Tylosin-degrading bacteria and application thereof

Abstract

The present application belongs to the technical field of microorganisms, and particularly relates to a tylosin-degrading bacterium and application thereof. Through extensive screening, a new strain of Rhodococcus rhodochrous TYL-1 with good tylosin-degrading effect is found, the preservation number of which is CGMCC No. 38881. The strain can accelerate the biodegradation of tylosin at 30-35 DEG C, maintain good degradation function at pH 5-9, and has a degradation half-life of 3.85 days (about 90.4 hours), and can be used for bioremediation of tylosin-polluted environment, and has good application value.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically, this invention relates to a tylosin-degrading bacterium and its application. Background Technology

[0002] Tylosin (TYL) is a antibiotic produced by *Streptomyces freundii*. Streptomyces fradiae Tylosin is a macrolide antibiotic produced through fermentation, specifically targeting mycoplasma. It inhibits peptidyl transferase activity and prevents bacterial protein synthesis by specifically binding to the functional region of the 23S rRNA of the large 50S ribosomal subunit of bacteria. It exhibits significant antibacterial activity against various Gram-positive (G+) bacteria and some Gram-negative (G-) bacteria, as well as spirochetes. It is one of the most potent macrolide antibiotics against mycoplasma and is widely used to prevent and treat swine epidemic pneumonia, chronic respiratory disease in chickens, and various infectious diseases caused by mycoplasma. It was also long used as a feed additive to promote livestock and poultry growth. Tylosin has advantages such as low toxicity, high efficiency, no residue, and a broad antibacterial spectrum. As an animal-specific antibiotic, it is less likely to cause cross-resistance. However, its bioavailability is low due to the first-pass effect in the liver and intestines; approximately 50%–70% is excreted unchanged or as active metabolites in feces and urine, continuously entering livestock wastewater and soil. Tylosin is relatively stable in the natural environment and degrades slowly, making traditional physicochemical treatment methods inefficient at removing it. Given the unique advantages of microbial degradation, utilizing microorganisms to degrade antibiotics has become a current research hotspot. Several highly efficient tylosin-degrading bacteria have been successfully screened from environmental substrates: Wang et al. (2025) isolated Kurthia gibsonii TYL-A1, which, under optimized conditions of 30℃, pH 7, 3% inoculum, and yeast extract as the nitrogen source, could degrade 99% of 75 mg / L tylosin within 5 days; Feng et al. (2021) reported a strain... Bacillus velezensis7 The degradation rate of TYL within 3 days reached over 85%. Conducting screening and validation studies on natural degrading bacteria targeting tylosin is expected to enrich the germplasm resources of microorganisms that degrade veterinary antibiotics, and is of great significance for developing efficient and green bio-enhanced remediation technologies and improving environmental pollution. Summary of the Invention

[0003] Through extensive screening, this invention discovered a new strain that exhibits good degradation activity against tylosin, thus completing this invention.

[0004] In one aspect, the present invention discloses a strain that degrades tylosin, said strain being Rhodococcus roseum TYL-1, deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38881, located at Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, on May 26, 2026.

[0005] In one aspect, the present invention discloses a microbial agent comprising the aforementioned Rhodococcus roseum (… Rhodococcus rhodochrous TYL-1.

[0006] In one embodiment, the microbial agent is a liquid microbial agent, a solid microbial agent, or a powder.

[0007] In some embodiments, the microbial agent is a liquid microbial agent, which includes emulsions, suspensions, and fermentation broths containing Rhodococcus roseum TYL-1.

[0008] In one embodiment, the microbial agent is a powder, which includes lyophilized powder and wettable powder.

[0009] In one embodiment, the powder is a lyophilized powder containing Rhodococcus roseum TYL-1, and the lyophilized powder also contains a lyophilization protectant and a buffer to maintain the activity of the strain.

[0010] In one embodiment, the bacterial agent is a solid bacterial agent, prepared by immobilizing the bacterial cells onto a solid carrier.

[0011] In one embodiment, the present invention discloses the application of the aforementioned microbial agent in the preparation of biological agents for treating livestock and poultry breeding waste.

[0012] In one aspect, the present invention discloses the application of the aforementioned Rhodococcus roseum TYL-1 and Rhodococcus roseum TYL-1-containing bacterial agents in the degradation of tylosin.

[0013] In one embodiment, the present invention discloses a method for degrading tylosin in the environment, comprising adding the aforementioned strain or agent to wastewater or soil containing tylosin.

[0014] In this invention, the Rhodococcus roseum TYL-1 is a Gram-positive bacterium with milky white colonies that are round, hemispherical, and raised with a moist, sticky, and glossy surface and neat, smooth edges.

[0015] This invention obtains a strain capable of efficiently degrading tylosin from aquaculture wastewater through enrichment, domestication, isolation, and purification. Morphological and molecular biological identification confirms that this strain belongs to *Rhodococcus roseum*, and it is named *Rhodococcus roseum*. Rhodococcus rhodochrousTYL-1. This strain can accelerate the biodegradation of tylosin at 30-35℃, maintain good degradation function at pH 5-9, and has a degradation half-life of 3.85 days (approximately 90.4 hours), indicating that Rhodococcus roseum TYL-1 can be used as a biodegrading bacterium for the bioremediation of tylosin-contaminated environments.

[0016] Beneficial effects This invention provides a novel tylosin-degrading strain, enriching the tylosin-degrading strain library. The strain of this invention can degrade 100% of tylosin at a low concentration of 1 μg / ml, and even at a higher concentration of 10 μg / ml, the degradation rate can reach 57%, demonstrating significant degradation efficiency. Compared with known degrading bacteria in the prior art (such as Bacillus velezensis), the strain of this invention maintains high activity over a wide pH range of 5-9 and has a significantly shortened half-life. This strain can be widely used for the treatment and remediation of aquaculture wastewater. Attached Figure Description

[0017] Figure 1 Morphological characteristics of strain TYL-1: A: Colony morphology; B: Gram staining microscopy (40×10).

[0018] Figure 2 Electron microscopic observation of strain TYL-1.

[0019] Figure 3 : 16S rDNA PCR electrophoresis image of strain TYL-1.

[0020] Figure 4 Phylogenetic tree of strain TYL-1.

[0021] Figure 5 Growth curve of strain TYL-1.

[0022] Figure 6 Effects of temperature and pH on the degradation ability of strain TYL-1.

[0023] Figure 7 Effects of different inoculum amounts on the degradation ability of strain TYL-1.

[0024] Figure 8 Effects of different initial concentrations of antibiotics on the degradation ability of strain TYL-1.

[0025] Figure 9 Toxicity assessment of TYL degradation products by strain TYL-1. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Unless otherwise specified, the equipment and reagents used in the embodiments and experimental examples are commercially available. Unless otherwise stated, all reagents used in this invention are analytical grade reagents. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0027] Reagents: (1) Preparation of tylosin (TYL) stock solution and stock solution Dissolve 100 mg of tylosin standard in 10 mL of sterile deionized water, filter through a 0.22 μm sterile filter membrane to prepare an antibiotic stock solution with a concentration of 10 mg·mL⁻¹, aliquot into 1 mL tubes, and store at -20°C protected from light.

[0028] Weigh 10.0 mg of tylosin standard, dissolve it in chromatographic grade methanol and dilute to 100 mL to prepare a 100 μg / mL TYL stock solution. After filtration through a 0.22 μm organic filter membrane, dispense the solution and store at 4°C protected from light.

[0029] (2) Culture medium LB medium: yeast extract 5.0 g·L⁻¹, tryptone 10.0 g·L⁻¹, NaCl 10.0 g·L⁻¹, adjust pH to 7.0±0.1, autoclave at 121℃ for 15 min for later use.

[0030] MSM medium: Dissolve 4.3 g Minimal Salt Medium powder (main components: K₂HPO₄ 1500 mg / L, KH₂PO₄ 500 mg / L, (NH₄)₂SO₄ 1000 mg / L, NaCl 500 mg / L, FeSO₄·7H₂O 10 mg / L) in 1 L of deionized water and adjust the pH to 7.2 ± 0.1. After sterilization, cool to approximately 50°C and add 0.5 mL of 2000×Ca²⁺ under aseptic conditions. + &Mg² + Solution, mix well and set aside.

[0031] Screening medium: MSM medium was autoclaved at 121°C for 15 min, cooled to about 50°C, and antibiotic stock solution was added under aseptic conditions to obtain medium containing different concentrations of TYL.

[0032] Solid culture medium: Before sterilization, add 15-20 g / L agar powder to the corresponding liquid culture medium, and keep the other steps unchanged. After cooling, pour into plates.

[0033] In this invention, those skilled in the art will understand that the Rhodococcus roseum TYL-1 and strain TYL-1 refer to the strain with the preservation number CGMCC No.38881.

[0034] Example 1: Screening of strains that degrade tylosin 1.1 Enrichment culture of antibiotic-degrading bacteria After thoroughly mixing the aquaculture wastewater sample by inverting it, pour it into a 50 mL sterile centrifuge tube and centrifuge at 3000 r / min for 5 min to remove large suspended solids such as feed residue and fecal particles. Use a pipette to extract 10 mL of the supernatant and inoculate it into LB liquid medium (containing 1 μg / mL tylosin to inhibit the growth of other bacteria). Place the medium in a constant temperature shaking incubator and incubate at 37℃ and 180 r / min for 24-48 h, until the bacterial solution becomes noticeably turbid, completing the initial enrichment of the tolerant bacterial population.

[0035] Results: After enriching and culturing the aquaculture wastewater in LB medium containing low concentrations of antibiotics for 24 h, the bacterial solution became significantly turbid, indicating that the microorganisms that could tolerate low concentrations of tylosin in the sample had initially proliferated.

[0036] 1.2 Domestication and culture of antibiotic-degrading bacteria The enriched bacterial culture was inoculated into liquid culture medium at a 1% inoculum, and continuous transfer and acclimatization were carried out using a gradient of antibiotic concentrations. Acclimatization was performed by incubating at 37℃ and 180 r / min in the dark for 5 days as one acclimatization cycle, with the acclimatization concentrations decreasing sequentially by 1%. 5 10 15 and 20 μg / mL. The OD600 of the bacterial culture was measured as an indicator of bacterial growth. If the bacterial population grew stably (OD600 ≥ 0.4), the domestication was considered successful, and the domestication culture of antibiotic-degrading bacteria was completed.

[0037] Results: The enriched bacterial culture was transferred to MSM inorganic salt medium for continuous gradient acclimatization. The bacterial community was still able to grow stably under antibiotic stress of 20 μg / mL with an OD600 of 0.46, indicating that the acclimatization system was successfully constructed and a mixed bacterial community with tylosin as the carbon source was obtained.

[0038] 1.3 Isolation and purification of antibiotic-degrading bacteria The bacterial culture from the last acclimatization cycle was serially diluted to 10⁻⁴-10⁻⁸ with sterile physiological saline. 100 μL of the diluted solution was evenly spread onto MSM agar plates containing 20 μg / mL tylosin and incubated upside down at 37°C for 48-72 h. Colonies of varying morphology, size, and color were picked and inoculated onto MSM agar plates. This four-zone streak purification process was repeated 2-3 times until the colonies on the plates exhibited uniform morphology and were free from contamination, thus obtaining single colonies with tylosin as the sole carbon source. The obtained single strains were inoculated onto LB broth and cultured at 37°C and 180 r / min with shaking for 1 day. The enriched bacterial culture was mixed with 50% sterile glycerol at a 1:1 volume ratio, labeled, and stored at -80°C.

[0039] Results: After dilution, plating, isolation, and purification, three morphologically distinct strains were obtained on MSM solid plates containing 20 μg / mL tylosin. After 2-3 rounds of streak purification, single colonies of each strain showed uniform morphology, neat edges, and no contaminating microorganisms, indicating that a single strain using tylosin as the sole carbon source had been obtained and could be used for subsequent identification and degradation function verification.

[0040] 1.4 Screening of antibiotic-degrading bacteria After activation, the strains stored at -80℃ were inoculated at a 1% inoculum into MSM liquid medium containing 30 μg / mL tylosin. Three replicates were established for each strain, along with a blank control group without bacterial inoculation. The culture was kept at 37℃. The strain was cultured at a constant temperature of 135 r / min for 3 days. Samples were taken, filtered through a 0.22 μm organic filter membrane, and analyzed by high-performance liquid chromatography to calculate the antibiotic degradation ability of the strain.

[0041] The formula for calculating the degradation rate is: Degradation rate (%) = (C0) Ct) / C0×100% (Formula ①) C0 represents the initial concentration of TYL (μg / mL), and Ct represents the residual concentration of TYL in the experimental group after 3 days of culture (μg / mL). HPLC conditions: Symmetry Shield RP18 column (250 mm length, 3.9 mm inner diameter), mobile phase: acetonitrile:methanol:0.005 mol / L ammonium dihydrogen phosphate = 50:35:15, column temperature 25℃, flow rate 0.6 mL / min, injection volume 20 μL, detection wavelength 290 nm.

[0042] 1.5 Identification of antibiotic-degrading bacteria The strains that were screened and were able to effectively degrade tylosin were subjected to morphological observation and molecular biological identification to determine the species.

[0043] (1) Morphological observation of antibiotic-degrading bacteria Colony morphology observation: The purified strain was streaked onto LB agar plates and incubated upside down at 37°C for 24 h. The morphological characteristics of the colonies, including shape, size, color, gloss, elevation, and edge features, were observed and recorded. Colonies were picked for Gram staining and microscopic examination, as well as scanning electron microscopy.

[0044] Results: Colony growth morphology as follows Figure 1 As shown in Figure A. Colonies are milky white, round or hemispherical, with a moist, viscous, and glossy surface, and smooth, regular edges. Gram staining microscopic examination results are as follows. Figure 1 As shown in Figure B, this is a Gram-positive bacterium, as shown in the transmission electron microscope scan. Figure 2 As shown.

[0045] (2) Molecular biological identification of antibiotic-degrading bacteria Genomic DNA from degrading bacteria was extracted using the Ezup column-based bacterial genomic DNA extraction kit and used as a template for PCR amplification. PCR amplification of the strain was performed using universal primers 27F and 1492R for bacterial 16S rDNA; the primer sequences are shown in Table 1. The PCR reaction system was established according to Table 2.

[0046] Table 1 Primer Sequences ; Table 2 PCR reaction system ; Reaction procedure: 94℃ pre-denaturation for 5 min, 94℃ for 30 s, 50℃ for 30 s, 72℃ for 60 s, 30 cycles, final 72℃ for 10 min, and storage at 4℃. PCR amplification products were detected by 1% agarose gel electrophoresis, and bright bands were observed using a gel imaging system for identification. A target band of approximately 1500 bp was considered amplified successfully.

[0047] The amplified product was sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. The sequencing results were submitted to the NCBI GenBank database, and sequence similarity was compared using the BLAST system. 16S rRNA sequences of strains with high sequence similarity were selected, and a phylogenetic tree was constructed using MEGA software with the neighbor-joining method.

[0048] result: Using the bacterial genomic DNA as a template, PCR amplification was performed using 27F and 1492R primers, respectively. The agarose gel electrophoresis results are as follows: Figure 3 The data shows that TYL-1 appears as a single bright band without tails at approximately 1500 bp, located second from the right, indicating that the 16S rDNA fragment was successfully amplified.

[0049] The sequences of the screened strains were compared with sequences in the BLAST database, and a phylogenetic tree was constructed using MEGA 12.1 as follows: Figure 4 As shown in the figure. The results showed that this strain had a homology of over 99.78% with Rhodococcus roseum. Strain TYL-1 was identified as Rhodococcus roseum, and therefore named Rhodococcus roseum TYL-1. It is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38881, located at Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, on May 26, 2026.

[0050] 1.6 Drawing growth curves of bacterial strains After activation, the strain was cultured until the OD600 was approximately 0.5, which served as the seed culture. This seed culture was then inoculated into fresh LB medium at a 1% (v / v) ratio and cultured at 30 °C and 135 r / min in the dark. The OD600 was measured every 2 h using a spectrophotometer. 600 Absorbance. After the measurement, the absorbance was plotted on the x-axis as time, and the OD value was... 600 Plot the bacterial growth curve with the vertical axis as the ordinate.

[0051] The results showed that the growth curve of Rhodococcus roseum TYL-1 was as follows: Figure 5 As shown, the strain exhibits a slow growth period from 0 to 3 hours, enters the logarithmic growth phase from 3 hours onwards, and continues until 26 hours. During this phase, the bacteria multiply rapidly and have high activity, making it suitable for preparing bacterial suspensions. After 26 hours, the strain enters a stationary phase and shows a slow decline trend after 30 hours.

[0052] Example 2: Effects of different environmental conditions on the degradation of TYL by the strain of the present invention The effects of temperature and initial pH on the degradation ability of strain TYL-1 were investigated using single-factor experiments. After activation, the strain stored at -80℃ was inoculated into MSM liquid medium containing 10 μg / mL TYL at a 1% inoculum. Three replicates were set up for each condition, and a blank control group without bacterial inoculation was also set up.

[0053] 2.1 Effect of temperature on the degradation ability of Rhodococcus roseum TYL-1 Four temperature gradients (25, 30, 35, and 40°C) were set, the culture medium pH was 7.2, and the culture was carried out at a constant temperature of 180 r / min in the dark for 5 days. After that, samples were taken to determine the residual concentration of TYL and the degradation rate was calculated.

[0054] The results showed that, Figure 6Temperature also significantly affects the degradation rate of TYL. At 30 ℃, the degradation rate reached 43.09%, and at 35 ℃, the degradation rate was 52.75%. These results indicate that temperatures between 30 and 35 ℃ accelerate the biodegradation of TYL. Below 30 ℃, biodegradation is slow, at only about 5%. This suggests that strain TYL-1 is more resistant to high temperatures compared to lower temperatures.

[0055] 2.2 Effect of pH on the degradation ability of Rhodococcus roseum TYL-1 The pH of the MSM medium was adjusted to four gradients: 5.0, 6.0, 7.0, and 8.0. After culturing in the dark at 35℃ and 180 r / min for 5 days, samples were taken to determine the residual TYL concentration and calculate the degradation rate.

[0056] pH not only affects bacterial growth but also the stability of TYL; excessively acidic or alkaline conditions can cause the natural degradation of TYL. For example... Figure 6 The degradation effect was best at pH 3 or 11, but it was mostly natural degradation because TYL decomposes naturally under excessively acidic or alkaline conditions. However, at pH 7, the degradation efficiency of Rhodococcus roseum TYL-1 reached 48.37%, indicating that the strain can maintain good degradation function at pH 5-9.

[0057] 2.3 Effect of different inoculum sizes on the degradation ability of Rhodococcus roseum TYL-1 Inoculate with bacterial suspensions of 1%, 3%, 5%, 7%, and 9%, and incubate at 35℃ and 180 r / min in the dark for 5 days. Then, take samples to determine the residual concentration of TYL and calculate the degradation rate.

[0058] like Figure 7 Inoculation with bacterial suspensions at concentrations of 1%, 3%, 5%, 7%, and 9% degraded 8.25%, 22.71%, 43.73%, 28.69%, and 27.16% of TYL, respectively. It was found that the degradation rate increased with increasing inoculum concentration, with the best degradation effect observed at a 5% inoculum concentration.

[0059] 2.4 Effects of different antibiotic concentrations on the degradation ability of Rhodococcus roseum TYL-1 Initial tylosin concentrations of 1 μL / ml, 3 μL / ml, 5 μL / ml, 7 μL / ml, and 10 μL / ml were set, and the inoculum was 1% at a time. After incubation at 35°C and 180 r / min in the dark for 5 days, samples were taken to determine the residual TYL concentration and the degradation rate was calculated.

[0060] like Figure 8Initial antibiotic concentrations of 1 μg / ml, 2 μg / ml, 5 μg / ml, 7 μg / ml, and 10 μg / ml degraded TYL by 100%, 98.71%, 82.73%, 72.69%, and 57.16%, respectively. The study found that Rhodococcus roseum TYL-1 can be completely degraded at low concentrations.

[0061] 2.5 Degradation kinetics of strain TYL-1 Based on the single-factor optimization results, the optimal culture conditions were determined. Generally, the biodegradation process follows first-order reaction kinetics. The degradation kinetic curve was fitted (Formula ②). The graph is plotted with ln(Ct / C0) on the ordinate and t(h) on the abscissa. Ct = C0 × exp( kt) (②), use the formula to calculate the half-life of TYL: t1 / 2= ln2 / k C0 (mg / L) and Ct (mg / L) are the TYL concentrations at time 0 and time t, respectively, and k (h) is the concentration of TYL at time 0 and time t, respectively. 1) is the degradation rate constant.

[0062] The degradation curve of TYL was fitted using a first-order kinetic equation (as shown in Table 3 below). The regression coefficient for Rhodococcus roseum TYL-1 was 0.9880. The half-life of TYL after the addition of TYL-1 was 3.85 days, approximately 90.4 hours.

[0063] Table 3. Fitting TYL degradation curves to the first-order kinetic equation. ; 2.6 Toxicity assessment of TYL degradation products by strain TYL-1 Escherichia coli and Staphylococcus aureus were revived and cultured in LB broth to prepare bacterial suspensions, with OD600 adjusted to 0.5. The experiment was divided into two groups: T (biodegradation product group) and CK (control group). Strain TYL-1 was cultured in 10 mg / L MSM for 5 days, centrifuged at 8500 r / min, and the supernatant was passed through a 0.22 μm filter to form the biodegradation T group. CK consisted of 10 mg / L LTYL MSM. 1% (v / v) Escherichia coli and Staphylococcus aureus were inoculated into both groups, and the cultures were incubated at 37℃. The absorbance of the bacteria at 600 nm was measured using a spectrophotometer.

[0064] like Figure 9 As shown, Figure 9 Indicator bacteria A (Escherichia coli) and Figure 9The growth of the biodegradation treatment group (T) of Rhodococcus roseum indicator bacteria (Staphylococcus aureus) was superior to that of the negative control group (CK), indicating that the degradation products produced by Rhodococcus roseum after TYL-1 treatment were significantly less toxic than the parent compound. However, Staphylococcus aureus grew more slowly than Escherichia coli, possibly because TYL has a stronger inhibitory effect on Gram-positive bacteria, and its products may also have some inhibitory effect on Staphylococcus aureus. In summary, this indicates that TYL-1 can successfully detoxify TYL, producing a low-toxicity product.

[0065] This invention studies the growth and degradation characteristics of a bacterial strain, optimizing the initial concentration, temperature, pH, and inoculum size. Results show that changing the concentration of TYL induces a toxic-excitatory effect. This toxic-excitatory effect refers to the biphasic dose-response process by which cells or organisms exhibit a response to environmental stimuli. Specifically, low concentrations of TYL can serve as a carbon source for the growth of *Rhodococcus roseum* TYL-1, while excessively high concentrations inhibit its growth, thus reducing the degradation rate. In other words, low substrate concentrations promote strain growth, while high concentrations have an inhibitory effect. Temperature and pH significantly affect TYL degradation. Strain TYL-1 is best suited for growth at 30-35 °C; excessively high or low temperatures negatively impact its degradation. Temperature significantly regulates microbial metabolism and enzyme activity. At the optimal temperature of 35 °C, microbial activity increases; changes in temperature may lead to decreased enzyme activity, thus affecting degradation. Microbial growth and metabolism are directly affected by environmental pH, as microorganisms lack mechanisms to regulate their internal pH. Strain TYL-1 showed the best degradation performance at pH 7. Water, salt, and other organic molecules constitute the bacterial cytoplasm. The accumulation of organic acids and polyamines in the cytoplasm affects the internal pH balance of bacteria, thus impacting growth and metabolic activities, leading to reduced degradation. Inoculation with 5% of the strain accelerates TYL degradation. When the inoculation amount is below 5%, the degradation rate increases with increasing inoculation amount, possibly due to the shortened logarithmic phase of the strain, which accelerates TYL degradation. However, when the inoculation amount is greater than 5%, the degradation rate does not change significantly. TYL is the sole carbon source, and the added microorganisms compete for it; higher inoculation amounts may lead to nutrient deficiencies for bacterial growth. In summary, the optimal degradation conditions (35 ℃, pH 7.0, 5% inoculation amount) resulted in the degradation of 54.08% of tylosin after 5 days. The strain TYL-1 screened in this experiment has not been previously reported to have the function of degrading TYL. The degradation curve of TYL was fitted using a first-order kinetic equation. The regression coefficient (R2) of strain TYL-1 was 0.9880. The half-life of tylosin after the addition of strain TYL-1 was 3.85 days, indicating that the addition of strain TYL-1 can shorten the half-life of TYL and accelerate its degradation.

[0066] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection defined by the claims submitted herein.

Claims

1. A strain that degrades tylosin, characterized in that, The strain is Rhodococcus roseum ( Rhodococcus rhodochrous TYL-1, deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38881, located at Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, on May 26, 2026.

2. The strain according to claim 1, characterized in that, The Rhodococcus roseum TYL-1 is a Gram-positive bacterium with milky white, round or hemispherical colonies that are moist, sticky, and glossy with smooth, neat edges.

3. A microbial agent, characterized in that, The bacterial agent includes Rhodococcus roseum TYL-1 as described in claim 1.

4. The microbial agent according to claim 3, characterized in that, The microbial agent can be a liquid microbial agent, a solid microbial agent, or a powder.

5. The microbial agent according to claim 4, characterized in that, The microbial agent is a liquid microbial agent, which includes emulsions, suspensions, or fermentation broth containing Rhodococcus roseum TYL-1.

6. The microbial agent according to claim 4, characterized in that, The microbial agent is a powder, which includes freeze-dried powder and wettable powder.

7. The microbial agent according to claim 4, characterized in that, The bacterial agent is a solid bacterial agent, prepared by immobilizing the bacterial cells onto a solid carrier.

8. The use of the microbial agent according to claim 3 in the preparation of a biological agent for treating livestock and poultry breeding waste.

9. The use of the strain according to claim 1, and the bacterial agent according to claim 3, in the degradation of tylosin.

10. A method for degrading tylosin in the environment using the strain of claim 1 and the microbial agent of claim 3, characterized in that, The method includes adding the strain or agent to wastewater or soil containing tylosin.

Images