Lactobacillus animalis from cats and its application in improving cat urinary stone

Abstract

The application discloses a cat-derived animal lactobacillus for degrading oxalic acid and application thereof in improving cat stones, and belongs to the field of microbial application. The animal lactobacillus Nourse22-001 of the application was preserved in the China Center for Type Culture Collection of Wuhan University in Wuhan, China on December 15, 2025, and the preservation number is CCTCC NO: M20252880. The animal lactobacillus Nourse22-001 provided by the application has high oxalic acid degradation efficiency, can tolerate the acid-base and bile salt environment of the gastrointestinal tract of a cat, has strong intestinal colonization ability in the cat, grows well at the intestinal temperature of the cat, can enhance the immune function of the cat, up-regulate the expression of IgA and IgG, and inhibit intestinal harmful microorganisms such as Escherichia coli and Salmonella. The postbiotic prepared from the animal lactobacillus Nourse22-001 can relieve the inflammation degree of a cat suffering from urinary stones.

Description

Technical Field

[0001] This invention relates to the field of microbial applications, specifically to a feline lactobacillus strain that degrades oxalic acid and its application in improving feline stones. Background Technology

[0002] After being absorbed in the cat's intestines, oxalic acid is primarily metabolized by the kidneys and excreted in the urine. When the concentration of oxalic acid in the urine exceeds saturation, it can combine with free calcium ions in the urine to form calcium oxalate crystals or stones. The formation of calcium oxalate crystals can physically irritate the bladder and urethral mucosa, potentially causing minor local infections. As the crystals further aggregate and move, their surface can rub against or scratch the lining of the urinary tract, leading to a series of clinical symptoms in cats, such as frequent urination, urgency, difficulty urinating, and painful urination. Therefore, reducing the amount of oxalic acid ingested and absorbed by cats through food is of great importance in alleviating urinary stones in cats.

[0003] Currently, probiotics have been applied in the prevention and treatment of feline urinary stones. Patent CN118872776A discloses a pet food composition that improves urinary tract health by inhibiting urinary stone formation. Its components include 0.1%-1.5% urine acidifier, 0.05%-0.3% oxalate decomposing agent, 0.05%-0.5% citrate, and 0.05%-0.5% urinary tract repair agent. The oxalate decomposing agent includes various probiotics (such as *Lactobacillus oxalate*, *Lactobacillus animalis*, and *Lactobacillus acidophilus*). *Lactobacillus animalis* (… Lactobacillus animalis ( ) are Gram-positive facultative anaerobic bacteria, commonly found in the intestines of mammals. They have functions such as inhibiting pathogens, enhancing immunity, and regulating the intestinal microecology, and have received widespread attention.

[0004] The optimal growth temperature for *Lactobacillus animalis* currently reported is 37°C (e.g., strains ATCC 35046 and JCM 7708), but literature indicates that the core temperature of the cat's gut is 38.5°C ± 0.5°C (A non-invasive method to determine core temperature for cats and dogs using surface temperatures based on machine learning, 2024). This difference in temperature adaptability makes it difficult for non-cat-derived *Lactobacillus animalis* to effectively colonize the cat's gut (Probiotic potential of lactic acid bacteria isolated from canine and feline microbiota: functional profiling and host-adapted benefits, 2026), and therefore they cannot play a full role in cats. However, there are currently no reports on *Lactobacillus animalis* isolated from cats that can adapt to the cat's gut environment and achieve good colonization in the cat's gut. Summary of the Invention

[0005] The purpose of this invention is to provide an animal lactobacillus that can tolerate the cat's gastrointestinal environment, has good colonization ability, grows well at 38-39℃, and has the function of degrading oxalic acid, and its application.

[0006] In a first aspect, the present invention provides a strain of feline animal lactobacillus ( Lactobacillus animalis The strain No. 22-001 exhibited significantly improved oxalate degradation rate, gastrointestinal survival rate, and intestinal colonization ability compared to the original strain. This strain was deposited on December 15, 2025, at the China Center for Type Culture Collection, Wuhan University, Wuhan, China, with accession number CCTCCNO: M20252880 and the deposit name *Lactobacillus animalis* (…). Lactobacillus animalis )Nourse22-001.

[0007] A second aspect of the invention provides the use of the feline lactobacillus Nourse22-001 in cat food or feed.

[0008] Furthermore, the cat food or feed includes, but is not limited to, cat food, cat treats, or cat health food.

[0009] Furthermore, the feline lactobacillus Nourse22-001 can also be applied to other pets, such as foxes.

[0010] Furthermore, the feline lactobacillus Nourse22-001 can enhance the cat's immunity and inhibit harmful bacteria.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] 1. *Lactobacillus animalis* Nourse22-001 exhibits excellent in vitro oxalate degradation capabilities, achieving a degradation rate of 68.13% for potassium oxalate. In vivo testing with rats exhibiting oxalate crystallization and cats with calcium oxalate crystallization showed a significant decrease in urinary oxalate levels in both groups. Furthermore, calcium oxalate crystals completely disappeared in the urine of the affected cats by day 15 of feeding, indicating that this strain possesses highly efficient and rapid oxalate decomposition effects both in vivo and in vitro.

[0013] 2. Lactobacillus animalis Nourse22-001 exhibits good tolerance to the feline gastrointestinal environment, with a survival rate of 73.82% in a simulated feline gastrointestinal environment. It also demonstrates good growth and survival ability within the feline physiological body temperature range (38~39℃). Furthermore, it possesses outstanding intestinal colonization ability; even after 7 days of cessation of feeding, a viable count of 3.6 lg CFU / g can still be detected in the fecal matter, indicating that this strain can stably colonize the feline intestine for a long period and continue to function.

[0014] 3. The *Lactobacillus animalis* Nourse22-001 described in this invention exhibits broad-spectrum antibacterial activity, showing significant inhibitory effects against common pathogens such as *Escherichia coli*, *Salmonella*, *Staphylococcus aureus*, *Shigella*, and *Clostridium perfringens*, with the diameter of the inhibition zone increasing by 3% to 20% compared to the original strain. Furthermore, the metagenicity of this strain possesses anti-inflammatory activity; feeding it to cats with urinary stones significantly reduced the serum levels of pro-inflammatory factors TNF-α and IL-1β. Attached Figure Description

[0015] Figure 1 This is the developmental tree of Lactobacillus animalis Nourse22-001 in this invention.

[0016] Figure 2 This is a scanning electron microscope image of Lactobacillus animalis Nourse22-001 in this invention.

[0017] Figure 3 These are microscopic images of urinary crystals in rats fed with Nourse22-001 on days 0 and 7 of this invention. A and C are microscopic images of urinary crystals before and after 7 days of Nourse22-001 feeding, respectively; B and D are microscopic images of urinary crystals before and after 7 days of PBS feeding, respectively.

[0018] Figure 4The images show microscopic images of crystals in the urine of cats with urinary crystals fed Nourse22-001 on day 0 and day 21, respectively. A and C are microscopic images of crystals before and after feeding Nourse22-001 on day 21, respectively; B and D are microscopic images of crystals before and after feeding with empty capsules on day 21, respectively.

[0019] Figure 5 This is a diagram showing the results of the animal lactobacillus intestinal colonization test in this invention. Detailed Implementation

[0020] The terminology used in this invention, unless otherwise specified, generally has the meanings commonly understood by those skilled in the art. The invention is further described in detail below with reference to specific embodiments and data. It should be understood that these embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Those skilled in the art can make non-essential improvements and adjustments to the invention based on the above description.

[0021] In the following embodiments, various processes and methods not described in detail are conventional methods known in the art. The source, trade name, and components of the reagents used, if necessary, are indicated upon their first appearance, and subsequent use of the same reagents, unless otherwise specified, are identical to the initial indication.

[0022] This invention relates to the following culture media and reagents:

[0023] The artificial gastric juice was prepared with slight modifications based on the method of Li Hong et al. (Experimental study on the effects of Fangfeng Jierehe compound on gastric juice secretion, gastric emptying and intestinal peristalsis, 2020), with the pepsin content adjusted to 25 U / mL and the pH adjusted to 1.5.

[0024] The artificial intestinal fluid was prepared according to the method of Xue Junmin (Effects of tea polyphenols on mouse intestinal flora, intestinal enzyme activity and short chain fatty acids, 2018) with slight modifications, with the addition of pig bile powder (4 g / L) and pH adjusted to 7.2.

[0025] The method for preparing the intestinal digestion resistance screening medium is to add porcine bile powder (4 g / L) to the MRS basal medium and adjust the pH to 7.2.

[0026] MRS basic culture medium was purchased from Oxoid, UK; porcine bile powder and pepsin were purchased from Sigma-Aldrich; other reagents were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0027] PCR identification of bacterial species: The 16S rDNA sequence of the strain was amplified by PCR using universal primers 27F and 1492R. The target gene sequence amplified by PCR was sequenced, and the strain species was determined by comparing the sequence with the NCBI database Blast.

[0028] The universal primer sequences 27F and 1492R are as follows:

[0029] 27F: 5'-AGAGTTTGATCCTGGCTCAG-3';

[0030] 1492R: 5'-GGTTACCTTGTTACGACTT-3'.

[0031] Escherichia coli, Salmonella, Staphylococcus aureus, Shigella flexneri, and Clostridium perfringens were used as model strains in the antibacterial activity test. Escherichia coli and Salmonella were isolated from the feces of diarrheal cats; Staphylococcus aureus, Shigella flexneri, and Clostridium perfringens were purchased from the China Industrial Microbial Culture Collection Center, with strain numbers CICC21648, CICC21534, and CICC22949, respectively. Human-derived Lactobacillus was purchased from the Culture Collection Center of the University of Gothenburg, Sweden, with strain number CCUG 68343.

[0032] Example 1:

[0033] (1) Isolation of bacterial strains

[0034] Fresh feces were collected from healthy Chinese domestic cats, resuspended in PBS buffer, and then diluted to appropriate folds using a 10-fold serial dilution method. 100 μL of the diluted bacterial suspension was then spread onto MRS agar plates and incubated anaerobically at 38°C for 48 h. Plates with uniform colony distribution and good growth (less than 200 colonies per plate, and moist cells) were selected, and single colonies were picked.

[0035] (2) Functional identification

[0036] Single colonies were picked and inoculated into MRS liquid medium with a final concentration of 0.1% potassium oxalate, and cultured anaerobically at 38°C until OD500. 600 The value reached 0.80±0.05. In the experimental group, the inoculum was transferred to MRS liquid medium containing the same concentration of potassium oxalate at a rate of 1% (v / v) and anaerobic cultured at 38℃ for 48 h. After the culture was completed, the supernatant was taken for liquid chromatography to detect the oxalic acid content and the oxalic acid degradation rate was calculated. At the same time, a non-inoculated group was set up as a blank group. The oxalic acid degradation efficiency was calculated according to formula (1): Equation (1)

[0037] In the formula, C 空白 The blank control group contains oxalic acid in mg / mL; C样品 The value represents the oxalic acid content in the supernatant of the bacterial culture to be tested, in mg / mL.

[0038] Strains with an oxalic acid degradation rate greater than 30% were selected for molecular identification.

[0039] (3) Molecular identification

[0040] Strains with oxalic acid degradation efficiency greater than 30% were sequenced using 16S rDNA PCR, and the strain identified as *Lactobacillus animalis* was named DW-Y.

[0041] (4) Strain mutagenesis and strain selection

[0042] The original strain of *Lactobacillus animalis*, DW-Y, was irradiated with 150 Gy of cobalt-60 rays for 10 min. The mutagenic bacterial culture was then inoculated at 1% (v / v) into MRS liquid medium and cultured anaerobically at 38°C for 48 h for rejuvenation. After rejuvenation, the bacterial pellet was collected by centrifugation at 5000 ×g for 10 min at 4°C and inoculated into enteric-resistant selection medium for 7 consecutive days. Simulated gastric digestion screening was performed twice, on days 1 and 4, after which the culture was transferred to artificial gastric fluid, treated at 38°C for 1 h, centrifuged to collect the bacterial cells, and then transferred back to the enteric-resistant selection medium for further culture.

[0043] The bacterial cultures selected for gastrointestinal resistance were serially diluted 10-fold and then isolated and cultured. Twenty larger single colonies were picked and inoculated into MRS liquid medium, and cultured anaerobically at 38°C for 5 hours. The bacterial concentration (OD) before and after culture was measured. 600 The growth rate of each strain was calculated using the formula (2), and the three strains with the fastest growth rate were selected. Equation (2)

[0044] In the formula, V is the growth rate (h -1 ), OD 0h and OD 5h OD before and after cultivation 600 value.

[0045] The results are shown in Table 1. Strains DW-4, DW-10, and DW-12 showed the fastest growth rates after 5 hours of culture, with growth rates increasing by 41.27%, 41.27%, and 44.44% respectively compared to the original strain DW-Y. These three strains were selected for secondary screening.

[0046] Table 1 Growth rate of Lactobacillus from feline animals

[0047] serial number <![CDATA[5-hour growth rate (h -1 )]]> Percentage increase in growth rate (%) DW-Y 0.063 / DW-1 0.083 31.75 DW-2 0.087 38.10 DW-3 0.076 20.63 DW-4 0.089 41.27 DW-5 0.088 39.68 DW-6 0.068 7.94 DW-7 0.081 28.57 DW-8 0.085 34.92 DW-9 0.079 25.40 DW-10 0.089 41.27 DW-11 0.064 1.59 DW-12 0.091 44.44 DW-13 0.081 28.57 DW-14 0.080 26.98 DW-15 0.075 19.05 DW-16 0.070 11.11 DW-17 0.088 39.68 DW-18 0.076 20.63 DW-19 0.081 28.57 DW-20 0.079 25.40

[0048] After enrichment culture of the three bacterial strains, they were inoculated into MRS liquid medium containing a final concentration of 0.1% potassium oxalate and cultured anaerobically at 38℃ for 48 h. After the culture, the supernatant was collected for liquid chromatography to detect the oxalic acid content and to calculate the oxalic acid degradation efficiency. A control group without bacterial inoculation was also set up. The oxalic acid degradation efficiency was calculated according to formula (1).

[0049] The results are shown in Table 2. DW-12 showed the highest oxalic acid degradation efficiency, reaching 68.13%. Therefore, DW-12 was molecularly identified and used for subsequent testing.

[0050] Table 2 Degradation efficiency of Lactobacillus oxalate in feline animals

[0051] Oxalic acid degradation efficiency (%) DW-Y 39.46 DW-04 59.83 DW-10 39.59 DW-12 68.13

[0052] (5) Strain identification

[0053] Using the genomic DNA of the animal lactobacillus mutant strain DW-12 as a template, the 16S rDNA of the strain was identified by PCR.

[0054] The sequencing results were compared using BLAST on the NCBI website, and the results showed that DW-12 was *Lactobacillus animalis*. The mutant strain *Lactobacillus animalis* DW-12 was renamed *Lactobacillus animalis* Nourse22-001, and a phylogenetic tree was drawn. Figure 1 It is more closely related to animal lactobacillus in terms of evolutionary relationship.

[0055] The aforementioned *Lactobacillus animalis* of feline origin is currently deposited at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, on December 15, 2025, with accession number CCTCC NO: M20252880 and accession name *Lactobacillus animalis* Nourse 22-001. Lactobacillus animalis Nourse 22-001, the suggested classification name is *Lactobacillus animalis* (…). Lactobacillus animalis ).

[0056] (6) Gastrointestinal resistance and passage stability test

[0057] The original strain DW-Y and the identified mutant strain Nourse22-001 were inoculated at 1% (v / v) in MRS liquid medium and cultured anaerobically at 38℃ for 48 h. After the culture, the bacterial cells were placed in artificial gastric fluid for 1 h and then transferred to artificial intestinal fluid for 1 h. Samples were taken before and after treatment, and the viable cell count was determined by the serial dilution plate method, and the survival rate was calculated. The survival rate was calculated according to formula (3): Equation (3)

[0058] In the formula, P is the survival rate; n 后The number of viable bacteria in the bacterial culture after 2 hours of treatment, expressed in CFU; n 前 The number of viable bacteria in the bacterial culture before treatment is expressed in CFU.

[0059] The results are shown in Table 3. The mutagenic strain Nourse22-001 showed a significantly improved gastrointestinal survival rate compared to the original strain, with a gastrointestinal survival rate of 73.82%.

[0060] Table 3. Gastrointestinal survival rate of feline lactobacilli

[0061] Gastrointestinal survival rate (%) DW-Y 48.39 Nourse22-001 73.82

[0062] The original strain and the identified mutant strain Nourse22-001 were inoculated at 2% in MRS liquid medium and anaerobically cultured at 38°C for 48 h. This operation was repeated to culture the strains and passage them 10 times to evaluate their gastrointestinal resistance.

[0063] The results are shown in Table 4. The 10th generation Nourse22-001 showed good gastrointestinal resistance, with a gastrointestinal survival rate of 70.73%.

[0064] Table 4. Results of passage stability test of *Lactobacillus filamentosa* from felines.

[0065] DW-Y (10th generation) Nourse22-001 (10th generation) Gastrointestinal survival rate (%) 46.86 70.73

[0066] (7) Temperature tolerance test

[0067] The original bacteria and the mutant strain Nourse22-001 were activated and adjusted to the same initial concentration (1×0.5). 7 The CFU / mL values ​​were divided into two treatment groups: 38℃ and 39℃. After precise temperature control in a constant-temperature water bath for 2 h, tolerance was immediately terminated by an ice bath. The CFU / mL values ​​of each treatment group were calculated using gradient dilution plating and counting. The survival rate was calculated according to formula (4):

[0068] Equation (4)

[0069] The results are shown in Table 5. After treatment at 38℃ for 2 h, the survival rate of the original bacteria was 62%, while the survival rate of the mutant strain Nourse22-001 significantly increased to 89%. When the temperature rose to 39℃, the survival rate of the original bacteria further decreased to 28%, while the mutant strain still maintained a relatively high survival rate of 71%. The results indicate that the heat resistance of the mutant strain Nourse22-001 in the 38–39℃ range is significantly better than that of the original bacteria.

[0070] Table 5. Results of temperature tolerance test for feline lactobacilli.

[0071]

[0072] The original bacteria and the mutant strain Nourse22-001 were activated and adjusted to the same initial concentration (1×10⁻⁶). 7 (CFU / mL) was inoculated into MRS liquid medium at a 1% inoculum and cultured at 37℃, 38℃ and 39℃ for 24 hours, respectively. Counting was performed after the culture was completed.

[0073] The results are shown in Table 6. The number of viable bacteria in the mutant strain Nourse22-001 was not different when cultured at 37℃, 38℃ and 39℃, while the number of viable bacteria in the original strain decreased by more than 50% when cultured at 38℃ and above.

[0074] Table 6. Viable bacterial counts of *Lactobacillus felineis* cultured at different temperatures.

[0075]

[0076] (8) Antibacterial ability test

[0077] Escherichia coli, Salmonella, Staphylococcus aureus, Shigella flexneri, and Clostridium perfringens were cultured to the logarithmic growth phase. 10 µL of each bacterial culture was added to a Petri dish, and approximately 20 mL of LB agar (40–45°C) was poured in. After cooling and solidification, wells were punched in the dish. 50 µL of the fermentation broth of the test strain was added to each well, and the dish was incubated aerobically at 37°C for 24 h. After incubation, the diameter of the inhibition zone (DIZ) was measured using calipers. The DIZ diameter was calculated as the average of the maximum and minimum values ​​(the inner diameter of the punch was 6 mm; if there was no significant inhibitory effect, the DIZ diameter was recorded as 6 mm).

[0078] The results are shown in Table 7. The inhibition zones of Nourse22-001 against Escherichia coli, Staphylococcus aureus, Salmonella, Shigella flexneri, and Clostridium perfringens were 14.0 mm, 14.0 mm, 15.0 mm, 15.0 mm, and 14.0 mm, respectively.

[0079] Table 7 Evaluation of the antibacterial ability of Lactobacillus from feline animals

[0080]

[0081] (9) Evaluation of the feeding effect on rats with oxalic acid crystallization model

[0082] Using healthy SD rats as experimental animals, an oxalic acid crystallization model was established by feeding them a diet containing 5% oxalic acid and allowing them free access to water. Figure 3As shown, the oxalic acid crystallization model was considered successfully established when crystals were clearly observed in rat urine under a microscope and the urine pH was within the range of 5.5–6.0. ​​The experiment was divided into a Nourse22-001 group and a PBS control group. Both groups continued to be fed a diet containing 5% oxalic acid and had free access to water. The Nourse22-001 group received 1×110 mg of oxalic acid orally daily. 9 CFU / rat of Nourse22-001 bacterial culture was administered, while the PBS control group received an equal volume of PBS solution via gavage. Urine was collected from rats on day 0 and day 7 after gavage, and the oxalate content in the urine was detected using liquid chromatography. The oxalate content reduction rate was calculated. The oxalate content reduction rate was calculated according to formula (5): Equation (5)

[0083] In the formula, C0 is the oxalic acid content in urine on day 0 after gavage, in mg / mL, and C7 is the oxalic acid content in urine on day 7 after gavage, in mg / mL.

[0084] The results are shown in Table 8. After oral administration of Nourse22-001 bacterial strain for 7 days, the oxalic acid content in the urine of rats decreased to 0.179 mg / mL, which was 61.42% lower than before feeding and 59.04% lower than that in the PBS group.

[0085] The number of crystals in the urine of rats in the Nourse22-001 group and the PBS group was observed under a microscope on days 0 and 7 of feeding. On day 0 of feeding, a large number of crystals were observed in the urine of rats in both the Nourse22-001 group and the PBS group. Figure 3 (As shown in A and B); no crystals were observed in the urine of rats in the Nourse22-001 group on day 7 of feeding. Figure 3 As shown in Figure C), crystals were still present in the urine of rats in the PBS group. Figure 3 (As shown in D).

[0086] Table 8. Reduction rate of oxalate content in rat urine by *Lactobacillus felidus*

[0087]

[0088] Example 2:

[0089] Cats with calcium oxalate urinary stones were recruited and randomly divided into two groups: the Nourse22-001 group and a control group. The experiment lasted for 21 days. The Nourse22-001 bacterial suspension was concentrated and encapsulated to prepare bacterial preparation capsules (1×10⁻⁶). 8(CFU / capsule) In Group No. 22-001, cats were fed one capsule of the probiotic preparation once daily; cats in the control group were fed empty capsules without the probiotic preparation. Urine was collected from the cats after 14 days of feeding to test the oxalic acid content. Urine was collected again after 21 days of feeding, and the number of crystals was observed under a microscope.

[0090] The results are shown in Table 9. After feeding Nourse22-001 strain for 14 days, the oxalic acid content in the cat urine decreased to 4.21 mg / mL, which was 62.58% lower than before feeding and 69.89% lower than the oxalic acid content in the urine of the control group.

[0091] Cat urine samples were collected on days 0, 3, 6, 9, 12, 15, 18, and 21 of feeding and observed under a microscope for crystallization. The results are shown in Table 10. No crystals were observed in the cat urine from day 15 of feeding with Nourse22-001, while crystals were observed in the control group.

[0092] Crystallization was observed in the urine of cats in the Nourse22-001 group and the control group on days 0 and 21 of feeding. On day 0 of feeding, crystallization was observed in the urine of cats in the Nourse22-001 group and the control group. Figure 4 (As shown in A and B); no crystals were observed in the urine of cats in the Nourse22-001 group on day 21 of feeding ( Figure 4 As shown in Figure C), crystals were still present in the urine of the cats in the blank control group. Figure 4 (As shown in D).

[0093] Table 9. Reduction rate of oxalate content in urine of cats with crystalloid disease by *Lactobacillus felineis*

[0094]

[0095] Table 10 Crystallization in Cat Urine

[0096]

[0097] Note: ++ indicates a high number of crystals in urine; ++ indicates a moderate number of crystals in urine; + indicates a low number of crystals in urine, but they are still present; - indicates no crystals were observed in urine.

[0098] Example 3:

[0099] Twenty-four healthy cats, weighing 3-5 kg ​​and aged 1-2 years, were selected. The breeds included British Shorthair, Ragdoll, Garfield, American Shorthair, Maine Coon, and Chinese Domestic Cat, with four cats of each breed. These were evenly distributed into a control group, a human-derived group, a DW-Y group, and a Nourse22-001 group, with six cats in each group. The experiment lasted 28 days, divided into a feeding period (days 0-7) and a fasting period (days 8-28). During the feeding period, the cats were given probiotic capsules daily. The bacterial solution was concentrated and then encapsulated to create probiotic capsules (1×10⁻⁶). 8 Cats were given one capsule of the probiotic preparation (CFU / capsule) once daily during the feeding period. The capsules administered to cats in the human, DW-Y, and Nourse22-001 groups contained human *Lactobacillus animalis*, the original DW-Y bacteria, and the selected Nourse22-001 mutagenesis, respectively. Cats in the control group were given empty capsules without the probiotic preparation. Fecal samples were collected from cats before feeding, on day 3, day 7 of feeding, and on days 1, 3, 7, 14, and 21 after feeding was stopped. *Lactobacillus animalis* plate counts were performed, and the number of viable colonies was calculated. A viable colony count below 2.001 g CFU / g (i.e., 100 CFU / g) was considered as indicating no *Lactobacillus animalis* colonization in the cat.

[0100] The results are as follows Figure 5 As shown, the colonization ability of the Nourse22-001 mutant was better than that of the DW-Y original strain and human-derived *Lactobacillus*. After 7 consecutive days of feeding with the probiotic preparation, the bacterial concentrations in the human group, DW-Y group, and Nourse22-001 group were 3.2, 5.5, and 5.9 lg CFU / g, respectively. After 3 days of cessation of feeding, the concentrations in the human group, DW-Y group, and Nourse22-001 group were 2.0, 3.8, and 4.6 lg CFU / g, respectively, with Nourse22-001 being 2.6 and 0.8 lg (CFU / g) higher than the human group and DW-Y group, respectively. After 7 days of cessation of feeding, no colonization was observed in the intestines of the human group, while the concentrations in the DW-Y group and Nourse22-001 group were 2.5 and 3.6 lg CFU / g, respectively. Fourteen days after feeding was stopped, no colonization was observed in the cat intestines of the DW-Y group, while the Nourse22-001 group still had 2.8 lg CFU / g. Although the concentration difference between the Nourse22-001 group (5.9 lg CFU / g) and the DW-Y group (5.5 lg CFU / g) was not significant at the end of feeding, the colonization maintenance capacity of the Nourse22-001 group was significantly better than that of the DW-Y group after feeding was stopped. This indicates that the Nourse22-001 has an enhanced ability to persistently colonize the cat intestines, rather than just increasing the short-term peak concentration.

[0101] Example 4:

[0102] Twelve immunocompromised cats were recruited and evenly divided into a control group and a Nourse22-001 group, with six cats in each group. The experiment lasted for 21 days. The Nourse22-001 bacterial suspension was concentrated and encapsulated to prepare bacterial preparation capsules (1×10⁻⁶). 8 Cats were given one capsule of the probiotic preparation (CFU / capsule) once daily during the feeding period. Cats in the control group were given empty capsules without the probiotic preparation. Blood samples were collected from cats on days 0 and 21 to prepare serum, and the IgA, IgG, and IgM assays were performed according to the instructions of the kits.

[0103] The results are shown in Table 11. After 21 days of feeding, the serum IgA, IgG and IgM levels in the Nourse22-001 group were significantly higher than those in the control group, reaching 13.19, 7.08 and 61.96 g / L, respectively, representing increases of 80.44%, 91.87% and 74.49% compared to before feeding.

[0104] Table 11. Serum immunoglobulin levels in cats.

[0105]

[0106] Example 5:

[0107] Twelve cats with calcium oxalate urinary stones were recruited and randomly divided into two groups: the Nourse22-001 group and a control group. The experiment lasted for 21 days. The Nourse22-001 strain was fermented and cultured, then heat-inactivated at 95°C for 30 min. The absence of viable bacteria was verified by plate coating. The resulting product was then centrifuged and freeze-dried to prepare a postbiotic powder. The Nourse22-001 group was fed the postbiotic powder daily at a dose of 500 mg / kg body weight, evenly mixed into their diet. The control group was fed only their regular diet for 28 days. Serum samples were collected at the end of the experiment to measure serum TNF-α and IL-1β levels.

[0108] The levels of inflammatory factors in feline serum are shown in Tables 12 and 13. After 28 days of feeding, compared with the blank control group, the serum levels of TNF-α and IL-1β in the Nourse22-001 group decreased, with TNF-α decreasing from 29.97 ng / L to 18.97 ng / L (a decrease of 36.7%) and IL-1β decreasing from 7.86 ng / L to 4.12 ng / L (a decrease of 47.6%). These results indicate that the Nourse22-001 postbiotic can inhibit the inflammatory response in cats with urinary stones.

[0109] Table 12 TNF-α content in cat blood

[0110]

[0111] Table 13 Serum IL-1β levels in cats

[0112]

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A strain of animal lactobacillus derived from cats ( Lactobacillus animalis Nourse22-001, characterized in that, The animal lactobacillus Nourse22-001 was deposited on December 15, 2025, at the China Center for Type Culture Collection (CCTCC) of Wuhan University, Wuhan, China, with accession number CCTCC NO: M20252880.

2. The *Lactobacillus animalis* Nourse22-001 according to claim 1, characterized in that, Lactobacillus animalis Nourse22-001 possesses the following characteristics: a) It has the ability to degrade oxalic acid; b) It has the ability to tolerate cat stomach acid and bile salts; c) High number of viable bacteria colonizing the cat's intestines and long colonization time; d) It grows well at 38~39℃.

3. The use of a cat-derived strain of Lactobacillus animalis Nourse22-001 according to any one of claims 1 to 2 in the preparation of cat food.

4. The use of a cat-derived Lactobacillus animalis strain Nourse22-001 according to any one of claims 1 to 2 in the preparation of cat treats.

5. The use of a cat-derived strain of *Lactobacillus animalis* Nourse22-001 according to any one of claims 1 to 2 in the preparation of cat health food.

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