Abstract:Sufficient supply of oxygen is a major bottleneck in industrial biotechnological synthesis. One example is the heterologous production of rhamnolipids using Pseudomonas putida KT2440. Typically, the synthesis is accompanied by strong foam formation in the reactor vessel hampering the process. It is caused by the extensive bubbling needed to sustain the high respirative oxygen demand in the presence of the produced surfactants. One way to reduce the oxygen requirement is to enable the cells to use the anode of … Show more
“…Furthermore, another industrially related strain, P . putida KT2440, was reported to improve glycolipid surfactants production under similar oxygen-limited conditions with poised anode potential [ 51 ], highlighting the potential of anodic electro-fermentation to decrease the oxygen requirements of aerobic bioprocesses. Fig.…”
Background
Bacillus subtilis is generally regarded as a ubiquitous facultative anaerobe. Oxygen is the major electron acceptor of B. subtilis, and when oxygen is absent, B. subtilis can donate electrons to nitrate or perform fermentation. An anode electrode can also be used by microorganisms as the electron sink in systems called anodic electro-fermentation. The facultative anaerobic character of B. subtilis makes it an excellent candidate to explore with different electron acceptors, such as an anode. This study aimed to optimise industrial aerobic bioprocesses using alternative electron acceptors. In particular, different end product spectrum of B. subtilis with various electron acceptors, including anode from the electro-fermentation system, was investigated.
Results
B. subtilis was grown using three electron acceptors, i.e. oxygen, nitrate and anode (poised at a potential of 0.7 V vs. standard hydrogen electrode). The results showed oxygen had a crucial role for cells to remain metabolically active. When nitrate or anode was applied as the sole electron acceptor anaerobically, immediate cell lysis and limited glucose consumption were observed. In anode-assisted electro-fermentation with a limited aeration rate, acetoin, as the main end product showed the highest yield of 0.78 ± 0.04 molproduct/molglucose, two-fold higher than without poised potential (0.39 ± 0.08 molproduct/molglucose).
Conclusions
Oxygen controls B. subtilis biomass growth, alternative electron acceptors utilisation and metabolites formation. Limited oxygen/air supply enabled the bacteria to donate excess electrons to nitrate or anode, leading to steered product spectrum. The anode-assisted electro-fermentation showed its potential to boost acetoin production for future industrial biotechnology applications.
“…Furthermore, another industrially related strain, P . putida KT2440, was reported to improve glycolipid surfactants production under similar oxygen-limited conditions with poised anode potential [ 51 ], highlighting the potential of anodic electro-fermentation to decrease the oxygen requirements of aerobic bioprocesses. Fig.…”
Background
Bacillus subtilis is generally regarded as a ubiquitous facultative anaerobe. Oxygen is the major electron acceptor of B. subtilis, and when oxygen is absent, B. subtilis can donate electrons to nitrate or perform fermentation. An anode electrode can also be used by microorganisms as the electron sink in systems called anodic electro-fermentation. The facultative anaerobic character of B. subtilis makes it an excellent candidate to explore with different electron acceptors, such as an anode. This study aimed to optimise industrial aerobic bioprocesses using alternative electron acceptors. In particular, different end product spectrum of B. subtilis with various electron acceptors, including anode from the electro-fermentation system, was investigated.
Results
B. subtilis was grown using three electron acceptors, i.e. oxygen, nitrate and anode (poised at a potential of 0.7 V vs. standard hydrogen electrode). The results showed oxygen had a crucial role for cells to remain metabolically active. When nitrate or anode was applied as the sole electron acceptor anaerobically, immediate cell lysis and limited glucose consumption were observed. In anode-assisted electro-fermentation with a limited aeration rate, acetoin, as the main end product showed the highest yield of 0.78 ± 0.04 molproduct/molglucose, two-fold higher than without poised potential (0.39 ± 0.08 molproduct/molglucose).
Conclusions
Oxygen controls B. subtilis biomass growth, alternative electron acceptors utilisation and metabolites formation. Limited oxygen/air supply enabled the bacteria to donate excess electrons to nitrate or anode, leading to steered product spectrum. The anode-assisted electro-fermentation showed its potential to boost acetoin production for future industrial biotechnology applications.
“…A low aeration rate can bring nancial bene ts regarding operational costs and fewer foaming-related issues for industrial applications. Furthermore, another industrially related strain, P. putida KT2440, was reported to improve glycolipid surfactants production under similar oxygen-limited conditions with poised anode potential (Askitosari et al, 2020), highlighting the potential of anodic electro-fermentation to decrease the oxygen requirements of aerobic bioprocesses.…”
Background: Bacillus subtilis is generally regarded as a ubiquitous facultative anaerobe. Oxygen is the major electron acceptor of B. subtilis, and when oxygen is absent, B. subtilis can donate electrons to nitrate or perform fermentation. An anode electrode can also be used by microorganisms as the electron sink in systems called anodic electro-fermentation. The facultative anaerobic character of B. subtilis makes it an excellent candidate to explore with different electron acceptors, including an anode. This study aimed to optimise industrial aerobic bioprocesses using alternative electron acceptors. In particular, the change of metabolism and end product spectrum of B. subtilis with different electron acceptors, including anode from the electro-fermentation system, was investigated.
Results: B. subtilis was grown using three electron acceptors, i.e., oxygen, nitrate, and anode (poised at a potential of 0.70 V vs. standard hydrogen electrode). The results showed oxygen had a crucial role for cells to remain metabolically active. When nitrate or anode was applied as the sole electron acceptor anaerobically, immediate cell lysis and limited glucose consumption were observed. In anode assisted electro-fermentation with a limited aeration rate, acetoin, as the main end product showed the highest yield of 0.78 ± 0.04 molproduct/molglucose, 2-fold higher than without poised potential (0.39 ± 0.08 molproduct/molglucose).
Conclusions: Oxygen controls B. subtilis biomass growth, alternative electron acceptors utilisation and metabolites formation. Limited oxygen/air supply enabled the bacteria to donate excess electrons to nitrate or anode, leading to steered metabolic pathways. The anode assisted electro-fermentation showed its potential to boost acetoin production for future industrial biotechnology applications.
“…Pyocyanin PYO -0.034 V (Askitosari et al, 2020) Phenazine-1-carboxylic acid PCA -0.116 V (Askitosari et al, 2020) J o u r n a l P r e -p r o o f Riboflavin RF -0.210 V (Wu et al, 2014) J o u r n a l P r e -p r o o f…”
Section: Natural Mediators Produced By Biocatalystmentioning
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