Additionally, their innate capacities to oxidise ferrous iron and/or reduced inorganic sulfur compounds have gained recognition for their utility in biomining operations. Members of Acidianus and Metallosphaera have been applied in bioleaching operations to extract valuable metals from low-grade ores and mineral concentrates. The advances in Sulfolobus genetics have presented opportunities for their application as platform organisms in biotechnological and biorefinery processes due to the ability to cultivate these extremophilic organisms under non-sterile conditions. Furthermore, utilising inexpensive and sustainable feedstock such as lignocellulosic biomass is one key advantage of lowering cultivation costs. This review presents current research developments on thermoacidophilic Sulfolobales members, emphasising their whole-cell applications for biomining operations, biotechnology and biorefinery. Several laboratory-scale studies found these organisms promising for large-scale deployment based on their unique characteristics.