Novel plant nutrition enhancer with nano-selenium compounded with soil probiotics

Abstract

The invention provides a plant nutrition enhancer formed by compounding soil probiotics stenotrophomonas EGS12 and nano-selenium converted from the soil probiotics stenotrophomonas EGS12, aiming at the problems of improving soil quality, promoting plant growth, improving agricultural product quality, effectively improving the selenium enrichment capacity of crops and the like. The plant nutrition enhancer is prepared by compounding the soil probiotics stenotrophomonas EGS12 and nano-selenium converted from the soil probiotics stenotrophomonas EGS12. According to the nutrient supplement, natural stenotrophomonas is taken as a starting bacterium, the capacity of a selenium transfer channel in the bacterium is enhanced after gene editing, so that the stenotrophomonas EGS12 can efficiently convert sodium selenite into nano-selenium, the conversion efficiency is as high as 7.2 mg / L / h, meanwhile, the EGS12 also has efficient plant growth promoting effects of nitrogen fixation, potassium dissolution, phosphorus dissolution, biofilm generation, polyamine production, auxin production and the like, and the nutrient supplement can be used for preparing nano-selenium. The nano-selenium and the soil probiotics EGS12 have a synergistic interaction effect in a plant nutrition enrichment process. The plant nutrition enhancer provided by the invention is simple in preparation method, good in safety and low in cost, the capability of helping crops to cope with heat stress is improved by 30%, the immunity of the plants is improved, the pesticide consumption of the crops is reduced by 42%, meanwhile, the contents of selenoprotein and selenium polysaccharide in the crops are improved by 25.8%, and the nutritional quality of the crops is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of microbial technology, and in particular relates to a novel plant nutritional supplement composed of soil probiotics Oligotrophomonas EGS12 and nano-selenium transformed therefrom. Background Art

[0002] Selenium is an important trace element for organisms. It has the functions of enhancing human antioxidant and immunity, relieving chronic diseases and treating cancer. Selenium has the functions of participating in physiological metabolic processes (such as promoting photosynthesis, regulating antioxidant systems), enhancing stress resistance (disease resistance and coping with adverse environmental stress), and affecting growth and development (promoting seed germination, improving yield quality, etc.) for plants. Relevant geological surveys show that up to 72% of my country's regions are selenium-deficient and low-selenium areas. There is a selenium-deficient belt distribution area from Heilongjiang Province in the northeast to the Qinghai-Tibet Plateau in the southwest. Most of the provinces and cities along the region are in selenium-deficient or low-selenium areas. The lack of selenium content in the soil has caused the local population to have insufficient selenium intake, and it is necessary to pay attention to the reasonable supplementation of selenium nutrition. Healthy selenium supplementation can be achieved by reasonably matching and consuming selenium-rich agricultural products (selenium-rich rice, selenium-rich tea, selenium-rich fruits and vegetables, etc.) and selenium-rich animal foods (selenium-rich eggs, selenium-rich meat) in moderation.

[0003] Compared with inorganic selenium supplements with certain toxicity, nano-selenium has the characteristics of low toxicity, high conversion rate, and strong nutrition. It can be used as a new type of plant nutrition supplement to improve the absorption efficiency of crops to selenium and enhance the nutritional value of crops. At the same time, nano-selenium can promote plant growth, increase crop yields, and improve the quality of agricultural products, such as increasing the sweetness of fruits and improving the nutritional value of vegetables. Nano-selenium also has the effect of enhancing plant resistance and improving the resistance of plants to adverse environments such as pests and diseases, drought, and high temperature. In addition, the application of nano-selenium in agriculture is also environmentally friendly and will not pollute soil and water sources.

[0004] In the present invention, nano-selenium is biotransformed and enriched in a soil probiotic, oligotrophic monocytogenes EGS12. The efficiency of synthesizing nano-selenium is significantly improved after genetic modification. At the same time, in terms of plant nutrition, EGS12 can promote the absorption of nutrients such as nitrogen, phosphorus, and potassium by plants, and can also decompose minerals that are difficult to absorb to improve their effectiveness; in terms of resistance, EGS12 will secrete antibacterial substances to enhance plant disease resistance, and regulate plant physiological metabolism in adversity to improve its stress resistance; in terms of growth and development, EGS12 can produce growth hormones to promote seed germination and seedling growth, and improve plant yield and quality. In addition, EGS12 can also improve the soil environment, decompose organic matter to improve fertility, improve structure and permeability, increase soil water retention capacity, and create good soil conditions for plant growth.

[0005] The preparation method of the plant nutrient enhancer proposed in the present invention is simple, safe and low-cost, which can help crops improve their ability to cope with heat stress by 30%, improve plant immunity and reduce the use of agricultural drugs by 42%, while increasing the content of selenoprotein and selenopolysaccharide in crops by 25.8%, effectively improving the nutritional quality of crops. Summary of the invention

[0006] The present invention aims to improve soil quality, promote plant growth and improve the quality of agricultural products, and effectively improve the selenium-enriched capacity of crops. A plant nutrition enhancer composed of soil probiotics oligotrophic mononas EGS12 and nano-selenium generated by its transformation is proposed. The nutrition enhancer uses natural oligotrophic mononas as the starting bacteria, and after gene editing, the ability of the selenium transport channel in the bacteria is enhanced, so that oligotrophic mononas EGS12 can efficiently convert sodium selenite into nano-selenium, with a conversion efficiency of up to 7.2 mg / L / h. At the same time, EGS12 also has efficient nitrogen fixation, potassium dissolution, phosphorus dissolution, biofilm production, polyamine production, growth hormone production and other plant growth-promoting effects. Nano-selenium and soil probiotics EGS12 have a synergistic effect in the process of plant nutrient enrichment.

[0007] Preferably, the soil probiotic is Stenotrophomonas sp. EGS12.

[0008] Preferably, in the gene-edited Oligotrophomonas, the key enzyme gene SenB in the selenium metabolism pathway is overexpressed, and the gene of selenocysteine ​​methyltransferase (SMT) is introduced and heterologously expressed in EGS12, so that the efficiency of EGS12 in converting inorganic selenium into nano-selenium is increased to 7.2 mg / L / h.

[0009] Preferably, the method for converting nano-selenium by EGS12 is as follows: EGS12 is inoculated in 0.1 L of Luria-Bertani (LB) for propagation and activation, and then transferred to a 10 L fermenter (containing 2 mM Se(IV), sodium selenite), and the control conditions are 37°C, 200 rpm, and cultured for 48 h to prepare a seed solution. Next, the fermentation raw materials are added to a 500 L fermenter according to the following formula (sucrose 30 g / L, yeast powder 20 g / L, potassium dihydrogen phosphate 2 g / L, corn starch 5 g / L, magnesium sulfate 0.5 / L) and steam sterilized. The above seed solution is inoculated at a 2% inoculation amount, sodium selenite Se(IV) is poured into the fermenter with a selenium content of 0.5 g / L, and the fermentation conditions are controlled to a temperature of 37°C, a stirring speed of 200 rpm, and a fermentation time of 5 days. Fill directly after fermentation is completed.

[0010] Preferably, the method for converting EGS12 into nano-selenium, the second of which is: mixing bran with tap water in a ratio of 1:1 and then completing steam sterilization. The seed solution described in 0009 is inoculated at a 2% inoculation amount, and sodium selenite Se(IV) with a selenium content of 0.5 g / kg is mixed into a shallow dish. The solid fermentation conditions are controlled to a material layer thickness of 20 mm, a moisture content of 50%, a temperature of 37°C, and a fermentation time of 5 days. After fermentation, it is dried at low temperature to maintain the activity of the bacterial agent.

[0011] The preparation method of the plant nutrient enhancer proposed in the present invention is simple, safe and low-cost, which can help crops improve their ability to cope with heat stress by 30%, improve plant immunity and reduce the use of agricultural drugs by 42%, while increasing the content of selenoprotein and selenopolysaccharide in crops by 25.8%, effectively improving the nutritional quality of crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0013] Figure 1 This is a transmission electron micrograph of the transformation of nano-selenium by Oligotrophomonas EGS12. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with specific embodiments, but these embodiments are only exemplary and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention. Example

[0015] The plant nutrient supplement proposed by the present invention is used for strawberry planting. The results show that after spraying, the weight of single strawberry is significantly increased, and the nutritional quality of the strawberry meets the national standard for selenium-rich agricultural products.

[0016] This experiment was conducted in the Green Prevention and Control Ecological Town of Caidian District, Wuhan City, Hubei Province. Using clean water as the control group, foliar spraying was performed three times starting from the bud stage. After 25 times dilution (nanoselenium concentration: 10 mg / L), this crop nutrient enhancer can significantly increase the single fruit weight (29.31%), total phenols, anthocyanins, soluble sugars, color index and soluble protein of strawberries. Using the national standard method (GB5009.93), the total selenium content of the experimental group was measured to be 0.22 mg / kg, and the strawberries produced by this crop nutrient enhancer were determined to be selenium-rich strawberries (according to the selenium content standard of selenium-rich agricultural products T / CATEA0003-2022, the total selenium content of selenium-rich fruits is 0.01-0.30 mg / kg). Example

[0017] The plant nutrient supplement proposed by the present invention is used for tomato planting. The results show that after spraying, gray mold of tomatoes is well controlled and the shelf life of tomato fruits after picking is extended.

[0018] This experiment was conducted in a plantation in Guxiang Town, Liuyang City, Hunan Province. Using water and pyrimethanil (ash fly-40% pyrimethanil-suspension concentrate) as the control group, three leaf sprays were performed starting from the 7-leaf stage. The pathogenic bacteria of gray mold (Botrytis cinerea, CGMCC3.3789) were inoculated starting from the 9-leaf stage. The results showed that the control effect of this crop nutrient enhancer on gray mold after 25 times dilution (nanoselenium concentration: 10 mg / L) was equivalent to that of pyrimethanil, while the water group had a serious outbreak of gray mold. In addition, the shelf life of mature tomato fruits was extended by 32% after picking.

Claims

1. The present invention aims to improve soil quality, promote plant growth and improve the quality of agricultural products, and effectively improve the selenium-enriched capacity of crops. It proposes a plant nutrition enhancer composed of soil probiotics oligotrophic mononas EGS12 and nano-selenium generated by its transformation. The nutrition enhancer uses natural oligotrophic mononas as the starting bacteria, and after gene editing, the ability of the selenium transport channel in the bacteria is enhanced, so that oligotrophic mononas EGS12 can efficiently convert sodium selenite into nano-selenium, with a conversion efficiency of up to 7.2 mg / L / h. At the same time, EGS12 also has efficient nitrogen fixation, potassium dissolution, phosphorus dissolution, biofilm production, polyamine production, and growth factor production. Plant growth-promoting effects, nano-selenium and soil probiotics EGS12 have a synergistic effect in the process of plant nutrient enrichment.

2. The method according to claim 1, characterized in that Soil probiotics are Stenotrophomonas sp.EGS12 (Stereotrophomonas sp. EGS12).

3. The method according to claim 1, characterized in that In the gene-edited Oligotrophomonas, the key enzyme gene SenB in the selenium metabolism pathway was overexpressed, and the gene of selenocysteine ​​methyltransferase (SMT) was introduced and heterologously expressed in EGS12, which increased the efficiency of EGS12 in converting inorganic selenium into nano-selenium to 7.2 mg / L / h.

4. The method according to claim 1, characterized in that The method for converting nano-selenium by EGS12 is as follows: EGS12 is inoculated in 0.1 L of Luria-Bertani (LB) for propagation and activation, and then transferred to a 10 L fermenter (containing 2 mM Se(IV), sodium selenite), and the control conditions are 37°C, 200 rpm, and cultured for 48 h to prepare seed liquid. Next, the fermentation raw materials are added to a 500 L fermenter according to the following formula (sucrose 30 g / L, yeast powder 20 g / L, potassium dihydrogen phosphate 2 g / L, corn starch 5 g / L, magnesium sulfate 0.5 / L) and steam sterilized. The above seed liquid is inoculated at a 2% inoculation amount, and sodium selenite Se(IV) is poured into the fermenter with a selenium content of 0.5 g / L. The fermentation conditions are controlled to a temperature of 37°C, a stirring speed of 200 rpm, and a fermentation time of 5 days. After fermentation, it is directly filled.

5. The method according to claim 1, characterized in that The second method of converting EGS12 into nano-selenium is as follows: the bran is mixed with tap water in a ratio of 1:1 and then steam sterilized. The seed solution described in 0009 is inoculated at a 2% inoculation amount, and sodium selenite Se(IV) with a selenium content of 0.5 g / kg is mixed into a shallow dish. The solid fermentation conditions are controlled to be a material layer thickness of 20 mm, a moisture content of 50%, a temperature of 37°C, and a fermentation time of 5 days. After fermentation, it is dried at low temperature to maintain the activity of the bacterial agent.

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