Fermentation Redox and Dissolved Oxygen Control
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Solution Overview
Problem
Existing methods for cultivating microorganisms, such as lactic acid bacteria, face challenges in simultaneously regulating redox potential and dissolved oxygen, as oxygen addition increases redox potential, making it difficult to achieve a low redox environment beneficial for biomass and metabolic activity.
Innovation Solution
A method involving the simultaneous regulation of redox potential and dissolved oxygen using gas mixtures, like hydrogen, and oxygen injection, respectively, with a PID-type controller to maintain setpoints, decoupling these parameters to enhance microbial productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen is added to increase biomass and metabolic activity, then productivity improves, but redox potential increases which is harmful to anaerobic microorganisms
Solution Approach 1:
The patent implements a dual feedback control system where two sensors continuously monitor redox potential and dissolved oxygen levels, and two actuators (oxygen injection and reducing agent injection) are controlled by PID controllers to maintain both parameters within optimal ranges. This allows real-time adjustment to resolve the contradiction between maintaining low redox potential and providing sufficient oxygen for productivity.
Solution Approach 2:
The patent dynamically adjusts multiple parameters including redox potential, dissolved oxygen concentration, pH, temperature, and agitation speed to optimize microbial growth. By changing these parameters in a coordinated manner through automated control, the system resolves the contradiction between oxygen availability and redox potential maintenance.
2Reliability
If redox potential is maintained at low levels to preserve microorganism viability, then survival during conservation improves, but dissolved oxygen becomes limiting which reduces productivity
Solution Approach 1:
The patent introduces reducing agents (such as sodium sulfite or hydrogen gas) as intermediary substances that can lower redox potential without directly consuming oxygen. These intermediaries react with oxygen or accept electrons, thereby maintaining low redox potential while allowing dissolved oxygen levels to remain sufficient for microbial productivity.
3Productivity
If multiple parameters (redox potential and dissolved oxygen) are regulated simultaneously, then cultivation optimization improves, but system complexity increases
Solution Approach 1:
The patent employs a multi-functional control system where a single automated control unit coordinates multiple sensors and actuators to regulate redox potential, dissolved oxygen, pH, temperature, and agitation speed. This universal controller integrates multiple functions into one system, managing the complexity of simultaneous multi-parameter regulation through centralized automated control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in significant increases in biomass, acidifying activity, and productivity, with gains exceeding 50% at the freeze-dried product stage, demonstrating effective regulation of redox potential and dissolved oxygen to improve microbial cultivation outcomes.
Implementation Method 1
simultaneous regulations, preferably using gases or gas mixtures to ensure these regulations: advantageously the regulation of the redox potential will use the injection of a reducing gas or gas mixture (for example a gas mixture comprising hydrogen) into the culture medium
Implementation Method 2
Different compounds can be used as a reducing agent and induce a reduction and/or maintenance of the redox potential. Among these, we can cite sulphites, ammonia but also reducing gases such as hydrogen or mixtures containing hydrogen
Implementation Method 3
the regulation of the dissolved oxygen value will be done by injection of air or pure oxygen or even air enriched with oxygen into the culture medium
Implementation Method 4
Microorganisms can also be used for the production of biofuels, in particular by transforming sugar into ethanol
Data Source
AI summary
The invention relates to a method for cultivating microorganisms, particularly of the type that comprises the step of seeding a culture medium with one or more microorganism strains, and the step of cultivating the medium thus seeded, characterised in that it comprises, during the entirety or a portion of the cultivation, the two following and simultaneous adjustments: adjusting the amount of oxygen dissolved in the medium to a given dissolved-oxygen setpoint; adjusting the value of the redox potential Eh of the medium to a given setpoint value Eh.