Engineering <scp><i>A</i></scp><i>cidithiobacillus ferrooxidans</i> growth media for enhanced electrochemical processing

Li, Xiaozheng; Mercado, Roel; Berlinger, Sarah A.; Banta, Scott; West, Alan C.

doi:10.1002/aic.14628

Cited by 12 publications

(15 citation statements)

References 23 publications

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“…The highest initial Fe 2þ concentration tolerated by the cells in batch cultures was 0.5 M at pH 1.6. However, even at this concentration, the energy density of the media is quite low as compared to processes using heterotrophic bacteria with sugars as substrates (Li et al, 2014a).…”

Section: Introductionmentioning

confidence: 97%

Enhancing isobutyric acid production from engineered Acidithiobacillus ferrooxidans cells via media optimization

West²,

Banta³

2015

Biotech & Bioengineering

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The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans has previously been genetically modified to produce isobutyric acid (IBA) from carbon dioxide while obtaining energy from the oxidation of ferrous iron. Here, a combinatorial approach was used to explore the influence of medium composition in both batch and chemostat cultures in order to improve IBA yields (g IBA/mol Fe(2+)) and productivities (g IBA/L/d). Medium pH, ferrous concentration (Fe(2+)), and inclusion of iron chelators all had positive impact on the IBA yield. In batch experiments, gluconate was found to be a superior iron chelator because its use resulted in smaller excursions in pH. In batch cultures, IBA yields decreased linearly with increases in the final effective Fe(3+) concentrations. Chemostat cultures followed similar trends as observed in batch cultures. Specific cellular productivities were found to be a function of the steady state ORP (Oxidation-reduction potential) of the growth medium, which is primarily determined by the Fe(3+) to Fe(2+) ratio. By operating at low ORP, chemostat cultures were able to achieve volumetric productivities as high as 3.8 ± 0.2 mg IBA/L/d which is a 14-fold increase over the previously reported value.

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Section: Introductionmentioning

confidence: 97%

Enhancing isobutyric acid production from engineered Acidithiobacillus ferrooxidans cells via media optimization

West²,

Banta³

2015

Biotech & Bioengineering

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“…These transient transformations were made using modifications to the broad-host-range pJRD215 plasmid (17). The wild-type (WT) strain and the genetically modified strains have been investigated using a variety of medium compositions, including the addition of metal chelators, to improve growth rates and maximize chemical yields in batch and continuous cultures (16,18,19). Although several constitutive promoters of different strengths have been characterized with respect to driving gene expression, the need for inducible control of gene expression within this organism led to the identification of endogenous promoter sequences compatible with the growth conditions for A. ferrooxidans (12,20).…”

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confidence: 99%

Transposase-Mediated Chromosomal Integration of Exogenous Genes in Acidithiobacillus ferrooxidans

Inaba

Banerjee

Kernan

et al. 2018

Appl Environ Microbiol

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The development of as a non-model host organism for synthetic biology is hampered by a lack of genetic tools and techniques. New plating and liquid-based selection methods were developed to improve the identification of transformed cell lines. Enabled by these methods, a hyperactive transposase was used to generate mutants with integrated genes for the expression of the superfolder green fluorescent protein (sfGFP) gene or a 2-keto decarboxylase (KDC) gene, which enabled the production and secretion of isobutyric acid (IBA). An inverse PCR method was used to identify the insertion sites of the KDC gene in several mutants, leading to the identification of a region on the chromosome that may be suitable for future genetic insertions. These results demonstrate that functional exogenous metabolic genes have been chromosomally integrated into, and this advance will facilitate the future development of these cells for new biotechnology applications. is an iron- and sulfur-oxidizing chemolithoautotroph and is a key member of the microbial consortia used in industrial biomining applications. There is interest in exploiting these cells for other metal recovery applications as well as in developing them as unique nonmodel microbial cell factories. Plasmid-driven expression of exogenous genes has been reported, and homologous recombination has been used to knock out some gene expression. Here, new selection protocols facilitated the development of a transposition method for chromosomal integration of exogenous genes into This greatly expands the available genetic toolbox, which will open the door to greater metabolic engineering efforts for these cells.

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“…We have been developing an alternative electrofuels process which utilizes iron as an electron mediator and the bacterium Acidithiobacillus ferrooxidans as the production host [5,9,8,10]. A.…”

Section: Introductionmentioning

confidence: 99%

“…ferrooxidans is a gram-negative, aerobic, acidophilic chemolithoautotroph which is able to oxidize Fe 2+ or sulfur for energy while fixing atmospheric CO 2 [15]. Fe 2+ as an electron mediator has several advantages such as low cost, facile electrochemical reduction, and stability under the A. ferrooxidans growth environment [8]. In addition, A. ferrooxidans cells grow planktonically, and its genome has been sequenced [15].…”

Section: Introductionmentioning

confidence: 99%

“…Citrate and gluconate (which cannot be used as carbon sources by the cells) have been included as chelators to increase the solubility of the Fe 3+ ions and to reduce Fe 3+ inhibition [5,9]. Mg 2+ ions have also been included to increase medium conductivity which improves the energy efficiency during electrochemical iron reduction in continuous cultures [8].…”

Section: Introductionmentioning

confidence: 99%

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Development of reactor configurations for an electrofuels platform utilizing genetically modified iron oxidizing bacteria for the reduction of CO2 to biochemicals

Guan

Berlinger

et al. 2017

Journal of Biotechnology

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Electrofuels processes are potentially promising platforms for biochemical production from CO using renewable energy. When coupled to solar panels, this approach could avoid the inefficiencies of photosynthesis and there is no competition with food agriculture. In addition, these systems could potentially be used to store intermittent or stranded electricity generated from other renewable sources. Here we develop reactor configurations for continuous electrofuels processes to convert electricity and CO to isobutyric acid (IBA) using genetically modified (GM) chemolithoautotrophic Acidithiobacillus ferrooxidans. These cells oxidize ferrous iron which can be electrochemically reduced. During two weeks of cultivation on ferrous iron, stable cell growth and continuous IBA production from CO were achieved in a process where media was circulated between electrochemical and biochemical rectors. An alternative process with an additional electrochemical cell for accelerated ferrous production was developed, and this system achieved an almost three-fold increase in steady state cell densities, and an almost 4-fold increase in the ferrous iron oxidation rate. Combined, this led to an almost 8-fold increase in the steady state volumetric productivity of IBA up to 0.063±0.012mg/L/h, without a decline in energy efficiency from previous work. Continued development of reactor configurations which can increase the delivery of energy to the genetically modified cells will be required to increase product titers and volumetric productivities.

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Engineering Acidithiobacillus ferrooxidans growth media for enhanced electrochemical processing

Cited by 12 publications

References 23 publications

Enhancing isobutyric acid production from engineered Acidithiobacillus ferrooxidans cells via media optimization

Enhancing isobutyric acid production from engineered Acidithiobacillus ferrooxidans cells via media optimization

Transposase-Mediated Chromosomal Integration of Exogenous Genes in Acidithiobacillus ferrooxidans

Development of reactor configurations for an electrofuels platform utilizing genetically modified iron oxidizing bacteria for the reduction of CO2 to biochemicals

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