Engineering algae, artificial photosynthetic community and application

Abstract

The invention discloses engineering algae, an artificial photosynthetic community and application. The engineering algae provided by the invention is synechococcus slender for cloning and expressing heterologous sucrose permease and glyceraldehyde dehydrogenase, or cloning and expressing heterologous sucrose permease, glyceraldehyde dehydrogenase and sucrose synthase. The artificial photosynthetic community provided by the invention comprises the engineering algae provided by the invention and the P.megatherium. The engineering algae disclosed by the invention not only effectively improves the yield of sucrose, but also can achieve a synergistic effect with the P.megatherium to form an artificial photosynthetic community, and can realize conversion from carbon dioxide to polyhydroxyalkanoate under the condition of not adding an exogenous carbon source, so that the yield of the polyhydroxyalkanoate is improved. And a novel economical and feasible scheme and approach are provided for polyhydroxyalkanoate production.

Description

Technical Field

[0001] The present application relates to the technical field of artificial photosynthetic communities, and in particular to an engineered algae, an artificial photosynthetic community and applications. Background Art

[0002] Photosynthetic communities are micro-ecosystems composed of photoautotrophs and heterotrophs that utilize solar energy and carbon dioxide to convert biomass and various chemicals. Their applications encompass environmental protection, carbon emission reduction, and renewable energy production, making them a key potential pathway for achieving carbon-negative biomanufacturing. Photoautotrophs, typically including prokaryotic cyanobacteria and eukaryotic algae, convert carbon dioxide into oxygen and organic carbon through photosynthesis, providing the foundation for the growth and maintenance of heterotrophs.

[0003] In recent years, cyanobacteria have been designed as promising microbial cell factories due to their excellent carbon fixation capacity and low energy requirements, and have received widespread attention in the field of chemical production. However, the genetic modification tools for cyanobacteria are relatively limited, which seriously restricts their further industrial application. In addition, there are some problems with the monoculture system of cyanobacteria, such as long culture cycle and susceptibility to exogenous microbial contamination, which limits the stability and economy of its production process. In contrast, microorganisms in nature usually exist in the form of communities and show strong robustness in the face of complex environmental perturbations. Inspired by this, the design and construction of artificial photosynthetic communities including cyanobacteria and heterotrophic organisms has become a strategy with great potential, which can not only promote the sustainable growth of microorganisms, but also improve the biosynthesis efficiency of chemicals through metabolic synergy.

[0004] Therefore, the research and development of new photosynthetic communities has important value and significance for the production of related products. Summary of the Invention

[0005] The purpose of this application is to provide a new engineered algae, an artificial photosynthetic community based on the engineered algae and its application.

[0006] This application adopts the following technical solutions:

[0007] The first aspect of the present application discloses an engineered algae, which is a genetically modified Synechococcus elongatus, wherein the genetic modification includes constructing the expression of heterologous sucrose permease and glyceraldehyde dehydrogenase in Synechococcus elongatus, or constructing the expression of heterologous sucrose permease, glyceraldehyde dehydrogenase and sucrose synthase in Synechococcus elongatus.

[0008] It should be noted that the present application creatively cloned and expressed sucrose permease and glyceraldehyde dehydrogenase, or simultaneously cloned and expressed sucrose permease, glyceraldehyde dehydrogenase, and sucrose synthase in Synechococcus elongatus to produce the engineered algae of the present application. Compared to wild-type Synechococcus elongatus that had not undergone genetic modification, the engineered algae of the present application increased sucrose production by at least three times, with the engineered algae secreting approximately 0.9 g / L of sucrose on the sixth day of cultivation. Furthermore, studies have found that engineered algae expressing sucrose permease, glyceraldehyde dehydrogenase, and sucrose synthase simultaneously showed significantly increased growth rates compared to engineered algae expressing only sucrose permease and glyceraldehyde dehydrogenase. In one implementation of the present application, the biomass of the engineered algae expressing all three enzymes increased by 126% compared to the engineered algae expressing only two enzymes. In other words, the biomass and sucrose production of the engineered algae expressing all three enzymes were significantly higher than those expressing only two enzymes.

[0009] It should also be noted that the engineered algae of the present application not only effectively increases sucrose production, but more importantly, can also synergize with Priesteria gigantea to form an artificial photosynthetic community; in the artificial photosynthetic community, the two grow and interact with each other, and can achieve the conversion of carbon dioxide to polyhydroxyalkanoates without adding an exogenous carbon source. In one implementation of the present application, a polyhydroxyalkanoate yield of 0.29 g / L can be achieved.

[0010] In one implementation of the present application, the nucleic acid sequence of sucrose permease is the sequence shown in SEQ ID NO.1.

[0011] In one implementation of the present application, the sucrose permease is derived from Escherichia coli.

[0012] In one implementation of the present application, the glyceraldehyde dehydrogenase is the sequence shown in SEQ ID NO.2.

[0013] In one implementation of the present application, the glyceraldehyde dehydrogenase is derived from Synechococcus.

[0014] In one implementation of the present application, the sucrose synthase is the sequence shown in SEQ ID NO.3.

[0015] In one implementation of the present application, the sucrose synthase is derived from Synechocystis sp.

[0016] The second aspect of the present application discloses an artificial photosynthetic community containing the engineered algae of the present application.

[0017] In one implementation of the present application, the artificial photosynthetic community of the present application includes the engineered algae of the present application and Priesteria gigantea.

[0018] It should be noted that Priesteria gigantea is only a specific bacterial species used in one implementation of the present application to form an artificial photosynthetic community with the engineered algae of the present application. It is not excluded that the engineered algae of the present application can also be combined with other bacteria to form an artificial photosynthetic community, thereby realizing the preparation of polyhydroxyalkanoates or other metabolites or secondary metabolites.

[0019] It should also be noted that in one implementation of the present application, only the engineered algae and Priesteria gigantea of the present application are used to form an artificial photosynthetic community for the preparation of polyhydroxyalkanoates; it is understood that, on this basis, it is not ruled out that other algae and / or bacterial species can be added to the artificial photosynthetic community to form a more stable or more functional microecosystem.

[0020] In one implementation of the present application, the ratio of the engineered algae of the present application to Priesteria gigantea is 5:(0.125-0.5) in sequence.

[0021] The third aspect of the present application discloses the use of the engineered algae or the artificial photosynthetic community of the present application in the preparation of polyhydroxyalkanoates.

[0022] The fourth aspect of the present application discloses a method for preparing polyhydroxyalkanoate, comprising fermenting the artificial photosynthetic community of the present application and collecting the polyhydroxyalkanoate from the fermentation product.

[0023] In one implementation of the present application, the culture medium used for fermentation contains 50-150 mmol / L of sodium chloride.

[0024] In one implementation of the present application, the culture medium used for fermentation is BG11 culture medium.

[0025] In one implementation of the present application, the BG11 culture medium contains 50-150 mmol / L sodium chloride, 1-8 mmol / L ammonium chloride, 0.2-0.3 g / L yeast powder, and 2-4 g / L 4-hydroxyethylpiperazineethanesulfonic acid.

[0026] In one implementation of the present application, the fermentation conditions are 15-40° C., 60-200 rpm, and 3000-5000 Lux continuous illumination for 2-4 days.

[0027] In one implementation of the present application, after the engineered algae of the present application are cultured for 3-8 days, Priesteria gigantea is added to form the artificial photosynthetic community of the present application, and then the artificial photosynthetic community is fermented.

[0028] The beneficial effects of this application are:

[0029] The engineered algae of the present application not only effectively increases sucrose yield, but can also synergize with Priesteria gigantea to form an artificial photosynthetic community, and can achieve the conversion of carbon dioxide to polyhydroxyalkanoates without adding an exogenous carbon source, providing a new economically feasible solution and approach for the production of polyhydroxyalkanoates. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a graph showing the growth detection results of the engineered algae in the examples of this application;

[0031] Figure 2 This is a graph showing the sucrose secretion test results of the engineered algae in the examples of this application;

[0032] Figure 3 This is a graph showing the co-growth detection results of the engineered algae and Priesteria gigantea in the examples of this application;

[0033] Figure 4 This is a graph showing the growth test results of engineered algae at different sodium chloride concentrations in the examples of this application;

[0034] Figure 5 This is a graph showing the results of sucrose secretion testing of engineered algae at different sodium chloride concentrations in the examples of this application;

[0035] Figure 6 This is a graph showing the growth test results of engineered algae at different algae-bacteria ratios in the examples of this application;

[0036] Figure 7 This is a graph showing the growth detection results of Priesteria gigantea at different algae-fungus ratios in the examples of this application;

[0037] Figure 8 This is a fluorescence microscope observation result of the artificial photosynthetic community in the embodiment of the present application;

[0038] Figure 9 1 is a graph showing the fluorescence intensity and content of polyhydroxyalkanoate in artificial photosynthetic communities at different algae-bacteria ratios in the examples of the present application. DETAILED DESCRIPTION

[0039] Polyhydroxyalkanoates (PHA) are a class of natural polymers primarily synthesized by microorganisms. In recent years, they have become an important candidate material for replacing traditional petroleum-based plastics due to their excellent biodegradability and environmental friendliness. However, the current production process of PHAs in the market relies entirely on traditional carbon sources such as glucose, resulting in high production costs and limited economic benefits. By constructing artificial photosynthetic communities and combining phototrophic cyanobacteria with heterotrophic bacteria, the photosynthetic capacity of cyanobacteria can be fully utilized to convert carbon dioxide into organic matter, providing the necessary carbon source for heterotrophic organisms. This strategy is expected to reduce dependence on external traditional substrates, lower production costs, and improve the economic feasibility of PHA production, providing a new solution for the sustainable production of green chemicals and bioplastics, with broad application prospects.

[0040] Based on the above research and understanding, the present application creatively pioneered the development of a new engineered algae, namely, genetically modified Synechococcus elongatus, wherein the genetic modification includes constructing and expressing heterologous sucrose permease and glyceraldehyde dehydrogenase in Synechococcus elongatus, or constructing and expressing heterologous sucrose permease, glyceraldehyde dehydrogenase and sucrose synthase in Synechococcus elongatus.

[0041] Furthermore, the engineered algae of this application are combined with Priesteria gigantea to construct the artificial photosynthetic community of this application, thereby converting carbon dioxide into polyhydroxyalkanoates without adding an exogenous carbon source. This artificial photosynthetic community of this application reduces dependence on external traditional substrates, lowers production costs, and improves the economic feasibility of polyhydroxyalkanoate production, providing a new solution for the sustainable production of green chemicals and bioplastics.

[0042] The present invention is further described in detail below through specific examples. The following examples are only used to further illustrate the present invention and should not be construed as limiting the present invention.

[0043] Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0044] Example 1 Preparation of engineered algae

[0045] (1) Construction of pCyano-cscB recombinant plasmid

[0046] The construction of the sucrose permease recombinant plasmid (pCyano-cscB) refers to patent application CN118956708A. The nucleic acid sequence of the sucrose permease in this example is the sequence shown in SEQ ID NO. 1, which is derived from the genomic DNA of Escherichia coli ATCC700927.

[0047] SEQ ID NO.1:

[0048]

[0049] (2) Construction of pHN1-gapA recombinant plasmid

[0050] The glyceraldehyde dehydrogenase recombinant plasmid (pHN1-gapA) in this example uses the glyceraldehyde dehydrogenase gapA gene derived from Synechococcus PCC 7002, and the amino acid sequence encoded by the gene is shown in SEQ ID No. 2. The theophylline riboswitch sequence was inserted before the gapA gene sequence and sent to Jinweizhi Company for synthesis to obtain the Riboswitch-gapA gene fragment. The pHN1_lacUV5 plasmid was double-digested with NEB restriction endonucleases, and the digested plasmid was recovered using AxyPrepDNAGel Extraction Kit from Axygen. The Riboswitch-gapA gene fragment and the recovered pHN1_lacUV5 plasmid were seamlessly cloned using ClonExpress Ultra One Step Cloning Kit from Novozymes to obtain the recombinant plasmid pHN1-gapA.

[0051] SEQ ID No. 2:

[0052] MIRVAINGFGRIGRNFLRCWAGRENSQLQVVGINATTDTKSNAHMLRYDTMLGKFDGEIDYDANSLTVNGNVIKCCSDRNPLNLPWKEWGVDLVIESTGVFNTEEGSSKHITAGAQKVLITAPGKGGHIGTYVVGVNADQYGHDKQNVISNASCTTNCLAPIVKVLNDR FGIVKGTMTTVHSYTGDQRILDNSHRDLRRARAAAENIVPTSTGAAKAVALVIPEMKGKLNGIAMRVPTPNVSVVDLVAQVAKPTIAEEVNQVLKEASETYMKGILAYTEEPLVSCDFRGTDVSSTIDGSLTLAMDGDLIKVVAWYDNEWGYSQRVVDLAEIVAQNWQG*

[0053] (3) Construction of pAM-sps recombinant plasmid

[0054] The sucrose synthase recombinant plasmid (pAM-sps) uses the sucrose synthase sps gene derived from Synechocystis PCC6803, and the amino acid sequence encoded by the gene is shown in SEQ ID No. 3. The gene was synthesized by Jinweizhi Company to obtain the sps gene fragment. The pAM plasmid was double-digested with NEB restriction endonucleases, and the digested plasmid was recovered using AxyPrep DNAGel Extraction Kit from Axygen Company. The sps gene fragment and the recovered pAM plasmid were seamlessly cloned using ClonExpress Ultra One Step Cloning Kit from Novozymes Company to obtain the recombinant plasmid pAM-sps.

[0055] SEQ ID No.3:

[0056] *

[0057] (4) The preparation of engineering

[0058] Take a Synechococcus elongatus suspension in the exponential growth phase, collect the algae by centrifugation, wash three times with BG11 medium, and resuspend in BG11 medium. Then, add the recombinant plasmid, mix thoroughly, and incubate at 30°C in the dark for one day. After incubation, spread a nitrocellulose filter on a BG11 plate. Transfer the mixture of algal cells and recombinant plasmid DNA to the filter and incubate at 30°C in low light for one day. After incubation, transfer the filter to a BG11 plate containing the corresponding antibiotic and incubate at 30°C in low light until a transformed algae strain is obtained. The transformed algae strain is streaked onto a BG11 plate containing the corresponding antibiotic and incubated at 30°C in low light until a monoclonal strain is obtained that can be subcultured. The monoclonal strain selected from the resistance plate is inoculated into BG11 medium containing the corresponding antibiotic and incubated at 30°C in low light for 3 to 5 days until the culture turns green. PCR amplification is performed using the engineered algae genome as a template and primers for the exogenous gene transferred to the recombinant plasmid. When introducing the recombinant plasmid pCyano-cscB, use 10 μg / mL spectinomycin for resistance selection. When introducing the recombinant plasmid pHN1-gapA, use 10 μg / mL chloramphenicol for resistance selection. When introducing the recombinant plasmid pAM-sps, use 20 μg / mL kanamycin for resistance selection.

[0059] The heterologous sucrose permease and glyceraldehyde dehydrogenase genes on the recombinant plasmids pCyano-cscB and pHN1-gapA were integrated into the genome of Synechococcus elongatus by homologous recombination, and the resulting engineered algae was named Engineered Algae 1. The heterologous sucrose permease, glyceraldehyde dehydrogenase, and sucrose synthase genes on the recombinant plasmids pCyano-cscB, pHN1-gapA, and pAM-sps were integrated into the genome of Synechococcus elongatus by homologous recombination, and the resulting engineered algae was named Engineered Algae 2.

[0060] (5) Verification of sucrose secretion ability of engineered algae

[0061] Engineered algae 1 and engineered algae 2 were inoculated into BG11 medium containing the corresponding antibiotics for activation, and cultured under continuous light for 3 days to obtain seeds. The seed liquid was then inoculated into a new BG11 medium containing the corresponding antibiotics, the initial biomass OD730 was controlled to 0.1, and cultured under continuous light for 3 days. Then 150mmol / L sodium chloride, 1mmol / L IPTG and 1mmol / L theophylline were added, and cultured under continuous light for 6 days. After the culture was completed, the algae liquid was sampled and the OD730 was measured by microplate reader to characterize the algae concentration. At the same time, part of the algae liquid was taken, the supernatant was collected by centrifugation and filtered through a 0.22μm filter membrane, and the extracellular sucrose content was characterized using a sucrose detection kit. Three parallels were set up for each group. The same method was used to culture unmodified elongated Synechococcus, marked as wild algae, as a control group.

[0062] The growth of engineered algae and wild algae Figure 1 Compared to wild algae, engineered algae 1 grew more slowly after introducing the sucrose permease and glyceraldehyde dehydrogenase genes. Furthermore, introducing the sucrose synthase gene significantly boosted the growth of engineered algae 2, with its OD730 increasing by 126% compared to engineered algae 1. The biomass of the engineered algae was smaller than that of the wild algae. Combined with sucrose secretion, this suggests that this is because the carbon flux fixed by the engineered algae is directed more towards sucrose synthesis rather than cell growth.

[0063] Sucrose secretion of engineered algae and wild algae Figure 2 As shown in the figure, the unmodified wild algae secreted only 0.23g / L of sucrose, while the extracellular sucrose production of engineered algae 1 and 2 was three times and four times that of the wild algae, respectively. This demonstrates that genetic modification significantly enhanced the sucrose secretion capacity of Synechococcus elongatus, with the engineered algae able to secrete 0.90g / L of sucrose by the sixth day of culture.

[0064] Taking into account the growth and sucrose secretion of the algae strain, this example selected engineered algae 2 for further construction and testing of artificial photosynthetic communities.

[0065] Example 2 Polyhydroxyalkanoate-synthesizing bacteria with no antagonistic effect on engineered algae

[0066] Through plate culture, we investigated whether the engineered algae and Priestia megaterium MIBE00004 could grow together. The Priestia megaterium MIBE00004 used in this example refers to patent application CN116042447A.

[0067] Inoculate engineered algae 2 into BG11 medium containing the appropriate antibiotics for activation and incubate under continuous illumination for 3 days. Inoculate the seed solution into fresh BG11 medium containing the appropriate antibiotics and incubate under continuous illumination for 3 days. Spread the engineered algae solution onto BG11 plates and incubate under illumination until a dense green color appears. Activate Priesteria gigantea overnight and dilute the solution to an OD600 of 0.8. Use sterile tweezers to place four pieces of sterile filter paper on a BG11 plate. Add 10 μL of the diluted Priesteria gigantea solution and repeat three times. Use sterile water as a control. Incubate the plates at 30°C under illumination overnight and observe microbial growth.

[0068] The results of the antagonistic plate experiment between engineered algae and Priesteria gigantea are as follows: Figure 3 Green indicates the growth area of the engineered algae. In the control group with sterile water, no microorganisms grew near the bottom filter paper, while Priesteria gigantea grew around the other filter papers. This indicates that there is no antagonism between the engineered algae and Priesteria gigantea, and that the two can grow together.

[0069] It should be noted that Engineered Algae 2 and Priestia megaterium MIBE00004 are merely the preferred combination used in this example. It is understood that Engineered Algae 1 could also be used when the requirement for sucrose secretion is relatively low. Priestia megaterium MIBE00004, also used in this example as a strain with high cumulative polyhydroxyalkanoate production, could be used in this example. If the only consideration is the co-growth of an artificial photosynthetic community, or if the requirement for cumulative polyhydroxyalkanoate production is lower, other Priestia megaterium strains, not just Priestia megaterium MIBE00004, could also be used. Of course, other Priestia megaterium strains with even higher cumulative polyhydroxyalkanoate production could also be used. In short, the key to this example lies in the discovery of a new artificial photosynthetic community, namely, the co-growth community formed by Engineered Algae 1 or 2 and Priestia megaterium.

[0070] Example 3 Artificial photosynthetic community and salinity optimization

[0071] Activate engineered algae 2 to produce seeds. The resulting seed solution was inoculated into fresh BG11 medium containing the appropriate antibiotics, maintaining an initial biomass OD730 of 0.1, and cultured under continuous illumination for three days. Then, various concentrations of sodium chloride were added (in this case, 0, 50, 100, 150, and 200 mmol / L), along with 1 mmol / L IPTG and 1 mmol / L theophylline. Culture was then under continuous illumination for eight days. Every two days, the OD730 values were measured with a microplate reader to indicate algal concentration. Simultaneously, an appropriate amount of algal solution was collected, centrifuged, and filtered through a 0.22 μm filter. Sucrose content was determined using a sucrose assay kit. Three replicates were performed for each group.

[0072] The growth and sucrose secretion of engineered algae 2 under different sodium chloride concentrations are shown in Figure 2. Figure 4 and Figure 5 As shown. Figure 4 It can be seen that with the increase of sodium chloride concentration, the biomass of engineered algae 2 gradually decreased, indicating that sodium chloride has a certain stress effect on the growth of engineered algae. As for sucrose secretion, within the range of 0 to 150mmol / L, the higher the sodium chloride concentration, the higher the sucrose secretion of engineered algae 2. When the sodium chloride concentration is further increased to 200mmol / L, the sucrose production decreases. On the 8th day of cultivation at a sodium chloride concentration of 150mmol / L, the sucrose secretion of engineered algae 2 is the largest, at 1.06g / L. Figure 5 Therefore, a sodium chloride concentration of 150 mmol / L was selected for the fermentation culture of the artificial photosynthetic community.

[0073] Example 4 Growth Interaction of Artificial Photosynthetic Community

[0074] Engineered algae 2 was inoculated into BG11 medium containing the appropriate antibiotics and cultured under illumination for three days. The resulting seed solution was transferred to fresh BG11 medium to an initial biomass OD730 of 0.1 and cultured under continuous illumination for three days. 150 mmol / L sodium chloride, 1 mmol / L IPTG, and 1 mmol / L theophylline were then added, and cultured under continuous illumination for seven days to induce sucrose secretion. Following the incubation period, 4 mmol / L ammonium chloride, 0.214 g / L yeast extract, and 3 g / L HEPES (pH 7.5) were added, and the culture was inoculated with an overnight activated Priesteria gigantea culture solution to an OD of approximately 10. In this case, 0, 125, 250, 500, and 1000 μL of Priesteria gigantea culture solution were added at different times. Cultures were then cultured under continuous illumination for four days. Initial OD600 and OD730 values were measured using a microplate reader. Starting from day two, OD600 and OD730 values were measured every other day to indicate bacterial and algal concentrations, respectively. Three replicates were performed for each group.

[0075] The growth of engineered algae in artificial photosynthetic communities under different algae-bacteria ratios is as follows: Figure 6 As shown in the figure, as the inoculum amount of Priesteria gigantea increases, the biomass of the engineered algae gradually increases, and its growth is promoted compared to that of a single culture, indicating that Priesteria gigantea has a positive effect on the growth of the engineered algae in the artificial photosynthetic community.

[0076] Growth of Priesteria gigantea in artificial photosynthetic communities Figure 7 As shown in the figure, the biomass of Priesteria gigantea continued to increase even after the fourth day of cultivation, indicating that the sucrose synthesized and secreted by the engineered algae was sufficient to support its growth. Therefore, the artificial photosynthetic community of Synechococcus elongatus and Priesteria gigantea was stably maintained. Synechococcus elongatus was able to fix carbon dioxide, convert it into sucrose, and secrete it into the environment, providing the essential carbon source for the growth of Priesteria gigantea. In turn, Priesteria gigantea promoted the growth of Synechococcus elongatus.

[0077] The artificial photosynthetic community was observed using a fluorescence microscope. Figure 8 Under white light, both Synechococcus elongatus and Priesteria gigantea can be seen, while under green light, only Synechococcus elongatus, which appears red, can be observed.

[0078] Example 5 Characterization of polyhydroxyalkanoates in artificial photosynthetic communities

[0079] Engineered algae 2 was activated to produce seeds, and the seed solution was transferred to BG11 medium and cultured under continuous illumination for 3 days. 150 mmol / L sodium chloride, 1 mmol / L IPTG, and 1 mmol / L theophylline were then added, and the culture was continued under continuous illumination for 7 days. After the culture was completed, 4 mmol / L ammonium chloride, 0.214 g / L yeast extract, and 3 g / L HEPES (pH 7.5) were added, along with a Priesteria gigantea culture solution activated overnight to an OD of approximately 10. In this example, 0, 125, 250, 500, and 1000 μL of Priesteria gigantea culture solution were added, respectively. The culture was then continued under continuous illumination for 2 days. After the culture was completed, the fluorescence intensity of the polyhydroxyalkanoate (PHA) was measured using a microplate reader, and the PHA content was determined by gas chromatography-mass spectrometry after the methylation reaction. The injection volume was 1 μL, the split ratio was 15:1, the carrier gas was helium, the flow rate was 1 mL / min, the injection port temperature was 280°C, and the column temperature program was: 60°C for 2 min, then 10°C / min to 110°C, and then 20°C / min to 200°C. Three replicates were performed in each group.

[0080] The fluorescence intensity and content of polyhydroxyalkanoates in artificial photosynthetic communities under different algae-bacteria ratios are as follows: Figure 9 Compared to a monoculture of engineered algae, inoculation with Priesteria gigantea increased the fluorescence intensity of polyhydroxyalkanoates, which gradually decreased with increasing Priesteria gigantea inoculum. Polyhydroxyalkanoates were only detected in artificial photosynthetic communities with algae-to-bacteria ratios of 5:0.125, 5:0.25, and 5:0.5, respectively, and their levels decreased in that order. Ultimately, without the addition of an exogenous carbon source, the artificial photosynthetic community composed of Synechococcus elongatus and Priesteria gigantea was able to convert carbon dioxide into polyhydroxyalkanoates, with a polyhydroxyalkanoate yield of 0.29 g / L.

[0081] The above content is a further detailed description of the present application in conjunction with specific implementation methods, and the specific implementation of the present application cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present application belongs, several simple deductions or substitutions can be made without departing from the concept of the present application.

Claims

1. An engineered algae, characterized in that: The engineered algae is genetically modified Synechococcus elongatus, and the genetic modification includes constructing and expressing heterologous sucrose permease and glyceraldehyde dehydrogenase in Synechococcus elongatus, or constructing and expressing heterologous sucrose permease, glyceraldehyde dehydrogenase and sucrose synthase in Synechococcus elongatus.

2. The engineered algae according to claim 1, characterized in that: The nucleic acid sequence of the sucrose permease is the sequence shown in SEQ ID NO.1; Preferably, the sucrose permease is derived from Escherichia coli.

3. The engineered algae according to claim 1, characterized in that: The glyceraldehyde dehydrogenase is the sequence shown in SEQ ID NO.2; Preferably, the glyceraldehyde dehydrogenase is derived from Synechococcus.

4. The engineered algae according to any one of claims 1 to 3, characterized in that: The sucrose synthase is the sequence shown in SEQ ID NO.3; Preferably, the sucrose synthase is derived from Synechocystis.

5. An artificial photosynthetic community comprising the engineered algae according to any one of claims 1 to 4.

6. The artificial photosynthetic community according to claim 5, characterized in that: The invention comprises the engineered algae according to any one of claims 1 to 4, and Priesteria gigantea.

7. The artificial photosynthetic community according to claim 6, characterized in that: The ratio of the engineered algae to the Priesteria gigantea is 5:(0.125-0.5) in sequence.

8. Use of the engineered algae according to any one of claims 1 to 4 or the artificial photosynthetic community according to any one of claims 5 to 7 in the preparation of polyhydroxyalkanoates.

9. A method for preparing polyhydroxyalkanoate, characterized in that: The method comprises fermenting the artificial photosynthetic community according to any one of claims 5 to 7, and collecting polyhydroxyalkanoate from the fermentation product.

10. The preparation method according to claim 9, characterized in that: The culture medium used in the fermentation contains 50-150 mmol / L of sodium chloride; Preferably, the culture medium is BG11 culture medium; Preferably, the BG11 medium contains 50-150 mmol / L sodium chloride, 1-8 mmol / L ammonium chloride, 0.2-0.3 g / L yeast powder, and 2-4 g / L 4-hydroxyethylpiperazineethanesulfonic acid; Preferably, the fermentation conditions are 15-40°C, 60-200rpm, 3000-5000Lux continuous illumination for 2-4 days; Preferably, after the engineered algae according to any one of claims 1 to 4 is cultured for 3 to 8 days, Priesteria megaterium is added to form the artificial photosynthetic community according to any one of claims 5 to 7, and then the artificial photosynthetic community is fermented.

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