Application of cadmium selenide in microalgae culture

Abstract

The invention relates to application of cadmium selenide in microalgae culture and a method for culturing microalgae, which comprises the step of adding cadmium selenide into a culture system. According to the method, cadmium selenide (CdSe) is added into a microalgae culture system to obtain a CdSe-cyanobacteria hybrid, so that the growth speed and the photosynthetic activity of microalgae are improved. The practice of the invention creates a new path for breaking through the inherent bottleneck of a microalgae natural photosynthetic system and improving the photosynthetic carbon sequestration efficiency.

Description

Technical Field

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

[0002] Cyanobacteria (also known as blue algae, which belong to prokaryotic microalgae) are a type of microorganism with good environmental adaptability. They have attracted widespread attention due to their fast growth rate, simple cell structure and convenient genetic manipulation, and are regarded as a potential platform for sustainable biofuel and chemical production. However, the natural photosynthesis system of cyanobacteria has certain limitations, mainly reflected in its narrow spectral absorption range and low light capture and conversion efficiency. In order to overcome this bottleneck, researchers have explored the use of genetic engineering and synthetic biology to transform cyanobacteria so that they can use light energy more efficiently. However, due to the inherent characteristics of the natural photosynthetic system and problems such as light damage, improving the photosynthetic efficiency of cyanobacteria only through biological modification cannot maximize the conversion of solar energy and the fixation of CO2.

[0003] On the other hand, artificial photosynthetic systems mediated by semiconductor materials exhibit efficient light energy capture capabilities, can absorb light energy and generate electrons, and achieve high solar energy conversion efficiency. However, artificial photosynthetic systems have shortcomings in the selectivity of complex products, large-scale production potential, and long-term stability, which hinder their practical application. In order to overcome this technical difficulty, researchers have proposed an innovative solution, namely, to construct a hybrid system of semiconductor materials and microorganisms, and combine it with the rapidly developed synthetic biology technology in recent years to achieve light-driven carbon fixation to produce a variety of bio-based chemicals.

[0004] Cadmium selenide (CdSe) is an inorganic compound with unique photoelectric properties and a molecular weight of 191.36. It is a black to reddish black solid and belongs to the n-type II-VI semiconductor material. Cadmium selenide has a narrow direct transition band gap structure (1.76eV) and can effectively absorb the energy of visible light, so it is widely used in photoelectrochemical solar cells. Its crystal structure has two types: hexagonal and cubic. It is relatively stable at room temperature and does not react with air, water, alkali, etc.

[0005] Existing studies have shown that adding cadmium selenide to microalgae is toxic to them, inhibiting their growth and affecting their photosynthetic activity. Currently, there are no reports on the effect of adding cadmium selenide alone on the growth of microalgae. Summary of the invention

[0006] In the research, the team found that adding cadmium selenide at a low concentration to some microalgae can promote the growth of microalgae and improve their photosynthetic activity. Based on the above research, the present invention provides the application of cadmium selenide in microalgae cultivation.

[0007] In a specific embodiment, the cadmium selenide is a CdSe nanomaterial with a size of 50-150 nm.

[0008] The present invention also provides a method for culturing microalgae, which comprises the step of adding cadmium selenide into a culture system.

[0009] In a specific embodiment, the cadmium selenide is a CdSe nanomaterial.

[0010] In a specific embodiment, the working concentration of cadmium selenide is 85-212.5 μg / L.

[0011] In a specific embodiment, the microalgae is Synechococcus or an engineered bacterium thereof.

[0012] The present invention adds cadmium selenide to the microalgae culture system to obtain CdSe-cyanobacteria hybrids, thereby increasing the growth rate and photosynthetic activity of the microalgae. The practice of the present invention breaks through the inherent bottleneck of the natural photosynthetic system of cyanobacteria, improves the photosynthetic carbon fixation efficiency, and opens up a new path. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 These are SEM images of CdSe, Synechococcus PCC 7942 and CdSe-Synechococcus PCC 7942 hybrid.

[0014] Figure 2 Growth curve and chlorophyll content changes of Synechococcus PCC 7942 with different concentrations of CdSe added.

[0015] Figure 3 The effect of adding CdSe on the photosynthetic physiological parameters of Synechococcus PCC 7942. Among them, a is the change of oxygen release rate under different light intensities; bf are the changes of photosynthetic parameters of Fv / Fm, Y(Ⅱ), qL, and ETR(Ⅱ) in photosystem Ⅱ, respectively. gh is the change of photosynthetic parameters of Y(Ⅰ), qL, and ETR(Ⅰ) in photosystem Ⅰ.

[0016] Figure 4 The effect of adding CdSe on the energy and reducing power of Synechococcus PCC 7942. Where a is NADPH / NADP + A is the change of ATP concentration. DETAILED DESCRIPTION

[0017] 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.

[0018] 1. Construction of CdSe-microalgae hybrids

[0019] The experiment was conducted using Synechococcus sp. PCC 7942. Synechococcus sp. PCC 7942 was cultured in BG11 medium until the logarithmic phase, and then the initial OD 730 =0.1 concentration was transferred to fresh BG11 medium containing CdSe nanomaterials for cultivation to obtain CdSe-Synechococcus PCC 7942 hybrid. CdSe was in a suspension state in the BG11 medium. Scanning electron microscopy (SEM) observation ( Figure 1 ) shows that in the CdSe-Synechococcus PCC 7942 (Syn7942) hybrid, CdSe is attached to the surface of Synechococcus PCC 7942 cells.

[0020] 2. Effect of adding different concentrations of CdSe on the growth of Synechococcus PCC 7942

[0021] The CdSe-Schnechnos sp. PCC 7942 hybrids with different concentrations of CdSe were placed at 30°C, 150 rpm, and 50 μmolphotons / m 2 The effect of CdSe concentration on the growth of Synechococcus PCC 7942 was studied by plotting growth curves and detecting chlorophyll content.

[0022] The results are as follows Figure 2 As shown, low concentration (85-212.5 μg / L) of CdSe addition promoted the growth of Synechococcus PCC 7942, and the chlorophyll content was also higher than that of the control group, while higher concentration of CdSe addition inhibited the growth of Synechococcus PCC 7942.

[0023] 3. Effects of CdSe on photosynthetic activity, reducing power and energy of Synechococcus PCC 7942

[0024] The algal cells were cultured in BG11 medium containing 170 μg / L CdSe until the logarithmic phase, and the algal cells were collected and resuspended in BG11 medium. The algal cell concentration was adjusted to OD 730 The concentration of 10 mM NaHCO3 was 1.0, and 17 mL of algae solution was added. The algae solution was then analyzed using a YZQ201A (Yi Zongqi, China) instrument under different light intensities (dark, 100, 400, 800, 1200, 1600 μmol photons / m 2 / s) to detect the real-time concentration of oxygen and obtain the results of the whole-chain photosynthetic oxygen release rate. The photosynthetic physiological activity of algal cell photosystem II and photosystem I was measured using the P700 and Fluo modes of the pulse amplitude modulation fluorimeter Dual-PAM-100. + / NADPH detection kit (WST-8 method) and ATP detection kit were used to detect intracellular NADPH / NADP + and changes in ATP content.

[0025] The results are as follows Figure 3 and 4 As shown, at all light intensities tested (50-1600 μmolphotons / m 2 / s) can be observed in the CdSe-Synechococcus PCC 7942 hybrid relative to the control group. The maximum quantum yield (Fv / Fm) of CdSe-Synechococcus PCC 7942 is higher than that of Synechococcus PCC 7942 cells, indicating that CdSe can enhance its potential photosynthetic capacity. The increase in the actual quantum yield Y(II) and photochemical quenching qL further confirms this. The decrease in non-photochemical quenching (NPQ) indicates that the hybrid improves the light energy conversion efficiency of cyanobacteria, reduces the dissipation of light energy in the form of heat energy, and makes more light energy available for the photochemical reaction of photosynthesis, which is consistent with the ETR(II) results. Based on the measurement of P700, it was found that the effective quantum yield Y(I) of photosystem I in the CdSe-Synechococcus PCC 7942 hybrid increased by 71.13%, and the ETR increased by 64.24%. This indicates that the hybrid can transfer electrons and capture light energy more efficiently, and photosystem I obtains more energy and electrons, which enhances its activity, thereby increasing the quantum yield of photosystem I, that is, the efficiency of converting absorbed light energy into chemical energy, and ultimately promoting the overall efficiency of photosynthesis, thereby promoting the increase in the NADPH / NADP+ ratio and ATP content in algal cells.

[0026] The above experiments show that adding low concentrations of CdSe can improve the photosynthetic activity and reducing power content of Synechococcus PCC 7942.

[0027] 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 cadmium selenide in microalgae cultivation.

2. The use according to claim 1, characterized in that: The cadmium selenide is a CdSe nano material.

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

4. The method according to claim 3, characterized in that The cadmium selenide is a CdSe nano material.

5. The method according to claim 4, characterized in that The working concentration of cadmium selenide is 85-212.5μg / L.

6. The method according to any one of claims 3 to 5, characterized in that: The microalgae is Synechococcus or its engineered bacteria.

Images