Microalgae carbon sequestration system and microalgae carbon sequestration method thereof
By immobilizing ribulose-1,5-bisphosphate carboxyloxidase in microalgal cells using chitosan-silica hybrid gel microspheres and combining it with a photobioreactor, the technical challenges in microalgal carbon fixation were solved, achieving efficient microalgal carbon fixation and biomass increase.
Patent Information
- Application Number
- CN202511641504.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-11
- Publication Date
- 2026-02-06
AI Technical Summary
Microalgae-mediated photosynthetic carbon fixation faces technical difficulties and high costs in large-scale cultivation. Furthermore, traditional microalgae ponds have a high CO2 escape rate, and most algal species cannot tolerate high concentrations of CO2 or SOx/NOx.
Ribulose-1,5-bisphosphate carboxyl oxidase was immobilized in chitosan-silica hybrid gel microspheres for extracellular CO2 fixation in microalgae. Combined with a photobioreactor, photosynthesis was carried out to generate sugars, which were then converted into biomass by the microalgae cells.
It improved the carbon fixation efficiency of microalgae, increased microalgae biomass, shortened the carbon fixation cycle, and reduced the CO2 escape rate of traditional methods.
Abstract
Description
Technical Field
[0001] This invention relates to the field of microalgae carbon fixation technology, specifically to a microalgae carbon fixation system and a method for performing microalgae carbon fixation. Background Technology
[0002] Microalgae can not only fix carbon but also synthesize a variety of high-value-added products, making them a highly promising method for carbon fixation and emission reduction. However, it is regrettable that large-scale carbon fixation and emission reduction through microalgae-mediated photosynthetic carbon fixation still faces certain difficulties, mainly due to the challenges and high costs of large-scale cultivation technology.
[0003] Microalgae fix carbon primarily relies on various carbon dioxide concentration mechanisms (CCM) and inorganic carbon absorption systems within their cells. This allows CO2 to accumulate around Rubisco (ribulose-2-phosphate carboxyl oxidase) in the chloroplasts, enabling efficient photosynthesis. Rubisco is a key enzyme in photosynthesis; it mainly reacts with carbon dioxide to fix carbon, synthesizing biomass from inorganic carbon.
[0004] Microalgae absorb CO2 through photosynthesis and convert it into biomass such as lipids, proteins, and polysaccharides, thus completing carbon fixation. The carbon fixation efficiency of microalgae is 10 to 50 times that of terrestrial plants. Each ton of microalgae can fix approximately 1.83 to 2 tons of CO2. Traditional microalgae ponds have CO2 escape rates as high as 80%. Most algal species cannot tolerate high concentrations of CO2 or SOx / NOx. Summary of the Invention
[0005] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a microalgae carbon fixation system that can increase microalgae biomass and improve the efficiency of microalgae cells in fixing CO2.
[0006] The second objective of this invention is to provide a method for preparing a microalgae carbon fixation system, which is simple and easy to mass-produce industrially.
[0007] One of the objectives of this invention is achieved through the following technical solution: A microalgae carbon fixation system, the system comprising: Purified ribulose-1,5-bisphosphate carboxyloxidase (Rubisco). The chitosan-silica hybrid gel microspheres used to immobilize the ribulose-1,5-bisphosphate carboxyloxidase have a particle size of 150-250 μm, a porosity of 40-60%, and a pore size of 5-20 nm. The chitosan-silica hybrid gel microspheres may also optionally contain carbonic anhydrase. Live microalgae cells suspended in a culture medium, wherein the live microalgae cells can freely enter and exit the area surrounding the chitosan-silica hybrid gel microspheres, but cannot pass through the pores of the chitosan-silica hybrid gel microspheres; A photobioreactor is used to contain the culture medium and provide light to the live microalgal cells.
[0008] Furthermore, the chitosan-silica hybrid gel microspheres are formed in one step by a sol-gel method, and the ribulose-1,5-bisphosphate carboxyloxidase and the optional carbonic anhydrase are co-embedded inside during the formation process.
[0009] Furthermore, the loading of ribulose-1,5-bisphosphate carboxyloxidase in the chitosan-silica hybrid gel microspheres is 0.5-5 mg ribulose-1,5-bisphosphate carboxyloxidase / g chitosan-silica hybrid gel microspheres.
[0010] Furthermore, the live microalgae cells are selected from Chlorella vulgaris, Scenedesmus obliquus, or Arthrospira platensis.
[0011] Furthermore, the photobioreactor is a tubular or column-type photobioreactor with a light intensity of 100–400 μmol photons / m³. -2 s -1 The temperature is 25±2℃.
[0012] Furthermore, the outer surface of the chitosan-silica hybrid gel microspheres is further modified with a hydrophilic polymer layer to reduce the adhesion of the chitosan-silica hybrid gel microspheres and improve the mass transfer efficiency.
[0013] The second objective of this invention is achieved by the following technical solution: A method for microalgae carbon fixation using a microalgae carbon fixation system includes the following steps: S1. A gas containing CO2 is introduced into the culture medium, so that the CO2 dissolves and is fixed by the ribulose-1,5-bisphosphate carboxyl oxidase in the chitosan-silica hybrid gel microspheres to generate sugars. S2, The sugars are taken up by microalgal cells and converted into microalgal biomass through diffusion; S3. After 4–5 days of cultivation, microalgal biomass is harvested, wherein the carbon fixation rate is increased by at least 50% compared with the control system that does not use the chitosan-silica hybrid gel microspheres, and the harvesting cycle is shortened by at least 20%.
[0014] Furthermore, the sugars include 3-phosphoglyceric acid, glucose, or fructose.
[0015] Furthermore, the CO2-containing gas is flue gas from a coal-fired power plant, tail gas from a cement kiln, or biogas, with a CO2 volume fraction of 5-20%.
[0016] The third objective of this invention is achieved by the following technical solution: A method for producing chitosan-silica hybrid gel microspheres includes the following steps: S1. Dissolve chitosan in an acidic aqueous solution to obtain a chitosan solution; S2. Add tetraethyl orthosilicate (TEOS) to the chitosan solution and adjust the pH to 6.0-7.0 to form a sol; S3. Add the ribulose-1,5-bisphosphate carboxyl oxidase and the optional carbonic anhydrase to the sol and mix them evenly. S4. The resulting mixture is dropped into a coagulation bath containing a crosslinking agent to form spherical gel microspheres; S5. Wash with deionized water and store at 4 °C to obtain the chitosan-silica hybrid gel microspheres.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a microalgal carbon fixation system that moves the ribulose-1,5-bisphosphate carboxyl oxidase from the microalgal chloroplasts into a high-CO2 'micro-factory' outside the microalgal cells, namely chitosan-silica hybrid gel microspheres. This allows the ribulose-1,5-bisphosphate carboxyl oxidase to first efficiently fix carbon and generate sugars, which are then removed by the microalgal cells to produce microalgal biomass. This is a coupling of "extracorporeal carbon fixation and in vivo energy storage", which can increase the biomass of microalgae and improve the efficiency of CO2 fixation by microalgal cells. Detailed Implementation
[0018] The present invention will be further described below with reference to specific embodiments. It should be noted that, without conflict, the embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0019] Example This embodiment provides a microalgae carbon fixation system, the system comprising: Purified ribulose-1,5-bisphosphate carboxyloxidase (Rubisco). Chitosan-silica hybrid gel microspheres for immobilizing ribulose-1,5-bisphosphate carboxyloxidase have a particle size of 150-250 μm, a porosity of 40-60%, and a pore size of 5-20 nm. The chitosan-silica hybrid gel microspheres may also optionally contain carbonic anhydrase. Live microalgae cells suspended in the culture medium can freely enter and exit the area surrounding the chitosan-silica hybrid gel microspheres, but cannot pass through the pores of the chitosan-silica hybrid gel microspheres. A photobioreactor is used to contain culture media and provide light for living microalgal cells.
[0020] In this embodiment, the chitosan-silica hybrid gel microspheres are formed in one step by the sol-gel method, and ribulose-1,5-bisphosphate carboxyloxidase and optional carbonic anhydrase are co-embedded inside during the formation process.
[0021] In this embodiment, the loading of ribulose-1,5-bisphosphate carboxyloxidase in the chitosan-silica hybrid gel microspheres is 0.5-5 mg ribulose-1,5-bisphosphate carboxyloxidase / g chitosan-silica hybrid gel microspheres.
[0022] In this embodiment, the live microalgae cells are selected from Chlorella vulgaris, Scenedesmus obliquus, or Arthrospira platensis.
[0023] In this embodiment, the photobioreactor is a tubular or column-type photobioreactor, with a light intensity of 100–400 μmol photons / m³. -2 s -1 The temperature is 25±2℃.
[0024] In this embodiment, the outer surface of the chitosan-silica hybrid gel microspheres is further modified with a hydrophilic polymer layer to reduce the adhesion of the chitosan-silica hybrid gel microspheres and improve the mass transfer efficiency.
[0025] This embodiment also provides a method for microalgae carbon fixation using a microalgae carbon fixation system, including the following steps: S1. A gas containing CO2 is introduced into the culture medium, causing the CO2 to dissolve and be fixed by ribulose-1,5-bisphosphate carboxyl oxidase in the chitosan-silica hybrid gel microspheres to generate sugars. S2. Sugars are taken up by microalgal cells and converted into microalgal biomass through diffusion. S3. Harvest microalgal biomass after 4–5 days of cultivation, with a carbon fixation rate at least 50% higher than the control system without chitosan-silica hybrid gel microspheres, and a harvesting cycle at least 20% shorter.
[0026] In this embodiment, the sugars include 3-phosphoglyceric acid, glucose, or fructose.
[0027] In this embodiment, the CO2-containing gas is flue gas from a coal-fired power plant, tail gas from a cement kiln, or biogas, with a CO2 volume fraction of 5-20%.
[0028] This embodiment also provides a method for producing chitosan-silica hybrid gel microspheres, including the following steps: S1. Dissolve chitosan in an acidic aqueous solution to obtain a chitosan solution; S2. Add tetraethyl orthosilicate (TEOS) to the chitosan solution and adjust the pH to 6.0-7.0 to form a sol; S3. Add ribulose-1,5-bisphosphate carboxyl oxidase and optional carbonic anhydrase to the sol and mix well. S4. The resulting mixture is dropped into a coagulation bath containing a crosslinking agent to form spherical gel microspheres; S5. Wash with deionized water and store at 4 °C to obtain chitosan-silica hybrid gel microspheres.
[0029] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A microalgal carbon sequestration system, characterized by, The system comprises: purified ribulose-1,5-bisphosphate carboxylase / oxygenase (Rubisco); chitosan-silica hybrid gel microspheres for immobilizing the ribulose-1,5-bisphosphate carboxylase / oxygenase, with a particle size of 150-250 μm, a porosity of 40-60 %, and a pore size of 5-20 nm, and optionally containing carbonic anhydrase inside the chitosan-silica hybrid gel microspheres; live microalgal cells suspended in a culture solution, which are capable of freely entering and exiting the area around the chitosan-silica hybrid gel microspheres and are unable to pass through the pores of the chitosan-silica hybrid gel microspheres; a photobioreactor for containing the culture solution and providing light for the live microalgal cells.
2. A microalgal carbon sequestration system as claimed in claim 1, wherein, The chitosan-silica hybrid gel microspheres are formed in one step by a sol-gel method, and the ribulose-1,5-bisphosphate carboxylase / oxygenase and the optional carbonic anhydrase are co-encapsulated inside during the formation process.
3. The microalgal carbon sequestration system of claim 1, wherein, The loading amount of the ribulose-1,5-bisphosphate carboxylase / oxygenase in the chitosan-silica hybrid gel microspheres is 0.5-5 mg ribulose-1,5-bisphosphate carboxylase / oxygenase per gram of chitosan-silica hybrid gel microspheres.
4. The microalgal carbon sequestration system of claim 1, wherein, The live microalgal cells are selected from Chlorella vulgaris, Scenedesmus obliquus, or Arthrospira platensis.
5. The microalgal carbon sequestration system of claim 1, wherein, The photobioreactor is a tubular or column photobioreactor, the light intensity is 100-400 pmol photons m -2 -1 at a temperature of 25±2°C. 6. The microalgal carbon sequestration system of claim 1, wherein, The outer surface of the chitosan-silica hybrid gel microspheres is further modified with a hydrophilic polymer layer to reduce the adhesion of the chitosan-silica hybrid gel microspheres and improve the mass transfer efficiency.
7. A method for microalgal carbon fixation using the system of any one of claims 1-6, comprising the following steps: S1, passing a CO2-containing gas into the culture solution to dissolve CO2 and be fixed by the ribulose-1,5-bisphosphate carboxylase / oxygenase inside the chitosan-silica hybrid gel microspheres to generate a sugar; S2, the sugar is taken up by the microalgal cells by diffusion and converted into microalgal biomass; S3, harvesting the microalgal biomass after 4-5 days of cultivation, wherein the carbon fixation rate is increased by at least 50 % and the harvesting period is shortened by at least 20 % compared to a control system without using the chitosan-silica hybrid gel microspheres.
8. The microalgal carbon sequestration system of claim 1, wherein, The sugar includes 3-phosphoglycerate, glucose, or fructose.
9. The method for preparing a microalgae carbon fixation system as described in claim 1, characterized in that, The CO2-containing gas is flue gas from a coal-fired power plant, tail gas from a cement kiln, or biogas, with a CO2 volume fraction of 5-20 %.
10. A method for preparing the chitosan-silica hybrid gel microspheres of any one of claims 1-6, comprising: S1, dissolving chitosan in an acidic aqueous solution to obtain a chitosan solution; S2, adding tetraethyl orthosilicate (TEOS) to the chitosan solution and adjusting the pH to 6.0-7.0 to form a sol; S3, adding the ribulose-1,5-bisphosphate carboxylase / oxygenase and the optional carbonic anhydrase to the sol and mixing uniformly; S4, dropping the obtained mixture into a coagulation bath containing a crosslinking agent to form spherical gel microspheres; S5, washing with deionized water and storing at 4℃, to obtain the chitosan-silica hybrid gel microspheres.