Biology subjects

Marecos, S.

Publications and source records attributed to Marecos, S..

6 recordsLinked to original sources

bioRxiv2024

Bio-Accelerated Weathering of Ultramafic Minerals with Gluconobacter oxydans

Ultramafic rocks are an abundant source of cations for CO2 mineralization (e.g., Mg) and elements for sustainability technologies (e.g., Ni, Cr, Mn, Co, Al). However, there is no industrially useful process for dissolving ultramafic materials to release cations for CO2 sequestration or mining them for energy-critical elements. Weathering of ultramafic rocks by rainwater, release of metal cations, and subsequent CO2 mineralization already naturally sequesters CO2 from the atmosphere, but this natural process will take thousands to hundreds of thousands of years to remove excess anthropogenic CO2, far too late to deal with global warming that will happen over the next century. Mechanical acceleration of weathering by grinding can accelerate cation release but is prohibitively expensive. In this article we show that gluconic acid-based lixiviants produced by the mineral-dissolving microbe Gluconobacter oxydans accelerate leaching of Mg2+ by 20x over deionized water, and that leaching of Mg, Mn, Fe, Co, and Ni further improves by 73% from 24 to 96 hours. At low pulp density (1%) the G. oxydans biolixiviant is only 6% more effective than gluconic acid. But, at 60% pulp density the G. oxydans biolixiviant is 3.2x more effective than just gluconic acid. We demonstrate that biolixiviants made with cellulosic hydrolysate are not significantly worse than biolixiviants made with glucose, dramatically improving the feedstock available for bioleaching. Finally, we demonstrate that we can reduce the number of carbon atoms in the biolixiviant feedstock (e.g., glucose or cellulosic hydrolysate) needed to release one Mg2+ ion and mineralize one atom of carbon from CO2 from 525 to 1.

bioengineering↗

bioRxiv2024

Cross-species Comparison of Ultramafic Rock Bio-accelerated Weathering Performance

Carbon mineralization is a natural process that sequesters atmospheric CO2 by reacting it with cations (e.g., Mg2+, Ca2+) released by weathering of rocks to form solid carbonates. However, this process is too slow to capture the excess CO2 resulting from anthropogenic emissions in time to prevent significant warming of the atmosphere1-3. Additionally, accelerating carbon mineralization process by chemical or mechanical methods has proven prohibitively expensive to date4. Microbial rock-dissolution processes, including acidolysis, redoxolysis, and complexolysis, have the potential to accelerate weathering with low energy input5. However, there is no industrially useful microbe capable of dissolving ultramafic (rich in ferromagnesian minerals) rocks, suggesting that one will need to be discovered or built with synthetic biology. While microbes are known to dissolve ultramafic minerals6,7, the performance envelopes for these processes remain uncharacterized, and significant gaps exist in our knowledge of microbe-mineral interaction processes. Here, we make a normalized performance comparison of the dissolution of the ultramafic rock dunite (> 90% olivine ((Mg, Fe)2SiO4)) by three well-known mineral-dissolving microbes: Gluconobacter oxydans7-9, Sphingomonas desiccabilis10,11, and Penicillium simplicissimum12-14. We show that G. oxydans outperformed P. simplicissimum and S. desiccabilis, producing the most acidic biolixiviant (pH 2.15 when leaching 1% pulp density), and extracting the most magnesium (3,130 mg/L when leaching at 3% pulp density). Additionally, G. oxydans co-dissolves nine other metals, eight of which are critical for energy technologies (Cr, Mn, Co, Ni, Cu, and Zn)15,16 with a maximum dissolved concentration of 33 mg/L for Ni. While increasing the pulp density of the dunite (solid to liquid ratio) resulted in higher metal dissolution by G. oxydans and S. desiccabilis, notably pulp densities above 2% inhibited mineral dissolution by P. simplicissimum. Our results provide evidence that the gap in performance between G. oxydans and the other two microbes increases with pulp density, and thus, G. oxydans is best suited for process and genetic engineering to maximize performance and minimize costs and environmental impacts of bio-accelerated weathering. Finally, we propose that G. oxydans and P. simplicissimum can use cellulosic hydrolysate as a cost-effective substitute for glucose for biolixiviant production.

bioengineering↗

bioRxiv2024

Direct Genome-Scale Screening of Gluconobacter oxydans B58 for Rare Earth Element Bioleaching

The transition to a sustainable energy economy will require an enormous increase in the supply of rare earth elements (REE). Bioleaching offers a promising alternative to conventional hydrometallurgical methods for REE extraction from low-grade ores. However, exploiting this potential remains challenging due to large gaps in our understanding of the genetics involved, and inadequate biological tools to address them. We generated a highly non-redundant whole genome knockout collection for the bioleaching microbe Gluconobacter oxydans B58, reducing redundancy by 85% compared to the previous best collection. This new collection was directly screened for bioleaching neodymium from a synthetic monazite powder, identifying 89 genes important for bioleaching, 68 of which have not previously been associated with this mechanism. We conducted bench-scale experiments to validate the extraction efficiency of promising strains: 8 demonstrated significant increases in bioleaching by up to 111% (G. oxydans {delta}GO_1598, a disruption of the gene encoding the orotate phosphoribosyltransferase enzyme PyrE), and one strain significantly reduced it by 97% ({delta}GO_1096, a disruption of the gene encoding the GTP-binding protein TypA). Notable changes in biolixiviant pH were only observed for 3 strains, suggesting an important role for non-acid mechanisms in bioleaching. These findings provide valuable insights into further enhancing REE-bioleaching by G. oxydans through targeted genetic engineering.

synthetic biology↗

bioRxiv2023

High Efficiency Rare Earth Element Biomining with Systems Biology Guided Engineering of Gluconobacter oxydans

The global demand for critical rare earth elements (REE) is rising1 with the increase in demand for sustainable energy technologies like wind turbines2,3, electric vehicles2,3, and high efficiency lighting4. Current processes for producing REE require high energy inputs and can produce disproportionate amounts of hazardous waste. Biological methods for REE production are a promising solution to this problem. In earlier work we identified the most important genetic mechanisms contributing to the REE-bioleaching capability of Gluconobacter oxydans B585. Here we have targeted two of these mechanisms to generate a high-efficiency bio-mining strain of G. oxydans. Disruption of the phosphate-specific transport system through a clean deletion of pstS constitutively turns on the phosphate starvation response, yielding a much more acidic biolixiviant, and increasing bioleaching by up to 30%. Coupling knockout of pstS with the over-expression of the mgdh membrane-bound glucose dehydrogenase gene, results in up to 73% improvement of REE-bioleaching.

synthetic biology↗

bioRxiv2022

Practical and Thermodynamic Constraints on Electromicrobially-Accelerated CO2 Mineralization

By the end of the century tens of gigatonnes of CO2 will need to be removed from the atmosphere every year to maintain global temperatures. Natural weathering of ultramafic rocks and subsequent mineralization reactions can convert atmospheric CO2 into ultra-stable carbonates. But, while natural weathering will eventually draw down all excess CO2, this process will need hundreds of thousands of years to do it. The CO2 mineralization process could be accelerated by weathering ultramafic rocks with biodegradable lixiviants like organic acids. But, in this article we show that if these lixiviants are produced from cellulosic biomass, the demand created by CO2 mineralization could monopolize the worlds supply of biomass even if CO2 mineralization performance is high. In this article we demonstrate that electromicrobial production technologies (EMP) that combine renewable electricity and microbial metabolism could produce lixiviants for as little as $200 to $400 per tonne at solar electricity prices achievable within the decade. Furthermore, this allows the lixiviants needed to sequester a tonne of CO2 to be produced for less than $100, even with modest CO2 mineralization performance.

synthetic biology↗

bioRxiv2021

Thermodynamic Constraints on Electromicrobial Protein Production

Global consumption of protein is projected to double by the middle of the 21st century1. However, protein production is one of the most energy intensive and environmentally damaging parts of the food supply system today. Electromicrobial production technologies that combine renewable electricity and CO2-fixing microbial metabolism could dramatically increase the energy efficiency of commodity chemical production2-5. Here we present a molecular-scale model that sets an upper limit on the performance of any organism performing electromicrobial protein production. We show that engineered microbes that fix CO2 and N2 using reducing equivalents produced by H2-oxidation or extracellular electron uptake could produce amino acids with energy inputs as low as 64 MJ kg-1. This work provides a roadmap for development of engineered microbes that could significantly expand access to proteins produced with a low environmental footprint.

synthetic biology↗