Metals and minerals as a biotechnology feedstock: engineering biomining microbiology for bioenergy applications

Abstract

Developing new feedstocks for the efficient production of biochemicals and biofuels will be a critical challenge as we diversify away from petrochemicals. One possible opportunity is the utilization of sulfide-based minerals in the Earth's crust. Non-photosynthetic chemolithoautotrophic bacteria are starting to be developed to produce biochemicals from CO using energy obtained from the oxidation of inorganic feedstocks. Biomining of metals like gold and copper already exploit the native metabolism of these bacteria and these represent perhaps the largest-scale bioprocesses ever developed. The metabolic engineering of these bacteria could be a desirable alternative to classical heterotrophic bioproduction. In this review, we discuss biomining operations and the challenges and advances in the engineering of associated chemolithoautotrophic bacteria for biofuel production. The co-generation of biofuels integrated with mining operations is a largely unexplored opportunity that will require advances in fundamental microbiology and the development of new genetic tools and techniques for these organisms. Although this approach is presently in its infancy, the production of biochemicals using energy from non-petroleum mineral resources is an exciting new biotechnology opportunity.

Transposase-Mediated Chromosomal Integration of Exogenous Genes in Acidithiobacillus ferrooxidans

“…A. ferrooxidans is a key member of microbial consortia used in industrial bioleaching of copper and other metal sulfides, and it has been explored for use in other applications such as sour gas treatment, coal desulfurization, and electronic waste recycling (3)(4)(5). Recently, there has been interest in the development of A. ferrooxidans as a biotechnology platform organism for biofuel and biochemical production (6,7); however, this has been hampered by a lack of tools and techniques to genetically modify the cells.…”

Microbially Influenced Corrosion of Stainless Steel by Acidithiobacillus ferrooxidans Supplemented with Pyrite: Importance of Thiosulfate

“…A. ferrooxidans is an important microorganism in bioleaching operations due to its ability to interact directly with sulfidic ores through ferric iron (15,35). There have been some efforts to develop these cells as a platform for biofuel production (36)(37)(38)(39)(40).…”

“…Acidithiobacillus ferrooxidans is an acidophilic bacterium that oxidizes ferrous iron and reduced inorganic sulfur compounds under aerobic conditions and is known to play a key role in the industrial biomining of copper and other sulfide-rich ores (14,15). Although A. ferrooxidans is an obligate anaerobe and can grow on reduced inorganic sulfur compounds (RISCs) under anaerobic environments, it is commonly grown aerobically for the leaching of sulfide minerals in mining operations (16,17).…”

Can Sulfate Be the First Dominant Aqueous Sulfur Species Formed in the Oxidation of Pyrite by Acidithiobacillus ferrooxidans?

“…As pyrite is the most common and widely spread metal sulfide in the environment, knowledge of the mechanism of its oxidation and related pathways is fundamentally significant in the biochemistry and physiology of acidophilic iron- and sulfur-oxidizing bacteria and in pyrite biogeochemistry. Pyrite oxidation is one of the key biological reactions in exposed sulfide mineral deposits and particularly relevant in the bioleaching of metals from low-grade ores or concentrates (Schippers et al, 2014; Banerjee et al, 2017; Sethurajan et al, 2018; Werner et al, 2018). Characterization of its oxidation mechanism provides a basic understanding of the substrates, products and enzyme systems that should be considered to control the overall process.…”