Fermentation Process Nitrate Control for Methanotrophic Biomass
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Solution Overview
Problem
Methanotrophic microorganisms like Methylococcus capsulatus are sensitive to nitrogen-source loads, particularly ammonia, which can inhibit methane consumption and reduce biomass production due to ammonia oxidation, necessitating a controlled nitrogen-source regulation in fermentation processes.
Innovation Solution
A fermentation process and reactor design that maintains a nitrate concentration below 0.035 g/l and/or 0.01 g nitrate/g biomass by regulating the nitrogen-source, such as ammonia, to optimize biomass production while avoiding competitive inhibition of methane consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ammonia is supplied as nitrogen-source to support microbial growth, then biomass production is improved, but ammonia oxidation by methane monooxygenase enzymes creates competitive inhibition of methane consumption
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of ammonia in the fermentation broth and regulating the pH to maintain ammonia in a non-ionic form. By adjusting these parameters, the system optimizes nitrogen availability for biomass production while minimizing competitive oxidation by methane monooxygenase enzymes, thus resolving the contradiction between productivity and harmful side reactions
Solution Approach 2:
The patent implements feedback control through continuous monitoring of ammonia concentration and pH levels in the fermentation broth. The system automatically adjusts ammonia supply and pH control based on real-time measurements, ensuring that nitrogen is available for growth without exceeding thresholds that would trigger competitive oxidation, thereby balancing biomass production with methane consumption efficiency
2Productivity
If high concentrations of nitrogen-source are supplied to accelerate microbial growth, then biomass production increases, but methanotrophic microorganisms become sensitive to nitrogen load and methane consumption is inhibited
Solution Approach 1:
The patent applies dynamics by implementing a dynamic control strategy where ammonia supply rate is continuously adjusted based on the growth phase and current biomass concentration. During exponential growth, ammonia is supplied at higher rates to support rapid biomass production, while during stationary phase or when methane consumption drops, the supply is reduced to prevent inhibition, thus maintaining reliability of methane consumption while maximizing productivity
Solution Approach 2:
The patent employs periodic action through cyclic adjustment of ammonia feeding rates and pH control intervals. The system periodically measures biomass concentration and methane consumption rates, then adjusts ammonia supply in periodic cycles to match microbial demand, preventing nitrogen overload that would inhibit methane consumption while ensuring sufficient nitrogen for growth during active phases
3Quantity of substance
If ammonia oxidation is allowed to proceed to meet nitrogen demands, then nitrogen availability for growth is improved, but co-metabolic by-products are formed and methane consumption efficiency decreases
Solution Approach 1:
The patent applies local quality by creating different chemical environments in different zones of the fermentation system. Through localized pH control and ammonia dosing, the system maintains conditions where nitrogen is available for growth in the liquid phase while preventing ammonia oxidation in the gas-liquid interface where methane consumption occurs, thus protecting methane consumption efficiency while ensuring nitrogen availability
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 ensures high productivity of methanotrophic biomass by controlling nitrate levels, preventing stress and maintaining high biomass concentrations, demonstrated in both laboratory and industrial settings.
Implementation Method 1
Methane monooxygenase enzymes are responsible for rendering methanotrophy in methanotrophic microorganisms, and at the same time they carry out oxidations on available nitrogen-sources, leading to numerous co-metabolic by-products.
Implementation Method 2
When growing methanotrophic microorganisms, like M. capsulatus, nitrogen-sources, such as ammonia, is readily oxidized by the methane monooxygenases of Methylococcus capsulatus even at low extracellular concentrations if methane is not in large excess.
Data Source
AI summary
The present invention relates to a fermentation process for the fermentation of at least one microorganism, wherein the fermentation process comprises the steps of (a) allowing a fermentation broth comprising the at least one microorganism to flow in the fermentation reactor; (b) supplying a carbon-substrate to the fermentation reactor allowing the gaseous carbon-substrate to be dissolved, or partly dissolved, in the fermentation broth; (c) supplying a nitrogen-substrate to the fermentation reactor allowing the gaseous nitrogen-substrate to be dissolved, or partly dissolved, in the fermentation broth; and (d) maintaining a nitrate concentration of the fermentation broth below 0.035 g/l, and/or maintaining a nitrate concentration of the fermentation broth below 0.01 g nitrate/g biomass; wherein the at least one methanotrophic organism comprises at least one methanotrophic microorganism.