Presentation Information
[P02-259]Development of a High-Temperature Gas Fermentation Process with Simultaneous Product Recovery Using Genetically Modified Moorella thermoacetica
○Shota Nakatsugawa1, Junya Kato1,2, Daichi Morimoto2, Tatsuya Fujii1,2, Setsu Kato1, Yoshiteru Aoi1, Yutaka Nakashimada1 (1. Grad.Sch.Integer.Sci.Life,HiroshimaUniv. (Japan), 2. National Institute of Advanced Industrial Science and technology (Japan))
Keywords:
Gas fermentation,Acetone production,Bio reactor,Condensation recovery,Carbon recycling
[Objective]
Our research team is engaged in research utilizing gas fermentation technology to produce useful chemicals from CO and CO2 gas as feedstocks. Gas fermentation is a technology that synthesizes chemicals by metabolizing these gaseous substrates through microbial activity. It is expected to serve as a sustainable process that directly utilizes carbon dioxide as a resource and contributes to the realization of a low-carbon society. Our research team has adopted the thermophilic homoacetogenic bacterium Moorella thermoacetica for gas fermentation technology. This bacterium is characterized by its ability to produce acetic acid using gas as a substrate under high-temperature conditions of 50–60°C. Furthermore, by incorporating genetic engineering techniques, we have developed modified strains capable of producing low-boiling-point compounds such as acetone and ethanol. Acetone has a low boiling point of 56°C and tends to volatilize and transition to the gas phase under high-temperature cultivation conditions; it is therefore expected to reduce product inhibition and simplify the separation process. Therefore, this study aimed to design a bioreactor system capable of simultaneously producing and recovering acetone during high-temperature gas fermentation and to evaluate its effectiveness.
[Methods]
We attempted to recover volatile compounds generated during fermentation by installing a gas circulation line in the fermentation tank and incorporating a condenser into the line. First, we conducted a test in which a simulated fermentation broth containing 30 g/L of acetone was heated to 60°C, and acetone vapor was collected in the condenser while the gas was circulated. Next, we conducted fermentation tests using the constructed bioreactor with an acetone-producing strain (EMT-1) to evaluate the potential for acetone production and simultaneous recovery using this system.
[Results and Discussion]
In tests using simulated fermentation broth, it was confirmed that acetone recovery of up to 1.0 g/h is possible by capturing acetone vapor using a condenser. These results suggest that this system functions effectively as a mechanism for recovering volatile products. Furthermore, fermentation tests using the acetone-producing strain (EMT-1) demonstrated that acetone could be produced and recovered simultaneously while maintaining an anaerobic environment. This is believed to be due to the acetone that volatilized during high-temperature cultivation being transported to the condenser via gas recirculation.
[Conclusion]
This study established a bioreactor system capable of simultaneous recovery of volatile products during high-temperature gas fermentation. Results from simulation tests and fermentation tests using an acetone-producing strain demonstrated that this system enables acetone production and simultaneous recovery. This system enables the continuous production and separation/recovery of low-boiling-point compounds through gas fermentation under high-temperature conditions, demonstrating its potential as a useful foundational technology for future industrial applications.
Our research team is engaged in research utilizing gas fermentation technology to produce useful chemicals from CO and CO2 gas as feedstocks. Gas fermentation is a technology that synthesizes chemicals by metabolizing these gaseous substrates through microbial activity. It is expected to serve as a sustainable process that directly utilizes carbon dioxide as a resource and contributes to the realization of a low-carbon society. Our research team has adopted the thermophilic homoacetogenic bacterium Moorella thermoacetica for gas fermentation technology. This bacterium is characterized by its ability to produce acetic acid using gas as a substrate under high-temperature conditions of 50–60°C. Furthermore, by incorporating genetic engineering techniques, we have developed modified strains capable of producing low-boiling-point compounds such as acetone and ethanol. Acetone has a low boiling point of 56°C and tends to volatilize and transition to the gas phase under high-temperature cultivation conditions; it is therefore expected to reduce product inhibition and simplify the separation process. Therefore, this study aimed to design a bioreactor system capable of simultaneously producing and recovering acetone during high-temperature gas fermentation and to evaluate its effectiveness.
[Methods]
We attempted to recover volatile compounds generated during fermentation by installing a gas circulation line in the fermentation tank and incorporating a condenser into the line. First, we conducted a test in which a simulated fermentation broth containing 30 g/L of acetone was heated to 60°C, and acetone vapor was collected in the condenser while the gas was circulated. Next, we conducted fermentation tests using the constructed bioreactor with an acetone-producing strain (EMT-1) to evaluate the potential for acetone production and simultaneous recovery using this system.
[Results and Discussion]
In tests using simulated fermentation broth, it was confirmed that acetone recovery of up to 1.0 g/h is possible by capturing acetone vapor using a condenser. These results suggest that this system functions effectively as a mechanism for recovering volatile products. Furthermore, fermentation tests using the acetone-producing strain (EMT-1) demonstrated that acetone could be produced and recovered simultaneously while maintaining an anaerobic environment. This is believed to be due to the acetone that volatilized during high-temperature cultivation being transported to the condenser via gas recirculation.
[Conclusion]
This study established a bioreactor system capable of simultaneous recovery of volatile products during high-temperature gas fermentation. Results from simulation tests and fermentation tests using an acetone-producing strain demonstrated that this system enables acetone production and simultaneous recovery. This system enables the continuous production and separation/recovery of low-boiling-point compounds through gas fermentation under high-temperature conditions, demonstrating its potential as a useful foundational technology for future industrial applications.
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