Microalgae biological fertilizer for improving crop yield and stress resistance

Abstract

The invention discloses a microalgae biological fertilizer for improving crop yield and stress resistance, and belongs to the technical field of microorganisms. The thermophilic monolith ZGL1 disclosed by the invention can stably grow in a saline-alkali environment, shows strong saline-alkali tolerance, can maintain normal metabolism and growth under high saline-alkali concentration, and provides an ideal microbial resource for agricultural application of saline-alkali soil. The thermophile ZGL1 disclosed by the invention can simultaneously act on saline-alkali soil improvement, antibiotic and pesticide pollution treatment and crop stress resistance and yield increase, has remarkable ecological benefits and economic benefits, and provides an efficient and environment-friendly solution for agricultural ecological restoration of saline-alkali soil.

Description

Technical Field

[0001] The present invention relates to the technical field of microorganisms, and in particular to a microalgae biofertilizer capable of improving crop yield and stress resistance. Background Art

[0002] The high salt and alkalinity in saline-alkali lands lead to soil structure degradation and nutrient imbalance, severely restricting crop productivity. Traditional improvement methods, such as the application of organic manure, can improve fertility, but they carry the risk of residual antibiotics (such as enrofloxacin). These antibiotics have a long degradation cycle in saline-alkali environments, easily accumulating in the soil and disrupting the ecological balance. This can further contaminate the food chain and spread resistance genes (ARGs), threatening agricultural sustainability and environmental safety. Furthermore, the long-term residues of organophosphorus pesticides (such as chlorpyrifos) pose a potential toxic threat to soil ecology and crops.

[0003] Although microalgae have been shown to be able to degrade pesticides and antibiotics, and improve soil water retention and promote crop growth through mechanisms such as carbon and nitrogen fixation and secretion of exopolysaccharides (EPS) and auxins (IAA), their application in saline-alkali environments still faces significant limitations: existing research has mostly focused on non-saline-alkali conditions or single functions (such as growth promotion / degradation), with insufficient exploration of the mechanisms for the synergistic management of saline-alkali stress and antibiotic / pesticide pollution. Furthermore, most current research is based on Chlorella vulgaris, lacking the systematic development of new multifunctional algae species for saline-alkali lands. While some known salt-tolerant algae species (such as Chlorella vulgaris) can alleviate salt stress, there is still a gap in the simultaneous remediation efficiency and large-scale application technology for combined pollution (salinity and alkali + antibiotics / pesticides).

[0004] Therefore, developing functional algae strains that are salt- and alkali-tolerant, can efficiently degrade pollutants, and promote crop growth, and establishing supporting processes have become key innovative directions for solving the problems of ecological restoration and safe utilization of saline-alkali land. Summary of the Invention

[0005] In view of the problems existing in the above-mentioned prior art, the object of the present invention is to provide a microalgae biofertilizer that improves crop yield and stress resistance.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect of the present invention, a strain of Coelastrella thermophila ZGL1 is provided. The strain was deposited in the China Center for Type Culture Collection (CCTCC, address: Wuhan University, Wuhan, China) on May 26, 2025, and its deposit number is: CCTCC NO: M 20251193.

[0008] The thermophilic Coelastrella thermophila ZGL1 of the present invention is isolated from typical saline-alkali soil in Dongying, Yellow River Delta, and has the following main characteristics:

[0009] (1) Excellent salt and alkali resistance;

[0010] (2) secretion of exopolysaccharides and auxins under saline-alkali stress;

[0011] (3) Degradation of antibiotics and pesticides;

[0012] (4) Promote the growth of crops under saline-alkali stress conditions.

[0013] Therefore, the thermophilic Coelastrella thermophila ZGL1 of the present invention can be used as a new functional algae strain that is salt- and alkali-tolerant, has high pollutant degradation efficiency, and promotes crop growth, and can be applied to the ecological restoration of saline-alkali land.

[0014] The second aspect of the present invention provides an algae agent, which contains the above-mentioned Coelastrellathermophila ZGL1.

[0015] Preferably, in the algae agent, the Coelastrella thermophila ZGL1 exists in the form of cultured living algae, algae liquid or algae suspension.

[0016] Furthermore, the algae liquid is prepared by the following method:

[0017] Coelastrella thermophila ZGL1 was inoculated into BG11 medium and cultured under conditions of light intensity of 3000-5000 lux, temperature of 25-30° C., and pH 7.0-9.0.

[0018] A third aspect of the present invention provides use of the above-mentioned Coelastrella thermophila ZGL1 or algae agent in degrading antibiotics and / or pesticides.

[0019] In the above application, preferably, the antibiotic is enrofloxacin; and the pesticide is chlorpyrifos.

[0020] A fourth aspect of the present invention provides the use of the thermophilic Coelastrella thermophila ZGL1 or algae agent in at least one of the following (1)-(3):

[0021] (1) Promote crop growth;

[0022] (2) Alleviate crop stress;

[0023] (3) Prepare microalgae biofertilizers to improve crop yield and stress resistance.

[0024] In the above application, the crop stress is caused by salinity, alkali, antibiotics and / or pesticides.

[0025] The thermophilic Coelastrella thermophila ZGL1 and the algae agent prepared therefrom can alleviate the effects of stress conditions such as salinity, alkali, antibiotics, and pesticides on crop growth, and promote crop growth under stress conditions.

[0026] A fifth aspect of the present invention provides a microalgae biofertilizer for improving crop yield and stress resistance, wherein the microalgae biofertilizer comprises the above-mentioned Coelastrella thermophila ZGL1 or an algae agent as an active ingredient.

[0027] A sixth aspect of the present invention provides a method for promoting crop growth under stress conditions, comprising the following steps:

[0028] Coelastrella thermophila ZGL1 or algae agent is applied to the soil where crops are grown.

[0029] In the above method, the stress conditions include: one or more of saline-alkali stress, antibiotics and pesticides.

[0030] Beneficial effects of the present invention:

[0031] The thermophilic Coelastrella thermophila ZGL1 of the present invention can grow stably in a saline-alkali environment, exhibits strong salt-alkali tolerance, can maintain normal metabolism and growth under high salt-alkali concentrations, and provides an ideal microbial resource for agricultural applications in saline-alkali land.

[0032] Under saline-alkali stress, the thermophilic Coelastrella thermophila ZGL1 of the present invention secretes more exopolysaccharides and auxins, which helps to alleviate the salt stress of plants and promote the growth and development of plants.

[0033] The thermophilic Coelastrella thermophila ZGL1 of the present invention can effectively degrade the antibiotic enrofloxacin and the pesticide chlorpyrifos in water bodies, reduce the accumulation of these harmful substances in the environment, help prevent and control water pollution and improve water quality, and has important environmental protection significance.

[0034] Under saline-alkali stress, the thermophilic Coelastrella thermophila ZGL1 of the present invention can effectively promote crop growth, enhance crop resistance, reduce the negative impact of salt stress on crops, and provide an effective saline-alkali soil improvement solution.

[0035] The thermophilic Coelastrella thermophila ZGL1 of the present invention can promote crop growth under the combined stress of enrofloxacin and chlorpyrifos, significantly increase the biomass and growth rate of the crops, and reduce the damage to the crops caused by pesticide and antibiotic pollution.

[0036] Through the application of the algae agent of the present invention, it can simultaneously act on saline-alkali soil improvement, antibiotic and pesticide pollution control, and crop stress resistance and yield increase, with significant ecological and economic benefits, providing an efficient and environmentally friendly solution for saline-alkali land agricultural ecological restoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the morphology of algal cells of the algae strain isolated in Example 1.

[0038] Figure 2 This is the phylogenetic tree constructed based on the 18S rRNA gene sequence of the isolated algae strain in Example 1.

[0039] Figure 3 This is a graph showing the biomass changes of Coelastrella thermophila ZGL1 relative to Chlorella under saline-alkali stress.

[0040] Figure 4 It is the extracellular polysaccharide concentration of the thermophilic algae (Coelastrella thermophila) ZGL1 of the present invention after 15 days under saline-alkali stress.

[0041] Figure 5 It is the auxin concentration of the thermophilic algae (Coelastrella thermophila) ZGL1 of the present invention after 15 days under saline-alkali stress.

[0042] Figure 6 The invention discloses the promoting effect of the thermophilic algae (Coelastrella thermophila) ZGL1 on corn growth under non-salt-alkali stress conditions.

[0043] Figure 7 This is the promoting effect of the thermophilic Coelastrella thermophila ZGL1 of the present invention on corn growth under saline-alkali stress conditions.

[0044] Figure 8The effect of the thermophilic algae (Coelastrella thermophila) ZGL1 of the present invention on degrading the antibiotic enrofloxacin in water

[0045] Figure 9 The present invention shows the effect of the thermophilic monostellate algae (Coelastrella thermophila) ZGL1 on degrading the pesticide chlorpyrifos in water.

[0046] Figure 10 The figures show the colonization effects of the thermophilic Coelastrella thermophila ZGL1 of the present invention in the surface layer and root system of potted soil and soil containing pesticides. In the figure, a shows the surface colonization effect, and b shows the root colonization effect.

[0047] Figure 11 The invention discloses an effect of alleviating the pollution stress of crops caused by chlorpyrifos and enrofloxacin by the thermophilic Coelastrella thermophila ZGL1. DETAILED DESCRIPTION

[0048] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0049] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific examples. If the specific experimental conditions are not specified in the examples, they are usually based on conventional conditions or the conditions recommended by the reagent company; the reagents and consumables used in the following examples, unless otherwise specified, can be obtained through commercial channels.

[0050] Example 1: Isolation and identification of microalgae

[0051] 1. Isolation of microalgae

[0052] Soil samples were collected from typical saline-alkali land in Dongying, in the Yellow River Delta. Physically processed into a homogenous suspension, BG-11 medium was used to isolate microalgae using a serial dilution plating and streak method.

[0053] 2. Identification of microalgae:

[0054] (1) Morphological identification:

[0055] Observe the isolated microalgae cells under a microscope and examine their morphology. Note the size, morphology, and other relevant characteristics of the cells.

[0056] The results are as follows Figure 1 As shown, the obtained microalgae cells exhibited typical morphologies of unicellular green algae, including spherical, elliptical, and spindle shapes, with blunt end-cells. Juvenile cells were 4-7 μm in size, while mature cells were 8-12 μm in size, with thick, translucent cell walls.

[0057] (2) Molecular biological identification:

[0058] The 18S rRNA gene sequence of the algae strain was determined, and its nucleotide sequence is shown in SEQ ID NO. 1. The obtained gene sequence was compared with known sequences in the NCBI database to confirm the species of the algae strain. Based on the 18S rRNA gene sequence, multiple known species related to the isolated algae strain were selected for comparison. Using appropriate sequence alignment software (such as MEGA or ClustalX), all aligned sequences were aligned and a phylogenetic tree was constructed. This phylogenetic tree can help demonstrate the relationship between the isolated algae strain and other related species and further confirm its taxonomic status.

[0059] The 18S rRNA gene sequence analysis and BLAST comparison results confirmed that the obtained algae strain had a similarity of 99.93% with Coelastrella thermophila. The phylogenetic tree constructed based on the 18S rRNA gene sequence showed that the isolated algae strain (ZGL1) was very closely related to Coelastrella thermophila, with a bootstrap value of 98% ( Figure 2 ), indicating that the algae strain is a subspecies of Thermophilic Monostar algae.

[0060] Based on the above morphological and molecular biological identification results, the isolated algal strain was named Coelastrellathermophila ZGL1 and deposited with the following information:

[0061] Reference biological material (strain): Coelastrella thermophila ZGL1;

[0062] Suggested taxonomic name: Coelastrella thermophila;

[0063] Deposit number: CCTCC NO: M 20251193;

[0064] Preservation time: May 26, 2025.

[0065] Example 2: Investigation of salt and alkali tolerance of Coelastrella thermophila ZGL1

[0066] 1. Test method:

[0067] To 1 L of BG11 medium, 0.292 g of NaCl, 6.3918 g of Na2SO4, 0.52995 g of Na2CO3, and 3.78045 g of NaHCO3 were added to prepare a saline-alkali medium.

[0068] The purified Coelastrella thermophila ZGL1 was inoculated into saline-alkali medium, and the initial OD 680 The cell density was 1×10 5 cells / mL, the culture conditions were light intensity 4000 lux, temperature 28°C, and culture for 12 days.

[0069] Chlorella vulgaris (FACHB-2338) purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, was used as a control to observe its growth performance under the same saline-alkali stress conditions. Biomass was measured regularly, and a growth curve was plotted showing dry weight changes over time.

[0070] 2. Test results:

[0071] The results are as follows Figure 3 As shown in the data, under saline-alkali stress conditions, after 12 days of cultivation, the biomass growth rate of the thermophilic monostar algae (ZGL1) was significantly higher than that of the Chlorella vulgaris, indicating that the monostar algae has stronger salt-alkali tolerance and can continue to grow under higher salt-alkali concentrations.

[0072] Example 3: Determination of the secretion of growth-promoting substances by Coelastrella thermophila ZGL1

[0073] 1. Test method:

[0074] The secretion of growth-promoting substances by the thermophilic algae (Coelastrella thermophila) ZGL1 under saline-alkali stress was investigated, including the secretion of exopolysaccharides (EPS) and auxin (IAA).

[0075] The purified Coelastrella thermophila ZGL1 was inoculated into saline-alkali culture medium (same as in Example 2), and the initial OD 680 The cell density was 1×10 5cells / mL, the culture conditions were a light intensity of 4000 lux, a temperature of 28°C, and the culture was continued for 15 days.

[0076] Chlorella vulgaris (FACHB-2338) purchased from the Institute of Hydrobiology, Chinese Academy of Sciences was used as a control and cultured under the same conditions for 15 days.

[0077] After the culture was completed, samples were collected and the secretion of extracellular polysaccharides was determined by the anthrone method, and the secretion of IAA was determined by the Salkowski colorimetric method.

[0078] 2. Test results:

[0079] After 15 days of cultivation under saline-alkali stress conditions, the extracellular polysaccharide production of the thermophilic monolithic algae ZGL1 was 70 mg / L ( Figure 4 ), compared with common Chlorella, it showed significant exopolysaccharide secretion ability, indicating that it can secrete higher amounts of EPS under saline-alkali stress conditions, which helps to improve soil water retention and stability. At the same time, the IAA secretion reached more than 60μg / L on the 15th day ( Figure 5 ), indicating that ZGL1-2025 has a strong IAA secretion capacity in saline-alkali environments. The results show that the thermophilic ZGL1 not only tolerates stress in saline-alkali environments, but also secretes beneficial growth-promoting substances, which contribute to plant growth and ecological restoration.

[0080] Example 4: Crop growth promotion experiment using Coelastrella thermophila ZGL1

[0081] 1. Test method:

[0082] To evaluate the growth-promoting effects of the thermophilic algae ZGL1 (Coelastrella thermophila) on crops, corn pot experiments were conducted under both non-saline and saline-alkaline stress conditions. The potting soil used in the corn pot experiments was collected from the same region and had no significant differences in soil composition. 300 g of potting soil was used per pot. The experimental crops were corn of the same variety and similar growth characteristics.

[0083] Preparation of saline water: Add 0.292g NaCl, 6.3918g Na2SO4, 0.52995g Na2CO3 and 3.78045g NaHCO3 to 1L distilled water, stir to dissolve and then dilute to 1L to obtain saline water.

[0084] Preparation of algae solution: 1 mL of seed solution of Coelastrella thermophila ZGL1 (OD = 2) was centrifuged to collect the precipitate, and then resuspended in 1000 mL of distilled water to obtain an algae solution with a final concentration of 10,000 cells / mL.

[0085] Preparation of saline-alkali algae solution: Add 0.292g NaCl, 6.3918g Na2SO4, 0.52995g Na2CO3 and 3.78045g NaHCO3 to 1L algae solution and stir evenly.

[0086] 1.1 Non-salt-alkali stress:

[0087] Under non-salinity and alkali stress, the experiment was set up as follows:

[0088] CK: Add 100 mL of distilled water to each potting soil.

[0089] Treatment with monostellate algae: Add 100 mL of algae solution to each potting soil.

[0090] 1.2 Salt-alkali stress:

[0091] Under saline-alkali stress, the experiment was set up as follows:

[0092] Non-salt-alkali stress control (CK0): 100 mL of distilled water was added to each potting soil.

[0093] Salt-alkali stress (CK1): 100 mL of saline-alkali water was added to each potting soil.

[0094] Single Star + Salt-alkali: Add 100mL of salt-alkali algae solution to each potting soil.

[0095] Other culture conditions of each treatment under non-salt-alkali stress and saline-alkali stress were kept consistent, and the growth indicators of each treatment group (including plant height, leaf length, leaf width, root length, etc.) were investigated 14 days after planting.

[0096] 2. Test results:

[0097] The experimental results under non-salinity and alkali stress are as follows Figure 6 As shown, compared with the CK group, the average plant height, leaf length and leaf width of the Coelastrellathermophila ZGL1 treatment group increased by about 0.65%, 1.77% and 8.11%, respectively, indicating that the thermophilic Coelastrellathermophila ZGL1 can promote crop growth.

[0098] The experimental results under saline-alkali stress are as follows Figure 7 As shown in the data, under saline-alkali stress conditions, the average plant height of the monostar algae increased by about 42.4% and the average root length increased by about 48.3% compared with the saline-alkali stress group CK1, showing significant saline-alkali tolerance and growth advantages.

[0099] Example 5: Degradation of antibiotics and pesticides by Coelastrella thermophila ZGL1

[0100] 1. Test method:

[0101] Coelastrella thermophila ZGL1 was inoculated into BG11 medium with an initial OD value of 0.5. Chlorpyrifos and enrofloxacin were added to the medium respectively so that their initial concentrations were both 300 μg / L.

[0102] Chlorpyrifos and enrofloxacin were added to BG11 culture medium at a concentration of 300 μg / L to serve as controls for the degradation of pesticides and antibiotics, respectively.

[0103] The culture was continued for 7 days. During the culture process, 1.5 mL of sample was taken every day, centrifuged using a centrifuge tube, and the supernatant was taken. Subsequently, the sample liquid was filtered through a 0.2 μm particle size filter membrane through a syringe to ensure the purity of the filtered liquid for subsequent analysis. The treated sample liquid was concentrated and filtered according to the standard sample pretreatment process, and finally used for high-performance liquid chromatography (HPLC) and mass spectrometry analysis to determine the content of chlorpyrifos and enrofloxacin in the sample and calculate the degradation rate.

[0104] 2. Test results:

[0105] The degradation effect of Coelastrella thermophila ZGL1 on the antibiotic enrofloxacin is shown in Figure 2. Figure 8 As shown in the figure, the degradation rate of the monophyllous algae (DX) group (treated group) reached 66.03% within 7 days, and the concentration decreased from 300 μg / L to about 100 μg / L; while the degradation rate of the CK group (control group) was only 15.68%, and the concentration changed less, from 300 μg / L to 250 μg / L.

[0106] The degradation effect of Coelastrella thermophila ZGL1 on the pesticide chlorpyrifos Figure 9 As shown in the figure, the degradation rate of the DX group was 49.34%, and the concentration decreased from 300 μg / L to about 150 μg / L; while the degradation rate of the CK group was only 4.44%, and the concentration decreased from 300 μg / L to 275 μg / L.

[0107] Overall, the thermophilic algae (Coelastrella thermophila) ZGL1 has a significant effect on pollutant degradation, especially in the degradation of antibiotics, which shows that the thermophilic algae (Coelastrella thermophila) ZGL1 has great potential in pollutant control.

[0108] Example 6: Experiment on the colonization of Coelastrella thermophila ZGL1 in soil and its effect on alleviating crop pollutant stress

[0109] 1. Test method:

[0110] In order to verify the colonization ability of Coelastrella thermophila ZGL1 in polluted soil environment and its role in alleviating pollution stress, 1 mL of culture was used as the OD 680 The algae solution of Coelastrellathermophila ZGL1 with a concentration of ≈2.0 was centrifuged and the precipitate was resuspended in 50 mL of distilled water to obtain an algae solution dilution solution.

[0111] The experiment has five treatments, namely:

[0112] Coelastrella thermophila + chlorpyrifos group (Coelastrella thermophila + chlorpyrifos): the diluted solution of Coelastrella thermophila ZGL1 was added to the potting soil containing chlorpyrifos (100 mg / kg), with the addition amount per pot being 50 mL.

[0113] Chlorpyrifos group (chlorpyrifos): distilled water was added to the potting soil containing chlorpyrifos (100 mg / kg), with the amount added per pot being 50 mL.

[0114] Coelastrella thermophila + enrofloxacin group (Coelastrella + enrofloxacin): Add the diluted algae solution of Coelastrella thermophila ZGL1 to the potting soil containing enrofloxacin (100 mg / kg), with an addition amount of 50 mL per pot.

[0115] Enrofloxacin group (enrofloxacin): distilled water was added to the potting soil containing enrofloxacin (100 mg / kg), with the amount added per pot being 50 mL.

[0116] Blank control group (CK): distilled water was added to the potting soil without enrofloxacin and chlorpyrifos, with the amount added to each pot being 50 mL.

[0117] Lettuce seedlings at the two-leaf, one-heart stage were planted in the treated soils, with three replicates per group. Growth indicators, such as plant height, leaf color, and biomass, were regularly recorded over a 20-day cultivation period. Microscopic observation was also used to assess algal colonization in the soil surface and on the root surface.

[0118] 2. Test results:

[0119] The colonization of Coelastrella thermophila ZGL1 on the surface and root surface of chlorpyrifos-contaminated soil Figure 10 As shown, the microscopic images showed that the algae strain formed obvious attachments at the above-mentioned locations and the algal cells were well active, proving that the thermophilic single star algae (Coelastrella thermophila) ZGL1 successfully colonized the soil surface and the rhizosphere surface of lettuce in the soil environment contaminated by chlorpyrifos.

[0120] In the treatment groups with enrofloxacin and chlorpyrifos (both at 100 mg / kg), the lettuce plants that were not inoculated with algae showed significant toxicity symptoms and growth inhibition, while the group inoculated with the thermophilic monolithic algae (Coelastrella thermophila ZGL1) showed a growth alleviation effect, and the leaf color and plant height of the plants were significantly better than those of the control group ( Figure 11 These results indicate that Coelastrella thermophila ZGL1 can stably colonize under the stress of enrofloxacin and chlorpyrifos and alleviate the negative effects of pollution on crop growth, and has good environmental adaptability and potential for synergistic pollution degradation.

[0121] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A strain of Coelastrella thermophila ZGL1, whose deposit number is CCTCC NO: M20251193.

2. An algae agent, characterized in that: The algae agent contains the thermophilic monostar algae (Coelastrellathermophila) ZGL1 according to claim 1.

3. The algae agent according to claim 2, characterized in that In the algae agent, the thermophilic monostar algae (Coelastrellathermophila) ZGL1 exists in the form of cultured living algae, algae liquid or algae suspension.

4. The algae agent according to claim 3, characterized in that The algae liquid is prepared by the following method: Coelastrella thermophila ZGL1 was inoculated into BG11 medium and cultured under conditions of light intensity of 3000-5000 lux, temperature of 25-30° C., and pH 7.0-9.

0.

5. Use of the thermophilic Coelastrella thermophila ZGL1 according to claim 1 or the algae agent according to any one of claims 2 to 4 in degrading antibiotics and / or pesticides.

6. The use according to claim 5, characterized in that The antibiotic is enrofloxacin; the pesticide is chlorpyrifos.

7. Use of the thermophilic Coelastrella thermophila ZGL1 according to claim 1 or the algae agent according to any one of claims 2 to 4 in at least one of the following (1) to (3): (1) Promote crop growth; (2) Alleviate crop stress; (3) Prepare microalgae biofertilizers to improve crop yield and stress resistance.

8. The use according to claim 7, characterized in that The crop stress is caused by salinity, alkali, antibiotics and / or pesticides.

9. A microalgae biofertilizer for improving crop yield and stress resistance, characterized in that: The microalgae biofertilizer uses the thermophilic Coelastrella thermophila ZGL1 of claim 1 or the algae agent of any one of claims 2 to 4 as an active ingredient.

10. A method for promoting crop growth under stress conditions, characterized in that: The following steps are involved: Applying Coelastrella thermophila ZGL1 or algae agent to the soil where crops are grown; Preferably, the stress conditions include: one or more of saline-alkali stress, antibiotics and pesticides.

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