Generation of a Gluconobacter oxydans knockout collection for improved extraction of rare earth elements

Abstract

Bioleaching of rare earth elements (REEs), using microorganisms such as Gluconobacter oxydans, offers a sustainable alternative to environmentally harmful thermochemical extraction, but is currently not very efficient. Here, we generate a whole-genome knockout collection of single-gene transposon disruption mutants for G. oxydans B58, to identify genes affecting the efficacy of REE bioleaching. We find 304 genes whose disruption alters the production of acidic biolixiviant. Disruption of genes underlying synthesis of the cofactor pyrroloquinoline quinone (PQQ) and the PQQ-dependent membrane-bound glucose dehydrogenase nearly eliminates bioleaching. Disruption of phosphate-specific transport system genes enhances bioleaching by up to 18%. Our results provide a comprehensive roadmap for engineering the genome of G. oxydans to further increase its bioleaching efficiency.

Practical and thermodynamic constraints on electromicrobially accelerated CO2 mineralization

“…Schmitz et al. recently built a whole-genome map of acid production by G. oxydans ( Schmitz et al., 2021 ), the first step in whole genome engineering. Added together these breakthroughs make something that appeared almost impossible a few years ago, appear tantalizingly possible.…”

“…Rowe et al, 2018 discovered that S. oneidensis can use imported electrons to reduce NADH, and characterized the genes behind this pathway (Rowe et al, 2021). Schmitz et al recently built a wholegenome map of acid production by G. oxydans (Schmitz et al, 2021), the first step in whole genome engineering. Added together these breakthroughs make something that appeared almost impossible a few years ago, appear tantalizingly possible.…”

“…However, almost all mineral-dissolving microbes need to be powered by the degradation of plant biomass ( i.e ., the product of photosynthesis). For example, the mineral-dissolving microbe Gluconobacter oxydans B58 oxidizes the sugar glucose to the environmentally benign lixiviant (a mineral-dissolving compound) gluconic acid (glucose can be derived from the degradation of cellulose, one of the primary components of biomass) ( Reed et al., 2016 ; Schmitz et al., 2021 ).…”

Harnessing synthetic biology for sustainable biomining with Fe/S-oxidizing microbes

“…A deeper understanding of Fe/S-oxidizing microbes’ genes is nonetheless still needed for more detailed metabolic engineering towards desirable biomining properties, compared to the model chassis Escherichia coli and Saccharomyces cerevisiae . Schmitz et al (2021) harnessed high-throughput genome editing and sequencing approaches in the study of heterotrophic bacterium Gluconobacter oxydans to produce organic acids for rare earth elements biomining. They created a library of single-gene transposon mutants in G. oxydans and found the bioleaching rates of rare earth elements increased up to 18% when phosphate-specific transport systems genes were disrupted.…”

Efficient Production of 2,5-Diketo-D-gluconic Acid by Reducing Browning Levels During Gluconobacter oxydans ATCC 9937 Fermentation

“…2,5-DKG is commonly and directly synthesized using D-glucose as a substrate. In addition to 2,5-DKG being the precursor of 2-KLG, recent studies reported its synthesis may also increase rare-earth element recovery in wastewater (Jindra et al, 2016;Schmitz et al, 2021). As 2,5-DKG reactions during synthesis and decomposition processes are unclear, further research in these areas may provide insights on one-step 2-KLG synthesis and environmental protection.…”