A sulfate-reducing bacterium and its application in environmental bioremediation

Abstract

The present invention belongs to the technical field of environmental microbial remediation, and specifically relates to a sulfate-reducing bacterium and its application in environmental bioremediation. The sulfate-reducing bacterium XC116 is Desulfoscipio sp., and was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on March 12, 2024. The address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, and the deposit number is: CGMCC No. 41184. The present invention provides a novel sulfate-reducing bacterium strain XC116, which has been identified as Desulfoscipio a new species. This strain has unique metabolic diversity and can grow chemoautotrophically using CO2 and H2 as carbon sources, and can also achieve heterotrophic growth using various short-chain fatty acids such as lactic acid, pyruvic acid, formic acid, and hexanoic acid.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental microbial remediation, and specifically relates to a sulfate-reducing bacterium and its application in environmental bioremediation. Background Art

[0002] With the rapid development of industry and agriculture, a large number of metal and non-metal pollutants are discharged into aquatic and terrestrial environments, leading to increasingly serious environmental pollution problems. Among them, excessive sulfate input can cause soil acidification, and the acidic environment can activate heavy metal elements, making them extremely prone to migration under the action of factors such as surface runoff and soil seepage, and then causing combined pollution to the surrounding soil and water environments, ultimately threatening regional ecological security and public health. Sulfate-reducing bacteria (SRB) are a group of prokaryotic microorganisms that use organic compounds (chemolithoheterotrophic) or inorganic compounds (chemolithoautotrophic) as electron donors and produce sulfide through the sulfate reduction metabolic pathway. The uniqueness of these microorganisms lies in: on the one hand, they carry out anaerobic respiration using sulfate as the terminal electron acceptor; on the other hand, they can efficiently utilize pollutants such as organic acids, alcohols, and aromatic compounds in industrial and agricultural waste as electron donors and carbon sources, and finally reduce sulfate to highly reactive divalent sulfide ions. The metabolite sulfide ions can react with various heavy metal ions (such as Cd 2+ 、Pb 2+ 、Zn 2+ etc.) in wastewater to form precipitation reactions, generating insoluble metal sulfides, thereby significantly reducing the mobility and biological toxicity of heavy metals. This metabolic characteristic of SRB shows unique advantages in the field of environmental remediation: it can not only simultaneously remove three types of pollutants, namely heavy metals, sulfates, and organic pollutants, but also achieve the stabilization of heavy metals by forming metal sulfide precipitates.

[0003] Desulfallaceae Family is a representative taxonomic unit at the family level among SRB with the characteristic of spore production. Members of this family can use sulfate, sulfite, and thiosulfate as electron acceptors for energy metabolism. Currently, this family contains four recognized genera: Desulfallas 、 Desulfotruncus 、 Sporotomaculum and Desulfoscipio ,which have complex metabolic types. Desulfallas 、 Desulfotruncus and DesulfoscipioMembers of the genus are all strict anaerobes with respiratory metabolic capabilities. They can use a variety of carboxylic acids (including short-chain to long-chain fatty acids) and alcohols as electron donors and carbon sources, and use sulfate, sulfite, and thiosulfate as electron acceptors for chemoorganotrophic growth to produce sulfide ions, with the substrate being completely oxidized to CO2. In addition, members of these three genera can achieve chemolithoautotrophic growth in a CO2 / H2 environment; and can use pyruvate for fermentative growth under sulfate-free conditions. In contrast, Sporotomaculum Members of the genus cannot use inorganic electron acceptors for respiratory metabolism and can only grow fermentatively using benzoate or hydroxybenzoate as the sole carbon and energy source. Therefore, Desulfallas , Desulfotruncus and Desulfoscipio genera may represent an ecologically very important but underestimated group of SRB. They have a wide substrate spectrum (from simple organic compounds to long-chain fatty acids and some aromatic compounds) and play multiple key roles in the biogeochemical cycle, including participating in the biodegradation of organic pollutants and toxic and harmful pollutants, driving the carbon cycle and sulfur cycle, etc.

[0004] Currently isolated Desulfallas , Desulfotruncus and Desulfoscipio genus species have been found in a variety of anaerobic environments, including gas stations, acidic metal- and sulfate-containing wastewater, fresh water, hot compost, cold fjord sediments, and geothermal groundwater, etc., indicating that they have strong adaptability to a variety of environments due to their multiple metabolic capabilities. However, all species reported in the Desulfallaceae family to date were isolated and identified in 2008 or earlier, and only two species were found in each genus. Since 2009, few Desulfallaceae family species have been reported. Therefore, excavating more Desulfallaceae family sulfate-reducing bacteria strains and exploring their metabolic capabilities and substrate ranges can provide strain resources for the environmental remediation of metal and non-metal mixed contaminated sites. Summary of the Invention

[0005] The object of the present invention is to provide a sulfate-reducing bacterium XC116 and its application in environmental bioremediation.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A sulfate-reducing bacterium, sulfate-reducing bacterium XC116 ( Desulfoscipio sp.) was deposited with the General Microbiology Center of the China Committee for Culture Collection of Microorganisms on March 12, 2024, at the address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, with the deposit number: CGMCC No. 41184, and the taxonomic name is: Desulfoscipio sp.

[0008] The strain XC116 grows with lactate as the carbon source and electron donor and sulfate as the energy substrate in an anaerobic inorganic salt medium with sodium bicarbonate buffer salt.

[0009] The strain XC116 grows in an anaerobic inorganic salt medium containing sulfate and lactate.

[0010] A sulfate-reducing bacterium as described above, and the application of the strain in a sulfate reducing agent.

[0011] A sulfate-reducing bacterium as described above, and the application of the strain in degrading one or more of organic acids and precipitating heavy metals in the environment.

[0012] The organic acid is lactate and the heavy metal is iron.

[0013] A sulfate-reducing bacterium agent comprising the sulfate-reducing bacterium XC116 as described above.

[0014] A water pollution remediation bacterium agent comprising the sulfate-reducing bacterium XC116 as described above.

[0015] The bacterium agent contains the culture solution of the strain, the concentrated culture solution or the cultured bacterial suspension.

[0016] The culture solution grows with lactate as the electron donor and carbon source and sulfate as the electron acceptor in an anaerobic inorganic salt medium with 30 mM sodium bicarbonate buffer salt; the concentrated culture solution is obtained by centrifuging the obtained culture solution and storing the bacterial cells in a sealed anaerobic vial to obtain the concentrated culture solution.

[0017] The water pollutants are one or more of water heavy metals and organic acids.

[0018] The beneficial effects produced by the present invention are as follows:

[0019] The present invention provides a novel sulfate-reducing bacterium strain XC116, which is identified as DesulfoscipioA new species of the genus. This strain has unique metabolic diversity. It can carry out chemoautotrophic growth using CO2 and H2 as carbon sources, and can also achieve heterotrophic growth using various short-chain fatty acids such as lactic acid, pyruvic acid, formic acid, and caproic acid. Experiments show that in an anaerobic inorganic salt medium, when using 10 mM lactic acid as the carbon source, strain XC116 can completely reduce 480 mg / L of sulfate to sulfide ions within 50 days, synchronously achieving sulfate reduction and organic carbon conversion. In the in-situ remediation of mixed-pollution ecosystems, in the presence of sulfate, this strain of bacteria can not only effectively degrade sulfates and organic pollutants in water, but the sulfide ions produced by its metabolism can also form precipitates with heavy metal ions to achieve the synchronous removal of heavy metals. The present invention provides a microbial germplasm resource with important application value for the bioremediation of metal-nonmetal composite polluted sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a production curve graph of the sulfate-reducing bacterium XC116 of the present invention reducing sulfate to produce sulfide ions.

[0021] Figure 2 It is a scanning electron microscope image of the sulfate-reducing bacterium XC116 strain of the present invention.

[0022] Figure 3 It is a phylogenetic tree constructed by the homology comparison of the 16S rRNA gene sequences of the sulfate-reducing bacterium XC116 of the present invention and related strains.

[0023] Figure 4 It is the OD 600 value graph of the sulfate-reducing bacterium XC116 strain of the present invention growing for 1 month at different temperatures, pH values, and salinities.

[0024] Figure 5 It is a graph of the black precipitate formed by the reaction of the sulfide ions generated by the sulfate reduction of the sulfate-reducing bacterium XC116 strain of the present invention with ferric ions. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following further illustrates the specific embodiments of the present invention in conjunction with examples. It should be noted that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention and are not limited to the present invention.

[0026] The strain XC116 of the present invention was isolated from a contaminated groundwater sample and belongs to the members of the Desulfoscipio genus at the taxonomic level; this strain XC116 can completely reduce 480 mg / L of sulfate to sulfide ions within 50 days in an anaerobic inorganic salt medium using 10 mM lactic acid as the carbon source (see Figure 1), while reducing sulfate, it also has the effect of degrading organic carbon; in the in-situ metal and non-metal mixed pollution ecosystem, this strain can degrade sulfate and organic pollutants in polluted water, and the generated sulfide ions can precipitate and remove heavy metal ions.

[0027] The experimental methods, materials and reagents used in the following examples are all conventional methods unless otherwise specified.

[0028] Each liter of inorganic salt anaerobic medium contains: 1.0 g of NaCl, 0.5 g of MgCl2•6H2O, 0.2 g of KH2PO4, 0.3 g of NH4Cl, 0.3 g of KCl, 0.015 g of CaCl2•2H2O, 1.5 mg of FeCl2•4H2O, 190 μg of CoCl2•6H2O, 100 μg of MnCl2•4H2O, 70 μg of ZnCl2, 6 μg of H3BO3, 36 μg of Na2MoO4•2H2O, 24 μg of NiCl2•6H2O, 2 μg of CuCl2•2H2O, 6 μg of Na2SeO3•5H2O, 8 μg of Na2WO4•2H2O, and 0.025% (w / v) of resazurin oxygen indicator. After the headspace of the medium is heated to boiling under a high-purity N2 atmosphere and cooled to room temperature in an ice bath, 24 mg of L-cysteine, 48 mg of Na2S•9H2O, and 77 mg of DTT (dithiothreitol) are added as reducing agents to remove oxygen, and then 2.52 g of NaHCO3 (30 mM) is added as a buffer. The pH is adjusted to 7.2 - 7.3 by passing CO2 gas, and the volume is made up to 1 L with water. 80 mL of the medium is dispensed into 120 mL glass serum bottles, and the headspace gas is replaced with N2 / CO2 (80 / 20, v / v), sealed with butyl rubber stoppers and aluminum caps, and sterilized at 121 °C for 30 min.

[0029] Semi-solid medium for bacterial isolation: The preparation and components of the medium are the same as above. Preparation method of semi-solid medium: When dispensing the medium, 0.08 - 1% (w / v) of agar with a low gelling temperature (<30 °C) is added to the serum bottle containing 9 mL of the medium to prepare a semi-solid gel medium.

[0030] Preparation of Wolin complex vitamins: 20 μg / L of biotin, 20 μg / L of folic acid, 100 μg / L of pyridoxine hydrochloride, 50 μg / L of riboflavin, 50 μg / L of thiamine, 50 μg / L of pantothenic acid, 50 μg / L of niacin, 50 μg / L of vitamin B 12 50 μg / L, 50 μg / L of p-aminobenzoic acid, 50 μg / L of lipoic acid. The vitamin solution is filtered through a 0.22 μm pore size filter membrane into a sterile 2 mL centrifuge tube and stored at -20 °C for later use. 0.1 mL of Wolin complex vitamins is added to every 80 mL of the medium.

[0031] Spectrophotometric detection method of sulfide ions: Sample preparation: (1) 50 mM HCl; (2) 5 mM CuSO4 solution containing 50 mM HCl. Sample measurement: Pipette 3.9 mL of 5 mM CuSO4 solution containing 50 mM HCl into a 10 mL test tube, then use a syringe to draw 0.1 mL of the culture solution from the serum bottle and add it thereto, then invert and mix well. After standing for 30 s, measure the absorbance at 480 nm using an Agilent Cary 60 UV-Vis spectrophotometer. The mixture of 0.1 mL of the culture solution and 3.9 mL of HCl (50 mmol / l) is used as the blank.

[0032] Example 1: Enrichment, isolation and identification of sulfate-reducing bacterium strain XC116 of the present invention

[0033] (1) Enrichment of strain XC116: Place the collected contaminated groundwater sample, inorganic salt medium and other required sterile materials in an anaerobic glove box containing N2 / H2 (95 / 5, v / v) for about 2 h. Add about 5 mL of the groundwater sample to a 120 mL serum bottle containing 80 mL of the medium. After covering and sealing the rubber stopper, transfer the serum bottle out of the glove box. Use a syringe to add 0.1 mL of Wolin complex vitamins, 0.8 mL of 1 M sodium lactate, and 0.4 mL of 1 M sodium sulfate. Incubate in the dark and statically in a 30 °C incubator. Use a spectrophotometer to monitor the generation of the product sulfide ions. After all sulfate radicals are reduced to sulfide ions, transfer 3% (v / v) of the enriched culture to fresh above-mentioned inorganic salt liquid medium, and then add 0.1 mL of Wolin complex vitamins, 0.8 mL of 1 M sodium lactate, and 0.4 mL of 1 M sodium sulfate. Repeat this cycle for 7 consecutive subcultures.

[0034] (2) Isolation of strain XC116: After highly enriching culture by continuous subculture for 7 times, transfer 1 mL of the enriched solution to 9 mL of semi-solid agar medium in an uncured state containing 10 mM sodium lactate and 5 mM sodium sulfate as the 10 -1 dilution gradient, and then transfer 1 mL of the bacterial solution from this 10 -1 dilution bottle to a new medium as the 10 -2 dilution, and repeat this operation until the 10 -10Culture flasks with dilution degrees were used. After the agar had completely solidified, they were inverted and cultured in the dark. After the sodium sulfate had been reduced, black single bacteria would appear. Pick the black single colonies from the high-gradient dilution flasks and transfer them to a liquid inorganic salt medium. Thus, the first round of dilution and isolation work was completed. Then, 1 mL of the preliminarily isolated sulfate-reducing culture solution was transferred to 9 mL of semi-solid agar medium containing 10 mM sodium lactate and 5 mM sodium sulfate in an uncured state. Repeat the above dilution and isolation steps. After the agar had completely solidified, it was inverted and cultured in the dark. When black single bacteria appeared, pick the black single colonies from the high-gradient dilution flasks and transfer them to a liquid inorganic salt medium to complete the isolation of sulfate-reducing bacteria.

[0035] (3)Identification of strain XC116:

[0036] Morphological identification:

[0037] Centrifuge the sulfate-reducing bacteria broth obtained in step (2) at 4 °C and 15,000 xg for 10 min to collect cells in the logarithmic growth phase. After fixing the cells with 2.5% glutaraldehyde and dehydrating them, observe the cell morphology under an electron microscope (see Figure 2 ). The results showed that the cells of the sulfate-reducing bacteria strain XC116 isolated in the above steps were straight or slightly curved rod-shaped, with slightly pointed ends, a length of 2.0–4.0 μm, a width of 0.4–0.5 μm, and were Gram-negative.

[0038] 16S rRNA sequence homology analysis:

[0039] Extract the total DNA of the strain as an amplification template, and perform PCR amplification with the bacterial 16S rRNA universal primers 27F (5”-AGAGTTTGATCCTGGCTCAG-3”, sequence 1) and 1492R (5”-GGTTACCTTGTTACGACTT-3”, sequence 2). Submit the amplification product to a sequencing company for Sanger sequencing. The 16S rRNA gene fragment obtained by PCR amplification was 1442 bp, with a G+Cmol% of 56.2%. The gene sequence was compared online with the database of the Biotechnology Information Center. The 16S rRNA gene sequence alignment analysis showed that the sequence homology of strain XC116 with Desulfoscipio gibsoniae strain Groll (DSM 7213) was the highest, with a similarity of 95.4%. However, their abilities to utilize substrates were different. In an anaerobic medium containing sulfate, strain Groll could degrade aromatic compounds (such as benzoic acid, 3-hydroxybenzoic acid, phenol, catechol, benzaldehyde, 3-hydroxybenzaldehyde, etc.), but strain XC116 could not utilize these aromatic compounds.

[0040] > Desulfoscipio sp. strain XC116 (1442 bp)

[0041]

[0042] Constructing phylogenetic tree:

[0043] To understand the phylogeny of the rich community, the full-length 16S rRNA sequences were uploaded to NCBI for sequence alignment. Relevant closely related 16S rRNA sequences were selected, and a phylogenetic tree was constructed using MEGA software (Version 7.0) based on the maximum likelihood method (Maximallikelyhood, ML). The constructed phylogenetic tree was detected by the bootstrap method, with the number of bootstrap replicates set to 1000 times, and the sequence identity analysis was performed using the MegAlign program in the DNASTAR software package. The phylogenetic tree of strain XC116 is shown in Figure 3 Figure.

[0044] Based on gene sequence analysis, the lineage of the sulfate-reducing bacterial strain obtained by our cultivation belongs to Desulfoscipio , which is classified in the domain Bacteria, Desulfotomaculota phylum, Desulfotomaculia class, Desulfotomaculales order, Desulfallaceae family, Desulfoscipio genus.

[0045] Physiological and biochemical characteristics identification:

[0046] The above-mentioned isolated and purified strain XC116 was identified as a Gram-negative bacterium. This strain was deposited in the China General Microbiological Culture Collection Center (abbreviated as CGMCC, address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing) on March 12, 2024, with the deposit number CGMCC NO. 41184, hereinafter simply referred to as strain XC116.

[0047] Example 2: Growth characteristics analysis of strain XC116

[0048] Optimum temperature, optimum pH and optimum salinity growth experiments of strain XC116 were carried out, specifically as follows:

[0049] (1) Optimum temperature growth experiment: Using the above anaerobic inorganic salt liquid medium, 10 mM lactic acid, 5 mM sodium sulfate, and 0.1 mL of Wolin complex vitamin solution were added to each 80 mL of the medium, and 3% (v / v) of the pure culture of strain XC116 (OD 600 was 0.072) was inoculated. The cultures were incubated statically in the dark at 4°C, 10°C, 20°C, 30°C, 37°C, 40°C, 45°C and 50°C in an incubator, with three replicates set for each temperature. The OD 600 value in the culture flask was monitored every 10 days.

[0050] (2)Optimal pH growth experiment: Using the anaerobic inorganic salt liquid medium described above, treatment groups with pH 7.0 and pH 7.2 were set up; 30 mM 2-morpholinoethanesulfonic acid (MES) was used to replace 30 mM NaHCO3 buffer in the inorganic salt medium, and treatment groups with pH 5.5, pH 6.0, and pH 6.5 were set up; 20 mM HEPES was used to replace 30 mM NaHCO3 buffer in the inorganic salt medium, and treatment groups with pH 7.5, pH 7.8, pH 8.0, and pH 8.5 were set up; after preparation, 10 mM lactic acid, 5 mM sodium sulfate, and 0.1 mL of Wolin complex vitamin solution were added to 80 mL of the culture media with pH 5.5, pH 6.0, pH 6.5, pH 7.0, pH 7.2, pH 7.5, pH 7.8, pH 8.0, and pH 8.5 respectively, and 3% (v / v) of the pure culture of strain XC116 (OD 600 was 0.072) was inoculated. Three replicates were set for each treatment. The cultures were incubated statically in the dark in an incubator at 30 °C. The OD 600 value in the culture flask was monitored every 10 days.

[0051] (3)Optimal salinity growth experiment: Using the anaerobic inorganic salt liquid culture described above, media with NaCl contents of 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5% (w / v) were obtained by adding different concentrations of NaCl, and other conditions remained unchanged. Then, 10 mM lactic acid, 5 mM sodium sulfate, and 0.1 mL of Wolin complex vitamin solution were added to each 80 mL of the culture medium, and 3% (v / v) of the pure culture of strain XC116 (OD 600 was 0.072) was inoculated. Three replicates were set for each treatment. The cultures were incubated statically in the dark in an incubator at 30 °C. The OD 600 value in the culture flask was monitored every 10 days.

[0052] It can be seen from Figure 4 that the optimal growth temperature of strain XC116 is 30 °C, and the growth temperature range is 20 - 45 °C; the optimal pH is 6.5 - 7.2, and the growth pH range is 6.0 - 8.0; the optimal salinity is 0 g / L, and the growth salinity range is not limited to 0 - 5 g / L, and it can also survive and completely reduce sodium sulfate under the condition of 5 g / L.

[0053] Example 3: Degradation of lactic acid by strain XC116

[0054] Strain XC116 was cultured under the above optimal culture conditions, that is, the pH of the anaerobic inorganic salt liquid medium described above was adjusted to 7.0, 10 mM lactic acid and 5 mM sodium sulfate were added, NaCl was not added, and the culture was incubated statically in the dark at 37 °C. Then, the culture product was measured, specifically:

[0055] (1)Measure the process of sulfate reduction by strain XC116 using the spectrophotometry described above.

[0056] (2)Qualitatively and quantitatively analyze the organic acids produced during the lactic acid degradation process using high performance liquid chromatography. The specific analysis method is as follows: Agilent 1260 series liquid chromatograph equipped with a diode array detector (DAD); chromatographic column: CNW Athena C18-WP (250 mm × 4.6 mm, 5 μm). Before injection, each milliliter of the sample needs to be acidified with 2 μL of concentrated sulfuric acid (98%); chromatographic conditions: 20 mM pH 2.7 Na2HPO4 as the mobile phase; detection wavelength 210 nm; flow rate, 0.7 mL / min; column temperature, 30 °C; analysis time, 30 min; injection volume 20 μL.

[0057] Spectrophotometric detection showed that strain XC116 could produce 5 mM of sulfide ions after 1 month of cultivation, indicating that strain XC116 could completely convert 5 mM of sulfate into sulfide ions; detection of organic acids using high performance liquid chromatography found that only trace amounts of lactic acid were detected, indicating that most of the lactic acid was utilized by strain XC116 as an electron donor for the sulfate reduction process and degraded.

[0058] Example 4: The sulfide ions generated by strain XC116 during sulfate reduction react with metal ions to form a precipitate

[0059] Add 5 mM of lactic acid, 5 mM of ferric sulfate, and 0.1 mL of Wolin complex vitamins to 80 mL of anaerobic inorganic salt medium, and transfer the cultured strain XC116 according to an inoculation amount of 3% (v / v). Incubate statically in the dark at 30 °C, and take out the culture flask every 5 days during the cultivation period to observe the black precipitate.

[0060] The results showed that the sulfide ions generated by strain XC116 during sulfate reduction could react with ferric ions to form a black precipitate (see Figure 5 ).

[0061] In summary, the strain XC116 provided by the present invention can use organic acids (such as lactic acid, formic acid, butyric acid, caproic acid, caprylic acid, pyruvic acid, etc.) as electron donors and carbon sources in anaerobic inorganic salt medium, and reduce the electron acceptor sulfate to sulfide ions. At the same time, strain XC116 can also grow autotrophically using H2 and CO2 under sulfate conditions. Therefore, in sites contaminated with a mixture of organic matter, sulfate, and heavy metals, many organic substances (such as short-chain fatty acids) in wastewater and waste residues can be used as electron donors and carbon sources for strain XC116 to remove excessive sulfate in the site, and the resulting sulfide ions can also react with heavy metal ions to form precipitates, thereby reducing the toxicity of heavy metals to biological populations.

[0062] The above-described several embodiments are several implementation manners of the present invention and cannot be used as a limitation on the scope of the present invention. Without departing from the concept of the present invention, there can be various improved cases, all of which are within the protection scope of the present invention.

Claims

1. A sulfate-reducing bacterium, characterized in that: Sulfate-reducing bacterium XC116 ( Desulfoscipio sp.) was deposited at the China General Microbiological Culture Collection Center on March 12, 2024. Address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is: CGMCC No. 41184.

2. Use of the sulfate-reducing bacterium according to claim 1, characterized in that: Use of the sulfate-reducing bacterium XC116 as a sulfate reducing agent.

3. Use of the sulfate-reducing bacterium according to claim 1, characterized in that: Use of the sulfate-reducing bacterium XC116 in degrading one or more of lactic acid and precipitating heavy metals in the environment.

4. Use of sulfate-reducing bacteria according to claim 3, characterized in that: The heavy metal is iron.

5. A sulfate-reducing bacterial agent, characterized in that: Comprising the sulfate-reducing bacterium XC116 according to claim 1.

6. A water pollution remediation bacterial agent, characterized in that: Comprising the sulfate-reducing bacterium XC116 according to claim 1.

7. The microbial agent according to claim 6, characterized in that: The bacterial agent contains the culture solution, culture solution concentrate or cultured bacterial suspension of the strain.

8. The water pollution remediation bacterial agent according to claim 6, characterized in that: The water body pollutants are one or more of heavy metals and lactic acid in the water body.

Images