CN114015577A

CN114015577A - Construction method of synechococcus strain with cadmium ion stress resistance

Info

Publication number: CN114015577A
Application number: CN202111294462.5A
Authority: CN
Inventors: 梁成伟; 任玉东; 顾梓鹏; 张晓雯; 叶乃好
Original assignee: Qingdao University of Science and Technology; Yellow Sea Fisheries Research Institute Chinese Academy of Fishery Sciences
Current assignee: Qingdao University of Science and Technology; Yellow Sea Fisheries Research Institute Chinese Academy of Fishery Sciences
Priority date: 2021-11-03
Filing date: 2021-11-03
Publication date: 2022-02-08
Anticipated expiration: 2041-11-03
Also published as: CN114015577B

Abstract

The invention provides a construction method of a synechococcus strain with cadmium ion stress resistance. The invention comprises the following steps: 1) extracting RNA from the kelp, synthesizing cDNA, and performing PCR amplification by using a primer 1F and a primer 1R to obtain a kelp GST gene with a nucleotide sequence shown as SEQ ID No. 1; 2) the method comprises the following steps of (1) carrying out enzyme digestion, recovery and purification on a kelp GST gene, and connecting the kelp GST gene with a synechococcus protein expression vector to construct a synechococcus expression vector containing the kelp GST gene; 3) and centrifuging the synechococcus cultured to the logarithmic phase, collecting algae cells, resuspending, adding a synechococcus expression vector containing a kelp GST gene, and culturing to obtain the synechococcus strain with cadmium ion stress resistance. The invention utilizes the kelp GST gene to obtain the synechococcus strain with cadmium ion stress resistance, the synechococcus strain can normally grow under the condition of cadmium ion stress and can normally carry out photosynthesis, and the growth performance under the condition of cadmium ion stress is improved.

Description

Construction method of synechococcus strain with cadmium ion stress resistance

Technical Field

The invention relates to the technical field of algae genetic engineering, in particular to a construction method of synechococcus strain with cadmium ion stress resistance.

Background

Synechococcus (Synechococcus) is one of the most prominent representative groups of marine cyanobacteria, and was discovered in 1979 to be an ultra-miniature (0.5-2 μm) pellet-shaped photoautotrophic prokaryote. Synechococcus is widely distributed in oceans of the world in large numbers, particularly abundant in coastal waters, and generally abundant in tropical and temperate oceans at 10³-10⁵one/mL. Synechococcus is the dominant component in ultramicro plankton. Synechococcus is one of the major participants in the global carbon cycle and the major contributors to primary productivity, and about 1X 10 of Synechococcus and Prochloranthus (closely related species of Synechococcus) in the Earth's ocean are absorbed from the atmosphere each year¹⁰T carbon, corresponding to two thirds of the total amount of carbon dioxide fixed in the atmosphere at sea. In addition, synechococcus circulates rapidly in the marine micro-food net, has high energy conversion efficiency, and is one of the most important food sources of micro zooplankton.

Cadmium induces the production of ROS (reactive oxygen species), which causes lipid peroxidation and disrupts the intracellular ion balance. Cadmium is difficult to degrade in organisms and can be transmitted along with food nets, thus threatening the safety of marine food and human health. Cadmium ion concentrations in sediments and open waters are generally low, but cadmium emission concentrations in some offshore and estuary areas can become high due to leakage or man-made emissions. Cadmium has no known metabolic function in macroalgae; however, cadmium has been shown to be a cofactor for diatom carbonic anhydrase. In higher plants, cadmium ions interfere with growth, photosynthesis, transport of ions and water, and reduce enzyme activity through reactions between cadmium ions and thiol groups.

Since the synechococcus occupies an important position in a marine ecosystem, the research on the ecological environment of the synechococcus has important significance. Heavy metals in the ecological environment, particularly in the aquatic environment, have a significant impact on the growth of synechococcus. At present, the photosynthesis of the existing synechococcus can be reduced under the condition of cadmium ion stress, so that the normal growth is influenced.

Disclosure of Invention

The invention aims to provide a construction method of a synechococcus strain with cadmium ion stress resistance, and aims to solve the problem that the photosynthesis of the synechococcus is reduced under the cadmium ion stress condition to influence the normal growth in the prior art.

In order to solve the technical problem, the technical scheme of the invention is realized as follows:

the invention relates to a construction method of a synechococcus strain with cadmium ion stress resistance, which comprises the following steps:

1) taking giant kelp, extracting RNA, synthesizing cDNA,

using primer 1F: 5'-CCGGAATTCATGGCTCCCGTATT-3'

And primer 1R: 5'-CGGGGTACCCTAGGCCTTGGATG-3' the flow of the air in the air conditioner,

PCR amplification to obtain a kelp GST gene with a nucleotide sequence shown as SEQ ID No. 1;

2) the method comprises the following steps of (1) carrying out enzyme digestion, recovery and purification on a kelp GST gene, and connecting the kelp GST gene with a synechococcus protein expression vector to construct a synechococcus expression vector containing the kelp GST gene;

3) and centrifuging the synechococcus cultured to the logarithmic phase, collecting algae cells, resuspending, adding a synechococcus expression vector containing a kelp GST gene, and culturing to obtain the synechococcus strain with cadmium ion stress resistance.

The invention utilizes the connection of the giant kelp GST gene and the expression vector of the synechococcus protein to construct the synechococcus expression vector containing the giant kelp GST gene, and the synechococcus expression vector is added into synechococcus cells and cultured to obtain synechococcus strains with cadmium ion stress resistance; the kelp GST gene can be efficiently expressed in synechococcus, the growth rate of the obtained synechococcus strain with cadmium ion stress resistance under the condition of cadmium ion stress is obviously increased compared with the growth rate of a wild synechococcus strain under the condition of cadmium ion stress, and the chlorophyll fluorescence parameter Fv/Fm of the obtained synechococcus strain with cadmium ion stress resistance under the condition of cadmium ion stress does not obviously change compared with the chlorophyll fluorescence parameter Fv/Fm of the synechococcus strain under the condition of no stress; therefore, the synechococcus strain with cadmium ion stress resistance can still normally grow under the condition of cadmium ion stress, can normally carry out photosynthesis, and improves the growth performance under the condition of cadmium ion stress.

In a preferred embodiment, the amino acid sequence encoded by the kelp GST gene is shown in SEQ ID No. 2. The kelp GST gene is a kelp glutathione S-transferase gene, and the glutathione S-transferase (GST) is a multifunctional protein encoded by a large gene family, can be efficiently expressed in synechococcus, and improves the growth performance under the condition of cadmium ion stress. The nucleotide sequence of the kelp GST gene contains 606bp nucleotides, the sequence is a coding sequence of the GST gene, and the coding sequence can code a protein consisting of 201 amino acids shown as a sequence table SEQ ID No 2.

In a preferred embodiment, the synechococcus protein expression vector is pSyn-6. The present invention constructs synechococcus expression vector containing giant kelp GST gene connected with synechococcus protein expression vector, and converts the synechococcus expression vector into colibacillus E.coli DH5 alpha competent cell. pSyn-6 is the name of the vector, and the synechococcus protein expression vector is a commercial vector, has wide sources, convenient material taking, low price and easy obtainment.

As a preferred embodiment, the PCR amplification conditions are: pre-denaturation at 94 ℃ for 30 s; denaturation at 98 ℃ for 10s, annealing at 62 ℃ for 30s, extension at 72 ℃ for 1min, co-amplification for 30 cycles, and extension at 72 ℃ for 2 min. According to the GST gene sequence obtained from the kelp transcriptome sequence, enzyme cutting sites contained in the GST gene sequence are screened out through OMIGA software, specific primers, namely a primer 1F and a primer 1R, containing the GST gene sequence with the proper enzyme cutting sites are designed through Primer5.0 software, and the primer 1F and the primer 1R are manufactured into finished products by a primer company for direct use after the design is finished. The invention effectively controls the amplification condition and realizes the effective amplification of the kelp GST gene.

As a preferred embodiment, the step of resuspending is: centrifuging algae cells, removing supernatant, adding BG11 liquid culture medium, and resuspending; centrifuged again, the supernatant removed, BG11 liquid medium added and resuspended. The invention adopts a conventional heavy suspension method, so that the operation is simple and the realization is convenient; the volume of BG11 liquid medium used for the first resuspension is 10 times of the volume of BG11 liquid medium used for the second resuspension, and the first deep resuspension and the second repeated resuspension are performed to improve the resuspension effect.

As a preferred embodiment, the step of culturing is: firstly, placing the algae cells added with the synechococcus expression vector containing the giant kelp GST gene in a constant temperature water bath at 34 ℃ for standing for 4 hours; then, coating the algae liquid on a BG11 solid culture medium, and culturing under illumination at 27 ℃ for 8 days to grow single spots; finally, the single spot was inoculated into BG11 liquid medium and cultured. The invention adopts a conventional culture method, and the method comprises the steps of standing in a constant-temperature water bath, then performing illumination culture, and finally performing inoculation culture.

In a preferred embodiment, during the culture process, the BG11 solid medium is BG11 solid medium containing 10 μ g/mL spectinomycin, and the BG11 liquid medium is BG11 liquid medium containing 10 μ g/mL spectinomycin. The BG11 solid culture medium adopted in the culture process is the same as the BG11 liquid culture medium, and the selection is convenient.

As a preferred embodiment, the centrifugation is carried out at room temperature and 14000 rpm. The invention has mild centrifugation condition and convenient operation, and is usually centrifuged for 1-3 min.

Compared with the prior art, the invention has the beneficial effects that: the invention utilizes the connection of the giant kelp GST gene and the expression vector of the synechococcus protein to construct the synechococcus expression vector containing the giant kelp GST gene, and the synechococcus expression vector is added into synechococcus cells and cultured to obtain synechococcus strains with cadmium ion stress resistance; the kelp GST gene can be efficiently expressed in synechococcus, the growth rate of the obtained synechococcus strain with cadmium ion stress resistance under the condition of cadmium ion stress is obviously increased compared with the growth rate of a wild synechococcus strain under the condition of cadmium ion stress, and the chlorophyll fluorescence parameter Fv/Fm of the obtained synechococcus strain with cadmium ion stress resistance under the condition of cadmium ion stress does not obviously change compared with the chlorophyll fluorescence parameter Fv/Fm of the synechococcus strain under the condition of no stress; therefore, the synechococcus strain with cadmium ion stress resistance can still normally grow under the condition of cadmium ion stress, can normally carry out photosynthesis, and improves the growth performance under the condition of cadmium ion stress.

Drawings

FIG. 1 is a diagram showing the construction of a vector for expressing a glutathione S-transferase gene of a macroalgae according to an embodiment of the present invention;

FIG. 2 is a diagram showing the result of agarose gel electrophoresis of the amplification product of transgenic Synechococcus in experiment 1 according to the present invention;

FIG. 3 is a graph showing the growth rate variation of different Synechococcus in experiment 2 of the present invention at different times;

FIG. 4 is a graph showing the trend of the chlorophyll fluorescence parameter Fv/Fm of different Synechococcus in experiment 2 of the present invention under different conditions;

in the figure: diamond-wild synechococcus plants; ■ -Synechococcus strain having cadmium ion resistance; a-no cadmium ion stress; b-cadmium ion stress.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

1) taking giant kelp, extracting RNA, synthesizing cDNA,

using primer 1F: 5'-CCGGAATTCATGGCTCCCGTATT-3'

Preferably, the amino acid sequence encoded by the macroalgae GST gene is shown in SEQ ID No 2.

Preferably, the synechococcus protein expression vector is pSyn _ 6.

Preferably, the conditions for PCR amplification are: pre-denaturation at 94 ℃ for 30 s; denaturation at 98 ℃ for 10s, annealing at 62 ℃ for 30s, extension at 72 ℃ for 1min, co-amplification for 30 cycles, and extension at 72 ℃ for 2 min.

Preferably, the step of resuspending is: centrifuging algae cells, removing supernatant, adding BG11 liquid culture medium, and resuspending; centrifuged again, the supernatant removed, BG11 liquid medium added and resuspended.

Preferably, the step of culturing is: firstly, placing the algae cells added with the synechococcus expression vector containing the giant kelp GST gene in a constant temperature water bath at 34 ℃ for standing for 4 hours; then, coating the algae liquid on a BG11 solid culture medium, and culturing under illumination at 27 ℃ for 8 days to grow single spots; finally, the single spot was inoculated into BG11 liquid medium and cultured.

Preferably, during the culture process, the BG11 solid medium is BG11 solid medium containing 10 μ g/mL spectinomycin, and the BG11 liquid medium is BG11 liquid medium containing 10 μ g/mL spectinomycin.

Preferably, the centrifugation is carried out at room temperature and 14000 rpm.

Example one

cloning of GST Gene of S1 Macrocystis

The extraction kit of the total RNA of the macroalgae is a product of Omega Bio-Tek (USA) Limited (http:// www.omegabiotek.com /), the reverse transcription kit is a product of Excery bioengineering (HTTP:// agbio. com. cn), and various restriction enzymes are purchased from Nippon Biotechnology (USA) Limited (http// www.neb.com /), T₄DNA Ligase was purchased from Dalianbao bioengineering, Inc. (http:// takara. com. cn).

About 0.1g of fresh kelp was weighed and extracted for total RNA, specifically by the procedure described in the above Omega Bio-Tek plant hand sample extraction protocol, and cDNA synthesis (i.e., reverse transcription of RNA into cDNA using the template) was performed for extracted total RNA, specifically by the procedure described in the agbio protocol for first strand synthesis. Using the first strand of the synthesized cDNA as a template, under the guide of the primer 1F and the primer 1R, the sequence of the GST gene of the macroalgae is amplified by a conventional PCR method. The amplification conditions were: pre-denaturation at 94 ℃ for 30 s; denaturation at 98 ℃ for 10s, annealing at 62 ℃ for 30s, extension at 72 ℃ for 1min, co-amplification for 30 cycles, and extension at 72 ℃ for 2 min. After the reaction is finished, 2% agarose gel electrophoresis detection is carried out on the PCR amplification product, and DNA fragments of about 700bp are recovered and purified and sequenced to obtain the required kelp GST gene full length.

Primer 1F: 5' -CCGGAATTCATGGCTCCCGTATT-3' (underlined sequence is restriction enzyme EcoRI recognition site and protection base);

primer 1R: 5' -CGGGGTACCCTAGGCCTTGGATG-3' (underlined sequence is restriction enzyme KpnI recognition site and protection base);

according to the GST gene sequence obtained from the kelp transcriptome sequence, enzyme cutting sites contained in the GST gene sequence are screened out by OMIGA software, and specific primers-primer 1F and primer 1R-containing the GST gene sequence with proper enzyme cutting sites are designed by Primer5.0 software.

The sequencing result shows that the DNA fragment of about 700bp contains a 606bp nucleotide sequence shown in a sequence table SEQ ID No 1, the sequence is a coding sequence of a GST gene, the coding sequence can code a protein consisting of 201 amino acids shown in a sequence table SEQ ID No 2, and the protein is named as GST.

Construction of S2 GST gene synechococcus expression vector

The plasmid petite reagent kit was purchased from Tiangen Biotechnology (Beijing) Ltd (http:// www.tiangen.com /).

Carrying out double enzyme digestion on the DNA fragment containing the nucleotide shown in the sequence table SEQ ID No 1 and the synechococcus protein expression vector pSyn-6 of about 700bp obtained by PCR amplification in S1 by adopting EcoRI and KpnI, recovering, purifying and connecting enzyme digestion products, constructing the synechococcus expression vector of the macroalgae GST after enzyme digestion identification of the connecting product, and converting the synechococcus expression vector into a competent cell of Escherichia coli E.coli DH5 alpha. Extracting plasmids by a plasmid miniextraction kit, and performing sequencing identification to ensure that the macroalgae GST gene is connected to the synechococcus protein expression vector pSyn _ 6; FIG. 1 shows the construction scheme of the Synechococcus expression vector of the kelp GST.

Obtaining of S3 transgenic synechococcus

Transforming the synechococcus expression vector containing the giant kelp GST gene constructed by S2 into synechococcus, wherein the specific method comprises the following steps:

centrifuging the synechococcus cultured to logarithmic phase at room temperature and 14000rpm for 3min, and collecting 1.5mL of algal cells; centrifuging, removing the supernatant, adding 1mL BG11 liquid culture medium, and resuspending; centrifuging at 14000rpm for 1min at room temperature, removing the supernatant, adding 100 μ L BG11 liquid culture medium, and resuspending; then, 100ng of the synechococcus expression vector containing the macroalgae GST gene constructed by S2 was added, the centrifuge tube (EP tube) was gently moved, a black cap was attached to the EP tube, and the mixture was allowed to stand in a constant temperature water bath at 34 ℃ for 4 hours.

The EP tube was taken out, wiped with 70% ethanol, 100. mu.L of the algal solution was applied to BG11 solid medium containing 10. mu.g/mL spectinomycin, and cultured at 27 ℃ under light for 8 days to grow single spots, thereby obtaining transformants. Inoculating the single spot into BG11 liquid culture medium containing 10. mu.g/mL spectinomycin, and culturing to obtain Synechococcus strain with cadmium ion stress resistance.

Experiment 1 PCR identification of transgenic Synechococcus

Extracting genome DNA of the Synechococcus strain with cadmium ion stress resistance obtained in the first embodiment, performing PCR amplification by using 2F and 2R primers, and performing 2% agarose gel electrophoresis detection on a PCR amplification product; as can be seen from FIG. 2, the GST gene of the macroalgae was amplified from the Synechococcus; therefore, the transformation is successful, and the kelp GST gene realizes high-efficiency expression in synechococcus.

And (3) primer 2F: 5'-ATGGCTCCCGTATTCAACTA-3', respectively;

and (3) primer 2R: 5'-CTAGGCCTTGGATGCGTAG-3' are provided.

Experiment 2 cadmium ion tolerance analysis of transgenic Synechococcus

Diluting the wild synechococcus plants growing to logarithmic phase and the synechococcus plants with cadmium ion resistance obtained in the first embodiment to OD by adopting BG11 culture medium₇₅₀The value was 0.01, and the sample was added to a solution containing cadmium ions so that the concentration of cadmium ions in each sample was 0.2mg/L, and blank controls were added, respectively. The samples were placed in a constant temperature incubator at 100. mu. mol/(m)²S) light intensity and temperature of 25. + -. 2 ℃ and determining OD of the sample every 2 days₇₅₀Value, measured for 12 days, and chlorophyll fluorescence parameter Fv/Fm of the sample measured on day 10.

As can be seen from FIG. 3, the growth rate of the Synechococcus strain with cadmium ion stress resistance obtained by the present invention under the condition of cadmium ion stress is significantly increased compared with the growth rate of the wild Synechococcus strain under the condition of cadmium ion stress, which indicates that the Synechococcus strain with cadmium ion stress resistance obtained by the present invention has a faster growth rate under the condition of cadmium ion stress.

As can be seen from FIG. 4, the chlorophyll fluorescence parameter Fv/Fm of the wild synechococcus plant under the stress of cadmium ions is obviously reduced and almost dies compared with the chlorophyll fluorescence parameter Fv/Fm under the stress without cadmium ions; therefore, wild synechococcus plants do not normally perform photosynthesis under cadmium ion stress conditions. However, the chlorophyll fluorescence parameter Fv/Fm of the synechococcus strain with cadmium ion stress resistance obtained by the invention is only slightly reduced compared with the chlorophyll fluorescence parameter Fv/Fm of the synechococcus strain without cadmium ion stress, and the change is not obvious; therefore, the synechococcus strain with cadmium ion stress resistance can also carry out photosynthesis normally under the condition of cadmium ion stress.

Therefore, compared with the prior art, the invention has the beneficial effects that: the invention utilizes the connection of the giant kelp GST gene and the expression vector of the synechococcus protein to construct the synechococcus expression vector containing the giant kelp GST gene, and the synechococcus expression vector is added into synechococcus cells and cultured to obtain synechococcus strains with cadmium ion stress resistance; the kelp GST gene can be efficiently expressed in synechococcus, the growth rate of the obtained synechococcus strain with cadmium ion stress resistance under the condition of cadmium ion stress is obviously increased compared with the growth rate of a wild synechococcus strain under the condition of cadmium ion stress, and the chlorophyll fluorescence parameter Fv/Fm of the obtained synechococcus strain with cadmium ion stress resistance under the condition of cadmium ion stress does not obviously change compared with the chlorophyll fluorescence parameter Fv/Fm of the synechococcus strain under the condition of no stress; therefore, the synechococcus strain with cadmium ion stress resistance can still normally grow under the condition of cadmium ion stress, can normally carry out photosynthesis, and improves the growth performance under the condition of cadmium ion stress.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Sequence listing

<110> university of Qingdao science and technology; institute of aquatic products in yellow sea of China institute of aquatic science

<120> construction method of synechococcus strain with cadmium ion stress resistance

<130> 2021

<160> 6

<170> PatentIn version 3.5

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<213> Artificial sequence (SEQ ID No 1)

<400> 1

atggctcccg tattcaacta cttcggaatc cccgcccgtg gcgaggcaac ccgcgtcgct 60

ctggccgtcg ccggcgttga cttcgaggac aagcgcatgt ccttcgaaga gttcggtgcc 120

tccgagttca agactctgcc cgtctaccag atggacggaa ccgactacac ccagtcgacc 180

gcccttttgc gatacgccgg taagctcggc ggcacgtacc cggaaagccc tctcgccgcc 240

ctcaaggtgg acgagatcgt gatgatcgcg gaggacgtgt tcatcaacct cttctccacc 300

atgggagaga aggacgaggc caagaagttg cacaagtgcc agactctgat ggccggcaaa 360

gtgaaggagc tgctggagga catcgccagg aaggtggaat ccaacaagag ctcggccttc 420

tgcgtcgggg actgcctcac catcgccgac atcacgattc acgccgtgtt cgccacagtg 480

caggctggct tcctggctgg catccccaag accatggtgg aggacatctg tccatccctc 540

aaggcggtcg acaacgccgt catggcacac ccgaaggtga aggcgtacta cgcatccaag 600

gcctag 606

<210> 2

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<212> PRT

<213> Artificial sequence (SEQ ID No 2)

<400> 2

Met Ala Pro Val Phe Asn Tyr Phe Gly Ile Pro Ala Arg Gly Glu Ala

1 5 10 15

Thr Arg Val Ala Leu Ala Val Ala Gly Val Asp Phe Glu Asp Lys Arg

20 25 30

Met Ser Phe Glu Glu Phe Gly Ala Ser Glu Phe Lys Thr Leu Pro Val

35 40 45

Tyr Gln Met Asp Gly Thr Asp Tyr Thr Gln Ser Thr Ala Leu Leu Arg

50 55 60

Tyr Ala Gly Lys Leu Gly Gly Thr Tyr Pro Glu Ser Pro Leu Ala Ala

65 70 75 80

Leu Lys Val Asp Glu Ile Val Met Ile Ala Glu Asp Val Phe Ile Asn

85 90 95

Leu Phe Ser Thr Met Gly Glu Lys Asp Glu Ala Lys Lys Leu His Lys

100 105 110

Cys Gln Thr Leu Met Ala Gly Lys Val Lys Glu Leu Leu Glu Asp Ile

115 120 125

Ala Arg Lys Val Glu Ser Asn Lys Ser Ser Ala Phe Cys Val Gly Asp

130 135 140

Cys Leu Thr Ile Ala Asp Ile Thr Ile His Ala Val Phe Ala Thr Val

145 150 155 160

Gln Ala Gly Phe Leu Ala Gly Ile Pro Lys Thr Met Val Glu Asp Ile

165 170 175

Cys Pro Ser Leu Lys Ala Val Asp Asn Ala Val Met Ala His Pro Lys

180 185 190

Val Lys Ala Tyr Tyr Ala Ser Lys Ala

195 200

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<213> Artificial sequence (primer 1F)

<400> 3

ccggaattca tggctcccgt att 23

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cggggtaccc taggccttgg atg 23

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atggctcccg tattcaacta 20

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ctaggccttg gatgcgtag 19

Claims

1. A construction method of a synechococcus strain with cadmium ion stress resistance is characterized by comprising the following steps:

1) taking giant kelp, extracting RNA, synthesizing cDNA,

using primer 1F: 5'-CCGGAATTCATGGCTCCCGTATT-3'

2. The method for constructing the Synechococcus strain with cadmium ion stress resistance according to claim 1, wherein:

the amino acid sequence of the codogenic kelp GST gene is shown in SEQ ID No 2.

3. The method for constructing the Synechococcus strain with cadmium ion stress resistance according to claim 1, wherein:

the synechococcus protein expression vector is pSyn _ 6.

4. The method for constructing the Synechococcus strain with cadmium ion stress resistance according to claim 1, wherein:

the PCR amplification conditions are as follows: pre-denaturation at 94 ℃ for 30 s; denaturation at 98 ℃ for 10s, annealing at 62 ℃ for 30s, extension at 72 ℃ for 1min, co-amplification for 30 cycles, and extension at 72 ℃ for 2 min.

5. The method for constructing Synechococcus strain having cadmium ion stress resistance according to any one of claims 1 to 4, wherein:

the resuspension steps are as follows: centrifuging algae cells, removing supernatant, adding BG11 liquid culture medium, and resuspending; centrifuged again, the supernatant removed, BG11 liquid medium added and resuspended.

6. The method for constructing the Synechococcus strain with cadmium ion stress resistance according to claim 5, wherein:

the culturing steps are as follows: firstly, placing the algae cells added with the synechococcus expression vector containing the giant kelp GST gene in a constant temperature water bath at 34 ℃ for standing for 4 hours; then, coating the algae liquid on a BG11 solid culture medium, and culturing under illumination at 27 ℃ for 8 days to grow single spots; finally, the single spot was inoculated into BG11 liquid medium and cultured.

7. The method for constructing the Synechococcus strain with cadmium ion stress resistance according to claim 6, wherein:

in the culture process, the BG11 solid culture medium is a BG11 solid culture medium containing 10 mu g/mL spectinomycin, and the BG11 liquid culture medium is a BG11 liquid culture medium containing 10 mu g/mL spectinomycin.

8. The method for constructing the Synechococcus strain with cadmium ion stress resistance according to claim 5, wherein:

the centrifugation was carried out at room temperature and 14000 rpm.