Transformed ginsenoside sphingomonas SP122 and application thereof

Abstract

The invention relates to the technical field of microorganisms, in particular to transformed ginsenoside sphingomonas SP122 and application thereof. A strain of transformed ginsenoside sphingomonas SP122 capable of effectively degrading panax notoginseng autotoxic substances, namely saponin and phenolic acid is obtained through separation, the strain can be stably planted at the root of panax notoginseng, root rot pathogenic bacteria of panax notoginseng are inhibited, crude saponin is degraded, new saponin is generated, phenolic acid can be degraded, continuous cropping obstacles of panax notoginseng can be relieved, and it is verified through experiments that the strain has a good application prospect. By applying the strain, the seedling survival rate and dry weight of panax notoginseng can be increased, plant growth and dry matter accumulation are promoted, and the strain has wide application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of microorganisms, and in particular to transformation of ginsenoside Sphingomonas SP122 and application thereof. Background Art

[0002] Panax notoginseng (Burk.) FH Chen is a perennial herbaceous plant of the genus Panax in the Araliaceae family and an important Chinese medicinal material. However, due to the increasing severity of the continuous cropping problem of Panax notoginseng, the land resources suitable for Panax notoginseng cultivation in traditional farmland have been significantly reduced. Root rot is the main manifestation of the continuous cropping problem of Panax notoginseng, and self-toxicity may be the main cause of the formation of continuous cropping problem. Therefore, reducing the accumulation of self-toxic substances such as saponins in the soil of continuous cropping of Panax notoginseng is one of the effective ways to alleviate the continuous cropping problem of Panax notoginseng.

[0003] At present, the main strategies for dealing with this problem include biochar adsorption, crop rotation system and microbial degradation. However, the above measures to reduce self-toxic substances also have their limitations. Specifically, the process of biochar adsorption of self-toxic substances is mainly based on a reversible physical adsorption mechanism, which may cause the adsorbed substances to be released back into the soil environment under certain conditions, thus affecting their long-term effectiveness. On the other hand, although the crop rotation system can effectively alleviate the self-toxic effect, its practical application is often limited by a long implementation cycle, which may be detrimental to the efficient operation of agricultural production. In addition, although the introduction of exogenous microbial strains that can degrade saponin autotoxic substances into continuous cropping soil is regarded as a highly promising biological strategy, it still faces many challenges in practical application. Specifically, the colonization efficiency of these exogenous strains in the soil may not be high, resulting in insufficient survival in the soil, which in turn affects their degradation efficiency. At the same time, even if they are successfully colonized, their degradation efficiency may be affected by multiple factors such as the soil environment and competition from indigenous microorganisms, thus limiting their wide application in actual production. Therefore, in view of the existing challenges in pathogen and autotoxic substance abatement strategies, it has become an urgent need to explore efficient and non-chemical-dependent biological control methods.

[0004] The self-toxic substances in Panax notoginseng mainly include saponins and phenolic acids. Therefore, how to provide a microorganism that can effectively degrade saponins and phenolic acids in Panax notoginseng for biological control of Panax notoginseng has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] First, the present invention provides a transformed Sphingomonas ginsenosides SP122, which has a preservation number of CGMCC No.30965.

[0006] The above-mentioned transformed ginsenoside Sphingomonas SP122 was screened from the rhizosphere soil of Panax notoginseng. The strain was deposited in the General Microbiology Center of China Culture Collection Administration on June 14, 2024. The address of the depository unit is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing; Postal Code: 100101, Classification Name: Transformed ginsenoside Sphingomonas ginsenosidimutans, and the deposit number is CGMCC No. 30965.

[0007] In a second aspect, the present invention provides a microbial agent comprising the transformed Sphingomonas ginsenoside SP122.

[0008] In some embodiments, the microbial agent is a lyophilized powder of fermentation broth of transformed ginsenoside Sphingomonas sp122. The lyophilized powder of fermentation broth contains transformed ginsenoside Sphingomonas sp122.

[0009] In some embodiments, the fermentation broth freeze-dried powder also includes a freeze-drying protectant.

[0010] Specifically, the lyoprotectant includes but is not limited to skimmed milk powder, dextrin, lactose, and sucrose.

[0011] In a third aspect, the present invention provides the use of the transformed ginsenoside Sphingomonas SP122 or the microbial agent in inhibiting root rot pathogens.

[0012] Preferably, the root rot pathogen is the pathogen LD (Fusarium solani).

[0013] Preferably, the inhibitory effect on root rot pathogens is improved by using crude notoginseng saponins as a carbon source.

[0014] In a fourth aspect, the present invention provides the use of the transformed ginsenoside Sphingomonas SP122 or the microbial agent in regulating the degradation or production of crude notoginseng saponins.

[0015] In a fifth aspect, the present invention provides the use of the transformed ginsenoside Sphingomonas SP122 or the microbial agent in improving the survival rate of Panax notoginseng seedlings or the dry weight of Panax notoginseng.

[0016] In a sixth aspect, the present invention provides the use of the transformed ginsenoside Sphingomonas SP122 or the microbial agent in degrading phenolic acids.

[0017] Preferably, the phenolic acid is p-hydroxybenzoic acid, ferulic acid, coumaric acid or cinnamic acid.

[0018] In a seventh aspect, the present invention provides the use of the transformed Panax notoginseng saponin SP122 or the microbial agent in promoting plant growth or dry matter accumulation; preferably, the plant is a plant with continuous cropping obstacles; preferably, the plant is lettuce, tomato, strawberry or soybean.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention isolates and obtains a transformed ginsenoside Sphingomonas SP122 that can effectively degrade Panax notoginseng autotoxic substances - saponins and phenolic acids. The strain can stably colonize in the roots of Panax notoginseng, inhibit Panax notoginseng root rot pathogens, degrade crude saponins and generate new saponins, and can degrade phenolic acids to alleviate the obstacles of continuous cropping of Panax notoginseng. Experimental verification shows that the application of the strain can increase the survival rate of Panax notoginseng seedlings and the dry weight of Panax notoginseng, promote plant growth and dry matter accumulation, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a photograph of the culture of transformed ginsenoside Sphingomonas SP122.

[0022] Figure 2 It is a phylogenetic tree.

[0023] Figure 3 This is a diagram showing the results of identifying the ability of Sphingomonas sp122 to produce β-glucosidase after transformation of ginsenosides.

[0024] Figure 4 This is a graph showing the results of an inhibition experiment on root rot pathogens by transforming ginsenoside Sphingomonas SP122.

[0025] Figure 5 It is a growth curve of transformed ginsenoside Sphingomonas SP122.

[0026] Figure 6 This is a graph showing the seedling survival rate results of an indoor potted plant experiment.

[0027] Figure 7 This is a graph showing the dry weight results of individual plants from an indoor potted plant experiment.

[0028] Figure 8 This is a graph showing the degradation results of crude saponins in the culture medium by Sphingomonas ginsenoside-transforming bacteria SP122.

[0029] Fig. 9 This is a graph showing the degradation results of ginsenoside-transforming Sphingomonas SP122 on saponins in continuously cropped soil.

[0030] Fig.10 This is a graph showing the emergence of Panax notoginseng seedlings under the forest after being treated with transformed ginsenoside Sphingomonas SP122.

[0031] Fig.11 This is a graph showing the degradation of phenolic acid by Sphingomonas sp. SP122, a ginsenoside-transforming bacteria.

[0032] Fig.12 This is a graph showing the effect of transformed ginsenoside Sphingomonas SP122 on lettuce growth.

[0033] Fig.13 This is a graph showing the effect of transformed ginsenoside Sphingomonas SP122 on tomato growth.

[0034] Fig.14 This is a graph showing the effect of transformation of ginsenoside Sphingomonas SP122 on strawberry growth.

[0035] Fig.15 This is a graph showing the effect of transformation of ginsenoside Sphingomonas SP122 on soybean growth. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the statistical analysis, different asterisks represent significant differences, *p<0.05, **p<0.01, ***p<0.001.

[0037] The culture medium formula with crude saponin as the sole carbon source in the following examples is: 3g NaNO3, 1g KH2PO4, 0.5g KCl, 0.5g MgSO4·7H2O, 0.01g FeSO4·7H2O, 10g crude notoginseng saponin, 17g agar, 1000mL distilled water, dissolved, mixed, and adjusted to pH 7.0 with 1mol / L NaOH solution. Crude notoginseng saponin was purchased from Shaanxi Jinkangtai Biotechnology Co., Ltd.

[0038] Example 1 Isolation of Transformed Ginsenoside Sphingomonas SP122

[0039] The culture separation method was used to isolate soil microorganisms from the rhizosphere soil of Panax notoginseng stored in a refrigerator at 4°C. Bengal red and PDA culture media were used to isolate fungi, and LB, NA, R2A and modified Gao's medium No. 1 (Wang Luotao et al., 2020; van der Linde et al., 1999; Lin Hong et al., 2012) were used to isolate bacteria. Drawing on the method of culturomics, four culture media, NA, LB, R2A, and PDA, were selected to isolate and culture rhizosphere soil microorganisms of Panax notoginseng. Take different soil samples stored at 4°C, put 1g of each into a 15mL sterile centrifuge tube, add 9mL of sterile distilled water, shake at 120rpm for 30min, and let stand for 2min to make a soil bacterial suspension. Dilute the soil bacterial suspension to 10 with sterile water. 3 , 10 4 and 10 5 times, take 100 μL and add it to the surface of different solid culture media, spread it evenly with a spreader, and place it in a constant temperature incubator at 28°C for culture. At different culture times such as 3 days to 7 days, pick the single colonies on the corresponding plates and purify them uniformly on NA (bacteria) / PDA (fungus) culture medium. After purification three times, no foreign bacteria appeared, pick the single colonies for preservation and sequencing, fungi were subjected to ITS amplification sequencing (Guo Penghao et al., 2012), and bacteria were subjected to 16srDNA amplification sequencing (Cai et al., 2012). The sequencing results were compared with BLAST in the NCBI database (https: / / www.ncbi.nlm.nih.gov / ).

[0040] A microorganism was isolated and the streak separation photo is shown in the figure. Figure 1 As shown, the bacteria were sequenced by 16S sequencing, and after comparison on the NCBI platform, a phylogenetic tree was constructed, as shown in Figure 2 As shown, the bacterium was determined to be Sphingomonas ginsenosidimutans, named as Sphingomonas ginsenosidimutans SP122, and the preservation number is CGMCC No.30965.

[0041] Furthermore, the ability to produce β-glucosidase was identified. Esculin is a white needle-shaped crystal, which is hydrolyzed by β-glucosidase produced by microbial metabolism to produce esculin and glucose. Esculin will produce black substances when it encounters iron ions in the culture medium. The test results are shown in Figure 3 , the esculin culture medium turned black, indicating that the transformed Sphingomonas ginsenosides SP122 could produce β-glucosidase, and CK was the sterile water control group.

[0042] Example 2 Inhibition of pathogens by transformed ginsenoside Sphingomonas SP122 on crude saponin plates

[0043] In this example, the inhibition of root rot pathogens by transformed ginsenoside Sphingomonas SP122 was observed on plates with different concentrations of crude saponins. Figure 4 As shown in the figure, the colony radius of the pathogen LD (Fusarium solani) was significantly inhibited in the plates with different concentrations of crude saponin, and the inhibition ability increased with the increase of crude saponin concentration. The co-culture experiment of transformed ginsenoside sphingomonas SP122 and LD showed that SPX122 had a strong antagonistic effect on LD, and with the increase of crude saponin concentration, the colony diameter decreased significantly, indicating that the inhibitory effect of SPX122 on LD increased.

[0044] In order to study the degradation effect of ginsenoside-transforming Sphingomonas sp122 on crude saponins, crude saponins were also used as the sole carbon source. The results are as follows Figure 4 As shown, crude saponins significantly promoted the growth of transformed ginsenoside Sphingomonas SP122, and CK was the sterile water control group.

[0045] Example 3 Crude saponins affect the growth and biofilm formation of ginsenoside-transforming Sphingomonas sp122

[0046] In this embodiment, the transformation of ginsenoside sphingomonas SP122 was cultured in a culture medium with crude saponins as the sole carbon source. The transformed ginsenoside sphingomonas SP122 was cultured in LB medium, and the OD590 value was diluted to ≈0.4 using a microplate reader. 100 μL of bacterial solution was added to 200 mL of liquid culture medium with notoginseng crude saponins as the sole carbon source (10 mg / L of notoginseng crude saponins), and the treatment without bacterial solution was used as a blank control. It was placed on a shaker for shaking culture (28°C, 150r / min), and 200 μL was taken into a 96-well plate every 3 hours. The OD590 was measured with a microplate reader at an absorbance of 590nm, and a bacterial growth curve was drawn. At the same time, the crystal violet method (Wang Lijun et al., 2019) was used to determine the effect of crude saponins on bacterial biofilms.

[0047] In the culture medium with crude saponin as the only carbon source, the growth curve of bacteria is as follows Figure 5 As shown in the figure, with the extension of culture time, the strain grew, the OD value of the bacterial solution increased, and crude saponins promoted the growth of transformed ginsenoside Sphingomonas SP122. This shows that transformed ginsenoside Sphingomonas SP122 can tolerate crude saponins, and crude saponins of Panax notoginseng can promote the vegetative growth of the strain and occupy a larger ecological niche in the root system of Panax notoginseng.

[0048] Furthermore, the transformed ginsenoside Sphingomonas SP122 was inoculated into a 96-well plate in a culture medium containing crude saponins as the sole carbon source, and after culturing at 28°C for 52 h, the biofilm content was determined by the crystal violet method, and the OD490 value was read. Figure 5As shown, the biofilm amount of transformed ginsenoside Sphingomonas SP122 was significantly higher than that of CK (0 g / L, sterile water), indicating that crude saponins promoted the biofilm formation of transformed ginsenoside Sphingomonas SP122 and enhanced its colonization in the roots of Panax notoginseng.

[0049] Example 4 Effect of transformation of ginsenoside Sphingomonas SP122 on the growth of Panax notoginseng

[0050] Take a certain amount of crude Panax notoginseng saponin, add it to a small basin containing 1 kg of forest soil and mix well to make the saponin content in the soil 10 ppm, simulating the total saponin concentration in three-year-old Panax notoginseng soil (Wang Luotao, 2020), let it stand for 3 days for use, and obtain soil with exogenous addition of crude Panax notoginseng saponin. Mix the continuously planted soil of Panax notoginseng planted for three years in the greenhouse in Xundian with the treated unplanted forest soil in a ratio of 1:1, let it stand for 3 days for use, and obtain the continuously planted soil.

[0051] Select healthy Panax notoginseng seeds, sterilize them with 1.5% NaClO for 5 min, rinse them with sterile water for 3 times, and dry the surface water with sterile filter paper. There are 10 seeds in each pot, and 10 replicates for each treatment. The laboratory prepared the NA liquid culture solution of the transformed ginsenoside Sphingomonas SP122 and shook it to make the OD value of the bacteria ≈0.4. After the seedlings emerged completely, each pot was irrigated with 50mL of culture solution (culture solution = 1 part 5mL bacterial solution: 9 parts sterile water). Sterile water was used as the CK control group. The treatment group included four groups, and the treatment was as follows: the understory soil without Panax notoginseng was collected and divided into two parts, one of which was sterilized with 100℃ steam for 4 hours and set aside after heat dissipation, referred to as sterilization; the other part was not sterilized, referred to as non-sterilization; the two parts of soil were treated again, one of which was added with crude saponin at a concentration of 10mg / kg, and was potted (15cm diameter flower pot, each pot of soil was about 1kg) for standby use, referred to as saponin; the other part was added with 50% Panax notoginseng continuous cropping soil (Panax notoginseng soil planted for three consecutive years) + 50% of the above-mentioned treated understory soil (sterilization / non-sterilization), and was potted (15cm diameter flower pot, each pot of soil was about 1kg) for standby use, referred to as 50% continuous. Planting Panax notoginseng seeds. After potted plants are planted, they are randomly placed in the greenhouse of the Xundian base and routinely managed. Irrigate once a week for two consecutive months, and count the survival rate of seedlings. After Panax notoginseng continues to grow for two months, collect samples of the potted Panax notoginseng, clean them, sterilize them at 115℃ for 30 minutes, dry them at 60℃ for 3 days, weigh the dry weight, and calculate the dry weight of each plant.

[0052] The results of the indoor pot test on the survival rate of seedlings are as follows: Figure 6As shown in the figure, the transformed ginsenoside sphingomonas SP122 significantly increased the survival rate of Panax notoginseng in the unsterilized saponin-added soil, but there was no significant difference after sterilization. The transformed ginsenoside sphingomonas SP122 significantly increased the survival rate of Panax notoginseng in the continuously cropped soil. Comprehensive analysis shows that the transformed ginsenoside sphingomonas SP122 can significantly increase the survival rate of Panax notoginseng, and the effect is better in the continuously cropped soil and unsterilized soil, which indicates that the transformed ginsenoside sphingomonas SP122 can promote the growth of Panax notoginseng in the soil containing initial microorganisms, especially when saponins are present in the soil, which indicates that the transformed ginsenoside sphingomonas SP122 can not only degrade saponins, but may also assume more functions as a recruiter of beneficial microorganisms.

[0053] The results of the indoor pot test on dry weight of individual plants are as follows: Figure 7 As shown, the transformed ginsenoside Sphingomonas SP122 significantly increased the dry weight of individual plants in the four treatments. The transformed ginsenoside Sphingomonas SP122 can significantly promote the accumulation of Panax notoginseng dry matter, especially when continuous cropping is aggravated.

[0054] Example 5 Study on the degradation of crude saponins in culture medium by transforming ginsenoside Sphingomonas SP122

[0055] 500 μL of NA culture solution of transformed ginsenoside Sphingomonas SP122 was added to 50 mL of the sole carbon source culture solution containing 1 g / L crude saponins, and 2 mL of the liquid was taken after shaking on a shaker at room temperature for 72 h, and freeze-dried for 48 h (-40° C., 0.12 kpa), and an equal volume of 75% chromatographic methanol was added to the freeze-dried material to dissolve it, and the tip of the gun was blown evenly; 1 mL of the methanol solution was placed in a 1.5 mL centrifuge tube, 14000 rpm, centrifuged for 15 min, and the supernatant was taken for HPLC detection. The content of 12 saponins (R1, Rg1, Re, Rb1, Rd, Rf, Rb2, Rh1, Rc, Rh2, Rb3 and Rg3) in the crude saponins was determined by HPLC. The HPLC detection steps are as follows:

[0056] (1) HPLC detection conditions are: chromatographic column (4.6mm×150mm, 4μm, Agilent Poroshell 120EC-C18); mobile phase A: acetonitrile; mobile phase B: water; flow rate 1.0mL / min; column temperature 30℃; detection wavelength 203nm; injection volume 10μL. Elution gradient: 0-20min, 82% B; 20-40min, 82-57% B; 40-48min, 57-45% B; 48-54min, 45% B; 54-56min, 45-5% B; 56-71min, 5% B; 71-72min, 5-82% B; 72-74min, 82% B. Under these conditions, baseline separation of 12 major saponins can be achieved;

[0057] (2) Prepare standard solutions of 12 saponins. Accurately weigh the corresponding standard products into a 2 mL volumetric flask and dilute the solution with methanol in a certain proportion to prepare standard solutions of 5 ppm, 10 ppm, 25 ppm, 50 ppm, 100 ppm, 200 ppm and 500 ppm. Filter the obtained standard solutions with a 0.22 μm filter membrane for later use;

[0058] (3) Determination of linear relationship: HPLC was used for detection, and a standard curve was drawn with the chromatographic peak area (Y) as the ordinate and the sample concentration (X) as the abscissa.

[0059] (4) Weigh 0.2 g of crude saponin, dissolve it in 75% chromatographic methanol, sonicate for 30 min, centrifuge at 10,000 rpm for 10 min, filter the solution with a 0.22 μm filter membrane, and perform HPLC detection. The concentration of each monomer saponin in the crude saponin is calculated based on the standard curve, and the saponin conversion rate is calculated based on the concentration of each monomer saponin without inoculation of bacteria.

[0060] Test results such as Figure 8As shown, after inoculation of transformed ginsenoside Sphingomonas SP122, the saponin content in the solution changed, indicating that transformed ginsenoside Sphingomonas SP122 had a significant degradation of Panax notoginseng crude saponins, and the total saponin content was significantly lower than that of the blank treatment. The detailed results are as follows. In the transformed ginsenoside Sphingomonas SP122, the average degradation rates of Rg1 (degradation rate of 86.1%), Rh1 (degradation rate of 57.77%) and Rf (degradation rate of 36.33%) were above 10%, and the degradation rates of the remaining saponins were low (Rb1: 9.60%, Rb2: 5.77%, R1: 3.81%, Re: 3.23%, Rd: 7.11%, Rc: 2.53%), and Rg2 was also generated (generation rate of 100.8%). In addition, three new saponins were generated, namely Rh2 (generated concentration is 0.04 mg / g), Rg3 (generated concentration is 0.17 mg / g) and Rb3 (generated concentration is 1.44 mg / g).

[0061] The comprehensive analysis results showed that the transformed ginsenoside Sphingomonas SP122 could not only degrade saponins but also generate new saponins.

[0062] Example 6 Study on the effect of transformation of ginsenoside Sphingomonas SP122 on the degradation of saponins in continuous cropping soil and the emergence rate of Panax notoginseng under forest

[0063] In order to detect the effect of ginsenoside-transforming Sphingomonas SP122 in soil, a study on soil saponin degradation was conducted. The soil under the forest where Panax notoginseng was planted for three years was selected for bacterial treatment. The detailed treatment was as follows: the NA liquid culture medium of ginsenoside-transforming Sphingomonas SP122 was prepared in the laboratory and shaken to make the OD value of the bacteria ≈0.4, and then the soil was heated at 200mL / m 3 The soil under the continuous cropping forest was irrigated with a bacterial dose of , and the treated soil was turned and mixed evenly after irrigation. The treatment was carried out once a week, and irrigation was continued for 8 times for a total of two months. Before each treatment, the soil was taken for quantitative analysis of soil saponins, and the saponin degradation rate was calculated.

[0064] The results are as follows Fig. 9 As shown in the figure (CK represents the sterile water treatment group, SP represents the transformed ginsenoside Sphingomonas SP122 treatment group), the transformed ginsenoside Sphingomonas SP122 had different degrees of degradation on the five main saponins in the continuous cropping soil of Panax notoginseng. Among them, the early effect of SP on the degradation of R1 and Rg1 was higher than that of the control, and the difference in the degradation effect in the later stage was more significant; in the degradation of Rb1, R d and R eThe degradation effect of SP was significantly higher than that of CK. The comprehensive results of the five saponins showed that the degradation ability of SP was significantly higher than that of CK. The degradation effect of soil saponins clearly demonstrated the ability of Sphingomonas SP122 to degrade saponins, providing important evidence for the study of the degradation ability of Sphingomonas SP122 to transform ginsenosides.

[0065] Furthermore, the soil treated two months later was used to plant one-year-old seven-seed strips and Panax notoginseng seeds under the forest to study the emergence of Panax notoginseng seedlings under the forest after being treated with ginsenoside-transforming Sphingomonas SP122. The results showed that ( Fig.10 ), the transformed ginsenoside sphingomonas SP122 treatment significantly increased the emergence rate of one-year and two-year-old Panax notoginseng under the forest. Therefore, in the forest environment, the transformed ginsenoside sphingomonas SP122 treatment can significantly increase the emergence rate of one-year and two-year-old Panax notoginseng, and the effect is more significant in promoting the two-year-old Panax notoginseng, indicating that the transformed ginsenoside sphingomonas SP122 has greater application potential in actual production.

[0066] Example 7 Degradation effect of ginsenoside-transforming Sphingomonas sp122 on phenolic acids

[0067] Numerous research reports show that Sphingomonas can degrade a variety of polycyclic aromatic hydrocarbons and phenolic substances, can survive in nutrient-poor and harsh conditions, and has good environmental adaptability and tolerance. It has been reported that Sphingomonas can be used to produce carotene and bio-gum. Phenolic acids secreted by plant roots are the main substances that cause root autotoxicity, among which the soluble part and reversibly adsorbed components of phenolic acids are directly related to autotoxicity. Phenolic acids, such as benzoic acid, salicylic acid, and parahydroxybenzoic acid, were detected in the root secretions of continuously planted peanuts, melons, tobacco, and cucumbers. Phenolic acids have a significant inhibitory effect on seed germination and plant growth. Previous studies by our research group found that phenolic acid accumulation is also an important cause of the continuous cropping of Panax notoginseng. Therefore, this example tests the degradation effect of phenolic acid by transforming ginsenoside Sphingomonas SP122.

[0068] The soil was treated with transformed ginsenoside Sphingomonas SP122 for two consecutive months, and watered once a week. The OD value of the bacterial solution was 0.6 each time, and 50 ml was used each time. Sterile water treatment was used as the control group (CK). The initial content and final content of the four phenolic acids in the soil were detected by absolute quantitative detection. The degradation effects of bacteria on the four main phenolic acids in the soil are summarized as follows ( Fig.11), in p-hydroxybenzoic acid, the average degradation rate of the CK group was 5.03%, and the degradation ability after treatment with ginsenoside-transforming Sphingomonas SP122 was stronger than that of the control, with an average degradation rate of 26.33%; in ferulic acid, the average degradation rate after treatment with ginsenoside-transforming Sphingomonas SP122 was 15.71%; in p-coumaric acid, the average degradation rate of CK was 2.40%, while ginsenoside-transforming Sphingomonas SP122 had the strongest degradation ability, with an average degradation rate of 6.96%; in cinnamic acid, which had the lowest content in the soil, the average degradation rate of ginsenoside-transforming Sphingomonas SP122 was 0.62%. Therefore, the average degradation rate of CK for the four phenolic acids in the soil was 5.02%, and the degradation rate of ginsenoside-transforming Sphingomonas SP122 was 17.27%. Comprehensive analysis showed that the transformed ginsenoside Sphingomonas SP122 could significantly degrade phenolic acids in the soil, but there were differences in the degradation ability for different phenolic acids.

[0069] Example 8 Effect of Transformation of Ginsenoside Sphingomonas SP122 on Plant Growth

[0070] 1. Effect of Transformed Sphingomonas ginsenoside SP122 on Lettuce Growth

[0071] In order to explore the effect of transformed ginsenoside Sphingomonas SP122 treatment on plant growth, lettuce, which is sensitive to phenolic acid, was selected for growth measurement. Lettuce seeds were planted in soil treated with transformed ginsenoside Sphingomonas SP122 (treatment method is the same as Example 7) for two months, and the seedling survival rate, fresh weight per plant, dry weight per plant and root growth of the lettuce were counted.

[0072] The results show that Fig.12 ), there was no significant difference in the survival rate of lettuce after the transformation of ginsenoside Sphingomonas SP122; the transformation of ginsenoside Sphingomonas SP122 significantly increased the fresh weight of lettuce per plant and the dry weight of lettuce per plant; the transformation of ginsenoside Sphingomonas SP122 significantly increased the growth of root length, root surface area and root volume of lettuce. Therefore, the transformation of ginsenoside Sphingomonas SP122 promoted the growth of lettuce and the accumulation of dry matter.

[0073] 2. Effect of Transformed Sphingomonas ginsenoside SP122 on Tomato Growth

[0074] Studies have shown that phenolic acids affect the growth of tomato seedlings. Therefore, tomatoes were selected for growth measurement. Tomato seeds were planted in soil treated with transformed ginsenoside Sphingomonas SP122 (treatment method is the same as Example 7) for two months, and the survival rate, fresh weight per plant, dry weight per plant and root growth of tomatoes were counted.

[0075] The results show that Fig.13 ), the survival rate of tomato was significantly increased after the transformation of ginsenoside sphingomonas SP122; the fresh weight and dry weight of tomato were significantly increased after the transformation of ginsenoside sphingomonas SP122; the root length, root surface area and root volume of tomato were significantly increased after the transformation of ginsenoside sphingomonas SP122. Therefore, the transformation of ginsenoside sphingomonas SP122 promoted the growth of tomato and the accumulation of dry matter.

[0076] 3. Effect of Transformed Sphingomonas ginsenoside SP122 on Strawberry Growth

[0077] Studies have shown that the accumulation of phenolic acid in the soil is an important cause of strawberry continuous cropping problems. In order to study the degradation of phenolic acid by transformed ginsenoside Sphingomonas SP122, strawberries were selected for potted verification. Strawberry seedlings were transplanted into the soil treated (treatment method is the same as Example 7) for two months. After differences in growth appeared, the survival rate, fresh weight of a single plant, dry weight of a single plant and growth of new roots were counted.

[0078] The results show that Fig.14 ), the survival rate of strawberry was significantly increased after the transformation of ginsenoside sphingomonas SP122 treatment; the fresh weight and dry weight of the aboveground part of strawberry were significantly increased after the transformation of ginsenoside sphingomonas SP122 treatment; among the four root indexes, the transformation of ginsenoside sphingomonas SP122 treatment was slightly higher than the control, but there was no significant difference. Therefore, the transformation of ginsenoside sphingomonas SP122 treatment promoted the growth of the aboveground part of strawberry.

[0079] 4. Effect of Transformed Sphingomonas ginsenoside SP122 on Soybean Growth

[0080] Studies have shown that the accumulation of phenolic acid in the soil affects the growth of soybean seedlings. Therefore, soybeans were selected for potted plant verification. Soybean seeds were planted in the soil treated (the treatment method was the same as in Example 7) for two months. After differences in growth appeared, the survival rate of seedlings, fresh weight of single plant, dry weight of single plant and growth of new roots were counted.

[0081] The results show that Fig.15 ), there was no significant difference in the survival rate of soybeans after the treatment of transformed ginsenoside sphingomonas SP122 and CK; among the four root indexes, there were significant differences between the treatment of transformed ginsenoside sphingomonas SP122 and CK, and the treatment of transformed ginsenoside sphingomonas SP122 increased the growth of soybean root length and root volume. Therefore, the treatment of transformed ginsenoside sphingomonas SP122 promoted the growth of soybeans.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A transformed Sphingomonas ginsenosidimutans, characterized in that: The transformed ginsenoside Sphingomonas sp. SP122 has a deposit number of CGMCC No.30965.

2. A microbial agent containing the transformed ginsenoside Sphingomonas according to claim 1.

3. The microbial agent according to claim 2, characterized in that: The microbial agent is freeze-dried powder of fermentation broth transformed from Sphingomonas ginsenoside SP122.

4. The microbial agent according to claim 3, characterized in that: The fermentation broth freeze-dried powder also includes a freeze-drying protectant.

5. Use of the transformed ginsenoside Sphingomonas according to claim 1 or the microbial agent according to any one of claims 2 to 4 in inhibiting root rot pathogens.

6. The use according to claim 5, characterized in that: The inhibitory effect on root rot pathogens is improved by using notoginseng crude saponins as a carbon source.

7. Use of the transformed ginsenoside Sphingomonas according to claim 1 or the microbial agent according to any one of claims 2 to 4 in improving the survival rate of Panax notoginseng seedlings or the dry weight of Panax notoginseng.

8. Use of the transformed ginsenoside Sphingomonas according to claim 1 or the microbial agent according to any one of claims 2 to 4 in regulating the degradation or production of crude notoginseng saponins.

9. Use of the transformed ginsenoside Sphingomonas according to claim 1 or the microbial agent according to any one of claims 2 to 4 in degrading phenolic acid; Preferably, the phenolic acid is p-hydroxybenzoic acid, ferulic acid, coumaric acid or cinnamic acid.

10. Use of the transformed ginsenoside Sphingomonas according to claim 1 or the microbial agent according to any one of claims 2 to 4 in promoting plant growth or dry matter accumulation; preferably, the plant is a plant with continuous cropping problems; preferably, the plant is lettuce, tomato, strawberry or soybean.

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