Application of high-temperature-resistant and high-light cyanobacteria in preparation of biological photovoltaic device and biological photovoltaic device prepared from high-temperature-resistant and high-light cyanobacteria

Abstract

The invention relates to application of high-temperature-resistant and high-light cyanobacteria in preparation of a biological photovoltaic device, the high-temperature-resistant and high-light cyanobacteria is synechococcus PCC 7942 obtained by introducing C252Y mutation on an ATP synthase alpha subunit, and the reference sequence of the ATP synthase alpha subunit is shown as SEQ ID NO: 1. According to the invention, a high-tolerance mutant strain HL7942 is used as a photoelectric conversion core element, so that a biological membrane cathode is formed on a substrate, a biological photovoltaic device can stably carry out light energy conversion output under the condition of high temperature and high light (2400 [mu] mol photons m <-2 > s <-1 >, 35 DEG C), and the light current output level is increased by 2.54 times compared with that of an early-stage device. Chitosan is used for packaging a biological membrane electrode, so that a biological membrane is stably attached to a substrate while the photosynthetic activity is maintained, the photocurrent output density of the device is improved, and the stable output period of the device is prolonged.

Description

Technical Field

[0001] The present invention belongs to the field of biophotovoltaics, and specifically relates to the application of high-temperature and high-light resistant cyanobacteria in the preparation of biophotovoltaic devices and the biophotovoltaic devices prepared thereby. Background Art

[0002] Solar energy, the most abundant renewable energy, has received widespread attention. In order to fully develop and utilize solar energy for production and life, humans have developed three mainstream solar energy utilization methods: photothermal conversion, photochemical conversion, and photoelectric conversion. Among them, the power generation system that directly converts solar radiation energy into electrical energy is called photovoltaics. At present, the technical core of photovoltaics is to use semiconductor materials to convert solar energy into electrical energy. However, the preparation process of semiconductor photovoltaics involves the use of a variety of toxic raw materials and chemicals, and the treatment of waste photovoltaics also faces the problems of high difficulty and long cycle. Therefore, the development of efficient and clean solar energy utilization technology is of great significance to promoting the sustainable development of society.

[0003] Biophotovoltaics (BPV) is a new solar power generation technology that uses photosynthetic microorganisms such as cyanobacteria and eukaryotic microalgae as photoelectric conversion materials. Compared with traditional semiconductor photovoltaic technology, it has the characteristics of low toxicity, recyclability, and strong environmental compatibility, and is expected to provide a greener and more sustainable technical route for solar energy utilization. The output of biophotovoltaic devices has been significantly improved through the application of synthetic biology and the introduction of conductive nanomaterials, which has led to further development of biophotovoltaic devices.

[0004] However, existing research on bio-photovoltaic devices is limited to large-scale laboratory environments. In the actual application of the device, the outdoor light intensity and temperature change in a periodic rhythm, and its peak value far exceeds the suitable temperature for the cultivation of ordinary cyanobacteria. The dynamic changes of outdoor temperature and light have a high degree of overlap. When the natural light intensity is the strongest, it is often also the peak stage of the ambient temperature. High temperature and high light have a negative impact on the activity of cyanobacteria. Exceeding a certain level will cause cell death, thus affecting the stable operation of the bio-photovoltaic device in actual application.

[0005] Therefore, it is necessary to build a biophotovoltaic device that can operate stably in different environments, so as to obtain a system that can stably output photocurrent under high temperature and high light. In particular, a photosynthetic microorganism that is resistant to high temperature and high light is needed for electrode production, so as to expand the application of biophotovoltaic devices in different practical environments. Summary of the invention

[0006] In order to solve the above problems, the present invention provides the use of high-temperature and high-light resistant cyanobacteria in the preparation of biophotovoltaic devices.

[0007] In a specific embodiment, the thermotolerant and phototolerant cyanobacterium is Synechococcus PCC 7942 with a C252Y mutation introduced into the α subunit of the ATP synthase, wherein the reference sequence of the α subunit of the ATP synthase is shown in SEQ ID NO:1.

[0008] The present invention also provides a biophotovoltaic device, comprising an anode, a cathode, a buffer and an electrochemical cell;

[0009] The electrochemical cell is made of a transparent material, the buffer solution is contained in the electrochemical cell, and the anode and cathode are immersed in the buffer solution;

[0010] A cyanobacteria biofilm is attached to the outer wall of the cathode, and the buffer solution is a liquid that can maintain the activity of the cyanobacteria.

[0011] In a specific embodiment, the cathode is prepared by the following method:

[0012] S1: culturing the cyanobacteria to a logarithmic phase and collecting the cyanobacterial cells;

[0013] S2: resuspending the cyanobacterial cells to obtain an algae solution;

[0014] S3: adding the algae liquid dropwise onto a substrate, so that the cyanobacterial biofilm is attached to the substrate;

[0015] S4: adding chitosan solution dropwise onto the cyanobacteria biofilm and then drying it to obtain the cathode.

[0016] In a specific embodiment, the cyanobacterium is Synechococcus PCC 7942 with a C252Y mutation introduced into the ATP synthase α subunit, wherein the reference sequence of the ATP synthase α subunit is shown in SEQ ID NO:1.

[0017] In a specific embodiment, the algae cell density of the cyanobacterial biofilm is 1*10 5 -9*10 6 / cm 2 .

[0018] In a specific embodiment, the concentration of the chitosan solution is 0.2-1%.

[0019] In a specific embodiment, the material of the substrate is ITO.

[0020] In a specific embodiment, the anode is made of a conductive material. For example, conductive inorganic materials such as platinum, stainless steel, copper and tin dioxide, carbon materials such as carbon cloth, carbon felt, carbon paper, and conductive materials such as reduced graphene oxide can be used to prepare the anode.

[0021] In a specific embodiment, the biophotovoltaic device further comprises a reference electrode, which is an Ag / AgCl electrode filled with a saturated potassium chloride solution, and the reference electrode is also immersed in the buffer solution.

[0022] The present invention uses the highly tolerant mutant strain HL7942 as the core element for photoelectric conversion, so that it forms a biofilm cathode on the substrate, so that the biophotovoltaic device can generate a photoelectric conversion reaction under high temperature and high light (2400 μmol photons m -2 s -1 Under the conditions of 35°C and 120°C, the device can stably convert light energy into output, and the photocurrent output level is 2.54 times higher than that of the previous device. The biofilm electrode is encapsulated with chitosan, so that the biofilm maintains photosynthetic activity while stably attaching to the matrix, increasing the device's photocurrent output density and extending the device's stable output period. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of a single-chamber three-electrode biophotovoltaic device.

[0024] Figure 2 The photocurrent output results of the dynamic suspension and biofilm attachment devices under different lighting conditions.

[0025] Figure 3 It is the continuous photocurrent output level under high temperature and high light conditions. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0027] 1. Cyanobacteria strains used in the present invention

[0028] The strain used in the present invention is a high temperature and high light resistant mutant strain HL7942 of Synechococcus PCC 7942, which is obtained by introducing a C252Y mutation into the α subunit of ATP synthase (reference sequence as shown in SEQ ID NO: 1) in the wild type Synechococcus PCC 7942. This strain has been proven in our research to have good tolerance to high temperature and high light.

[0029] 2. Construction of a single-chamber three-electrode system biophotovoltaic device

[0030] The biophotovoltaic device in this embodiment is a single-chamber three-electrode system biophotovoltaic device, such as Figure 1 As shown, it includes an anode, a cathode and a reference electrode. A platinum electrode is used as the anode, an ITO electrode with a cyanobacteria biofilm is used as the cathode, and an Ag / AgCl electrode with a saturated potassium chloride solution as the filling liquid is used as the reference electrode. In the system, algae culture medium is used as the electrochemical system buffer.

[0031] The cathode is prepared as follows: a highly tolerant mutant strain HL7942 (a C252Y mutation is introduced into the α subunit of ATP synthase in Synechococcus PCC 7942 (reference sequence as shown in SEQ ID NO: 1)) is cultured to the logarithmic growth phase, and then centrifuged at 4000rpm-6000rpm for about 20 minutes at 22-25°C to collect algae cells. An appropriate amount of algae culture medium is used for resuspending, and the resuspended algae liquid is dripped onto the surface of the ITO electrode and dried at room temperature. After drying, the cyanobacteria form a uniform biofilm structure on the electrode surface, and an appropriate amount of 0.2% chitosan solution is dripped onto the surface to make the biofilm structure more stable.

[0032] A platinum electrode, a biofilm cathode and a Ag / AgCl saturated potassium chloride solution reference electrode were assembled, and an appropriate amount of algae culture solution was added to the single-chamber electrode pool as an electrochemical system buffer. The algae culture solution had the following components (1 L): 40 g / L K2HPO4·3H2O, 75 g / L MgSO4·7H2O, 36 g / L CaCl2·2H2O, 6 g / L Citric acid, 1 g / LEDTA·2Na, 20 g / L NaCO3, 1.5 g / L NaNO3, and 1 mL / L trace element stock solution. The components of the trace element stock solution are: 2.86 g / L H3BO3, 1.81 g / L MnCl2·4H2O, 0.222 g / L ZnSO4·7H2O, 0.39 g / L Na2MoO4·2H2O, 0.08 g / L CuSO4·5H2O, and 0.01 g / L CoCl2·6H2O.

[0033] 3. Comparison of photocurrent output between biofilm attachment system and dynamic suspension system

[0034] The constructed biophotovoltaic device was placed under two different strong light treatment conditions to measure the output photocurrent (compared with the dynamic suspension system without chitosan encapsulation). The results are as follows: Figure 2 As shown, under high light conditions, the present invention (biofilm-attached biophotovoltaic device) has a more excellent photocurrent output level, the output level under continuous light treatment conditions is increased by 1.26 times, and the output level under intermittent light treatment conditions is increased by 1.8 times.

[0035] It can be seen that the use of chitosan encapsulation can enable the biofilm to maintain photosynthetic activity while stably attaching to the matrix, thereby increasing the photocurrent output density of the device and extending the stable output period of the device.

[0036] 4. Output level of biophotovoltaic devices under high temperature and high light environment

[0037] At 35°C, 2400 μmol photons m -2 s -1 Light treatment. The results are as follows Figure 3 As shown, the output photocurrent of the biophotovoltaic device was measured under high temperature and high light conditions. Compared with the normal temperature conditions, the overall output level of the device increased to 2.2 times the original level. The replacement of mutant strains further improved the device output and increased the photocurrent output density to 2.54 times. This invention can stably output photocurrent under high temperature and high light conditions, providing technical support for the practical application of biophotovoltaics.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Application of high temperature and high light resistant cyanobacteria in the preparation of biophotovoltaic devices.

2. The use according to claim 1, characterized in that: The high temperature and high light resistant cyanobacteria is Synechococcus PCC 7942 with a C252Y mutation introduced into the ATP synthase α subunit, wherein the reference sequence of the ATP synthase α subunit is shown in SEQ ID NO:

1.

3. A biophotovoltaic device, characterized in that: including an anode, a cathode, a buffer and an electrochemical cell; The electrochemical cell is made of a transparent material, the buffer solution is contained in the electrochemical cell, and the anode and cathode are immersed in the buffer solution; A cyanobacteria biofilm is attached to the outer wall of the cathode, and the buffer solution is a liquid capable of maintaining the activity of the cyanobacteria.

4. The biophotovoltaic device according to claim 3, characterized in that: The cathode is prepared by the following method: S1: culturing the cyanobacteria to a logarithmic phase and collecting the cyanobacterial cells; S2: resuspending the cyanobacterial cells to obtain an algae solution; S3: adding the algae liquid dropwise onto a substrate, so that the cyanobacterial biofilm is attached to the substrate; S4: adding chitosan solution dropwise onto the cyanobacteria biofilm and then drying it to obtain the cathode.

5. The biophotovoltaic device according to claim 4, characterized in that: The cyanobacteria is Synechococcus PCC 7942 with a C252Y mutation introduced into the ATP synthase α subunit, wherein the reference sequence of the ATP synthase α subunit is shown in SEQ ID NO:

1.

6. The biophotovoltaic device according to claim 5, characterized in that: The algae cell density of the cyanobacterial biofilm is 1*10 5 -9*10 6 / cm 2 .

7. The biophotovoltaic device according to claim 5, characterized in that: The concentration of the chitosan solution is 0.2-1%.

8. The biophotovoltaic device according to claim 4, characterized in that: The material of the substrate is ITO.

9. The biophotovoltaic device according to any one of claims 4 to 8, characterized in that: The anode is made of conductive material.

10. The biophotovoltaic device according to any one of claims 4 to 8, characterized in that: A reference electrode is also included. The reference electrode is an Ag / AgCl electrode filled with a saturated potassium chloride solution. The reference electrode is immersed in the buffer solution.

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