Strain for degrading polyacrylamide and application thereof

Abstract

The invention relates to a strain for degrading polyacrylamide and application thereof in the technical field of destabilization treatment of oilfield produced water, the strain for degrading polyacrylamide is separated and screened from Jiangsu oilfield lamellar bank produced water, specifically enterobacter HY1, is preserved in China General Microbiological Culture Collection Center, and has the preservation number of CGMCC (China General Microbiological Culture Collection Center). The enterobacter sp.HY1HY1 strain is preserved in China General Microbiological Culture Collection Center (CGMCC), the preservation number is CGMCC NO 32105, the preservation time is October 9, 2024, the enterobacter is classified and named as enterobacter, the Latin literature is named as Enterobacter sp.HY1HY1, and the enterobacter sp.HY1HY1 strain has a gene sequence shown as SEQ ID NO: 1. The enterobacter HY1 has the characteristics of medium and high temperature resistance and hypersalinity resistance, the strain can effectively degrade polyacrylamide in shale oil produced water under the condition, and effective treatment of polyacrylamide in shale oil produced water in an oil field is realized.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield produced water destabilization treatment, and in particular to a bacterial strain for degrading polyacrylamide and an application thereof, which is used for degrading high-content polyacrylamide in oilfield produced water and is particularly suitable for producing water treatment with high shale layer temperature. Background Art

[0002] During the development of shale oil and gas fields, as the mining time increases, the energy of the oil layer itself will be continuously consumed, the pressure of the mined oil layer will continue to drop, and the oil well production will drop sharply, resulting in the inability to mine the remaining oil. Secondary or tertiary oil recovery technology is then used to supplement the formation energy and increase the pressure of the oil layer by artificial water injection, steam injection, chemical or biological agents, etc. In the field of oil extraction, polymer flooding technology is used. The injection of high molecular weight polyacrylamide into water can increase the viscosity of water, resulting in the difficulty of water flowing in the gaps between the oil layers when entering the formation, thereby increasing the recovery rate of crude oil. At the same time, polyacrylamide (HPAM) can also be used as a water plugging agent to effectively plug high aquifers, alleviating the problems of water injection fingering and channeling in the process of oil extraction in my country to a certain extent. When these injection liquids or injected steam condensate are mixed with crude oil, produced wastewater will be formed when the workstation is transferred to crude oil dehydration. Since the produced water needs to be injected back into the formation after treatment, the quality of the water will directly affect the oil recovery effect. HPAM is the main factor affecting the viscosity of oil produced water and the main object of post-treatment of oil field produced water.

[0003] After shale oil wells are put into production, the chemical composition of produced water is relatively complex, the concentration of organic pollutants is high, and the content of solid particles is high. The presence of polymers, surfactants and other additives makes it difficult to treat shale oil produced water. Microorganisms can degrade it. The content of polymers in the shale oil produced water system accounts for a large proportion, and the polymer is mainly polyacrylamide (HPAM). HPAM is considered to be a potential stabilizing substance for produced water due to its high molecular weight and high viscosity. The well fluid mainly includes three categories: acid, dialysis oil washing agent and slippery water. Slippery water fracturing fluid is mainly composed of a large amount of water and a small amount of additives. The additive components generally include drag reducers, hydrochloric acid, oil washing agents, anti-swelling agents, high-temperature corrosion inhibitors, degelling agents, etc.

[0004] HPAM itself is non-toxic and harmless, but its degraded monomer acrylamide can damage the peripheral nervous system of humans and animals. The long-term retention of HPAM in surface water and groundwater will inevitably cause potential harm to the local water environment. The toxicity caused by its accumulation, migration and transformation in the environment will gradually become apparent and will cause immeasurable harm to the ecological environment. The mineralization of shale oil produced water in Jiangsu oilfield is about 30,000 mg / L. K + 、SO4 2- , Ca 2+The content of other elements is relatively high; iron accounts for 91% of the metal elements in the sediment and 25% of the total suspended particulate matter. This indicates that some polyacrylamide is precipitated with suspended particles. From the perspective of polymer monitoring, the polymer concentration is stable below 100 mg / L, and the content entering the Chenbao Biochemical outlet is basically stable at 30-40 mg / L. The Zeta potential of the produced water is negative (-12 mv), which is caused by the adsorption of excessive anionic HPAM molecules on the surface of suspended particles. The negative charges on the HPAM surface repel each other, preventing the suspended particles from agglomerating, enhancing the stability of the produced water, and exacerbating the difficulty of shale oil produced water treatment. Therefore, the treatment of polymer-containing produced water has become an urgent problem to be solved, and the polymer-containing produced water must be effectively treated. Common treatment methods are chemical degradation, thermal degradation, mechanical degradation, and biological degradation.

[0005] The Fenton-like process effectively improves the effectiveness of the process, increases efficiency and reduces costs, but there are still some problems, such as large chemical consumption and serious environmental pollution. The large-scale application of catalytic technology is limited mainly by two factors: 1) the separation of the colloidal catalyst and the water suspension after treatment; 2) the mass transfer limitation of the fixed catalyst on the substrate.

[0006] Foreign scholars have found that the degradation products of HPAM can be used as nutrients for bacterial life activities, and in turn, nutrients will promote the degradation of HPAM. It is currently believed that biodegradation is a new way to harmlessly treat polymers for a long time. Due to the special environmental adaptability, high reproduction rate and variability of microorganisms, the use of strains that efficiently degrade HPAM to treat polymer-containing wastewater will become an effective means to solve the environmental problems caused by HPAM. Several aerobic bacteria isolated from environments and soils containing polyacrylamide and polyacrylates have been shown to be able to decompose these polymers. A few species belonging to the genera Enterobacter, Azomonas, Bacillus, Enterobacter, Pseudomonas and Clostridium can degrade 16-91% of HPAM under aerobic or anaerobic conditions.

[0007] In the prior art, Chinese invention patent application 2024102235753 discloses a polyacrylamide efficient degradation bacterium and its screening method and application. The disclosed polyacrylamide efficient degradation bacterium Alcaligenes faecalis EPDB-5 can quickly and efficiently degrade polyacrylamide in oilfield produced water, and can effectively degrade polyacrylamide solutions with a molecular weight of up to 22 million and a concentration of 500ppm, and has good adaptability in the application of various oilfield produced water. Chinese patent application 2023102066093 discloses a strain Tistrellabauzanensis that efficiently degrades polyacrylamide. The disclosed strain is screened and separated from the fracturing fluid backflow fluid of the oil field. The strain of the present invention is cultured in a selective liquid culture medium with polyacrylamide as the only nutrient source, and can significantly degrade HPAM after 7 days of culture. After optimizing the degradation process of the strain, the degradation efficiency reached 72.7% under the conditions of 175rpm, 37℃, 3% inoculum (v / v), pH=3.0, urea as nitrogen source, glucose as carbon source, 0.05g / L CuCl2, 0.1g / L CaCl2, and 0.1g / L ZnSO4. The degradation bacteria can significantly reduce the molecular weight of polyacrylamide from 3.7×10 6 Da was reduced to 1.87×10 5 Da, FTIR results showed that the amide groups of HPAM had been converted into carboxyl groups during the biodegradation process.

[0008] The temperature of shale oil produced water in Jiangsu Oilfield is generally around 40°C. The chemical composition of produced water is relatively complex and the concentration of organic pollutants is high. The presence of polymers, surfactants and other additives makes shale oil produced water treatment difficult, and the temperature resistance and mineralization resistance of biodegradable bacteria are also high. Therefore, it is necessary to destabilize the shale produced water and find bacteria with better temperature resistance for degradation treatment. Summary of the invention

[0009] Aiming at the destabilization treatment requirements of shale produced water in Jiangsu oilfield, the present invention provides a method for screening functional microorganisms from shale produced water in Jiangsu oilfield to efficiently degrade high-concentration polyacrylamide, which is used for the destabilization treatment of shale produced water in the region.

[0010] To achieve the above-mentioned purpose, the present invention first provides a strain for degrading polyacrylamide, characterized in that it is Enterobacter HY1, which is deposited in the General Microbiological Center of China Microorganism Culture Collection Administration Committee, with a deposit number of CGMCC NO 32105, a deposit time of October 9, 2024, a classification name of Enterobacter, and a Latin literary name of Enterobacter sp. HY1.

[0011] Furthermore, the 16S rDNA gene sequence of the Enterobacter HY1 of the present invention is shown as SEQ ID NO: 1.

[0012] The Enterobacter HY1 of the present invention is obtained by screening from produced water of shale oil fields.

[0013] The specific screening method of Enterobacter HY1 of the present invention comprises the following steps: Step 1: Take 10 ml of shale oil produced water into a conical flask containing 100 mL of enrichment medium, place the conical flask in a constant temperature shaker, culture at 40°C and 150 r / min for 48 h to prepare the seed solution; Step 2: placing the seed solution obtained in step 1 in an enriched medium containing HPAM with a mineralization degree of 5000 mg / L to 40000 mg / L for gradient acclimation to obtain a final seed solution; Step 3: Count the final seed solution obtained in step 2 using a cell counting plate under a microscope, pick the strain with the highest bacterial concentration and dilute it by 10 -5 -10 -7 Multiple times, using the continuous streaking method to pick a number of appropriate strains and place them in 100 mL of separation medium, and place them in a biochemical incubator at 4 0 for 48-72 hours; Step 4: Each strain isolated in step 3 was picked up and placed in 100 mL of enrichment medium, and placed in a constant temperature shaker, 40°C, 150 r / min shaking culture for 3 days; Step 5: Add each strain obtained in step 4 to a polyacrylamide culture medium, place in a constant temperature shaker, shake and culture at 40° C. and 150 r / min for 7 days, use the starch cadmium iodide method to measure the polyacrylamide content in the culture medium, and select the strain with the best polyacrylamide degradation effect, that is, screen out Enterobacter sp.HY1.

[0014] In order to adapt the strains to different mineralizations and HPAM concentrations, in step 2, the specific gradient acclimation process is as follows: 10 mL of the seed solution obtained in step 1 is inoculated into 100 mL of the enrichment medium, the medium is prepared according to the mineralization of 5000 mg / L and the polyacrylamide concentration of 50 ppm, and the first-level bacterial solution is obtained by culturing at 40°C and 150 r / min for 7 days. Then 10 mL of the first-level bacterial liquid was added to 100 mL of enriched medium, and the medium was prepared according to a mineralization of 10,000 mg / L and a polyacrylamide concentration of 100 ppm. The medium was cultured at 40°C, 150 r / min for 7 days to obtain a second-level bacterial liquid. Then 110 mL of the second-level bacterial liquid was added to 100 mL of enriched medium, and the medium was prepared according to a mineralization of 20,000 mg / L and a polyacrylamide concentration of 250 ppm. The medium was cultured at 40°C, 150 r / min for 7 days to obtain a third-level bacterial liquid. Then 10 mL of the third-level bacterial liquid was added to 100 mL of enriched medium, and the medium was prepared according to a mineralization of 40,000 mg / L and a polyacrylamide concentration of 500 ppm. The medium was cultured at 40°C, 150 r / min for 7 days to obtain a final seed liquid that was gradually acclimated.

[0015] Furthermore, the composition of the enrichment medium is: 10 g·L -1 Tryptone, 5 g·L -1 Yeast extract powder, dilute to 1L with sterile deionized water, adjust pH to 7; The components of the separation medium are: 10 g•L -1 Tryptone, 5 g·L -1 Yeast extract powder, 2.59 g•L - 1 CaCl2, 1.75 g L -1 MgCl2, 7.90 g•L -1 Na2SO4, 17.74 g•L -1 NaCl, 20 g L -1 Agar, dilute to 1 L with sterile deionized water, adjust pH to 7 with 1 M NaOH and 1 M HCl, and the final mineralization is 30,000 mg / L; The components of the polyacrylamide culture medium are as follows: 0.5 g polyacrylamide, 2.59 g·L -1 CaCl2, 1.75 g•L -1 MgCl2, 7.90 g•L -1 Na2SO4, 17.74 g•L -1 NaCl, dilute to 1 L with sterile deionized water, adjust pH to 7 with 1 M NaOH and 1 M HCl, and the final mineralization is 30,000 mg / L; To ensure the performance of the above culture media, the above culture media were wet sterilized at 121°C and 0.1MPa for 30min.

[0016] The Enterobacter HY1 obtained by screening of the present invention is enriched and domesticated in a culture medium containing mineralization and polyacrylamide with different concentration gradients during screening, and the HPAM concentration and mineralization are gradually increased during the domestication period to finally prepare a seed solution, and the seed solution obtained by screening is inoculated into 100 ml of an enrichment culture medium, and the bacterial solution is picked out by a continuous streaking method to separate the culture medium, and the polyacrylamide content in the culture medium is measured by a starch cadmium iodide method, and the strain with the best polyacrylamide degradation effect is selected, that is, the Enterobacter HY1 of the present invention is screened. The pH, temperature, mineralization and other conditional factors of the strain obtained by screening are changed during the HPAM degradation process, and the degradation effect is analyzed. Under the degradation conditions of temperature of 40°C, pH of 7, and mineralization of 30000 mg / L, 200 ml of a polyacrylamide solution with a concentration of 500 ppm is prepared, and 12.5% ​​of the bacterial solution is inoculated. After seven days, the degradation rate of HPAM degradation by the strain HY1 is 37.5%, and the degradation ability of the high-molecular polyacrylamide is strong. Therefore, the present invention screens and separates Enterobacter sp.HY1, which can adapt to a wider temperature range and mineralization range than the degrading bacteria in the prior art. Under the temperature condition of 35-45°C, the mineralization is 30000 mg / L, and the polyacrylamide is 500 ppm. The degradation rate can reach 24.5-37.5% after culturing for 7 days. Under this condition, the strain can effectively degrade the polyacrylamide in the shale oil produced water of Jiangsu Oilfield, thereby realizing the effective treatment of the polyacrylamide in the shale oil produced water of the oilfield.

[0017] The present invention also provides an application of the bacterial strain for degrading polyacrylamide in degrading oilfield produced water, characterized in that the bacterial strain is Enterobacter sp. HY1.

[0018] In order to adapt to the conditions of shale layer produced water, the degradation conditions of the bacterial strain for degrading polyacrylamide in oil field produced water are: pH 6-8; temperature 30°C-45°C; mineralization 10000mg / L-40000mg / L.

[0019] Furthermore, the degradation conditions of the bacterial strain for degrading polyacrylamide in oilfield produced water are: pH 7, temperature 40°C, and mineralization of 30,000 mg / L.

[0020] Furthermore, the inoculation amount of the bacterial solution is 10% to 15%.

[0021] The desulfurization bacteria agent involved in the present invention has been submitted for biological deposit, and the deposit information is as follows: BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the phylogenetic tree of Enterobacter HY1 of the present invention.

[0023] Figure 2 This is the result of the degradation of HPAM by Enterobacter HY1 under temperature changing conditions.

[0024] Figure 3 This is the result of the degradation of HPAM by Enterobacter HY1 under changing pH conditions.

[0025] Figure 4 This is the result of the degradation of HPAM by Enterobacter HY1 under the conditions of changing mineralization.

[0026] Figure 5 The scanning electron microscope images of HPAM before and after degradation are shown in Figure 1. (a) is the image of HPAM before degradation, and (b) is the image of HPAM after degradation.

[0027] Figure 6 Infrared spectra of HPAM before and after degradation. DETAILED DESCRIPTION

[0028] Example 1: Screening and Isolation of Enterobacter HY1 The following culture medium was used for the screening separation: The composition of the enrichment medium is: 10 g•L -1 Tryptone, 5 g·L -1 Yeast extract powder, dilute to 1L with sterile deionized water, adjust pH to 7; The composition of the separation medium is: 10 g•L -1 Tryptone, 5 g·L -1 Yeast extract powder, 2.59 g•L - 1 CaCl2, 1.75 g L -1 MgCl2, 7.90 g•L -1 Na2SO4, 17.74 g•L -1 NaCl, 20 g L -1 Agar, dilute to 1 L with sterile deionized water, adjust pH to 7 with 1 M NaOH and 1 M HCl, and the final mineralization is 30,000 mg / L; The components of the polyacrylamide culture medium are as follows: 0.5 g polyacrylamide, 2.59 g•L -1 CaCl2, 1.75 g L - 1 MgCl2, 7.90 g•L -1 Na2SO4, 17.74 g•L -1NaCl, dilute to 1 L with sterile deionized water, adjust pH to 7 with 1 M NaOH and 1 M HCl, and the final mineralization is 30000 mg / L; The above culture media were all wet sterilized at 121°C and 0.1MPa for 30 min.

[0029] The specific screening method includes the following steps: Step 1: Take 10 ml of shale oil produced water into a conical flask containing 100 mL of enrichment medium, place the conical flask in a constant temperature shaker, culture at 40°C and 150 r / min for 48 h to prepare the seed solution; Step 2: The seed solution obtained in step 1 is placed in an enrichment medium containing HPAM with a mineralization of 5000 mg / L to 40000 mg / L for gradient acclimation to obtain the final seed solution; the specific gradient acclimation process in this step is: 10 mL of the seed solution obtained in step 1 is inoculated into 100 mL of the enrichment medium, the medium is prepared according to a mineralization of 5000 mg / L and a polyacrylamide concentration of 50 ppm, and the primary bacterial solution is obtained by culturing at 40°C and 150 r / min for 7 days. 10 mL of the first-level bacterial solution was added to 100 mL of the enriched medium, and the medium was prepared according to a mineralization of 10,000 mg / L and a polyacrylamide concentration of 100 ppm, and the medium was cultured at 40° C. and 150 r / min for 7 days to obtain a second-level bacterial solution. 110 mL of the second-level bacterial solution was added to 100 mL of the enriched medium, and the medium was prepared according to a mineralization of 20,000 mg / L and a polyacrylamide concentration of 250 ppm, and the medium was cultured at 40° C. and 150 r / min for 7 days to obtain a third-level bacterial solution. 10 mL of the third-level bacterial solution was added to 100 mL of the enriched medium, and the medium was prepared according to a mineralization of 40,000 mg / L and a polyacrylamide concentration of 500 ppm, and the medium was cultured at 40° C. and 150 r / min for 7 days to obtain a final seed solution that was gradually acclimated. Step 3: Count the final seed solution obtained in step 2 using a cell counting plate under a microscope, pick the strain with the highest bacterial concentration and dilute it by 10 -5 -10 -7 Multiple times, using the continuous streaking method to pick a number of appropriate strains and place them in 100 mL of separation medium, and place them in a biochemical incubator at 4 0 for 48-72 hours; Step 4: Each strain isolated in step 3 was picked up and placed in 100 mL of enrichment medium, and placed in a constant temperature shaker, 40°C, 150 r / min shaking culture for 3 days; Step 5: Add each strain obtained in step 4 to a polyacrylamide culture medium, place in a constant temperature shaker, shake and culture at 40° C. and 150 r / min for 7 days, use the starch cadmium iodide method to measure the polyacrylamide content in the culture medium, and select the strain with the best polyacrylamide degradation effect, that is, screen out Enterobacter sp.HY1.

[0030] The following analysis is performed on the strain HY1 obtained by screening: The physiological and biochemical characteristics of Enterobacter HY1 were identified according to Bergey's Manual: Taxonomic identification was performed by 16S rDNA analysis, and some strains HY1 were selected for DNA extraction, 16S rDNA amplification and sequencing. The sequencing results are shown in SEQ ID NO: 1, and biological preservation was performed. The preservation information is: deposited in the General Microbiological Center of the China Microbiological Culture Collection Administration, the preservation number is: CGMCC NO 32105, the preservation time is October 9, 2024, the classification name is: Enterobacter, and the Latin literary name is: Enterobacter sp.HY1.

[0031] The sequence of strain HY1 was submitted to NCBI, and its homology was compared with the published sequences in the Genbank database in the Blast online program. Other strain sequences with higher homology were selected, analyzed using MeGA11.0 software, and a phylogenetic tree was constructed using the Neighbor-Joining method. Figure 1 As shown. Through BLAST comparison, it was found that HY1 showed 100% similarity with Enterobacter. Therefore, through the colony morphology, bacterial morphology and 16S rDNA determination of polyacrylamide efficient degradation bacteria, HY1 and Enterobacter gene sequences are basically consistent, and the similarity is more than 99%. HY1 was identified as Enterobacter, Enterobacter. At the same time, after physiological and biochemical identification, its Gram staining was negative, the bacteria were red, the spores were green, catalase was positive, methyl red was negative, VP was positive, and gelatin liquefaction was negative.

[0032] Depend on Figure 1 It can be seen that the screened strain HY1 belongs to Enterobacter in terms of phylogeny. Phylogenetic analysis shows that the sequence similarity between the 16S rDNA of the Enterobacter HY1 of the present invention and Enterobacter sp. RO-3 is as high as more than 99%. Example 2

[0033] This example studies the optimal pH value, mineralization and temperature of Enterobacter HY1 obtained in Example 1; In order to explore the optimal environmental conditions for the strain to degrade polyacrylamide, especially the temperature resistance and mineralization resistance, Enterobacter HY1 was inoculated into the enrichment medium and placed in a constant temperature shaker at 40°C and 150r / min for 7 days as seed liquid. The pH, temperature, mineralization and other conditions of the strain HY1 in the process of HPAM degradation were changed to analyze the degradation effect of the strain.

[0034] The degradation results of Enterobacter HY1 under different conditions are shown in Figure 2-Figure 4 As shown, the results showed that: the pH was adjusted between 6-9, with the optimal pH being 7, the temperature was adjusted between 30°C and 45°C, with the optimal temperature being 30°C, the mineralization was adjusted between 10000 mg / L and 40000 mg / L, with the optimal mineralization concentration being 10000 mg / L.

[0035] Within the above experimental conditions, the degradation effect of Enterobacter HY1 was best at 30℃, pH 7, and mineralization of 10000 mg / L. However, in the single factor experiment at 40℃ or 30000 mg / L mineralization, the degradation rate of 500 ppm HPAM was still above 35%, indicating that the strain oil is resistant to high temperature and salt.

[0036] Example 3: Degradation Verification Experiment 1. Experiment on simulated degradation of polyacrylamide solution by Enterobacter HY1 According to the high temperature and high salt characteristics of shale oil produced water in Jiangsu Oilfield, the shale oil produced water environment was simulated, and Enterobacter HY1 was inoculated into the enrichment medium, placed in a constant temperature shaker, and cultured for 7 days at 40°C, 30000mg / L, and 150r / min as seed liquid. Under the above conditions, 200ml of 500ppm polyacrylamide solution was prepared and inoculated with 12.5% ​​of strain HY1. After seven days, the degradation rate of HPAM by strain HY1 was 37.5%, the removal rate of TN was 89.74%, and the removal rate of COD was 89.76%, among which the absolute degradation rate removed the influence of natural degradation of HPAM.

[0037] The polyacrylamide (HPAM) before and after degradation by strain HY1 was characterized, and the imaging results were obtained using a scanning electron microscope (FEI-Verios 460L). Figure 5 As shown in the figure, the surface of the HPAM sample is very tight and shiny, while the surface of the polyacrylamide is broken and holes appear after degradation, indicating that the growth metabolism of strain HY1 effectively degrades polyacrylamide, breaking it into fragments, oligomers or other small molecular organic matter.

[0038] Infrared spectroscopy (FTIR, Bruker IFS113V, Germany) was used to determine the changes in the functional groups of HPAM before and after degradation. Figure 6 As shown in the figure, before degradation, the -1 The characteristic absorption peak of free -NH2 is 2937cm -1 The characteristic absorption peak of methylene antisymmetric stretching vibration is at 1667cm-1, and the characteristic absorption peak of carbonyl is at 1667cm-1. After degradation, the characteristic absorption peak of free -NH2 becomes narrower. -1 The characteristic peak at 1140 cm -1 The absorption peak at is obvious during the degradation process, which is related to the stretching vibration of ethers, indicating that microorganisms effectively utilize the HPAM carbon chain during the degradation process.

[0039] At the same time, the change of HPAM molecular weight before and after degradation was also tested. From the data results, it can be seen that Mw degraded from 22688152 to 8077033, and the PD value decreased from 82.32 to 2.396, which means that the polyacrylamide molecular chain was broken and the molecular weight distribution became narrower. At the same time, under the conditions of 45°C, 40000mg / L mineralization, 500ppm polyacrylamide solution, 150r / min oscillation culture for 7 days, the degradation rate of polyacrylamide reached 24.5%. The above two groups of experiments fully proved that strain HY1 can tolerate high temperature and high salt environment, and has a significant degradation effect on high concentration of polyacrylamide.

[0040] 2. Experiment on degradation of polyacrylamide solution used in shale oil produced water in Jiangsu Oilfield by Enterobacter HY1 Enterobacter HY1 was inoculated into the enrichment medium and placed in a constant temperature shaker at 40°C and 150r / min for 5 days as seed liquid. 200ml of 250ppm polyacrylamide solution was prepared with real shale oil produced water, and 12.5% ​​of strain HY1 was inoculated and cultured at 40°C and 150r / min for 7 days. The degradation rate of HPAM by strain HY1 was 60.7%.

Claims

1. A strain for degrading polyacrylamide, characterized in that: It is Enterobacter HY1, deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number: CGMCC NO.32105, the deposit time is October 9, 2024, the classification name is: Enterobacter, and the Latin literary name is: Enterobacter sp. HY1.

2. The bacterial strain for degrading polyacrylamide according to claim 1, characterized in that: The 16S rDNA gene sequence of the Enterobacter HY1 is shown in SEQ ID NO:

1.

3. The bacterial strain for degrading polyacrylamide according to claim 1 or 2, characterized in that: The Enterobacter HY1 was screened and obtained from produced water of a shale oil field.

4. The bacterial strain for degrading polyacrylamide according to claim 3, characterized in that: The specific screening method includes the following steps: Step 1: Take 10 ml of shale oil produced water into a conical flask containing 100 mL of enrichment medium, place the conical flask in a constant temperature shaker, culture at 40°C and 150 r / min for 48 h to prepare the seed solution; Step 2: placing the seed solution obtained in step 1 in an enriched medium containing HPAM with a mineralization degree of 5000 mg / L to 40000 mg / L for gradient acclimation to obtain a final seed solution; Step 3: Count the final seed solution obtained in step 2 using a cell counting plate under a microscope, pick the strain with the highest bacterial concentration and dilute it by 10 -5 -10 -7 Multiple times, using the continuous streaking method to pick a number of appropriate strains and place them in 100 mL of separation medium, and place them in a biochemical incubator at 4 0 for 48-72 hours; Step 4: Each strain isolated in step 3 was picked up and placed in 100 mL of enrichment medium, and placed in a constant temperature shaker, 40°C, 150 r / min shaking culture for 3 days; Step 5: Add each strain obtained in step 4 to a polyacrylamide culture medium, place in a constant temperature shaker, shake and culture at 40° C. and 150 r / min for 7 days, use the starch cadmium iodide method to measure the polyacrylamide content in the culture medium, and select the strain with the best polyacrylamide degradation effect, that is, screen out Enterobacter sp.HY1.

5. The bacterial strain for degrading polyacrylamide according to claim 4, characterized in that: In step 2, the specific gradient acclimation process is as follows: 10 mL of the seed solution obtained in step 1 is inoculated into 100 mL of the enrichment medium, the medium is prepared according to the mineralization degree of 5000 mg / L and the polyacrylamide concentration of 50 ppm, and the primary bacterial solution is obtained by culturing at 40°C and 150 r / min for 7 days. Then 10 mL of the first-level bacterial liquid was added to 100 mL of enriched medium, and the medium was prepared according to a mineralization of 10,000 mg / L and a polyacrylamide concentration of 100 ppm. The medium was cultured at 40°C, 150 r / min for 7 days to obtain a second-level bacterial liquid. Then 110 mL of the second-level bacterial liquid was added to 100 mL of enriched medium, and the medium was prepared according to a mineralization of 20,000 mg / L and a polyacrylamide concentration of 250 ppm. The medium was cultured at 40°C, 150 r / min for 7 days to obtain a third-level bacterial liquid. Then 10 mL of the third-level bacterial liquid was added to 100 mL of enriched medium, and the medium was prepared according to a mineralization of 40,000 mg / L and a polyacrylamide concentration of 500 ppm. The medium was cultured at 40°C, 150 r / min for 7 days to obtain a final seed liquid that was gradually acclimated.

6. The bacterial strain for degrading polyacrylamide according to claim 4 or 5, characterized in that: The composition of the enrichment medium is: 10 g·L -1 Tryptone, 5 g·L -1 Yeast extract powder, dilute to 1L with sterile deionized water, adjust pH to 7; The components of the separation medium are: 10 g•L -1 Tryptone, 5 g·L -1 Yeast extract powder, 2.59 g•L -1 CaCl2, 1.75 g L -1 MgCl2, 7.90 g•L -1 Na2SO4, 17.74 g•L -1 NaCl, 20 g L -1 Agar, dilute to 1 L with sterile deionized water, adjust pH to 7 with 1 M NaOH and 1 M HCl, and the final mineralization is 30,000 mg / L; The components of the polyacrylamide culture medium are as follows: 0.5 g polyacrylamide, 2.59 g·L -1 CaCl2, 1.75 g L -1 MgCl2, 7.90 g•L -1 Na2SO4, 17.74 g•L -1 NaCl, dilute to 1 L with sterile deionized water, adjust pH to 7 with 1 M NaOH and 1 M HCl, and the final mineralization is 30,000 mg / L; The above culture media were all wet sterilized at 121°C and 0.1MPa for 30 min.

7. Use of a bacterial strain for degrading polyacrylamide in degrading oil field produced water, characterized in that: The bacterial species is Enterobacter sp.HY1.

8. The use according to claim 7, characterized in that The degradation conditions of the bacterial strain for degrading polyacrylamide in oilfield produced water are as follows: pH is 6-8; temperature is 30-45°C; and mineralization is 10000mg / L-40000mg / L.

9. The use according to claim 7, characterized in that The degradation conditions for the bacterial strain to degrade polyacrylamide in oilfield produced water are: pH 7, temperature 40° C., and mineralization degree 30,000 mg / L.

10. The use according to claim 8, characterized in that The inoculation amount of the bacterial solution is 10% to 15%.

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