Methylobacterium single-cell protein fermentation broth treatment method, fertilizer water agent and preparation method thereof

Abstract

The invention discloses a treatment method of methylobacterium single-cell protein fermentation liquor. The treatment method comprises the following steps: carrying out heat preservation on the fermentation liquor for producing single-cell protein thalli at 62-68 DEG C for 100-120 minutes; ultrasonic intermittent treatment is conducted in the last 10-20 minutes of the heat preservation process, the ultrasonic frequency is 18-20 Hz, and the power is 100-120 W; cooling to 35-45 DEG C, and keeping the pH value at 6.0-7.5; carrying out enzymolysis for 3-5 hours by using neutral protease and nuclease; centrifugally separating the fermentation supernatant and mycoprotein; adding chitosan, humic acid and trace elements into the supernate, and uniformly mixing to obtain a pretreatment solution; the invention further discloses a water fertilizing agent prepared from the pretreatment liquid. According to the treatment method of the methylobacterium single-cell protein fermentation liquor, the comprehensive utilization rate of the methylobacterium single-cell protein fermentation liquor is increased when the single-cell protein is produced and the water fertilizing agent is prepared. The produced fertilizer water agent is high in content of organic matters such as amino acid and long in shelf life.

Description

Technical Field

[0001] The present invention belongs to the technical field of fertilizers, and particularly relates to a method for treating a fermentation broth of Methylobacterium single-cell protein, a fertilizer and water agent, and a preparation method thereof. Background Art

[0002] Single-cell protein is an important biological resource, which has a high protein content, rich and balanced amino acid content, similar amino acid composition to fish meal, and also contains rich vitamins and mineral elements. It can be used as feed to promote livestock and poultry production, improve feed utilization rate, replace fish meal, soybeans, bone meal, meat, and skim milk powder, and has high added value.

[0003] In the process of producing single-cell protein using Methylobacterium with methanol as the carbon source, the fermentation broth is centrifuged and separated into a cell concentrate and a waste supernatant. The cell concentrate is dried to make a microbial protein product, and the supernatant still contains free amino acids, polypeptides, nucleic acids, and inorganic salts. However, due to the too low concentration of the supernatant, its direct utilization value is small. If processes such as ultrafiltration concentration are used, the treatment volume is large, the recovery ratio is small, and the cost is high. Direct discharge treatment of the supernatant will not only cause environmental pollution but also be a waste, greatly reducing the overall biological utilization rate of the single-cell protein production process. Summary of the Invention

[0004] The purpose of the present invention is to efficiently and comprehensively utilize the fermentation broth of Methylobacterium single-cell protein and improve the overall biological utilization rate of the single-cell protein production process.

[0005] The technical solution of the present invention is as follows:

[0006] A method for treating a fermentation broth of Methylobacterium single-cell protein, comprising the following steps:

[0007] Step 1: Heat the fermentation broth for producing single-cell protein cells to 62 - 68 °C and keep warm for 100 - 120 min; perform ultrasonic intermittent treatment in the last 10 - 20 minutes during the heat preservation process, the frequency of the ultrasonic wave is 18 - 20 Hz, and the power is 100 - 120 W;

[0008] Step 2: Cool down to 35 - 45 °C, adjust the pH value to 6.0 - 7.5; add neutral protease and nuclease for enzymatic hydrolysis for 3 - 5 hours;

[0009] Step 3: Centrifuge and separate the fermentation supernatant and cell protein;

[0010] Step 4: Add chitosan, humic acid, and trace elements to the supernatant, mix evenly to obtain a pretreatment solution; the addition amount of chitosan is 0.1 - 0.3 wt% of the supernatant, and the addition amount of humic acid is 2.0 - 4.0 wt% of the supernatant.

[0011] The treatment method of the Methylobacterium single-cell protein fermentation broth of the present invention is as follows: in the first step, it is incubated at 62-68 °C for 100-120 min, and ultrasonic intermittent treatment is assisted in the last 10-20 minutes of incubation to rupture the cell walls of the senescent cells in the single-cell protein bacteria produced by fermentation, releasing proteins, fats, carbohydrates, nucleic acids, vitamins, inorganic compounds, etc. inside the cells. In the second step, proteins and nucleic acids are enzymatically hydrolyzed into soluble amino acids, small peptides or free amino acids, etc. by neutral protease and nuclease, and enter the supernatant during the centrifugal separation in the third step, so that the concentrations of soluble amino acids, small peptides, free amino acids, carbohydrates, nucleic acids, vitamins, inorganic compounds, etc. in the supernatant increase, improving the utilization value of the supernatant and reducing the treatment cost of the supernatant, making the supernatant a valuable resource that can be directly utilized; while those relatively young bacterial cells will not rupture under the conditions of 62-68 °C and incubation for 100-120 min described in the first step, and under the action of low-power ultrasonic waves in the last 10-20 minutes, and maintain a complete cell morphology, thus being separated in the third step and becoming high-quality bacterial protein for use in fields such as food, feed, medicine, and chemical industry. Through the method of the present invention, both the supernatant and the bacterial protein of the single-cell protein fermentation broth can be effectively utilized, improving the comprehensive utilization rate of the Methylobacterium single-cell protein fermentation broth. In the fourth step, a pretreatment solution is obtained by adding chitosan, humic acid and trace elements to the supernatant. The chitosan and humic acid act synergistically to promote the chelation of amino acids and trace elements, forming amino acid-trace element complexes, preventing the precipitation of trace elements in the pretreatment solution, and improving the biological utilization rate of trace elements.

[0012] Preferably, trehalose is also added to the supernatant in the fourth step, and the addition amount is 0.5-1.0 wt% of the supernatant. Trehalose can inhibit the high-temperature degradation of amino acids, extend the shelf life of the pretreatment solution, and is beneficial for the further prepared water fertilizer agent to have a longer shelf life and fertility.

[0013] Preferably, the ultrasonic intermittent treatment is: ultrasonic treatment for 10 seconds - 5 minutes each time, and intermittent for 10 seconds - 5 minutes. The above ultrasonic intermittent treatment procedure of the present invention can lyse senescent bacterial cells; at the same time, it slightly activates the cell walls of young bacterial cells, changing their structures without rupturing and being convenient for centrifugal separation, which is beneficial to improving the dissolution rate of nutritional elements such as proteins and fats during the use of bacterial protein.

[0014] Preferably, the trace elements are at least one of boron, copper, calcium, iron, manganese, molybdenum, zinc and selenium. Specifically, their soluble salts can be used, such as EDTA-chelated zinc, EDTA-chelated manganese, EDTA-chelated calcium, EDTA-chelated selenium, ammonium molybdate and sodium selenite. Chitosan, humic acid and trace elements in the present invention are added to the pretreatment liquid simultaneously, so that the soluble ionic state of the trace elements is converted into a chelated state, or the chelated state is stably maintained to facilitate the absorption and utilization by plants.

[0015] Preferably, a dispersant is added in the fourth step. More preferably, the dispersant is sodium polyacrylate, and the addition amount is 0.05-0.1 wt% of the supernatant. The dispersant is beneficial to the uniform dispersion of chitosan, humic acid and trace elements in the pretreatment liquid without precipitation.

[0016] Preferably, the addition amount of the neutral protease is 0.1-0.5 wt% of the fermentation broth, and the addition amount of the nuclease is 0.1-0.5 wt% of the fermentation broth.

[0017] The present invention also provides a preparation method of a fertilizer and water agent. The pH value of the obtained pretreatment liquid is adjusted to 2.0-6.5 to obtain the fertilizer and water agent.

[0018] The present invention provides a fertilizer and water agent prepared by the above method.

[0019] The technical effects of the present invention are as follows:

[0020] The treatment method of the methylobacterium single-cell protein fermentation broth of the present invention co-produces and prepares a fertilizer and water agent while producing single-cell protein, improving the comprehensive utilization rate of the methylobacterium single-cell protein fermentation broth. The produced fertilizer and water agent has high organic matter content such as amino acids and a long shelf life, and the chelated trace elements are beneficial to the absorption and utilization by plants. Specific Embodiments

[0021] The following describes the present invention in detail with reference to the embodiments.

[0022] Example 1

[0023] I. Treat a methylobacterium single-cell protein fermentation broth, and the steps are as follows:

[0024] Step 1: Heat the fermentation broth for producing single-cell protein bacteria to 62-65 °C and maintain this temperature for 100 min; perform ultrasonic intermittent treatment in the last 10 minutes of the heat preservation process. The frequency of the ultrasonic wave is 18 Hz, and the output power is 100 W; the program of the ultrasonic intermittent treatment is: every 10 seconds of ultrasonic treatment, with an interval of 5 minutes.

[0025] Step 2: Cool down to 35°C and adjust the pH value to 6.0; add neutral protease and nuclease. The addition amount of neutral protease is 0.1 wt% of the fermentation broth, and the addition amount of nuclease is 0.5 wt% of the fermentation broth. Enzymatically hydrolyze at 35°C for 3 hours.

[0026] Step 3: Centrifuge and separate the fermentation supernatant and cell protein with a disc centrifuge. Keep the cell protein for making food or feed. Take the fermentation supernatant and measure the total protein content in the fermentation supernatant by ultraviolet spectrophotometry. Record the measurement results in Table 1.

[0027] Step 4: Based on the supernatant, add 0.1 wt% chitosan, 2.0 wt% humic acid, 0.5 wt% trehalose, 0.1 g / L ammonium molybdate, 0.05 g / L sodium selenite, and then add 0.05 wt% sodium polyacrylate based on the supernatant. Mix evenly to obtain the pretreatment solution.

[0028] II. Preparation of fertilizer and water agent

[0029] Add citric acid to the obtained pretreatment solution to adjust the pH value to 4.0 to obtain the fertilizer and water agent.

[0030] Example 2

[0031] I. Treat a Methylobacterium single-cell protein fermentation broth, and the steps are as follows:

[0032] Step 1: Heat the fermentation broth of producing single-cell protein cells to 65 - 68°C and keep this temperature for 110 min; perform ultrasonic intermittent treatment in the last 20 minutes of the heat preservation process. The frequency of the ultrasonic wave is 20 Hz, and the output power is 120 W. The program of ultrasonic intermittent treatment is: ultrasonic treatment for 10 seconds each time, and intermittent for 10 seconds.

[0033] Step 2: Cool down to 45°C and adjust the pH value to 7.5; add neutral protease and nuclease. The addition amount of neutral protease is 0.5 wt% of the fermentation broth, and the addition amount of nuclease is 0.3 wt% of the fermentation broth. Enzymatically hydrolyze at 45°C for 5 hours.

[0034] Step 3: Centrifuge and separate the fermentation supernatant and cell protein with a disc centrifuge. Keep the cell protein for making food or feed. Take the fermentation supernatant and measure the total protein content in the fermentation supernatant by ultraviolet spectrophotometry. Record the measurement results in Table 1.

[0035] Step 4: Based on the supernatant, add 0.3 wt% chitosan, 4.0 wt% humic acid, 1.0 wt% trehalose, 0.1 g / L ammonium molybdate, 0.05 g / L sodium selenite, and then add 0.10 wt% sodium polyacrylate based on the supernatant. Mix evenly to obtain the pretreatment solution.

[0036] II. Preparation of the fertilizer and water agent

[0037] Add citric acid to the obtained pretreated liquid to adjust the pH value to 4.5 to obtain the fertilizer and water agent.

[0038] Example 3

[0039] I. Treat a methylobacterium single-cell protein fermentation broth, and the steps are as follows:

[0040] Step 1: Heat the fermentation broth for producing single-cell protein bacteria to 65 - 68 °C and maintain this temperature for 110 min; perform ultrasonic intermittent treatment in the last 20 minutes of the heat preservation process, the frequency of the ultrasonic wave is 20 Hz, and the output power is 120 W; the program of the ultrasonic intermittent treatment is: every 5 minutes of ultrasonic treatment, with an interval of 5 minutes.

[0041] Step 2: Cool down to 40 °C and adjust the pH value to 7.0; add neutral protease and nuclease, the addition amount of neutral protease is 0.3 wt% of the fermentation broth, and the addition amount of nuclease is 0.1 wt% of the fermentation broth. Enzymolysis for 5 hours.

[0042] Step 3: Centrifuge and separate the fermentation supernatant and the cell protein by a disc centrifuge, and retain the cell protein for making food or feed. Take the fermentation supernatant, and use the ultraviolet spectrophotometry method to measure the total protein content in the fermentation supernatant, and record the measurement results in Table 1.

[0043] Step 4: Based on the supernatant, add 0.3 wt% of chitosan, 4.0 wt% of humic acid, 1.0 wt% of trehalose, 0.1 g / L of ammonium molybdate, 0.05 g / L of sodium selenite, and then add 0.10 wt% of sodium polyacrylate based on the supernatant, and mix evenly to obtain the pretreated liquid.

[0044] II. Preparation of the fertilizer and water agent

[0045] Add citric acid to the obtained pretreated liquid to adjust the pH value to 6.5 to obtain the fertilizer and water agent.

[0046] Example 4

[0047] I. Treat a methylobacterium single-cell protein fermentation broth, and the steps are as follows:

[0048] Step 1: Heat the fermentation broth for producing single-cell protein bacteria to 62 - 65 °C and maintain this temperature for 100 min; perform ultrasonic intermittent treatment in the last 10 minutes of the heat preservation process, the frequency of the ultrasonic wave is 18 Hz, and the output power is 100 W; the program of the ultrasonic intermittent treatment is: every 10 seconds of ultrasonic treatment, with an interval of 5 minutes.

[0049] Step 2: Cool down to 35°C and adjust the pH value to 6.0; add neutral protease and nuclease. The addition amount of neutral protease is 0.1 wt% of the fermentation broth, and the addition amount of nuclease is 0.5 wt% of the fermentation broth. Carry out enzymatic hydrolysis for 3 hours.

[0050] Step 3: Centrifuge and separate the fermentation supernatant and cell protein with a disc centrifuge. Keep the cell protein for making food or feed. Take the fermentation supernatant and measure the total protein content in the fermentation supernatant by ultraviolet spectrophotometry. Record the measurement results in Table 1.

[0051] Step 4: Based on the supernatant, add 0.1 wt% chitosan, 2.0 wt% humic acid, 0.1 g / L ammonium molybdate, 0.05 g / L sodium selenite, and then add 0.05 wt% sodium polyacrylate based on the supernatant. Mix evenly to obtain the pretreatment liquid.

[0052] II. Preparation of water fertilizer

[0053] Adjust the pH value of the obtained pretreatment liquid to 6.0 with citric acid to obtain the water fertilizer.

[0054] Example 5

[0055] I. Treat a Methylobacterium single-cell protein fermentation broth, and the steps are as follows:

[0056] Step 1: Heat the fermentation broth for producing single-cell protein cells to 62 - 65°C and keep this temperature for 100 min; carry out ultrasonic intermittent treatment in the last 10 minutes of the heat preservation process. The frequency of the ultrasonic wave is 18 Hz, and the output power is 100 W. The program of ultrasonic intermittent treatment is: ultrasonic treatment for 10 seconds each time, with an interval of 5 minutes.

[0057] Step 2: Cool down to 35°C and adjust the pH value to 6.0; add neutral protease and nuclease. The addition amount of neutral protease is 0.1 wt% of the fermentation broth, and the addition amount of nuclease is 0.5 wt% of the fermentation broth. Carry out enzymatic hydrolysis for 3 hours.

[0058] Step 3: Centrifuge and separate the fermentation supernatant and cell protein with a disc centrifuge. Keep the cell protein for making food or feed. Take the fermentation supernatant and measure the total protein content in the fermentation supernatant by ultraviolet spectrophotometry. Record the measurement results in Table 1.

[0059] Step 4: Based on the supernatant, add 0.1 wt% chitosan, 2.0 wt% humic acid, 0.1 g / L ammonium molybdate, 0.05 g / L sodium selenite, and mix evenly to obtain the pretreatment liquid.

[0060] II. Preparation of water fertilizer

[0061] Add the obtained pretreatment liquid to citric acid to adjust the pH value to 2.0 to obtain a fertilizer agent.

[0062] Comparative Example 1

[0063] I. Treat a Methylobacterium single-cell protein fermentation broth. The method used in this comparative example is different from that in Example 5 in that step I is absent. Start directly from step II, that is, directly use the fermentation broth for producing single-cell protein bacteria bodies, control the temperature to 35 °C, and adjust the pH value to 6.0; add neutral protease and nuclease, the addition amount of neutral protease is 0.1 wt% of the fermentation broth, and the addition amount of nuclease is 0.5 wt% of the fermentation broth. Enzymatically hydrolyze at 35 °C for 3 hours. Then, carry out steps III and IV in the same method as in Example 5 to obtain a pretreatment liquid. During the treatment process, take the fermentation supernatant, and use ultraviolet spectrophotometry to measure the total protein content in the fermentation supernatant, and record the measurement results in Table 1.

[0064] II. Prepare a fertilizer agent

[0065] Adjust the pH value of the obtained pretreatment liquid to 6.0 to obtain a fertilizer agent.

[0066] Comparative Example 2

[0067] I. Treat a Methylobacterium single-cell protein fermentation broth. The method used in this comparative example is different from that in Example 5 in that step IV is different. In step IV of this comparative example, chitosan and humic acid are not added. The specific steps of step IV in this comparative example are as follows:

[0068] Step IV: Based on the supernatant, add 0.1 g / L of ammonium molybdate and 0.05 g / L of sodium selenite, and mix evenly to obtain a pretreatment liquid.

[0069] During the treatment process, take the fermentation supernatant, and use ultraviolet spectrophotometry to measure the total protein content in the fermentation supernatant, and record the measurement results in Table 1.

[0070] II. Prepare a fertilizer agent

[0071] Adjust the pH value of the obtained pretreatment liquid to 6.0 to obtain a fertilizer agent.

[0072] Comparative Example 3

[0073] I. Treat a Methylobacterium single-cell protein fermentation broth. The method used in this comparative example is different from that in Example 5 in that step IV is different. In step IV of this comparative example, chitosan is not added. The specific steps of step IV in this comparative example are as follows:

[0074] Step IV: Based on the supernatant, add 2.1 wt% of humic acid, 0.1 g / L of ammonium molybdate, and 0.05 g / L of sodium selenite, and mix evenly to obtain a pretreatment liquid.

[0075] During the treatment process, take the fermentation supernatant, and use ultraviolet spectrophotometry to measure the total protein content in the fermentation supernatant. The measurement results are recorded in Table 1.

[0076] II. Preparation of water fertilizer

[0077] Adjust the pH value of the obtained pretreatment liquid to 6.0 to obtain the water fertilizer.

[0078] Comparative Example 4

[0079] I. Treat a single-cell protein fermentation broth of Methylobacterium. The method used is different from that in Example 5 in Step 4. In Step 4 of this comparative example, humic acid is not added, specifically as follows:

[0080] Step 4: Based on the supernatant, add 2.1 wt% chitosan, 0.1 g / L ammonium molybdate, and 0.05 g / L sodium selenite, mix evenly to obtain the pretreatment liquid.

[0081] During the treatment process, take the fermentation supernatant, and use ultraviolet spectrophotometry to measure the total protein content in the fermentation supernatant. The measurement results are recorded in Table 1.

[0082] II. Preparation of water fertilizer

[0083] Adjust the pH value of the obtained pretreatment liquid to 6.0 to obtain the water fertilizer.

[0084] Detection:

[0085] Conduct the following detections on the water fertilizers prepared in Examples 1 to 5 and Comparative Examples 1 to 4. The detection results are recorded in Table 1:

[0086] 1. Detection of amino acid content

[0087] Use the conventional acid hydrolysis method in GB / T 18246-2019 "Determination of Amino Acids in Feed" for determination. The measurement results are shown in Table 1.

[0088] 2. Detection of chelation rate

[0089] The test method is as follows:

[0090] Sample treatment: Put 2 ml of the water fertilizer into a 200 Da dialysis bag, place it in 200 ml of deionized water for dialysis for 24 hours, change the water every 5 hours, change the water three times in total, combine the dialysis solutions of the three times, and use atomic absorption spectrometry (AAS) to measure the concentration of free metal ions in the dialysis solution.

[0091] Chelation rate (%) = (1 - C free / C total ) × 100%

[0092] C free : Concentration of metal ions in the dialysis solution

[0093] C total : Total metal concentration

[0094] 3. Shelf life: Seal and keep at 25 °C for 6 months, then take samples to detect the content of free amino acids.

[0095] Table 1

[0096]

[0097] It can be seen from the results in Table 1 that: By adopting the treatment method of the methylobacterium single-cell protein fermentation broth of the present invention, in step one, while keeping the fermentation broth at 62 - 68 °C, low-frequency ultrasonic treatment is carried out. The protein content in the fermentation supernatant obtained from Examples 1 to 5 is relatively high, all reaching above 94 g / L, and the amino acid content in the prepared fertilizer agent is also relatively high, all above 8.8 wt%. In Comparative Example 1, step one was not carried out, and enzymatic hydrolysis was directly started from step two, and then the protein content in the separated fermentation supernatant was relatively low, only 27 g / L, and the amino acid content in the prepared fertilizer agent was also relatively low, being 2.7 wt%. It can be seen that by adopting the method of the present invention, the aging cell walls of the single-cell protein bacteria generated by fermentation can be broken, the proteins inside the cells can be released, the utilization value of the supernatant can be improved, and the supernatant can become a valuable resource that can be directly utilized.

[0098] It can also be seen from Table 1 that: The chelation rate of the fertilizer agents prepared in each example is above 47%, while the chelation rates of the fertilizer agents prepared in Comparative Examples 2 to 4 are relatively low, being 15%, 30% and 32% respectively. From the technical solutions: Compared with Example 5, the difference in Comparative Example 2 is only that chitosan and humic acid are not added in step four, but the chelation rate of the prepared fertilizer agent is 36% less than that of Example 5; Compared with Example 5, the difference in Comparative Example 3 is only that chitosan is not added in step four. Although the amount of humic acid added is relatively large, equal to the total amount of chitosan and humic acid in Example 5, the chelation rate of the prepared fertilizer agent is still far less than that of Example 5, with a difference of 21%; Compared with Example 5, the difference in Comparative Example 4 is only that humic acid is not added in step four. Although the amount of chitosan added is relatively large, equal to the total amount of chitosan and humic acid in Example 5, the chelation rate of the prepared fertilizer agent differs from that of Example 5 by 19%. Thus, it can be seen that in the present invention, chitosan and humic acid act synergistically to promote the chelation of amino acids and trace elements.

[0099] It can also be seen from Table 1 that in the technical solution of the present invention, the content of free amino acids in the fertilizer aqueous solutions prepared in Example 1, Example 2 and Example 3 is relatively higher than that in the fertilizer aqueous solutions prepared in Example 4, Example 5 and each comparative example after being placed for 6 months. The difference between Examples 1 to 3 and other examples and comparative examples lies in the addition of trehalose. It can be seen that trehalose can inhibit the decomposition of amino acids and is beneficial to the preservation of the fertilizer aqueous solution.

[0100] It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in each of the above-described embodiments of the present invention can be combined with each other as long as they do not conflict with each other. In addition, the above are only partial embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

Claims

1. A method for treating a methylobacterium single-cell protein fermentation broth, characterized in that, It includes the following steps: Step 1: Heat the fermentation broth for producing single-cell protein bacteria to 62 - 68 °C and keep it warm for 100 - 120 min; perform ultrasonic intermittent treatment in the last 10 - 20 minutes during the heat preservation process, the frequency of the ultrasonic wave is 18 - 20 Hz, and the power is 100 - 120 W; Step 2: Cool down to 35 - 45 °C, adjust the pH value to 6.0 - 7.5; add neutral protease and nuclease for enzymatic hydrolysis for 3 - 5 hours; Step 3: Centrifuge to separate the fermentation supernatant and the cell protein; Step 4: Add chitosan, humic acid and trace elements to the supernatant, mix evenly to obtain a pretreatment solution; the addition amount of chitosan is 0.1 - 0.3 wt% of the supernatant, and the addition amount of humic acid is 2.0 - 4.0 wt% of the supernatant.

2. The treatment method of the methylobacterium single cell protein fermentation broth according to claim 1, characterized in that, Trehalose is also added to the supernatant in Step 4, and the addition amount is 0.5 - 1.0 wt% of the supernatant.

3. The treatment method of the methylobacterium single-cell protein fermentation broth as described in claim 1, characterized in that, The ultrasonic intermittent treatment is: ultrasonic treatment for 10 seconds - 5 minutes each time, with an intermittent period of 10 seconds - 5 minutes.

4. The treatment method of the methylobacterium single-cell protein fermentation broth according to claim 1, wherein, The trace elements are at least one of boron, copper, calcium, molybdenum, iron, manganese, zinc and selenium.

5. The treatment method of the methylobacterium single-cell protein fermentation broth according to claim 1, wherein A dispersant is added in Step 4.

6. The method for treating the methylobacterium single cell protein fermentation broth according to claim 5, characterized in that, The dispersant is sodium polyacrylate, and the addition amount is 0.05 - 0.1 wt% of the supernatant.

7. The treatment method of the methylobacterium single-cell protein fermentation broth according to claim 1, characterized in that, The addition amount of the neutral protease is 0.1 - 0.5 wt% of the fermentation broth, and the addition amount of the nuclease is 0.1 - 0.5 wt% of the fermentation broth.

8. A preparation method of a fertilizer and water agent, characterized in that, Adjust the pH value of the pretreatment solution obtained in any one of Claims 1 to 7 to 2.0 - 6.5 to obtain a water fertilizer agent.

9. A water-fattening agent, characterized in that, It is made by the method of Claim 8.

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