Streptobacterium parvum and application thereof in degradation of polyvinyl alcohol

Abstract

The invention relates to a strain of Catellibacterium sp. PVA-1, which is preserved in China General Microbiological Culture Collection Center (CGMCC), the address is Institute of Microbiology, Chinese Academy of Sciences, 3 #, 1 # yard, West Beichen Road, Chaoyang District, Beijing, and the preservation number is CGMCC No.32622. The strain can grow by using PVA as a unique carbon source and energy source, the PVA is completely mineralized into CO2 and H2O, and under a pure culture condition, the PVA can be converted into CO2 and H2O. Under the conditions of 30 DEG C and 200 r / min, the degradation efficiency of the strain on PVA in PVA-containing simulated wastewater reaches 90% or above.

Description

Technical Field

[0001] The invention relates to a strain of Streptobacillus parvus, which can efficiently degrade polyvinyl alcohol (PVA) in water and belongs to the technical field of environmental microorganisms. Background Art

[0002] Polyvinyl alcohol (PVA) is a chemical raw material derived from petroleum cracking products. With its excellent water solubility, adhesion, film toughness, wear resistance and strong organic solvent tolerance, it has been widely used in many fields such as textiles, paper products manufacturing, food packaging and medical devices. As one of the most produced water-soluble polymers, the production and consumption of PVA continues to grow, resulting in a large amount of PVA being discharged into the environment. Due to its large surface activity, PVA can quickly form a large amount of foam in water, which not only leads to oxygen enrichment of the water body, but also increases the viscosity of the water body, seriously inhibiting or even destroying the respiratory activity of aquatic organisms, thereby causing environmental pollution and posing a threat to the ecological balance. Therefore, the degradation of PVA is crucial for environmental protection.

[0003] However, PVA is difficult to degrade under natural conditions and must be treated with physical, chemical or biological methods. Among them, physical and chemical methods such as ultrafiltration membrane separation, radiation, salting out flocculation, advanced oxidation and single ozone oxidation, although these methods are effective, have the problems of high cost and possible secondary pollution. In contrast, biological degradation of PVA is more economical and efficient.

[0004] Unfortunately, PVA has poor biodegradability and is difficult to be degraded by ordinary microorganisms. Despite this, there are still specific functional microorganisms or enzymes that can degrade PVA. Studies have shown that the distribution of these PVA-degrading bacteria in nature is relatively limited, and they can usually only be found in environments contaminated by PVA, such as PVA textile wastewater and papermaking wastewater. Since Nord first discovered that Fusarium can degrade PVA in 1936, researchers have successfully isolated and purified some PVA-degrading bacteria, such as PseudomonasO-3, Pseudomonas vesicularis PD, Pseudomonas putida, Bacillus magaterium, Acinetobacter sp. and Xanthomonas sp. However, due to low efficiency and other reasons, most of these strains still cannot meet the needs of practical applications. Therefore, screening and isolating efficient PVA-degrading strains has become the core task of developing PVA microbial degradation technology. Summary of the invention

[0005] Aiming at the current situation that the existing polyvinyl alcohol (PVA) degradation strains are not effective enough, the present invention provides a microbacterium and its application in degrading polyvinyl alcohol. The strain can use PVA as the only carbon source and energy source for growth, and then completely mineralize PVA into CO2 and H2O, thereby playing the role of degrading PVA.

[0006] A strain of Streptobacillus parvum PVA-1 is deposited in the General Microbiology Center of the China Microbiological Culture Collection Administration, the address of which is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, the deposit number is: CGMCC No.32622, the deposit date is: November 14, 2024, and its 16S rDNA sequence is shown in SEQ ID No: 1. Unless otherwise specified, the Streptobacillus parvum described in the present invention refers to the Streptobacillus parvum PVA-1 strain.

[0007] The strain was isolated from the activated sludge of a sewage treatment pond. It is Gram-negative, has no spores and no capsule. The cells are 0.6*2.3 microns in size, arranged in pairs and forming filaments. The filaments are flat rather than cylindrical, and the terminal cells are not round.

[0008] The beneficial effects of the Streptobacillus parvus provided by the present invention are:

[0009] 1) The strain can use PVA as the sole carbon source and energy source for growth, and completely mineralize PVA into CO2 and H2O. Under pure culture conditions, the degradation efficiency of PVA in simulated wastewater containing PVA is more than 90% at 30°C and 200r / min.

[0010] 2) The bacteria have a high tolerance to PVA, and can tolerate up to 1000ppm of PVA. Under pure culture conditions, the degradation rate of 1000ppm of PVA in inorganic salt medium reaches more than 90% in 144 hours;

[0011] 3) The strain has a simple cultivation method, fast growth rate and strong environmental adaptability, high safety, does not damage the original environment, and has no secondary pollution.

[0012] The present invention also claims a microbial agent comprising the above-mentioned Streptobacillus sp.

[0013] Preferably, the fermentation method of Streptobacillus parvus comprises the following steps:

[0014] (1) Primary seed culture: Under sterile conditions, Streptobacillus parvus is inoculated into a nutrient medium and cultured at 25-35°C and 180-300 rpm for 20-36 hours to obtain a primary seed culture solution;

[0015] (2) Secondary seed culture: under sterile conditions, the primary seed culture solution obtained in step (1) is inoculated into a nutrient medium at a ratio of 1-10 vol%, and cultured at 25-35° C. and 180-300 r / min for 20-36 hours to obtain a secondary seed culture solution;

[0016] (3) Fermentation: sterilize the fermentation medium, then inoculate the secondary seed culture solution obtained in step (2) into the fermentation medium at a ratio of 1-10 vol%, and ferment at 25-35° C., 180-300 r / min, and aeration ratio of 1:(1-2). During the fermentation process, adjust the pH to 6.5-7.5, stop the fermentation after 20-36 hours, and obtain the fermentation solution.

[0017] Furthermore, the composition of the nutrient medium is: 5-15 g / L tryptone, 3-8 g / L yeast extract powder, 5-15 g / L sodium chloride, the solvent is water, and the pH is 6.5-8.0.

[0018] Furthermore, the fermentation medium is composed of: 10-50 g / L carbon source, 5-15 g / L nitrogen source, K + 1.0-1.5g / L, Mg 2+ 0.02-0.5g / L, Ca 2+ 0.1-0.5g / L, Mn 2+ 0.01-0.5 g / L, the solvent is water, and pH=6.5-8.

[0019] Furthermore, the carbon source is selected from one or more of glucose, potassium sodium tartrate, sucrose, starch, succinic acid or sodium citrate.

[0020] Furthermore, the nitrogen source is selected from one or more of potassium nitrate, diammonium phosphate, urea, yeast powder, peptone or ammonium chloride.

[0021] The ions and salts involved in the culture medium can all be derived from inorganic compounds. + The source is one or more of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium sulfate, potassium chloride, and potassium nitrate, wherein the Mg 2+ The source is one or more of magnesium sulfate and magnesium chloride, wherein the Ca 2+ The source is one or more of calcium chloride and calcium nitrate, and the Mn 2+ The source is one or more of manganese sulfate monohydrate, manganese sulfate tetrahydrate, manganese nitrate or manganese chloride.

[0022] The ventilation ratio described in the present invention refers to the ratio of the volume of air introduced into the fermentation tank per minute to the total volume of the fermentation liquid.

[0023] In actual application, the form of the final Streptobacillus product can be determined according to actual use and storage needs. When a liquid product is needed, the fermentation broth can be diluted to the required concentration and used directly. When a solid product is needed, the fermentation broth can be centrifuged to obtain bacterial sludge, and then spray drying or freeze drying can be used to obtain solid bacterial powder.

[0024] The present invention also claims a method for purifying sewage and wastewater using the activated solution of Streptobacillus parvus or the microbial agent, comprising the step of applying the activated solution of Streptobacillus parvus or the microbial agent containing Streptobacillus parvus to the sewage and wastewater.

[0025] Furthermore, the concentration of polyvinyl alcohol in the wastewater is below 1000 mg / L, preferably below 500 mg / L.

[0026] Furthermore, the salinity of the wastewater is below 2%, preferably below 1%.

[0027] Furthermore, the inoculation amount of the activated solution of Streptobacillus parvus or the microbial agent is 500 ppm or more, preferably 500-10000 ppm, and most preferably 500-1000 ppm.

[0028] The present invention also claims to protect the use of the above-mentioned Streptobacillus sp. and microbial agent in the field of sewage and wastewater purification.

[0029] Preferably, the Streptobacillus parvus and microbial agent are used to degrade polyvinyl alcohol in sewage and wastewater.

[0030] Furthermore, the concentration of polyvinyl alcohol in the wastewater is below 1000 mg / L, preferably below 500 mg / L.

[0031] Furthermore, the salinity of the wastewater is below 2%, preferably below 1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a colony photo of Streptobacillus parvus. DETAILED DESCRIPTION

[0033] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0034] Example 1: Isolation, screening and evaluation of strains

[0035] 1. Isolation and initial screening of strains

[0036] The activated sludge from the sewage treatment pool of a printing and dyeing factory in Shaanxi was selected for strain enrichment screening. 5 mL of activated sludge was added to 50 mL of enrichment solution containing 200 mg / L PVA as the sole carbon source. The solution was cultured on a shaking table at 30°C and 200 r / min for 7 days to obtain a round of enrichment solution. Then 5 mL of the first round of enrichment solution was transferred to the next round of enrichment solution containing 500 mg / L PVA as the sole carbon source. After 7 days of culture, a second round of enrichment solution was obtained. The second round of enrichment solution was gradiently diluted to 10 -3 , 10 -4 , 10 -5 The enrichment solution at the concentration was used for strain spreading and separation. The plate used a solid inorganic salt selection medium with PVA as the only carbon source (0.5 g / L dipotassium hydrogen phosphate, 0.5 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate, 0.1 g / L sodium chloride, 1 g / L ammonium sulfate, 0.01 g / L ferrous sulfate heptahydrate, 0.01 g / L manganese sulfate monohydrate, 20 g / L agar, 300 mg / L PVA). After dilution and spreading, the plate was inverted in a 30°C incubator for static culture for 48 h, and then a single colony was picked for purification on a nutrient agar plate. The purified single bacteria were transferred to a nutrient slant medium and cultured at 30°C for 24 h, and then transferred to a 4°C refrigerator for use.

[0037] The single bacteria screened were subjected to high-throughput sequencing and identification. After screening out pathogenic bacteria, four strains were finally obtained, which were named PVA-1, PVA-2, PVA-3 and PVA-4.

[0038] 2. Rescreening and Evaluation of Strain

[0039] Preparation of activation solution:

[0040] Under a sterile environment, 4 bacterial strains were selected and inoculated into 250 mL Erlenmeyer flasks containing 50 mL LB medium (10 g / L tryptone, 5 g / L yeast extract powder, 10 g / L sodium chloride, water as solvent, and pH = 7.0). The flasks were placed in a shaking incubator at 30 ° C and 200 r / min for 24 h to obtain the activation solution of each strain.

[0041] The evaluation medium (0.5 g / L potassium hydrogen phosphate, 0.5 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate, 0.1 g / L sodium chloride, 1 g / L ammonium sulfate, 0.01 g / L ferrous sulfate heptahydrate, 0.01 g / L manganese sulfate monohydrate, 400 mg / L PVA) was dispensed into 250 mL Erlenmeyer flasks, with 50 mL of the medium in each flask, sterilized at 121°C for 20 min, and after the inorganic salts were cooled after sterilization, sterilized PVA was added thereto to make the concentration of PVA 200 mg / L;

[0042] Evaluation method: 0.1 mL of activation solution of four strains was added to the evaluation culture medium respectively. Three parallel experiments were set up for each group of experiments. 0.1 mL of nutrient culture medium was added to the blank group. Samples were taken regularly and centrifuged to detect the content of PVA. The concentration of PVA was determined by I2-KI colorimetric method. The degradation effect of PVA is shown in Table 1.

[0043] Table 1 PVA degradation effect of each strain

[0044]

[0045] As shown in Table 1, strains PVA-1, PVA-2, PVA-3, and PVA-4 all have PVA degradation effects. Compared with PVA-2, PVA-3, and PVA-4, strain PVA-1 has more prominent advantages and can achieve a PVA degradation rate of more than 90% in 96 hours, so PVA-1 was selected as the research object.

[0046] 3. Identification of strains

[0047] The genomic DNA of strain PVA-1 was extracted and used as a template to amplify 16S rDNA. The PCR product was then extracted and DNA sequencing was performed using a sequencer ABI3730-XL. The spliced ​​sequence file was compared with the data in the NCBI 16S database using the NCBI Blast program to obtain the species information with the greatest sequence similarity to the species to be tested. It was found that it belonged to the genus Catellibacterium and was identified as Streptobacillus spp., which was named Streptobacillus spp. PVA-1.

[0048] Example 2: Study on strain characteristics

[0049] Preparation of activation solution: Under a sterile environment, pick the PVA-1 slant strain of Streptobacillus parvum and inoculate it into a 250mL Erlenmeyer flask containing 50mL of nutrient medium. Place the flask in a shaker at 30℃ and 200r / min and culture for 24h to obtain the activation solution of Streptobacillus parvum for later use.

[0050] 2.1 Temperature tolerance test

[0051] For the preparation of experimental culture medium, weigh 10 g of tryptone, 5 g of yeast extract powder, and 10 g of sodium chloride, dissolve them in 1000 mL of distilled water, adjust the pH to 6.5-8.0, take 50 mL of each into 250 mL Erlenmeyer flasks, sterilize at 121°C for 20 min, and set aside.

[0052] 1 vol% of the activated solution of Streptobacillus parvum was inoculated into the experimental culture medium under sterile conditions, and the reaction system was cultured at a speed of 200 r / min and different temperatures (10°C, 20°C, 30°C, and 40°C). Three parallel groups were set up under each experimental condition, and samples were taken after 48 hours to detect the OD 600 The values ​​were averaged to determine their growth.

[0053] Table 2 Growth of Streptobacillus spp. at different temperatures

[0054] temperature 24h 48h 72h 10℃ 0.05 0.18 0.20 20℃ 1.2 2.66 2.74 30℃ 1.43 2.97 2.99 40℃ 0.11 0.32 0.44

[0055] As shown in Table 2, the growth state of Streptobacillus parvus is best at a temperature of 20-30℃. When the temperature is lower or higher than this, the growth of the bacteria is obviously inhibited. It can also be seen that the optimal growth temperature of the bacteria is 30℃.

[0056] 2.2 Salinity tolerance experiment

[0057] For the preparation of experimental culture medium, 10 g of tryptone, 5 g of yeast extract powder and different concentration gradients of sodium chloride (0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%) were weighed and dissolved in 1000 mL of distilled water. The pH was adjusted to 6.5-8.0, and 50 mL of each was dispensed into 250 mL Erlenmeyer flasks. The mixture was sterilized at 121°C for 20 min and set aside.

[0058] Under sterile conditions, 1 vol% of Streptobacillus microti was inoculated into the experimental culture medium, and the reaction system was cultured at 30°C and 200 r / min. Three parallel groups were set up under each experimental condition, and samples were taken after 48 hours to detect the OD 600 The values ​​were averaged to determine their growth.

[0059] Table 3 Growth of Streptobacillus sp. under different salinity conditions

[0060] salinity 24h 48h 72h 0.5％ 1.28 2.90 3.24 1.0％ 0.92 2.11 2.51 2％ 0.67 1.54 1.77 3％ 0.32 0.86 1.11 4％ 0.11 0.35 0.75 5％ 0.11 0.21 0.51

[0061] It can be seen from Table 3 that with the increase of salinity, the growth of Streptobacillus is inhibited, and the inhibition effect increases with the increase of salinity. When the salinity exceeds 2.0%, its growth is almost completely inhibited. The salinity between 0.5-1.0% is more suitable for the growth of Streptobacillus.

[0062] 2.3 pH tolerance test

[0063] For the experimental culture medium preparation, 10 g of tryptone, 5 g of yeast extract powder, and 10 g of sodium chloride were weighed and dissolved in 1000 mL of distilled water, and the pH was adjusted to 6.5-8.0. 50 mL of each was dispensed into 250 mL Erlenmeyer flasks and sterilized at 121°C for 20 min. After the culture medium was cooled, the pH of the culture medium was adjusted under sterile conditions, and the pH gradient was set to 5.5, 6.5, 7.5, and 8.5.

[0064] Under sterile conditions, 1 vol% of Streptobacillus microti was inoculated into each experimental culture medium, and the reaction system was cultured at 30°C and 200 r / min. Three parallel groups were set up under each experimental condition, and samples were taken after 48 hours to detect the OD 600 The values ​​were averaged to determine their growth.

[0065] Table 4 Growth of Streptobacillus sp. under different pH conditions

[0066]

[0067]

[0068] As shown in Table 4, the pH between 5.5 and 8.5 had little effect on Streptobacillus parvus. 600 The value first increases and then decreases, and the optimum pH is 6.5.

[0069] Example 3: Small-scale experiment on laboratory simulated wastewater culture medium

[0070] 3.1 PVA tolerance evaluation

[0071] (1) The evaluation culture medium (0.5 g / L potassium dihydrogen phosphate, 0.5 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate, 0.1 g / L sodium chloride, 1 g / L ammonium sulfate, 0.01 g / L ferrous sulfate heptahydrate, 0.01 g / L manganese sulfate monohydrate) was dispensed into 250 mL conical flasks, 50 mL per flask, sterilized at 121°C for 20 min, and after cooling after sterilization, sterilized PVA was added to the flask to make different concentration gradients of PVA (200 mg / L, 400 mg / L, 600 mg / L, 1000 mg / L) for later use.

[0072] (2) Evaluation method: Streptobacillus microti powder was added to the evaluation culture medium at a dosage of 500 mg / L. Three parallel groups were set up for each experiment. The reaction system was placed at 30°C and 200 r / min. The remaining amount of PVA was detected every day. The concentration of PVA was determined by I2-KI colorimetric method. The experimental results are shown in Table 5. The experimental arrangement is as follows:

[0073] Experimental group 1: PVA 200 mg / L;

[0074] Experimental group 2: PVA 400 mg / L;

[0075] Experimental group 3: PVA 600 mg / L;

[0076] Experimental group 4: PVA 1000 mg / L.

[0077] Table 5 Degradation effect of Streptobacillus parvus on PVA at different concentrations

[0078]

[0079]

[0080] As shown in Table 5, the tolerance of Streptobacillus parvus to PVA can reach 1000 mg / L, and it has a good degradation effect on PVA within 1000 mg / L. It can degrade 200 mg / L of PVA to 14 mg / L in 96 hours, with a degradation efficiency of 93%. It can degrade 1000 mg / L of PVA to 34 mg / L in 144 hours, with a degradation rate of more than 96%.

[0081] 3.2 Evaluation of inoculum size

[0082] Different amounts of Streptobacillus microti powder (200 mg / L, 500 mg / L, 800 mg / L) were added to the reaction system, and three parallel experiments were set for each dosage. The reaction system was then placed at 30°C and 200 r / min. The remaining amount of PVA was detected every day. The concentration of PVA was determined by the I2-KI colorimetric method. The experimental results are shown in Table 6.

[0083] The specific experimental arrangements are as follows:

[0084] Control group: Streptobacillus microti powder 0 mg / L;

[0085] Experimental group 1: Streptobacillus microti powder 200 mg / L;

[0086] Experimental group 2: Streptobacillus minor powder 500 mg / L;

[0087] Experimental group 3: Streptobacillus microti powder 800 mg / L.

[0088] Table 6 Degradation effect of different inoculation amounts of Streptobacillus microti on PVA

[0089]

[0090] It can be seen from Table 6 that when the PVA concentration is 500 mg / L, with the increase of the inoculum amount of Streptobacillus parvus, the PVA degradation efficiency and degradation rate gradually increase. Considering the comprehensive economic efficiency, the dosage is set to 500 mg / L, which is the best.

[0091] Example 4: Application experiment in actual wastewater

[0092] 4.1 Experimental Supplies

[0093] (1) Experimental water: effluent from the aerobic section of a chemical enterprise in Hunan;

[0094] (2) Experimental bacterial agent: freeze-dried powder of Streptobacillus parvus;

[0095] 4.2 Evaluation Method

[0096] Take 50mL of experimental water and put it in a 250mL conical flask, add Streptobacillus microti powder into it, and the dosage is set to 500mg / L. Set up 3 parallel groups, and take another group without adding bacterial agent as blank control. The reaction system is placed at 30℃ and 200r / min for evaluation, and the remaining amount of PVA is detected every day. The concentration of PVA is determined by I2-KI colorimetric method.

[0097] 4.3 Experimental Results

[0098] Table 7 Degradation effect of Streptobacillus spp. on PVA in actual wastewater

[0099]

[0100] As shown in Table 7, 144 hours after the addition of Streptobacillus powder to the water body, the PVA in the water sample dropped to 24 mg / L, and the removal rate of PVA could reach more than 90%. Compared with the control group, the degradation effect of the experimental group was outstanding.

[0101] Example 5: Fermentation production of Streptobacillus parvus PVA-1

[0102] 1. Fermentation

[0103] 1) Primary shake flask activation

[0104] In a sterile environment, pick 1 ring of Streptobacillus microti strains and inoculate it into a 250mL Erlenmeyer flask containing 100mL of nutrient medium (5g / L yeast extract, 10g / L tryptone, 10g / L sodium chloride, pH=7.0, sterilized at 121℃ for 20min), and culture it at 30℃ and 180r / min for 24h to obtain a primary activation solution.

[0105] 2) Preparation of secondary seed solution

[0106] In a sterile environment, transfer 10 mL of the first-level activation solution to four 1L Erlenmeyer flasks containing 500 mL of nutrient medium (5 g / L yeast extract, 10 g / L trypsin, 10 g / L sodium chloride, pH = 7.0, sterilized at 121°C for 20 min), and culture at 30°C and 180 r / min for 24 h to obtain the second-level activation solution.

[0107] 3) 50L tank fermentation

[0108] The fermentation medium was sterilized at 121°C for 20 minutes. The final fermentation medium formula was: 35 g / L starch, 10 g / L soy protein, 0.2% magnesium sulfate, 0.1% manganese sulfate, 0.5% calcium chloride, and 0.6% potassium dihydrogen phosphate. The secondary seed culture solution was inoculated into the fermentation medium at an inoculation rate of 5-10 vol%, and the fermentation tank was filled with 70%. Sodium hydroxide was used to initially adjust the pH to 7.0, and the aeration ratio was 1:1.25 (m 3 ·min / m 3 ), 180rpm, 30 ℃ fermentation culture, during the fermentation process by adding ammonia to control pH = 7, the fermentation cycle is about 30h, when the dissolved oxygen begins to rise, the fermentation is stopped immediately, at this time the fermentation is in the late logarithmic phase, the fermentation liquid count live bacteria count of 20 billion CFU / mL, the bacteria have the strongest vitality, the least fermentation nutrient residues, storage live bacteria decay less.

[0109] 2. Post-treatment process of fermentation broth

[0110] In order to obtain bacterial powder, the fermentation liquid can be treated by freeze-drying post-processing process. After freeze-drying, the number of live bacteria counted in the bacterial powder can reach 290 billion CFU / g.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A strain of Catellibacterium sp., characterized in that: It is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number: CGMCC No.32622.

2. A microbial agent, characterized in that: The active ingredient comprises the Streptobacillus parvus according to claim 1.

3. The fermentation method of Streptobacillus parvus according to claim 1, characterized in that: The method comprises the following steps: (1) primary seed culture: inoculating Streptobacillus microti in a nutrient medium under sterile conditions, culturing at 25-35° C. and 180-300 r / min for 20-36 hours to obtain a primary seed culture solution; (2) Secondary seed culture: under sterile conditions, the primary seed culture solution obtained in step (1) is inoculated into a nutrient medium at a ratio of 1-10 vol%, and cultured at 25-35° C. and 180-300 r / min for 20-36 hours to obtain a secondary seed culture solution; (3) Fermentation: sterilize the fermentation medium, then inoculate the secondary seed culture solution obtained in step (2) into the fermentation medium at a ratio of 1-10 vol%, and ferment at 25-35° C., 180-300 r / min, and aeration ratio of 1:(1-2). During the fermentation process, adjust the pH to 6.5-7.5, stop the fermentation after 20-36 hours, and obtain the fermentation solution.

4. The fermentation method according to claim 3, characterized in that The nutrient culture medium comprises: 5-15 g / L tryptone, 3-8 g / L yeast extract powder, 5-15 g / L sodium chloride, the solvent is water, and the pH value is 6.5-8.

0.

5. The fermentation method according to claim 3 or 4, characterized in that: The fermentation medium is composed of: 10-50 g / L carbon source, 5-15 g / L nitrogen source, K + 1.0-1.5g / L, Mg 2+ 0.02-0.5g / L, Ca 2+ 0.1-0.5g / L, Mn 2+ 0.01-0.5 g / L, the solvent is water, and pH=6.5-8.

6. The fermentation method according to claim 5, characterized in that The carbon source is selected from one or more of glucose, sodium potassium tartrate, sucrose, starch, succinic acid or sodium citrate; The nitrogen source is selected from one or more of potassium nitrate, diammonium phosphate, urea, yeast powder, peptone or ammonium chloride.

7. A method for purifying wastewater, characterized in that: The method comprises the steps of applying the activated solution of Streptobacillus parvus described in claim 1 or the microbial agent described in claim 2 to sewage and wastewater.

8. The method according to claim 7, characterized in that The concentration of polyvinyl alcohol in the wastewater is below 1000 mg / L, preferably below 500 mg / L.

9. The method according to claim 7, characterized in that: The salinity of the wastewater is below 2%, preferably below 1%.

10. Use of the Streptobacillus parvus according to claim 1 and the microbial agent according to claim 2 in the field of sewage and wastewater purification; preferably, the Streptobacillus parvus and the microbial agent are used to degrade polyvinyl alcohol in sewage and wastewater.

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