A strain of serratia marcescens and its use

Abstract

The application discloses a Serratia marcescens strain and application thereof, and belongs to the field of environmental biological technology, and particularly relates to a Serratia marcescens strain and application thereof.The Serratia marcescens strain is Serratia marcescens A2, which is preserved in the China General Microbiological Culture Collection Center, 1 Xibenchengli Xijie 3, Chaoyang District, Beijing, on May 26, 2022, and has a preservation number of CGMCC No.24974.The Serratia marcescens strain is used for adsorbing heavy metal molybdenum.

Description

Technical Field

[0001] This invention belongs to the field of environmental biotechnology, specifically relating to a *Serratia marcescens* strain and its applications. Background Technology

[0002] Molybdenum, a rare high-melting-point heavy metal, is an important raw material for metal processing due to its high melting point. However, the production and processing of molybdenum and its compounds generate pollutants such as molybdenum-containing wastewater and particulate matter. Furthermore, sudden events such as tailings leaks can cause severe molybdenum pollution in water and soil. As a trace element essential for plant growth, molybdenum accumulates in large quantities in the roots, stems, and leaves of plants after entering the soil, eventually entering the animal body and causing molybdenum poisoning. Molybdenum in the environment is also transferred to the human body through the food chain. The presence of molybdenum in the human body can increase the number of neutrophils and lymphocytes in alveolar lavage fluid, leading to respiratory inflammation. Molybdenum is also toxic to human reproductive organs. In addition, molybdenum in the human body has certain heritability and carcinogenicity. Therefore, research on the removal of heavy metal molybdenum from the environment is of great significance. Currently, among the methods for heavy metal removal, microbial methods are characterized by low cost and good efficiency. However, their poor specificity, strict climate requirements, and slow growth limit their development. Therefore, finding a suitable microbial removal method for heavy metal molybdenum in cold regions is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to address the lack of a suitable microbial removal method for heavy metal molybdenum in cold regions, and to provide a *Serratia marcescens* strain and its application.

[0004] A strain of Serratia marcescens, namely Serratia marcescens A2, is deposited at the China General Microbiological Culture Collection Center (CGMCC) at No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, on May 26, 2022, with accession number CGMCC No. 24974.

[0005] A type of Serratia serratifolia strain was used to adsorb the heavy metal molybdenum.

[0006] Morphological characteristics of a *Serratia marcescens* strain: When the strain was streaked onto beef extract peptone medium and incubated at 30°C for 24 hours, the colonies were approximately 1 mm in diameter, regularly round, red, with a smooth, raised, and moist surface, opaque, and viscous in texture.

[0007] The present invention has the following beneficial effects:

[0008] 1. Using the Serratia marcescens of the present invention to remove heavy metal molybdenum, the removal rate of heavy metal molybdenum can reach 17-38% at room temperature (30℃);

[0009] II. Using the Serratia marcescens of the present invention to remove heavy metal molybdenum, the removal rate of heavy metal molybdenum can reach 27-59% at low temperature (10°C).

[0010] The present invention also provides a method for screening and identifying the above-mentioned Serratia marcescens, comprising the following steps: sequentially enriching and culturing the collected soil and screening it step by step to obtain the bacteria;

[0011] The soil in question was collected from the topsoil of a garbage recycling station in Harbin. Attached Figure Description

[0012] Figure 1 The image shows the removal effect of a *Serratia marcescens* strain on heavy metal molybdenum at room temperature in Example 1.

[0013] Figure 2 The effect of a *Serratia marcescens* strain on the removal of heavy metal molybdenum at low temperature in Example 1 is shown in the figure. Detailed Implementation

[0014] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications and substitutions made to the methods, steps, or conditions of the present invention without departing from the essence of the invention are within the scope of the present invention.

[0015] Specific Implementation Method 1: The screening and identification of a *Serratia marcescens* strain in this implementation method includes the following steps:

[0016] (I) Enrichment and Screening: Topsoil was collected from a landfill in Harbin to obtain soil samples. 5g of the soil sample was placed in 45mL of beef extract peptone medium and cultured at 30℃ and 200r / min for 24h for bacterial enrichment. 2mL of the enriched culture was then transferred to a medium containing MoO4. 2- After the 100 mg / L beef extract peptone medium became turbid in the enrichment flask, 1 mL of the enrichment medium was transferred to a medium containing MoO4. 2- The beef extract peptone medium with a concentration of 200 mg / L was gradually increased in MoO4. 2- To achieve a concentration of 3000 mg / L, the enriched culture medium was placed in sterile physiological saline and subjected to 10 [units of concentration]. -1 ~10 -9 Nine different dilutions were performed, and 20 μL of each dilution was spread onto a substrate containing MoO4. 2- On solid agar plates, inverted and incubated at 30°C for 3 days, select single red colonies from the plates containing MoO4. 2- The solid beef extract peptone plates were streaked three times to obtain pure bacteria, which were then numbered and preserved in glycerol.

[0017] The beef extract peptone culture medium formula is as follows: sodium molybdate, 3.0g beef extract, 10.0g peptone, 5.0g NaCl, 1000mL water, pH 7.4-7.6, sterilized at 120℃ for 30min.

[0018] The MoO4-containing 2- The solid beef extract peptone formula is as follows: 3000mg sodium molybdate, 15.0g agar, 3.0g beef extract, 10.0g egg white, 5.0g NaCl, 1000mL water, pH 7.4-7.6, sterilized at 120℃ for 30min.

[0019] (II) Identification: The selected red strains were sent to Shanghai Meiji Biotechnology Co., Ltd. for sequencing. The nucleotide sequence is as follows:

[0020]

[0021] The sequencing results were compared with BLAST sequences on the NCBI website and identified as Serratia marcescens, as shown in Table 1.

[0022] Table 1

[0023]

[0024]

[0025] Specific Implementation Method Two: The difference between this implementation method and Specific Implementation Method One is that: a strain of Serratia marcescens, namely Serratia marcescens A2, is deposited at the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, on May 26, 2022, with accession number CGMCC No. 24974.

[0026] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that a *Serratia marcescens* strain is used to adsorb the heavy metal molybdenum. The other steps are the same as in Specific Implementation Method One or Two.

[0027] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that a *Serratia marcescens* strain is used to adsorb heavy metal molybdenum at room temperature or low temperature, specifically by following these steps:

[0028] 1. Add *Serratia marcescens* strain to a culture medium containing sodium molybdate to obtain a mixed culture medium;

[0029] The inoculum size of *Serratia marcescens* in the mixed culture medium described in step one is 1%.

[0030] The *Serratia marcescens* strain mentioned in step one is *Serratia marcescens* A2, deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, on May 26, 2022, with accession number CGMCC No. 24974.

[0031] The formulation of the sodium molybdate-containing culture medium mentioned in step one is as follows: sodium molybdate 0.5 mmol to 20 mmol, beef extract 3.0 g, peptone 10.0 g, NaCl 5.0 g, water 1000 mL; the pH of the culture medium is 7.4 to 7.6, and it is sterilized at 120℃ for 30 min.

[0032] Second, first place the mixed culture medium in a shaker, and then incubate it at 10℃ or 30℃ for 4 days. After taking it out, centrifuge it at 4℃ and a centrifugation speed of 6000r / min~8000r / min for 8min~10min to complete the adsorption.

[0033] The beneficial effects of the present invention are verified through the following embodiments:

[0034] Example 1: A *Serratia marcescens* strain was used to adsorb the heavy metal molybdenum at room temperature, specifically by following these steps:

[0035] 1. Add *Serratia marcescens* strain to each of the five groups of culture media containing sodium molybdate to obtain mixed culture media;

[0036] The inoculum size of *Serratia marcescens* in the mixed culture medium described in step one is 1%.

[0037] The *Serratia marcescens* strain mentioned in step one is *Serratia marcescens* A2, deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, on May 26, 2022, with accession number CGMCC No. 24974.

[0038] The formula for the sodium molybdate-containing culture medium mentioned in step one is as follows: sodium molybdate, beef extract 3.0g, peptone 10.0g, NaCl 5.0g, and water 1000mL; the pH of the culture medium is 7.4-7.6, and it is sterilized at 120℃ for 30min.

[0039] In step one, the concentrations of sodium molybdate in the five culture media containing sodium molybdate were 0.5 mM, 1 mM, 5 mM, 10 mM, and 20 mM, respectively.

[0040] Second, first place the mixed culture medium in a shaker, then shake it at 30℃ for 4 days. After taking it out, centrifuge it at 4℃ and a centrifugation speed of 8000r / min for 10 minutes to complete the adsorption.

[0041] The removal effect of a *Serratia marcescens* strain on the adsorption of heavy metal molybdenum at room temperature in Example 1 is shown in the figure. Figure 1 As shown.

[0042] Example 2: A *Serratia marcescens* strain was used to adsorb the heavy metal molybdenum at room temperature, specifically by following these steps:

[0043] 1. Add *Serratia marcescens* strain to each of the five groups of culture media containing sodium molybdate to obtain mixed culture media;

[0044] The inoculum size of *Serratia marcescens* in the mixed culture medium described in step one is 1%.

[0045] The *Serratia marcescens* strain mentioned in step one is *Serratia marcescens* A2, deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, on May 26, 2022, with accession number CGMCC No. 24974.

[0046] The formula for the sodium molybdate-containing culture medium mentioned in step one is as follows: sodium molybdate, beef extract 3.0g, peptone 10.0g, NaCl 5.0g, and water 1000mL; the pH of the culture medium is 7.4-7.6, and it is sterilized at 120℃ for 30min.

[0047] In step one, the concentrations of sodium molybdate in the five culture media containing sodium molybdate were 0.5 mM, 1 mM, 5 mM, 10 mM, and 20 mM, respectively.

[0048] Second, first place the mixed culture medium in a shaker, then incubate at 10℃ for 4 days. After taking it out, centrifuge it at 4℃ and a centrifugation speed of 8000r / min for 10 minutes to complete the adsorption.

[0049] The removal effect of a *Serratia marcescens* strain on the adsorption of heavy metal molybdenum at room temperature in Example 2 is shown in the figure. Figure 2 As shown.

[0050] Under the treatment conditions described in Example 1: at room temperature, when the molybdenum concentration in the culture medium was 1 mM, Serratia marcescens showed good adsorption of molybdenum, with an adsorption rate of 37.88%; at low temperature, when the molybdenum concentration in the culture medium was 0.5 mM, Serratia marcescens showed good adsorption of molybdenum, with an adsorption rate of 58.66%.

Claims

1. The application of a *Serratia marcescens* strain, characterized in that... The *Serratia marcescens* strain was used to adsorb the heavy metal molybdenum; the removal rate of heavy metal molybdenum at 30℃ can reach 17-38%; the removal rate of heavy metal molybdenum at 10℃ can reach 27-59%. The strain is *Serratia marcescens* (Serratia marcescens). Serratia marcescens A2 is deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing. The deposit date is May 26, 2022, and the accession number is CGMCC No. 24974.

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