Strain with low-temperature and saline-alkaline tolerance, protease production and siderophore production and application thereof

Abstract

This invention relates to a strain of *Niallia oryzisoli* XG-146 that is resistant to low temperatures, salt, and alkali, and possesses both protein-degrading and siderophore-producing functions, as well as its applications. This invention falls under the field of industrial wastewater treatment and non-point source pollution control. It solves the technical problems of existing bacterial agents, such as poor stress resistance, limited functionality, and incomplete treatment of complex pollution. The strain is CGMCC No. 38206. The application of this strain in industrial wastewater and non-point source pollution control is described. The XG-146 strain described in this invention can grow stably at 10~35℃, is salt and alkali resistant, and produces siderophores with a SU value of 76.45%. It also possesses strong protein-degrading function. Through "triple stress resistance synergy + dual function superposition," it simultaneously achieves the degradation of organic pollutants, interception of non-point source pollution, and activation of iron in water bodies in high-salt and high-alkali industrial wastewater, solving the technical problems of existing bacterial agents, such as poor stress resistance, limited functionality, and incomplete treatment of complex pollution.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment and non-point source pollution control, specifically involving a strain of bacteria that is resistant to low temperature and salt and alkali, has protein-degrading and siderophore-producing functions, and its applications. Background Technology

[0002] Niallia oryzisoli, a functional strain of the genus Niallia, is naturally adapted to complex polluted habitats and possesses fundamental potential for organic pollutant degradation and nutrient transformation. Existing studies have confirmed its efficient degradation of macromolecular organic matter such as starch and protein, and its activation of iron in the environment through siderophore production. It exhibits excellent stress resistance and ecological compatibility in scenarios such as the purification of lightly polluted water bodies and the remediation of organic soil pollution. However, existing isolates lack the synergistic stress resistance characteristics of low-temperature, salt-, and alkali-tolerant properties, as well as the functional synergy of "protein degradation and siderophore production," making it difficult to adapt to the extreme environments of high-salt and high-alkali industrial wastewater and the complex pollutant composition of non-point source pollution, resulting in insufficient treatment efficiency and adaptability.

[0003] Industrial wastewater from industries such as chemical processing, dyeing and printing, and food processing often exhibits high salinity (NaCl concentration can reach 400 mmol / L) and high alkalinity (pH ≥ 9.0), and contains a large amount of proteinaceous organic pollutants. Some wastewater also faces low-temperature stress (around 10℃) during winter discharge, creating a complex treatment challenge of "extreme environment + organic pollution." Simultaneously, non-point source pollution such as urban surface runoff and agricultural runoff carries proteinaceous pollutants and suspended organic matter into water bodies, easily leading to eutrophication and black and odorous water. Existing treatment technologies have significant shortcomings: physicochemical methods (such as chemical oxidation and membrane separation) are energy-intensive, prone to secondary pollution, and have poor agent stability under extreme environments; conventional biological methods often use microbial agents that are not resistant to salt, alkali, and low temperatures, possessing only a single degradation function and unable to efficiently decompose proteinaceous pollutants. Furthermore, the lack of iron in water bodies inhibits the synergistic metabolism of microorganisms, resulting in significant difficulties in achieving industrial wastewater standards and unstable non-point source pollution interception effects, becoming a prominent bottleneck in pollution control. Summary of the Invention

[0004] In order to solve the technical problems of poor stress resistance, single function, and incomplete treatment of complex pollution by existing bacterial agents, this invention provides a strain of bacteria that is resistant to low temperature and salt and alkali, and has the functions of protein decomposition and iron carrier production, as well as its application.

[0005] The strain of Niallia oryzisoli XG-146, which is resistant to low temperatures and salt and alkalis, and has the functions of protein decomposition and siderophore production, is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCCNo.38206 and deposit date of April 9, 2026.

[0006] Furthermore, the concentrations of glucose in the Niallia oryzisoli XG-146 functionally enhanced fermentation medium were 15.0 g / L, defatted soybean meal powder 20.0 g / L, yeast extract 5.0 g / L, ammonium sulfate 3.0 g / L, sodium chloride 17.5 g / L, dipotassium hydrogen phosphate 2.5 g / L, potassium dihydrogen phosphate 1.0 g / L, magnesium sulfate 0.5 g / L, calcium chloride 0.1 g / L, ferrous sulfate 0.01 g / L, and humic acid 2.0 g / L.

[0007] The microbial agent of the present invention, which has the functions of low temperature and salt and alkali resistance, protein decomposition and iron carrier production, includes Niallia oryzisoli XG-146.

[0008] The present invention relates to the application of strains with low-temperature and salt-alkali resistance, protein-degrading and siderophore-producing functions in the treatment of industrial wastewater and non-point source pollution.

[0009] The *Niallia oryzisoli* XG-146 strain described in this invention can grow stably at 10–35°C (with weak growth at 5°C), tolerate alkaline environments with NaCl concentrations of 0–400 mmol / L and pH 11.0, produce siderophores with a SU value of 76.45%, and possesses strong protein-degrading capabilities. Through a combination of "triple stress resistance synergy + dual functional superposition," it simultaneously achieves the degradation of organic pollutants, interception of non-point source pollution, and activation of iron in water bodies in high-salt and high-alkali industrial wastewater, solving the technical problems of poor stress resistance, single function, and incomplete treatment of complex pollution by existing bacterial agents. The *oryzisoli* XG-146 strain of this invention combines low-temperature resistance, salt tolerance, alkali tolerance, protein degradation, and siderophore production capabilities, making it applicable to the purification and non-point source pollution interception of high-salt and high-alkali industrial wastewater, providing a novel and efficient microbial resource for deep purification of industrial wastewater and control of non-point source pollution.

[0010] Niallia oryzisoli XG-146 is a bacterium belonging to the genus Niallia. It is deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 38206 and deposit date of April 9, 2026. Attached Figure Description

[0011] Figure 1 The results of siderophore screening for strain XG-146;

[0012] Figure 2 The results of protein decomposition screening for strain XG-146;

[0013] Figure 3 Phylogenetic tree constructed for strain XG-146. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0016] Example 1: Isolation and screening of Niallia oryzisoli XG-146 as described in this invention

[0017] 1. Materials and Methods

[0018] 1.1 Experimental Materials

[0019] In September 2025, surface sediment from the Jinghu Lake area of ​​the Sino-Singapore Tianjin Eco-City in Binhai New Area, Tianjin, was transported back to the School of Environmental Science and Engineering at Harbin Institute of Technology via cold chain. In a clean bench, 5g of sediment was placed in an Erlenmeyer flask containing glass beads and 50mL of sterile water, and shaken at 180 rpm for 30 minutes at room temperature. Then, a gradient dilution was performed, resulting in 10... -3 10 -4 10 -5 100 μL of each gradient was spread onto LB agar plates, with each gradient repeated three times (different dilutions were used in this example to better screen for selectable single colonies), and incubated at 28°C for 48 h. After 48 h of incubation, strains with different characteristics were selected for isolation, numbered, and cultured separately.

[0020] 1.2 Identification of bacterial siderophores

[0021] The purified strain was reactivated and transferred to LB agar plates for 24 hours. Single colonies were then picked with sterile toothpicks and inoculated onto Chromeazurol S (CAS) solid detection medium. The plates were incubated upside down at 37°C for 2-3 days. The size of the discoloration zone around the colony was observed. The colony diameter d and the discoloration zone diameter D were measured using the cross-cross method, and the ratio D / d was calculated. Further experiments were conducted on strains exhibiting a clear discoloration zone.

[0022] (1) The activated bacterial growth was inoculated into SA iron-limited liquid medium and cultured in a shaker at 37 ˚C for 48 h;

[0023] (2) Transfer the bacterial suspension to be tested after 48 hours of growth to a sterilized 10 mL centrifuge tube and centrifuge at 13,000 rpm for 15 min.

[0024] (3) Transfer the supernatant to a test tube treated with concentrated hydrochloric acid, add a certain amount of freshly prepared CAS detection solution to make the volume ratio of supernatant to detection solution 1:1, mix thoroughly and let stand at room temperature for 1 h.

[0025] (4) Measure the absorbance value (As) at a wavelength of 630 nm. Use double-distilled water as a control to zero the sample. Use the absorbance value (Ar) at a wavelength of 630 nm obtained by mixing the uninoculated SA iron-limiting medium with the test solution as a reference value. Express the iron carrier activity unit as follows:

[0026] Su≈(Ar-As) / Ar×100;

[0027] In the formula: Su is the iron carrier content; Ar is the OD value of the supernatant of the uninoculated SA iron-limited medium and the CAS detection solution; As is the OD value of the supernatant of the SA iron-limited medium and the CAS detection solution of the inoculated strain.

[0028] When the number of ferrocarrier activity units is less than 10, it is generally considered negative, and the mixture of ferrocarrier and test solution does not show any color change.

[0029] 1.3 Screening of strains with protein-degrading ability

[0030] The isolated and purified bacterial strains were inoculated onto SKM (2% skim milk powder) bacterial agar plates using sterile toothpicks. Each gradient was repeated three times and incubated at 28°C for 24–48 h. Colonies exhibiting a protein-lysing zone were selected, and the colony diameter d and the protein-lysing zone diameter D were measured using the cross-crossing method. The D / d ratio was calculated, and strains with the highest ratios were selected for purification, and their protein-dissolving effect was repeatedly verified.

[0031] 1.4 Identification of salt-tolerant strains

[0032] LB solid medium containing 50, 100, 200, 300, 400, 450, 500, 550, 600, and 650 mmol / L NaCl was prepared. The isolated and purified bacterial strains were inoculated onto LB solid medium using the streak plating method, with a medium without NaCl used as a control. The medium was sealed and inverted in a constant temperature incubator at 28 ℃ for 24–48 h, during which colony growth was observed.

[0033] 1.5 Screening of alkali-resistant strains

[0034] LB solid culture media with pH values ​​ranging from 7 to 12.5 were prepared. The isolated and purified bacterial strains were inoculated onto LB solid culture media using the streak plating method, with the pH 7 medium used as a control. The media were sealed and inverted in a constant temperature incubator at 28 °C for 24–48 h, during which colony growth was observed. Further identification was performed based on the colony growth.

[0035] 1.6 Screening of cryogenic strains

[0036] The strain was inoculated into LB liquid medium at a relative volume inoculum of 2% and cultured at temperatures of 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃ and 40℃ for 24 h. The OD value of three parallel samples was measured at a wavelength of 600 nm to investigate the adaptability of the strain to different temperatures.

[0037] 1.7 Identification of strains

[0038] 16S rRNA identification: Bacterial genomic DNA extraction kit from Beijing Solarbio Biotechnology Co., Ltd. was used to extract and purify the bacterial DNA. PCR amplification was performed using universal bacterial primers 27F / 1492R. The PCR amplification system was 25 µL: 2.5 µL 10× buffer, 0.5 µL Taq enzyme, 0.5 µL primer 27F, 0.5 µL primer 1492R, 1 µL DNA template, and 20 µL ddH2O. The reaction program was: 95℃ pre-denaturation for 5 min; 94℃ denaturation for 50 s, 56℃ annealing for 30 s, 72℃ extension for 1.5 min, for 30 cycles; a final extension at 72℃ for 10 min; and storage at 4℃. The PCR amplification products were sent to RuiBiotech for sequencing. The sequencing results of the bacterial 16S rRNA were compared with the NCBI database, and a phylogenetic tree was constructed.

[0039] Physiological and biochemical identification: The preserved strain was streaked in three zones on a solid LB medium plate, single colonies were isolated and their morphology was described, and the strain was Gram stained and physiologically and biochemically identified according to the "Handbook of Common Bacterial System Identification".

[0040] 2 Results and Analysis

[0041] 2.1 Initial screening of strains with siderophore-producing ability

[0042] A total of 832 strains with different morphologies were screened from the sediment. Among them, 8 strains simultaneously exhibited low temperature tolerance, salt tolerance, alkali tolerance, siderophore production, and protein solubilization. Strain XG-146, with relatively good overall performance, was selected. The isolated and purified XG-146 strain was inoculated onto CAS medium. After a period of cultivation, a distinct discoloration zone formed around the colony. Figure 1 (Screening results for siderophores of strain XG-146) The diameter of the discoloration zone D of XG-146 is 9.30 mm, the colony diameter d is 2.19 mm, and the D / d ratio is 4.25, indicating that strain XG-146 has a very strong ability to produce siderophores with high iron chelation capacity.

[0043] 2.2 Determination of iron-producing capacity

[0044] Using method 1.2, the Su value of siderophore production by strain XG-146 at 37℃ was 76.45%, indicating that the strain has a very strong siderophore production capacity.

[0045] 2.3 Screening of strains with protein-degrading ability

[0046] The isolated and purified XG-146 strain was inoculated onto SKM medium. After a period of cultivation, a distinct deproteinization zone formed around the colony. Figure 2 (The results of protein decomposition screening for strain XG-146) The diameter of the protein decomposition zone D of XG-146 is 14.04 mm, the colony diameter d is 5.92 mm, and the D / d ratio is 2.37, indicating that strain XG-146 has a strong protein decomposition function.

[0047] 2.4 Identification of Salt Stress Resistance

[0048] Table 1 shows the salt stress resistance of strain XG-146. As shown in Table 1, strain XG-146 can grow normally at NaCl concentrations ranging from 0 to 400 mmol / L, indicating that strain XG-146 has strong salt tolerance.

[0049] Table 1. Identification of salt stress resistance in strain XG-146

[0050]

[0051] Note: + indicates growth; - indicates no growth.

[0052] 2.5 Identification of resistance to alkali stress

[0053] Table 2 shows the alkali stress resistance identification of strain XG-146. As shown in Table 2, strain XG-146 can grow normally under pH 11.0 conditions, indicating that strain XG-146 has strong alkali resistance.

[0054] Table 2. Identification of alkaline stress resistance in strain XG-146

[0055]

[0056] Note: + indicates growth; - indicates no growth.

[0057] 2.6 Low-temperature resistance assessment

[0058] Table 3 shows the low temperature stress identification of strain XG-146. As shown in Table 3, strain XG-146 grows well in the range of 10-35℃, and only grows weakly at 5℃ and 40℃, indicating that strain XG-146 has a strong ability to withstand low temperatures.

[0059] Table 3 Identification of low-temperature stress in strain XG-146

[0060]

[0061] Note: +, -, and W represent good growth (OD > 0.5), weak growth (0.5 > OD > 0.2), and no growth (OD < 0.2), respectively.

[0062] 2.7 Identification of strain XG-146

[0063] 2.7.1 Physiological and Biochemical Experiments

[0064] The colony characteristics of strain XG-146 on LB agar are as follows: it forms creamy yellow, round, raised colonies with a smooth, uniform surface and no wrinkles; it does not produce water-soluble or fat-soluble pigments; the colonies are regular in shape and easy to pick; and it is identified as a Gram-positive bacterium by Gram staining. Some physiological and biochemical indicators of strain XG-146 are shown in the table below. Based on the descriptions of the physiological and biochemical characteristics of *Niallia oryzisoli* in Bergey's Manual of Bacteriology and related literature, strain XG-146 shares the same physiological and biochemical characteristics as the type species *Niallia oryzisoli*. Therefore, based on these physiological and biochemical indicators, strain XG-146 is likely *Niallia oryzisoli*.

[0065] Table 4 Physiological and biochemical results of Niallia oryzisoli XG-146

[0066]

[0067] Note: + indicates a positive result; - indicates a negative result.

[0068] 2.7.2 Identification of 16S rRNA

[0069] After sequencing the 16S rRNA sequence, BLAST alignment in NCBI revealed that the 16S rRNA gene sequence of strain XG-146 had a 99% similarity to *Niallia oryzisoli*. The phylogenetic tree of XG-146 showed that strain XG-146 and *Niallia oryzisoli* (1DS3-10) belong to the same smallest branch, indicating a close evolutionary distance. Based on comprehensive physiological and biochemical indicators, strain XG-146 was identified as *Niallia oryzisoli*.

[0070] Example 2

[0071] Functionally enhanced fermentation medium (1L system) adapted for Niallia oryzisoli XG-146 strain:

[0072] Formula: 15.0 g / L glucose, 20.0 g / L defatted soybean meal powder, 5.0 g / L yeast extract, 3.0 g / L ammonium sulfate, 17.5 g / L sodium chloride, 2.5 g / L dipotassium hydrogen phosphate, 1.0 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate, 0.1 g / L calcium chloride, 0.01 g / L ferrous sulfate, 2.0 g / L humic acid, 1000 mL deionized water, pH 9.0-9.5.

[0073] Key process parameters:

[0074] pH adjustment: The pH of the culture medium is precisely adjusted to 9.0-9.5 using 1 mol / L NaOH solution. No secondary adjustment is required after sterilization, directly adapting to the alkaline growth requirements of the strain.

[0075] Sterilization conditions: autoclave at 121℃ for 20 minutes, cool to below 30℃ and then aseptically inoculate (avoid high temperature to prevent damage to the protein activity in defatted soybean meal powder and ensure the induction effect).

[0076] Inoculation rate: Inoculate Niallia oryzisoli XG-146 seed culture (OD) at 2% (v / v). 600 =0.8-1.0), shortening the strain's adaptation period and enabling it to quickly enter the logarithmic growth phase;

[0077] Fermentation control: Temperature is controlled at 15-20℃ (simulating the low temperature conditions of industrial wastewater in winter, and simultaneously enhancing the low temperature resistance of the strain), shaking speed is 180rpm (to ensure sufficient dissolved oxygen, promote aerobic metabolism and efficient expression of functional enzymes), and fermentation cycle is 48h;

[0078] Endpoint indicator: The bacteria enter the stationary phase, with a viable count ≥ 1.0 × 10⁻⁶. 9 CFU / mL, protease activity ≥150U / mL, siderophore SU value ≥75%, fully meet the application requirements for industrial wastewater and non-point source pollution treatment as described in this invention.

[0079] Table 5 shows a comparison of the core parameters of the ordinary LB medium and the functionally enhanced fermentation medium of the present invention.

[0080] Table 5 Comparison of core parameters between ordinary LB medium and the functionally enhanced fermentation medium of this invention

[0081]

[0082] Example 3: Combined process of microbial inoculant and biochemical reactor (suitable for deep treatment of high-salt and high-alkali industrial wastewater)

[0083] Applicable scenarios: High-salt and high-alkali industrial wastewater treatment systems in industries such as chemical, printing and dyeing, and food processing (daily treatment capacity 1000-10000 m³). 3 It is suitable for the deep purification of industrial wastewater containing protein pollutants with a concentration of 0-400 mmol / L NaCl, pH 9.0-11.0, and can be combined with existing biochemical reactors to achieve COD compliance discharge.

[0084] Preparation of microbial inoculum: The Niallia oryzisoli XG-146 strain of this invention, which was stored under cold conditions, was inoculated into a functionally enhanced fermentation medium and cultured at 15°C and 180 rpm in a shaker for 48 h in a low-temperature-high-salt-high-alkali co-culture environment (the medium contained 300 mmol / L NaCl and pH 9.5) until the strain reached its OD value. 600 The seed culture of *Niallia oryzisoli* XG-146 was obtained by achieving a concentration of 0.8-1.0. A 2% inoculum was then added to a fermentation medium containing pretreated industrial wastewater, and the culture was expanded at 15°C for 48 hours to enhance the strain's adaptability to wastewater pollutants, resulting in a liquid inoculum (with a viable count of *Niallia oryzisoli* XG-146 ≥ 1.0 × 10⁻⁶). 9 (CFU / mL)

[0085] Reactor modification and operation: A microbial agent dosing device is added to the aeration zone of the existing biochemical reactor. Liquid microbial agent is continuously added at a ratio of 0.2%-0.3% of the wastewater volume. The hydraulic retention time (HRT) of the reactor is controlled at 8-10 h and dissolved oxygen (DO) ≥ 2.0 mg / L. The Niallia oryzisoli XG-146 strain colonizes in the reactor. Under stress-tolerant conditions, it secretes proteases to degrade proteinaceous organic pollutants in the wastewater and produces iron carriers to chelate iron, thereby enhancing the synergistic metabolic activity of microorganisms in the reactor and simultaneously reducing COD and organic nitrogen load.

[0086] Industrial Operation and Maintenance: Monitor the COD, pH, and salinity of the influent and effluent weekly, and dynamically adjust the bacterial agent dosage according to the pollutant concentration (increase the dosage to 0.4% when COD > 500 mg / L); test the bacterial activity in the reactor every 30 days, and when the viable count of Nialliaoryzisoli XG-146 is below 1.0 × 10⁻⁶... 6 When the concentration reaches CFU / mL, add 20% fresh liquid bacterial agent; the process is synchronized with the reactor's regular backwashing and sludge discharge, requiring no additional modifications to the core equipment.

[0087] Table 6 shows the comparison of indicators before and after treatment of high-salt and high-alkali industrial wastewater using the method of this embodiment; where n is the number of test samples, n=5, the data in the table are the average values ​​of the measurements, and the treatment time is controlled at 9h for the hydraulic retention time of the reactor.

[0088] Table 6 Comparison of indicators before and after treatment of high-salt and high-alkali industrial wastewater by liquid bacterial agent-biochemical reactor

[0089]

[0090] Example 4: Integrated process of sponge city facilities and microbial agents (suitable for urban non-point source pollution interception and treatment)

[0091] Applicable scenarios: Grass swales along urban roads, sponge infiltration strips in residential areas, rain gardens and other non-point source pollution control facilities, which are suitable for intercepting and purifying protein pollutants and suspended organic matter carried by road runoff and rainwater in residential areas, reducing the impact of non-point source pollution on receiving water bodies.

[0092] Preparation of percolation-type bacterial agent: Based on the Niallia oryzisoli XG-146 seed culture in Example 3, 4% modified zeolite (adsorbent carrier + salinity buffer), 3% humic acid (pH buffer), and 2% stress-resistance protectant (trehalose) were added. After stirring evenly, granular bacterial agent with a particle size of 3-5 mm was prepared. Vacuum dried to a moisture content ≤12%, and the viable count of Niallia oryzisoli XG-146 was ≥6.0×10⁻⁶. 7 CFU / g;

[0093] Sponge City Facility Retrofitting and Operation: A 10cm thick layer of granular microbial agent is laid in the lower part (15-20cm deep) of the infiltration layer of the sponge city facility, and an 8cm layer of quartz sand and a 5cm layer of planting soil are laid on top. Pollution-tolerant herbaceous plants (such as bermudagrass and zoysia grass) are planted. During rainfall, non-point source runoff flows through the planting soil and quartz sand layer. Suspended particulate matter is intercepted, protein pollutants are adsorbed by zeolite, and the microbial strains simultaneously secrete proteases to degrade pollutants and produce iron carriers to promote plant growth, forming a synergistic interception system of "adsorption-degradation-plant absorption".

[0094] Operation and maintenance management: Apply granular bacterial agent every 6 months (the amount applied is 25% of the initial amount), and apply an additional time before the rainy season (June and September); regularly clean the surface of the facility of fallen leaves and debris to avoid clogging and affecting runoff infiltration; monitor the COD concentration of the effluent from the facility every quarter to ensure that the non-point source pollution interception efficiency is ≥65%.

[0095] The comparison of indicators before and after processing urban non-source runoff using the method of this embodiment is shown in Table 7, where n is the number of samples detected, n=5, the data in the table are the average values ​​of the measurements, and the processing time is 60 days of continuous operation.

[0096] Table 7 Comparison of indicators before and after urban non-point source runoff treatment using granular microbial agents and sponge city facilities

[0097]

[0098] Example 5: Emergency Purification Bacterial Agent - Rapid Treatment Process for Polluted Water (Adapted for Sudden Pollution Emergency Response)

[0099] Applicable scenarios: Emergency treatment of water pollution caused by sudden excessive discharge of industrial wastewater (COD>800mg / L) and concentrated inflow of non-point source pollution, which is suitable for the needs of rapidly reducing pollutant load and preventing pollution spread.

[0100] Preparation of emergency compound microbial agent: The seed culture from Example 3 was inoculated into a functionally enhanced fermentation medium at a 2% inoculation rate, and cultured at 15℃ and 180rpm for 48 hours until the viable count of Niallia oryzisoli XG-146 in the fermentation broth was ≥1.0×10⁻⁶. 9 CFU / mL; Add 5% polyaluminum chloride (coagulant) and 3% humic acid (buffer) to the fermentation broth, stir evenly to make a suspension of emergency bacterial agent, which has both flocculation and degradation functions;

[0101] Emergency addition and treatment: In polluted water bodies (such as emergency regulating ponds for industrial wastewater, polluted river sections), add emergency bacterial agent at a ratio of 0.5%-0.8% of the water volume, turn on the aeration device (speed 80-100 rpm) and mix for 30 minutes, with a retention time of 6-8 hours; the coagulant aid quickly flocculates suspended solids and some pollutants in the water, the bacterial strains simultaneously degrade proteinaceous organic matter, and the iron carriers enhance the synergistic effect of microorganisms, rapidly reducing COD concentration;

[0102] Post-emergency maintenance: Monitor the COD concentration of the effluent within 24 hours after emergency treatment. Once the standard is met, gradually reduce the dosage until it is stopped. If the pollution area is large, multiple applications can be made in different areas. 15 days after emergency treatment, apply a conventional liquid bacterial agent (dosage 0.1%) to strengthen the restoration of the water body's micro-ecology and prevent pollution rebound.

[0103] The comparison results of indicators before and after the treatment of the suddenly polluted water body using the method of this embodiment are shown in Table 8; where n is the number of test samples, n=5, the data in the table are the average values ​​of the measurements, and the treatment time is 7 hours of emergency stay.

[0104] Table 8 Comparison of indicators before and after emergency treatment of polluted water bodies with microbial agents.

[0105]

Claims

1. A strain of bacteria that is resistant to low temperature and salt-alkaline, and has the functions of degrading protein and producing siderophore, characterized in that, The strain with low temperature and salt tolerance, protein decomposition and siderophore production functions is Niallia oryzisoli XG-146, which is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38206 and deposit date of April 9, 2026. 2.The strain of low temperature and salt-alkaline resistant, protease producing and siderophore producing according to claim 1, characterized in that, The Niallia oryzisoli XG-146 functionally enhanced fermentation medium contained the following concentrations: glucose 15.0 g / L, defatted soybean meal powder 20.0 g / L, yeast extract 5.0 g / L, ammonium sulfate 3.0 g / L, sodium chloride 17.5 g / L, dipotassium hydrogen phosphate 2.5 g / L, potassium dihydrogen phosphate 1.0 g / L, magnesium sulfate 0.5 g / L, calcium chloride 0.1 g / L, ferrous sulfate 0.01 g / L, and humic acid 2.0 g / L.

3. A microbial inoculant having low-temperature and saline-alkaline tolerance, protease-degrading and siderophore-producing functions, characterized in that, Microbial agents with low-temperature and salt-alkali resistance, protein decomposition and siderophore production functions include Nialliaoryzisoli XG-146 as described in claim 1.

4. The application of the strains described in claim 1, which are resistant to low temperatures and salt and alkali, and have the functions of protein decomposition and iron carrier production, in the treatment of industrial wastewater and non-point source pollution.

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