Application of boron nitride in microalgae culture

Abstract

The invention relates to application of boron nitride in microalgae culture and a method for culturing microalgae, which comprises the step of adding boron nitride into a culture system. By constructing a hexagonal boron nitride-cyanobacteria co-culture system and combining the carbon dioxide adsorption performance of a nano material and the biological directional synthesis capability of cyanobacteria, more efficient carbon dioxide capture and conversion are realized, and meanwhile, the growth speed and biomass of cyanobacteria and the yield of a target product are also improved. The innovative strategy not only can enhance the photosynthetic carbon sequestration efficiency of cyanobacteria, but also provides a new technical route for promoting green and low-carbon development, and gives consideration to both high economic benefit and low-carbon environmental protection.

Description

Technical Field

[0001] The invention belongs to the field of material-microorganism intersection, and specifically relates to the application of boron nitride in microalgae cultivation. Background Art

[0002] As photosynthetic autotrophic organisms, cyanobacteria play a key role in the global carbon cycle, and their carbon fixation capacity is of great significance for alleviating global warming. Cyanobacteria directly use solar energy through photosynthesis to convert carbon dioxide into biofuels and chemicals, becoming a "negative carbon" production platform for green biomanufacturing.

[0003] The photosynthetic efficiency and carbon fixation capacity of cyanobacteria are the key to achieving efficient light-driven carbon fixation. However, the key carbon fixation enzyme 1,5-bisphosphate carboxylase / oxygenase (Rubi sco) in cyanobacteria has efficiency shortcomings such as low catalytic efficiency, high oxygen sensitivity and limited activity optimization space, which limits the performance of cyanobacteria in the process of photosynthetic carbon fixation. In order to break through these mechanistic bottlenecks, researchers have rationally transformed the photosynthetic system of cyanobacteria, for example, by overexpressing key enzymes such as Rubi sco, sedoheptulose-1,7-bisphosphatase (SBPase), fructose 1,6-bisphosphate aldolase (FBA) and transketolase (TK). However, due to the inherent characteristics of the natural photosynthetic system, the simple biological transformation strategy has limitations in improving the efficiency of photosynthetic carbon fixation and fails to fully realize the maximum potential for CO2 fixation.

[0004] Boron Nitride (BN) is an important inorganic non-metallic material. It is widely used in many fields due to its unique physical and chemical properties. Boron nitride is composed of two elements, boron (B) and nitrogen (N), and has a variety of crystal structures, the most common of which are hexagonal boron nitride (h-BN) and cubic boron nitride (c-BN). Among them, h-BN has a layered structure, similar to graphite, so it is also called "white graphite". This structure gives h-BN many unique properties.

[0005] There is currently no research on using h-BN to improve the photosynthetic carbon fixation efficiency of microalgae. Summary of the invention

[0006] In the study, our team proposed an innovative co-cultivation model, namely, a nanomaterial-cyanobacteria co-cultivation system with carbon dioxide capture performance. This co-cultivation model combines the efficient carbon dioxide adsorption characteristics of nanomaterials and the directional catalytic ability of cyanobacterial cells, thereby achieving efficient light-driven carbon fixation. In the exploration of the co-cultivation system, we found that h-BN has efficient CO2 adsorption capacity, which can adsorb and enrich carbon dioxide and transfer it to cyanobacteria, thereby improving the carbon fixation efficiency of cyanobacteria. The establishment of a co-cultivation system of h-BN and cyanobacteria can improve the carbon fixation efficiency and product synthesis of cyanobacteria, and achieve a significant improvement in the efficiency of carbon dioxide capture and conversion.

[0007] Based on the above research, the present invention provides the application of boron nitride in microalgae cultivation.

[0008] In a specific embodiment, the boron nitride is hexagonal boron nitride.

[0009] The present invention also provides a method for culturing microalgae, comprising the step of adding boron nitride into a culture system.

[0010] In a specific embodiment, the boron nitride is hexagonal boron nitride.

[0011] In a specific embodiment, the working concentration of hexagonal boron nitride is 200-1000 mg / L.

[0012] In a specific embodiment, no TES buffer needs to be added to the culture system of the microalgae.

[0013] In a specific embodiment, the microalgae is Synechococcus or an engineered bacterium thereof.

[0014] The present invention achieves more efficient carbon dioxide capture and conversion by constructing a hexagonal boron nitride-cyanobacteria co-culture system, combining the carbon dioxide adsorption performance of nanomaterials and the biological directed synthesis ability of cyanobacteria, while also increasing the growth rate, biomass and target product yield of cyanobacteria. This innovative strategy can not only enhance the photosynthetic carbon fixation ability of cyanobacteria and improve the overall efficiency of the system, but also provide a new technical route for promoting green and low-carbon development, taking into account both improving economic benefits and low-carbon environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The effect of adding different concentrations of h-BN on the growth of Synechococcus PCC 7942 (PCC7942). A is the growth curve under air conditions; B is the growth curve under CO2 conditions; C is the statistical graph of chlorophyll content in algae cells on the 6th day under air conditions.

[0016] Figure 2Scanning electron microscope photos of h-BN and h-BN-cyanobacteria co-culture system after ultrasonic treatment.

[0017] Figure 3 Effects of adding different concentrations of h-BN materials on the growth (A) and trehalose production (B) of trehalose-producing engineered strain QY053.

[0018] Figure 4 Dry weight and growth curve of strains with (B-1 and B-2) and without (A-1 and A-2) TES buffer added to the culture system.

[0019] Figure 5 The bar graph shows the dry weight of cells of the strains with and without TES buffer added to the system.

[0020] Figure 6 The growth curve and cell dry weight bar graph of the co-culture of Synechococcus PCC 7942 with high inoculation concentration and h-BN nanosheets. DETAILED DESCRIPTION

[0021] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0022] 1. Effect of adding h-BN material on the growth of Synechococcus PCC 7942 under different ventilation conditions

[0023] Synechococcus PCC 7942 was cultured in BG11 medium until the logarithmic phase, and then the initial OD 730 =0.05 was transferred to fresh BG11 medium containing 100 mg / L, 200 mg / L, and 500 mg / L h-BN, and cultured under two culture conditions: air flow and air containing 3% CO2, with a culture temperature of 28-32°C and an illumination of 200 μmol photons·m -2 ·s -1 .

[0024] The results are as follows Figure 1 As shown, ventilation conditions are either air ( Figure 1 A) or 3% CO2 ( Figure 1 B), the algae strains added with h-BN material grew faster, significantly better than the control group without material. The growth rate of the algae strains in the experimental group with air aeration conditions showed a positive correlation with the h-BN concentration within a certain range. The higher the concentration of the added material, the better the growth-promoting effect. Chlorophyll situation on the 6th day ( Figure 1C) also confirmed this result; the experimental group with aeration conditions of 3% CO2 had no significant difference from the control group at a material concentration range of 100 mg / L, and at a high concentration of 500 mg / L, the biomass increased by about 20%. It is speculated that the addition of h-BN can improve the ability of algal cells to obtain CO2, thereby promoting the growth of algal strains.

[0025] 2. Scanning electron microscopy of h-BN material and co-culture with Synechococcus

[0026] The h-BN material and the co-culture system were photographed by scanning electron microscope. Figure 2 As shown in the figure, the size of hexagonal boron nitride after ultrasonic treatment is about 40-100nm. The size of the treated material will be more uniform, and the probability of adhering to the surface of cyanobacteria cells will increase, increasing the contact area and interaction between the material and cyanobacteria. In the co-culture system, scanning electron microscopy (SEM) observations found that the surface structure of cyanobacterial cells remained basically intact, without obvious damage or deformation. The material co-cultured with cyanobacteria showed a clear aggregation trend, randomly scattered around the cyanobacteria in irregular shapes, forming a non-uniform aggregate structure.

[0027] 3. Effect of h-BN on the growth and trehalose production of QY053 strain

[0028] Strain QY053 is a trehalose-producing engineered strain constructed with Synechococcus PCC 7942 as the chassis. The strain was cultured in BG11 medium until the logarithmic phase, and then the initial OD 730 =0.1 was transferred to fresh BG11 medium containing 200 mg / L, 500 mg / L, and 1000 mg / L h-BN. During the culture process, 3% CO2 was passed through the medium at a temperature of 28-32°C and an illumination of 150 μmol photons·m -2 ·s -1 .

[0029] The growth curve was drawn and the trehalose content on the 11th day was detected. Figure 3As shown, the biomass of the experimental group with h-BN material added is higher than that of the control group. The higher the concentration of the added material, the better the growth of the algae strain. According to the average value, the group with the best growth effect - the group with 1000 mg / L h-BN added has a maximum increase of 31% in biomass compared with the control group without the material. From the analysis of trehalose production, the trehalose production of the experimental group with h-BN added was increased by 15% (200 mg / L), 37.1% (500 mg / L) and 37.6% (1000 mg / L) on the 9th day compared with the control group without the material. From the above data, it can be seen that the algae strain with the addition of h-BN material not only has a certain degree of increase in biomass, but also the trehalose production is positively correlated with the h-BN concentration within a certain range.

[0030] 4. Effect of TES buffer on the h-BN material-algae co-culture system

[0031] TES is a biological buffer with good buffering capacity and is widely used in laboratory research and development and chemical pharmaceutical synthesis. Whether TES buffer is added to the culture medium may affect the culture effect of algae strains in the co-culture system.

[0032] The culture conditions were as follows: the light intensity was 150 μmol photons·m -2 ·s -1 , the temperature was 30°C, and the initial inoculation concentration was OD 730 =0.1. The culture period was 8 days, h-BN material was added at concentrations of 100 mg / L and 500 mg / L, and air was ventilated (CO2 content in the air was 0.04%). The sampling time was the 2nd, 4th and 6th day, and the pH and OD were tested. 730 And cell dry weight (cell dry weight, CDW).

[0033] like Figure 4 As shown in the figure, although the pH value change of the system with TES buffer is smaller than that of the system without buffer, the system without TES buffer can more obviously reflect the growth-promoting effect of the material on cyanobacteria. Figure 5 It can be seen from the column comparison chart that the growth state of cyanobacteria in the system without adding buffer is better and the biomass is higher. According to the value of cell dry weight, in the system without adding TES buffer, the growth-promoting effect of 100 mg / L material on cyanobacteria increased by 13.3% and 10.3% on the 4th and 8th days respectively; the increase values ​​of 500 mg / L material were 20.1% and 46.6% respectively.

[0034] 5. Co-culture of Synechococcus PCC 7942 with high inoculation concentration and hexagonal boron nitride (h-BN) nanomaterials

[0035] In order to exclude the possibility that h-BN promoted the growth of cyanobacterial biomass due to the light shielding effect at the initial stage of low OD inoculation, cyanobacteria with an initial inoculation OD of 1.5 were co-cultured with boron nitride.

[0036] The culture conditions were as follows: the boron nitride material concentration was set to 100 mg / L, and the light intensity was 150 μmol photons·m -2 ·s -1 , the temperature was 30°C, and the initial inoculation concentration was OD 730 =1.5. Ventilate.

[0037] The results are as follows Figure 6 As shown, the biomass of Synechococcus with added boron nitride material increased significantly compared with the control without added material. The increments were 22.7% on the second day, 15% on the third day, 16.5% on the fourth day, and 11.4% on the fifth day.

[0038] The above experiments show that h-BN has good biocompatibility, can achieve effective carbon fixation, and can significantly promote the growth of cyanobacteria and the synthesis of target compounds. In the co-culture system, the addition of h-BN material improves the adsorption and utilization of carbon dioxide by cyanobacteria and improves the efficiency of photosynthetic carbon fixation. The addition of h-BN to the co-culture system can enhance the capture of CO2 in the culture system by cyanobacteria, increase the concentration of CO2 around cyanobacterial cells, improve the efficiency of CO2 transport into cells, enhance the carbon fixation reaction in the dark reaction, and thus improve the biomass accumulation of cyanobacteria and the directional synthesis of target metabolites. This study shows that h-BN can effectively promote the absorption and fixation of carbon dioxide by cyanobacteria, providing a new strategy for the capture and resource utilization of carbon dioxide.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Application of Boron Nitride in Microalgae Cultivation.

2. The use according to claim 1, characterized in that: The boron nitride is hexagonal boron nitride.

3. A method for culturing microalgae, characterized in that: The method comprises the step of adding boron nitride into the culture system.

4. The method according to claim 3, characterized in that The boron nitride is hexagonal boron nitride.

5. The method according to claim 4, characterized in that The working concentration of hexagonal boron nitride is 200-1000 mg / L.

6. The method according to claim 4, characterized in that There is no need to add TES buffer in the culture system of the microalgae.

7. The method according to any one of claims 3 to 6, characterized in that: The microalgae is Synechococcus or its engineered bacteria.

Images