Extremophilic electroactive microorganisms: Promising biocatalysts for bioprocessing applications

Chaudhary, Srishti; Yadav, Ravi Kumar; Singh, Ramandeep; Sadhotra, Chetan; Patil, Sunil A.

doi:10.1016/j.biortech.2021.126663

Cited by 19 publications

(15 citation statements)

References 113 publications

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“…However, humin still contributed as a solid‐phase electron mediator for CO 2 ‐fixing acetogenesis, even in the presence of hydrogen, although the decrease in the electron equivalents via humin suggested the preferable use of hydrogen as an electron donor. The contribution of DET from the cathode to the bacterium was very small (less than 0.5 meq/chamber), although M. thermoacetica is electroactive (Chaudhary et al, 2022; Philips et al, 2016), indicating that DET was less favored compared with humin and electrolyzed hydrogen in this MES.…”

Section: Resultsmentioning

confidence: 84%

“…The CO 2 solubility in water at 55°C is still high (18.4 mmol‐CO 2 /L, Carroll et al, 1991). An acetogenic electroactive thermophile Moorella thermoacetica (Chaudhary et al, 2022; Philips et al, 2016) has been used to resolve the biochemistry of the Wood–Ljungdahl pathway (Drake et al, 2008). However, to date, only two studies have used M. thermoacetica in DET‐based MESs.…”

Section: Introductionmentioning

confidence: 99%

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Humin‐promoted microbial electrosynthesis of acetate from CO₂ by Moorella thermoacetica

Pham

Masuda

et al. 2022

Biotech & Bioengineering

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Humin, an insoluble fraction of humic substances at any pH, has been reported to be an extracellular electron mediator (EEM) that functions in carbon dioxide (CO 2 )fixing acetogenesis. Here, we show that humin promotes the microbial electrosynthesis (MES) of acetate from CO 2 using Moorella thermoacetica. Yeast extract, essential for the reaction of M. thermoacetica, resulted in the heterotrophic production of organic acids including acetate, hydrogen, and methane. Excluding the effect of yeast extract, MES with 13 g/L of suspended humin poised at −510 mV (vs. Ag/AgCl) achieved a CO 2 -fixing acetate production of 24.2 mg-acetate/L/day (1.9 mg-acetate/day/g-humin); this is 10-folds higher than the humin-free MES, with 90.3% of the coulombic efficiency. Although M. thermoacetica is an electroactive bacterium, it obtains electrons for acetogenesis mostly via humin. The suspended humin-assisted MES poised at −810 mV (vs. Ag/AgCl) increased the acetate production rate to 39.3 mg-acetate/L/day using electrons mainly from electrolyzed hydrogen and humin. Immobilization increased the humin's EEM efficiency, as indicated by the acetate production rate of 20.8 mg-acetate/L/day (6.9 mg-acetate/ day/g-humin) with a 98.7% coulombic efficiency in MES with 3 g/L of immobilized humin poised at −510 mV (vs. Ag/AgCl). These results suggest that humin-assisted MES has high potential for microbial CO 2 fixation.

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Section: Resultsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Humin‐promoted microbial electrosynthesis of acetate from CO₂ by Moorella thermoacetica

Pham

Masuda

et al. 2022

Biotech & Bioengineering

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“…Expanding the database of EET‐capable extremophiles is pivotal to unravel their EET mechanisms and associated components, understand their roles in mineral cycling or biogeochemical processes via EET in such extreme environments, and leverage their full potential for various promising microbial electrochemical technologies. It may also reveal unknown microbial diversity and metabolic capabilities in extreme environments (Chaudhary et al, 2022). The EET‐capable haloalkaliphiles can survive and function under extreme haloalkaline conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Studying electromicrobiology of the extreme habitats is desired to broaden the understanding and ecology of EAMs and their roles in biogeochemical processes, novel EET pathways and components, and exploring their unique metabolic traits for different bioelectrochemical applications (Babu et al, 2015; Chaudhary et al, 2022; Dopson et al, 2016; Rampelotto, 2013; Shrestha et al, 2018). The improved understanding of ecology and diversity of EET‐capable extreme microorganisms may also provide clues about extraterrestrial life on other planets with implications to the Astrobiology field (Ren et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…The improved understanding of ecology and diversity of EET‐capable extreme microorganisms may also provide clues about extraterrestrial life on other planets with implications to the Astrobiology field (Ren et al, 2019). Furthermore, it will provide additional microbial resources essential to broaden the understanding of metabolic evolution and molecular‐level adaptations according to extreme environmental conditions (Arora & Panosyan, 2019; Chaudhary et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

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Geoalkalibacter halelectricus SAP‐1 sp. nov. possessing extracellular electron transfer and mineral‐reducing capabilities from a haloalkaline environment

Yadav

Singh

Sundharam

et al. 2022

Environmental Microbiology

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The extracellular electron transfer (EET)-capable electroactive microorganisms (EAMs) play crucial roles in mineral cycling and interspecies electron transfer in different environments and are used as biocatalysts in microbial electrochemical technologies. Studying EAMs from extreme environments is desired to advance the electromicrobiology discipline, understanding their unique metabolic traits with implications to extreme microbiology, and develop specific bioelectrochemical applications. Here, we present a novel haloalkaliphilic bacterium named Geoalkalibacter halelectricus SAP-1, isolated from a microbial electroactive biofilm enriched from the haloalkaline lake sediments. It is a rod-shaped Gram-negative heterotrophic anaerobe that uses various carbon and energy sources and respires on soluble and insoluble terminal electron acceptors. Besides 16S-rRNA and wholegenome sequence-based phylogeny, the GGDC values of 21.7%, ANI of 78.5%, and 2.77% genomic DNA GC content difference with the closest validly named species Geoalkalibacter ferrihydriticus (DSM 17813 T ) confirmed its novelty. When grown with the solid-state electrode as the only electron acceptor, it produced 460 AE 23 μA/cm 2 bioelectrocatalytic current, thereby confirming its electroactivity. Further electrochemical analysis revealed the presence of membrane redox components with a high formal potential, putatively involved in the direct mode of EET. These are distinct from EET components reported for any known electroactive microorganisms, including well-studied Geobacter spp., Shewanella spp., and Desulfuromonas acetexigens. The capabilities of G. halelectricus SAP-1 to respire on soluble and insoluble electron acceptors including fumarate, SO 4 2À , Fe 3+ , and Mn 4+ suggests its role in cycling these elements in haloalkaline environments.

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Extremophiles: How Smart Are the Cells to Cope with the Environment?

Chakraborty,

Diwan,

Mitra

2024

Trends in Biotechnology of Polyextremophiles

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Extremophilic electroactive microorganisms: Promising biocatalysts for bioprocessing applications

Cited by 19 publications

References 113 publications

Humin‐promoted microbial electrosynthesis of acetate from CO₂ by Moorella thermoacetica

Humin‐promoted microbial electrosynthesis of acetate from CO₂ by Moorella thermoacetica

Geoalkalibacter halelectricus SAP‐1 sp. nov. possessing extracellular electron transfer and mineral‐reducing capabilities from a haloalkaline environment

Extremophiles: How Smart Are the Cells to Cope with the Environment?

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Extremophilic electroactive microorganisms: Promising biocatalysts for bioprocessing applications

Cited by 19 publications

References 113 publications

Humin‐promoted microbial electrosynthesis of acetate from CO2 by Moorella thermoacetica

Humin‐promoted microbial electrosynthesis of acetate from CO2 by Moorella thermoacetica

Geoalkalibacter halelectricus SAP‐1 sp. nov. possessing extracellular electron transfer and mineral‐reducing capabilities from a haloalkaline environment

Extremophiles: How Smart Are the Cells to Cope with the Environment?

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Humin‐promoted microbial electrosynthesis of acetate from CO₂ by Moorella thermoacetica

Humin‐promoted microbial electrosynthesis of acetate from CO₂ by Moorella thermoacetica