A Clostridium and Its Application

Abstract

The present invention relates to the field of microorganisms, and particularly to a Bacillus fusiformis and its application. The present invention provides a Bacillus fusiformis named WGS3, with a preservation number of CGMCC No. 30041. It has good reduction activity towards sodium selenite and can generate nano-selenium with high safety and high biological activity. It has been determined that this strain can prepare nano-selenium at a high sodium selenite concentration of 150 mmol / L, and the suitable culture conditions are 35 °C and pH 7. After being prepared into immobilized Bacillus fusiformis WGS3 microspheres, the nano-selenium synthesis efficiency can be increased by 7.1% at a concentration of 100 mmol / L.

Description

Technical Field

[0001] The present invention relates to the field of microorganisms, and in particular to a clostridium and an application thereof. Background Art

[0002] Selenium is a common trace element in the human body and an essential component of human health. Selenium plays an important role in human life and is generally believed to have the effects of anti-oxidation, anti-aging, inhibiting the replication of viral genetic material, and improving vision. At present, dietary selenium supplementation is the most effective and direct way to improve selenium deficiency in the human body. The content of selenium in the earth's crust is only 0.05×10 -6 , and its distribution is extremely dispersed, mostly in the form of heavy metal selenides. How to rationally utilize selenium has become an urgent problem to be solved. Among the current methods for synthesizing selenium, biological methods have the advantages of being green and safe, low cost, mild synthesis conditions, and environmentally friendly compared to chemical and physical methods. Synthetic selenium, nano-selenium, has the advantages of low toxicity, strong biocompatibility, and easy absorption compared to inorganic selenium, and is currently one of the safest and most reliable ways to supplement selenium.

[0003] The biosynthetic method for producing nanoselenium relies on microorganisms (such as bacteria and fungi) using selenium-containing compounds as substrates. These compounds are then converted into nanoselenium through the action of enzymes and other metabolites during their growth and development. This method is low-cost, mild, safe, and environmentally friendly. The surface of these microbially synthesized nanoselenium particles can be attached to bioorganic molecules such as polysaccharides and proteins, resulting in high biological activity, a small, uniform particle size, a stable structure, and easy absorption by organisms. These nanoselenium particles are an excellent source of selenium as an additive and fertilizer.

[0004] The biosynthetic production of nano-selenium is a hot research topic both domestically and internationally. With the advancement of science and technology, an increasing number of microorganisms have been discovered capable of converting and synthesizing nano-selenium. However, low conversion efficiency remains a challenge in practical applications. Therefore, research and application of microbial nano-selenium synthesis, including its high-concentration tolerance and efficient conversion, are crucial for the development of green functional agriculture and the improvement of dietary health. Summary of the Invention

[0005] In view of this, the present invention provides a Clostridium and application thereof, which has the ability to reduce sodium selenite to nano-selenium.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions.

[0007] The present invention provides Bacillus fusiformis, whose deposit number is CGMCC No.30041.

[0008] The present invention also provides a method for culturing the above-mentioned Bacillus fusiformis, which includes: inoculating the above-mentioned Bacillus fusiformis into a culture medium, adjusting the pH to 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 or 8, and culturing at 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C or 37°C to obtain a culture.

[0009] In some specific embodiments of the present invention, the culture medium for the above-mentioned culturing method is LB medium, which may contain 100 mmol / L, 110 mmol / L, 120 mmol / L, 130 mmol / L, 140 mmol / L or 150 mmol / L sodium selenite.

[0010] The present invention also provides the use of the above-mentioned Bacillus fusiformis in the preparation of immobilized microbial microspheres.

[0011] In some specific embodiments of the present invention, the preparation for the above-mentioned use includes: mixing a sodium alginate solution, biochar, and a bacterial suspension of the above-mentioned Bacillus fusiformis to obtain a mixed solution; dropping the mixed solution drop by drop into a calcium chloride solution, keeping it immersed for 20 min, 25 min, 30 min, 35 min or 40 min, filtering, and washing to obtain the immobilized microbial microspheres.

[0012] In some specific embodiments of the present invention, the preparation for the above-mentioned use includes the following steps:

[0013] S1: Inoculating the seed solution of the above-mentioned Bacillus fusiformis into a culture medium, which is a sterile culture medium containing sodium selenite, culturing, centrifuging, discarding the supernatant, and resuspending with physiological saline to obtain a bacterial suspension;

[0014] S2: Mixing a sodium alginate solution, biochar, and the bacterial suspension to obtain a mixed solution;

[0015] S3: Dropping the mixed solution drop by drop into a calcium chloride solution, keeping it immersed for 20 min, 25 min, 30 min, 35 min or 40 min, filtering, and washing to obtain the immobilized microbial microspheres;

[0016] The sodium alginate solution may be a 3.5%, 4%, 4.5% or 5% sodium alginate solution;

[0017] The content of the biochar in the mixed solution can be 1%, 1.5% or 2%;

[0018] The concentration of the calcium chloride solution can be 0.5%, 1% or 2%.

[0019] The present invention also provides immobilized microbial microspheres, which contain the above-mentioned Bacillus fusiformis.

[0020] In some specific embodiments of the present invention, the above-mentioned immobilized microbial microspheres further contain sodium alginate and biochar.

[0021] In some specific embodiments of the present invention, the preparation method of the above-mentioned immobilized microbial microspheres includes: mixing a sodium alginate solution, biochar, and a bacterial suspension of the above-mentioned Bacillus fusiformis to obtain a mixed solution; dropping the mixed solution into a calcium chloride solution drop by drop, and maintaining the immersion for 20 min, 25 min, 30 min, 35 min or 40 min, filtering, and washing to obtain the immobilized microbial microspheres.

[0022] In some specific embodiments of the present invention, the preparation method of the above-mentioned immobilized microbial microspheres includes the following steps:

[0023] S1: Inoculating the seed solution of the above-mentioned Bacillus fusiformis into a culture medium, the culture medium is a sterile culture medium containing sodium selenite, culturing, centrifuging, discarding the supernatant, and resuspending with physiological saline to obtain a bacterial suspension;

[0024] S2: Mixing a sodium alginate solution, biochar, and the bacterial suspension to obtain a mixed solution;

[0025] S3: Dropping the mixed solution into a calcium chloride solution drop by drop, and maintaining the immersion for 20 min, 25 min, 30 min, 35 min or 40 min, filtering, and washing to obtain the immobilized microbial microspheres;

[0026] The sodium alginate solution can be a sodium alginate solution of 3.5%, 4%, 4.5% or 5%;

[0027] The content of the biochar in the mixed solution can be 1%, 1.5% or 2%;

[0028] The concentration of the calcium chloride solution can be 0.5%, 1% or 2%.

[0029] The present invention also provides the application of the above-mentioned Bacillus fusiformis or the above-mentioned immobilized microbial microspheres in reducing sodium selenite.

[0030] In some specific embodiments of the present invention, the sodium selenite reduction in the above application is the reduction of sodium selenite in water bodies.

[0031] The present invention also provides the application of the above-mentioned Bacillus fusiformis or the above-mentioned immobilized microbial microspheres in the preparation of nano-selenium.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0033] In the present invention, through enrichment culture, rescreening, and purification and separation of selenium-rich soil, Bacillus fusiformis WGS3 is obtained. The Bacillus fusiformis WGS3 screened by the present invention has a strong reduction ability for sodium selenite and can synthesize nano-selenium. At the same time, the Bacillus fusiformis WGS3 can tolerate a high concentration of sodium selenite of 150 mmol / L under culture conditions; moreover, when the concentration of sodium selenite is 50 mmol / L, it can efficiently synthesize it into nano-selenium in 6 h. The microspheres prepared after calcium alginate immobilization treatment can improve the synthesis efficiency by 7.1% at a sodium selenite concentration of 100 mmol / L, and can shorten the preparation time by 6 h (from 24 h to 18 h). It shows excellent sodium selenite tolerance and high conversion efficiency, and has broad application prospects and industrial value in the treatment of high-selenium environments and the industrial production of nano-selenium.

[0034] Biological deposit description

[0035] Biological material: WGS3, taxonomic name: Bacillus fusiformis, was deposited at the General Microbiology Center of the China Committee for Culture Collection of Microorganisms on March 15, 2024. The address of the deposit center is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Beichen West Road, Chaoyang District, Beijing; the deposit number is CGMCC No. 30041. Description of the drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0037] Figure 1 Shows the morphological diagram of Bacillus fusiformis WGS3 of the present invention on LB agar medium;

[0038] Figure 2 Shows the growth curve (OD 600 ) of Bacillus fusiformis WGS3 of the present invention, where A shows pure LB medium and B shows LB medium containing 100 mmol / L sodium selenite;

[0039] Figure 3 Phylogenetic tree of Clostridium WGS3 of the present invention;

[0040] Figure 4 Showing the effect of Clostridium WGS3 of the present invention on the synthesis of nano-selenium at different initial sodium selenite concentrations;

[0041] Figure 5 Showing the effect of Clostridium WGS3 of the present invention on the synthesis of nano-selenium at different pH values;

[0042] Figure 6 Showing the effect of Clostridium WGS3 of the present invention on the synthesis of nano-selenium at different temperatures;

[0043] Figure 7 Showing immobilized Clostridium WGS3 microspheres;

[0044] Figure 8 Showing the situation of synthesizing nano-selenium by immobilized Clostridium WGS3 microspheres at a sodium selenite concentration of 100 mmol / L. Detailed implementation manners

[0045] The present invention discloses a Clostridium and its application. Those skilled in the art can draw on the content of this article and appropriately improve the process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all regarded as included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make changes or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0046] The Clostridium of the present invention is named WGS3 and has the ability to reduce sodium selenite to nano-selenium.

[0047] Furthermore, the most suitable growth pH of Clostridium WGS3 of the present invention is 7.

[0048] Furthermore, the most suitable growth temperature of Clostridium WGS3 of the present invention is 35 °C.

[0049] The present invention discloses a method for obtaining the above-mentioned Clostridium WGS3:

[0050] (1) Collecting selenium-rich soil in Hailun City, Heilongjiang Province as the microbial source of the Clostridium;

[0051] (2) Enriching and culturing the microbial source with a liquid LB medium containing sodium selenite to obtain an enriched mixed bacterial solution;

[0052] (3) Dilute the obtained bacterial solution with sterile water into bacterial solutions with different concentration gradients, and spread the diluted bacterial solutions with different concentration gradients onto LB agar media containing sodium selenite for cultivation;

[0053] (4) Pick single colonies from the above media and streak-culture them on fresh LB agar media containing sodium selenite. Repeat this operation several times until pure bacteria are obtained.

[0054] Pick pure bacterial colonies and streak-culture them on LB agar media at a temperature of 35°C. The morphological characteristics of this strain are: the colonies are white, nearly round, opaque, with a smooth and flat surface and neat edges. Pick pure bacterial colonies and streak-culture them on agar media containing sodium selenite at a temperature of 35°C. The colonies are red and the edges are light red.

[0055] Further, the LB agar medium comprises the following components by mass concentration: 5% tryptone, 10% yeast extract, 5% NaCl, 2% agar powder, and the pH is 7.2.

[0056] Further, the concentration of sodium selenite in the liquid LB medium is 10 - 100 mmol / L.

[0057] It should be understood that the expression "one or more of..." individually includes each of the objects recited after the said expression and various different combinations of two or more of the recited objects, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited objects should be understood to have the same meaning, unless otherwise understood from the context.

[0058] The terms "comprising", "having" or "containing", including the use of their grammatical synonyms, should generally be understood as open and non-restrictive, for example, not excluding other unrecited elements or steps, unless specifically stated otherwise or understood from the context.

[0059] It should be understood that as long as this application is still operable, the order of steps or the order of performing certain actions is not important. In addition, two or more steps or actions can be carried out simultaneously.

[0060] The use of any and all examples or exemplary language in this document, such as "for example" or "including", is merely intended to better illustrate this application and does not limit the scope of this application. No language in this specification should be construed as indicating that any unclaimed element is essential for the practice of this application.

[0061] In addition, the numerical ranges and parameters used to define this application are approximate values. The relevant numerical values in the specific examples have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual testing methods. Therefore, unless otherwise expressly stated, it should be understood that all ranges, amounts, values, and percentages used in this disclosure are modified by the word "about." As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range.

[0062] Unless otherwise specified, the raw materials, reagents, consumables and instruments involved in the present invention are all common commercial products and can be purchased from the market.

[0063] The present invention will be further described below with reference to the embodiments.

[0064] Example 1: Isolation of bacterial strains

[0065] This implementation case provides a method for obtaining WGS3 of Bacillus fusiformis, which specifically includes the following steps:

[0066] (1) Selenium-rich soil was collected from Hailun City, Heilongjiang Province and used as a microbial source for Clostridium WGS3.

[0067] (2) Take 1 g of soil sample and place it in a 250 mL conical flask. Add 100 mL of sterile saline and place it in a shaking incubator. Shake and mix at 120 r / min for 3 h. Remove and let it stand for 2 h. Aspirate the supernatant and inoculate 5% of the supernatant into LB liquid medium containing 10 mmol / L sodium selenite. Place the supernatant in a constant temperature shaking incubator at 35°C and 180 r / min for 36 h. After observing the turbidity of the culture medium, remove it and place it in a 4°C refrigerator for later use to obtain the initial mixed bacterial solution.

[0068] (3) Take 9 test tubes, numbered 1 to 9, and add 9 mL of sterile saline to each tube. Pipette 1 mL of the solution from the initial mixed bacterial solution into test tube No. 1 and mix it evenly. Pipette 1 mL of the solution into test tube No. 2 and mix it evenly. Then repeat this process from No. 2 to No. 3. Repeat this process until all 9 test tubes are filled and mixed evenly to obtain 10% of the original sample solution. -1 , 10 -2 , ... 10 -7 Concentration of diluted mixed bacteria solution.

[0069] (4) Move the LB solid culture medium container containing 10 mmol / L sodium selenite to the clean bench and sterilize it by ultraviolet irradiation for 30 min. When the temperature drops to 40-50°C, pour an appropriate amount into several sterile culture dishes. After cooling and solidification, the coating operation can be carried out.

[0070] (5) Pipette 100 μL of the diluted mixed bacterial solution onto the surface of the solid medium, evenly spread it with a spreader that has been sterilized by burning and cooled, then seal it with a sealing film and place it in an incubator for inverted cultivation at a temperature of 35°C. Correspondingly, three parallel groups are set for each concentration of the diluted mixed bacterial solution.

[0071] (6) Check the growth status of the strains in the petri dishes at all times within 48 h, pick them separately according to the different colony morphologies and colors, streak-culture them on the LB solid medium containing 10 mmol / L sodium selenite, and then perform multiple streak-cultures on the individual colonies with good growth until single colonies are isolated to obtain the purified strain Clostridium WGS3. Among them, the streak-culture diagram of Clostridium WGS3 is as Figure 1 shown.

[0072] Inoculate the seed liquid into fresh LB liquid medium and LB liquid medium containing 100 mmol / L sodium selenite respectively at an inoculation amount of 2%, culture them in a shaking incubator at 35°C and 180 r / min, take samples every 2 h, and use a spectrophotometer to measure the light absorption value at 600 nm until the decline phase (about 32 h) ends. The results are as Figure 2 shown.

[0073] It should be noted that the above-mentioned LB agar medium includes the following components by mass concentration: 5% tryptone, 10% yeast extract, 5% NaCl, and the pH is 7.2. The sterilization method is moist heat sterilization: temperature 121°C, time 20 min. When preparing the LB solid medium, first dissolve tryptone, yeast extract and NaCl in water according to the above mass concentration, then adjust its pH to 7.2, and then add agar powder to it at a mass concentration of 2%, mix well and sterilize to obtain the LB solid medium.

[0074] In addition, the preparation method of the LB medium containing sodium selenite is as follows: Dissolve 17.294 g of anhydrous sodium selenite solid in 100 mL of sterile deionized water to prepare a 1 mol / L sodium selenite stock solution. In a laminar flow hood, take 1 mL of the sodium selenite stock solution and add it to 99 mL of LB liquid medium and mix well to obtain a 10 mmol / L sodium selenite LB liquid medium.

[0075] Example 2: Identification of strains

[0076] This implementation case is to identify the obtained Clostridium WGS3 strain. Specifically, after the strain is expanded in culture, DNA extraction is carried out, and then the general primer PCR amplification technology of bacteria is used to amplify DNA, and 16S rDNA sequencing is carried out by Jilin Wenyu Technology Co., Ltd. The sequencing results are as follows:

[0077]

[0078] The homology comparison and retrieval were carried out with the 16S rDNA gene sequences in the GenBank database through the BLAST program in NCBI. The comparison results showed that the gene sequences of strain WGS3 had high homology with the 16S rDNA gene sequences of multiple strains in the class Bacilli. The 16S rDNA gene sequences of 12 of these bacteria were selected, and the 16S rDNA gene sequence of 1 bacterium in the genus Methanobacterium was selected as the outgroup. The MEGA software was used to perform phylogenetic tree analysis according to the Neighbor-Joining tool to construct a phylogenetic tree, as Figure 3 shown. Combining with the morphological characteristic indexes of Clostridium, it was preliminarily identified as Clostridium and named Clostridium WGS3. In addition, after the expansion culture of Clostridium WGS3, a part of it could be mixed with glycerol and stored frozen in a -80 °C refrigerator, and a part could be streaked on a test tube slant and stored in a 4 °C refrigerator. Clostridium (Bacillus fusiformis) WGS3 in this implementation case has been deposited in the China General Microbiological Culture Collection Center, and the deposit number is CGMCC No. 30041.

[0079] Example 3: Reduction ability of Clostridium WGS3 to sodium selenite under the influence of different factors

[0080] In practical applications, the influencing factors in the natural environment are complex and changeable, which directly affect the growth and functions of microorganisms. Therefore, to explore its tolerance performance and selenium production efficiency, the experiment was carried out with the concentration of sodium selenite, pH, and temperature as variables, as follows.

[0081] (1) Influence of sodium selenite concentration on the synthesis of nano-selenium by Clostridium WGS3.

[0082] a) The preserved strain was taken out from the -80 °C refrigerator, melted at room temperature, inoculated into the LB liquid medium, and cultured at 35 °C and 180 r / min in an oscillating incubator for 24 h, and then taken out and stored in a 4 °C refrigerator. This bacterial liquid was used as the seed liquid.

[0083] b) LB liquid media with sodium selenite concentrations of 50, 100, 120, and 150 mmol / L and a pH of 7 were prepared (the preparation method was as described in Example 1). After autoclaving at 121 °C for 20 min, 98 mL of each was taken and placed into a 250 mL conical flask in a laminar flow hood, 2 mL of the seed liquid was inoculated, and cultured at 35 °C and 180 r / min in an oscillating incubator to determine the selenium production efficiency under the corresponding conditions. Each treatment had three replicates, and samples were taken every 24 h.

[0084] c) The nano-selenium was determined by the following method: Take 2 mL of the fermentation broth and transfer it into a centrifuge tube (sampling was performed for three replicates); centrifuge at 8000 r / min for 10 min, discard the supernatant, and take the precipitate; add 1 mL of 1 mol / L Na2S solution to the precipitate and dissolve it by shaking; after standing for 1 h, centrifuge and take the supernatant, and measure the absorbance at 500 nm to determine the reduction efficiency under the corresponding conditions. Each concentration had three replicates.

[0085] The results are as Figure 4 shown. At a concentration of 50 mmol / L, it could be completely converted into nano-selenium in 6 h. As the concentration increased, the time required for conversion prolonged. 100 mmol / L required 24 h, 120 mmol / L required 30 h, and 150 mmol / L required 36 h. As the concentration increased, the toxic stress on the bacteria in the early stage increased, the lag time prolonged, and the reduction time also prolonged accordingly.

[0086] (2) Effect of pH on the synthesis of nano-selenium by Clostridium sp. WGS3

[0087] Prepare LB liquid media with a sodium selenite concentration of 100 mmol / L and pH values of 5, 6, 7, 8, and 9. The remaining operations were the same as above. Determine the selenium production efficiency under the corresponding conditions. Each pH had three replicates, and samples were taken every 24 h. The results are as Figure 5 shown. At pH 7 - 8, it could all be converted into nano-selenium, while too acidic or too alkaline conditions were not suitable for the growth of the bacteria and the synthesis of enzymes.

[0088] (3) Effect of temperature on the synthesis of nano-selenium by Clostridium sp. WGS3

[0089] Prepare LB liquid media with a sodium selenite concentration of 100 mmol / L and pH of 7. The remaining operations were the same as above. Determine the selenium production efficiency under the corresponding conditions. Each temperature had three replicates. The results are as Figure 6 shown. At a concentration of 100 mmol / L, the lower the temperature, the lower the conversion efficiency, indicating that the enzyme activity was lower at this time. As the temperature increased, the conversion rate increased accordingly, and the metabolism of the bacteria and the activity of the enzymes increased. At 35°C, 100 mmol / L of nano-selenium could be synthesized in 24 h, and the efficiency was in the first echelon of the research on the synthesis of nano-selenium by bacteria.

[0090] Example 4: Immobilized microorganisms enhanced the synthesis of nano-selenium by Clostridium sp. WGS3

[0091] This example provides an immobilized microorganism microsphere preparation containing the above-mentioned Clostridium sp. WGS3 and straw biochar with excellent adsorption and biocompatibility, which can improve the synthesis rate of nano-selenium under the same conditions. The preparation steps are as follows.

[0092] (1) Take out the preserved strain from the -80°C refrigerator. After melting at room temperature, inoculate it into the LB liquid medium and culture it in a shaking incubator at 35°C and 180 r / min for 24 h. After taking it out, store it in the 4°C refrigerator. This bacterial liquid is the seed liquid;

[0093] (2) Prepare an LB liquid medium with a sodium selenite concentration of 150 mmol / L and a pH of 7 (the preparation method is as described in Example 1). After autoclaving at 121°C for 20 min, take 98 mL in a clean bench and put it into a 250 mL conical flask, inoculate 2 mL of the seed liquid, and culture it in a shaking incubator at 35°C and 180 r / min for 24 h. After taking it out, centrifuge at 8000 rpm / min, take the thallus, resuspend it with normal saline to obtain a bacterial suspension and dilute it until its OD 600 = 1.0 ± 0.02. This operation is carried out in a sterile environment;

[0094] (3) Prepare a sodium alginate solution with a mass concentration of 4% (4 g / 100 mL), mix the bacterial suspension and straw biochar into it to obtain a 4% sodium alginate-bacteria-biochar mixed solution, where the biomass carbon content is 2% (2 g / 100 mL);

[0095] (4) Use a syringe to suck the sodium alginate-bacteria-biochar solution and drop it into the 1% calcium chloride solution drop by drop, and keep it immersed for 30 min;

[0096] (5) After filtration, wash it with sterile water to obtain immobilized Clostridium WGS3 microspheres (as Figure 7 shown), and store it in a 0.9% normal saline environment.

[0097] Weigh 2 g of the immobilized microspheres with the surface moisture wiped off by a filter paper after washing, put them into 100 mL of an LB liquid medium with a sodium selenite concentration of 100 mmol / L and a pH of 7, culture them in a shaking incubator at 35°C and 180 r / min for 24 h, and set three replicates. Detect the nano-selenium concentration every 2 h. The results are as Figure 8 shown. At a sodium selenite concentration of 100 mmol / L, the lag phase is shortened to 4 h, and the total conversion time is shortened to 18 h. Compared with the free bacteria synthesizing nano-selenium in Example 3, the conversion efficiency is increased by 7.1%. It shows that the calcium alginate microspheres ensure the survival of the bacteria and the activity of the enzyme, reduce the toxic stress of sodium selenite on the thallus to a certain extent, and shorten the adaptation time of the bacteria. The addition of straw biochar can reduce the sodium selenite concentration of the overall solution relying on its excellent adsorption performance, and also reduce the toxic stress so that Clostridium WGS3 can survive in a relatively safer environment.

[0098] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. Bacillus fusiformis, characterized in that, The preservation number is CGMCC No. 30041.

2. The culturing method of Bacillus fusiformis according to claim 1, wherein, It includes: Inoculate the Bacillus fusiformis described in claim 1 into a culture medium, adjust the pH to 7-8, and culture at 34-36 °C to obtain a culture.

3. Use of Bacillus fusiformis as claimed in claim 1 in the preparation of immobilized microbial microspheres, characterized in that, The preparation includes: mixing a sodium alginate solution, biochar, and a bacterial suspension of the Bacillus fusiformis described in claim 1 to obtain a mixed solution; dropping the mixed solution into a calcium chloride solution drop by drop, maintaining the immersion for 20-40 min, filtering, and washing to obtain the immobilized microbial microspheres.

4. Immobilized microbial microspheres, characterized in that, It contains the Bacillus fusiformis described in claim 1, as well as sodium alginate and biochar; The preparation method of the immobilized microbial microspheres includes: mixing a sodium alginate solution, biochar, and a bacterial suspension of the Bacillus fusiformis described in claim 1 to obtain a mixed solution; dropping the mixed solution into a calcium chloride solution drop by drop, maintaining the immersion for 20-40 min, filtering, and washing to obtain the immobilized microbial microspheres.

5. Use of the Bacillus fusiformis described in claim 1 or the immobilized microbial microspheres described in claim 4 in reducing sodium selenite.

6. Use of the Bacillus fusiformis described in claim 1 or the immobilized microbial microspheres described in claim 4 in the preparation of nano-selenium.

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