Staphylococcus xylosus with lipid degradation function and application thereof in fermented food

Abstract

The application discloses a Staphylococcus xylosus with lipid degradation function and application thereof in fermented food, and belongs to the field of microorganisms. The application provides a Staphylococcus xylosus S3, wherein the Staphylococcus xylosus S3 has the ability of degrading lipids, and can effectively improve the acid value and TBARS value of fermented surimi after 48 hours of fermentation. Therefore, the Staphylococcus xylosus S3 can adjust the hydrolysis degree of lipids in fermented surimi to an ideal range, and has wide application prospects in the food industry.

Description

Technical Field

[0001] This invention relates to a strain of Staphylococcus xylose with lipid degradation function and its application in fermented foods, belonging to the field of microbiology. Background Technology

[0002] Lipid degradation is one of the key biochemical reactions in food flavor formation. During food fermentation, lipids decompose through oxidation and enzymatic hydrolysis to produce volatile flavor compounds such as aldehydes, ketones, and alcohols, which are important sources of characteristic aromas in food. In the early stages of fermentation, endogenous enzymes are mainly responsible for lipid degradation, while in the middle and later stages, the lipid degradation capabilities of microorganisms play a crucial role. Microorganisms can produce lipid degradation enzymes (lipases and phospholipases) to hydrolyze glycerides and phospholipids in raw materials into easily oxidized free fatty acids. Free fatty acids (especially unsaturated fatty acids) are extremely unstable and easily oxidized to form hydroperoxides or volatile flavor compounds. Hydroperoxides are further oxidized to form volatile flavor compounds. The ratio of the transparent zone diameter (D) to the colony diameter (d) reflects the degree of lipid hydrolysis, while the acid value reflects the level of free fatty acids in the lipid hydrolysis products. Free fatty acids are directly related to the formation of volatile flavor compounds. The TBARS value reflects the degree of lipid oxidation; within a certain range, the higher the degree of lipid oxidation, the richer and more intense the flavor.

[0003] Traditional fermentation strains (such as lactic acid bacteria) have limited lipid degradation capabilities, relying mainly on endogenous enzymes in the food raw materials during fermentation, resulting in slow and limited flavor compound formation. Fermented foods often involve the addition of large amounts of salt, and lactic acid bacteria have poor adaptability to high-salt environments, further reducing their lipid degradation ability. Furthermore, during natural fermentation, the types and amounts of lipid degradation products are significantly affected by the quality of the raw materials and fermentation conditions, leading to poor flavor stability and large flavor fluctuations between different batches, making it difficult to meet the demands of standardized industrial production. *Staphylococcus xylose* is listed as a "microorganism with a safe use record" by the International Dairy Federation (IDF) and is also included in the "List of Microorganisms that can be used in food." It exhibits strong salt tolerance and good acid tolerance, making it suitable as an inoculum for fermented meat. However, current fermentation strains have weak lipid degradation capabilities, resulting in limited improvement in the lipid-based flavor of the product and a limited flavor profile. Therefore, it is essential to screen for strains with strong lipid degradation capabilities to target and regulate the flavor of fermented foods. Summary of the Invention

[0004] The purpose of this invention is to provide a strain of Staphylococcus xylose with lipid-degrading function and its application in fermented foods. This provides a microbial resource for the production of high-quality flavor-enhancing fermented foods, while also contributing to the development of high-quality domestically produced starter cultures.

[0005] This invention provides a Staphylococcus xylosus S3 strain, which was deposited at the Guangdong Provincial Center for Microbial Culture Collection on February 24, 2025, with accession number GDMCC No: 65894.

[0006] The present invention provides a microbial preparation containing the aforementioned Staphylococcus xylose S3.

[0007] The present invention provides a product containing the aforementioned Staphylococcus xylose S3 or the aforementioned microbial preparation.

[0008] In one embodiment, the product includes, but is not limited to, fermented foods.

[0009] In one embodiment, the fermented food includes fermented meat; the meat includes fish, shrimp, or squid.

[0010] In one embodiment, the fish include large yellow croaker, golden pomfret, mackerel, tilapia, crucian carp, silver carp, snakehead, grass carp, perch, and black carp.

[0011] This invention provides a method for degrading lipids by adding the Staphylococcus xylose S3 to a lipid-containing system for fermentation.

[0012] In one embodiment, the lipid-containing system includes a culture medium or meat products.

[0013] In one embodiment, the meat product includes minced meat, chunks of meat, or strips of meat.

[0014] In one embodiment, a seed culture of Staphylococcus xylose S3 with an OD value of 0.6-0.8 is inoculated into sterilized fish paste at an inoculation rate of 1%-3% v / v, and fermented at 30-37°C for 32-60 hours.

[0015] This invention provides the application of the Staphylococcus xylose S3 or the microbial preparation in regulating the degree of lipid oxidation in fermented meat.

[0016] This invention provides the application of the Staphylococcus xylose S3 or the microbial preparation in improving the flavor of fermented meat.

[0017] Beneficial effects:

[0018] This invention provides a strain of Staphylococcus xylosus S3, which possesses the ability to degrade lipids. When fermented in fish paste for 48 hours, this strain effectively increases the acid value and TBARS value of the fermented fish paste. Therefore, Staphylococcus xylosus S3 can regulate the degree of lipid hydrolysis in fermented fish paste to an ideal range, and has broad application prospects in the food industry.

[0019] Preservation of biological materials

[0020] A strain of Staphylococcus xylosus S3, taxonomically named Staphylococcus xylosus, was deposited on February 24, 2025, at the Guangdong Provincial Center for Microbial Culture Collection (GDMCC No: 65894), located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou. Attached Figure Description

[0021] Figure 1 This is a colony morphology diagram of Staphylococcus xylitol S3.

[0022] Figure 2 This is a microscopic morphological image of Staphylococcus xylitol S3.

[0023] Figure 3 This is a growth curve of Staphylococcus xylitol S3.

[0024] Figure 4 Transparency diagrams of lipolysis for Example 2 and Comparative Examples 1-6.

[0025] Figure 5 The figures are D / d diagrams of the transparent rings for Example 2 and Comparative Examples 1-6; different capital letters AD indicate significant differences between different groups (P<0.05).

[0026] Figure 6 The acid value diagrams are for fermented fish meat prepared in Example 2 and Comparative Examples 1-7; different capital letters AG indicate significant differences between different groups (P<0.05).

[0027] Figure 7 The TBARS values ​​of fermented fish meat prepared in Example 2 and Comparative Examples 1-7 are shown in the figure; different capital letters AG indicate significant differences between different groups (P<0.05). Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments. Unless otherwise stated, the raw materials used in the embodiments and comparative examples of the present invention are all commercially available raw materials.

[0029] *Staphylococcus xylosus* S3 (preservation number: GDMCC No: 65894) was isolated from sauerkraut in the laboratory; *Staphylococcus xylosus* YCC3 and *Staphylococcus wartii* G2 were isolated from sausages in the laboratory; *Staphylococcus saprophyticus* S10 was isolated from fermented sausages in the laboratory; *Staphylococcus xylosus* (commercial 1) was obtained from SACCO (Shanghai Haoyue Biotechnology Co., Ltd.); *Staphylococcus xylosus* (commercial 2) was obtained from Chr. Hansen (Denmark)... S-SX, Version: 8PI GLOB EN 05-30-2022), Staphylococcus aureus (commercial) sourced from Chr. Hansen (S.S.). CS-300, Version: 7PI GLOB CN 17-11-2020). All culture media used in the embodiments and comparative examples of this invention were purchased from Qingdao Haibo Biotechnology Co., Ltd.

[0030] Example 1: Isolation and purification of bacterial strains

[0031] Prepare the culture medium according to mannitol high-salt agar and sterilize at 120℃ for 15 min. Take a certain amount of sour meat, aseptically mince it, dilute it with sterile water, and then spread it on the prepared mannitol high-salt agar plates and incubate at 37℃ for 48 h. Pick single colonies and streak them on mannitol high-salt agar plates for further purification. Repeat this step 4-5 times. Observe the morphological characteristics of the isolated and purified strains under a microscope. Amplify 16S RNA using primers 27f (5'-AGAGTTTGATCCTGGCTCAG-3') and 1492r (5'-GGTTACCTTGTTACGACTT-3') and identify it by comparison with the NCBI database. Finally, study the growth curve of the strain. Inoculate 500 μL of bacterial culture with an OD value of 0.6 into 5 mL of nutrient broth and determine its growth curve using a fully automated growth curve analyzer.

[0032] The bacterial amplification sequence is as follows (SEQ ID No. 1):

[0033]

[0034] By comparing with the NCBI database, the strain was identified as Staphylococcus xylosus and named Staphylococcus xylosus S3. The Staphylococcus xylosus S3 was deposited on February 24, 2025 at the Guangdong Provincial Center for Microbial Culture Collection, with accession number GDMCC 65894, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0035] The colony morphology of *Staphylococcus xylose* on the S3 mannitol high-salt culture medium plate is as follows: Figure 1 As shown.

[0036] The microscopic morphology of the *Staphylococcus xylosus* S3 strain is as follows: Figure 2 As shown, Staphylococcus xylitol is arranged in a spherical pattern.

[0037] The growth curve of Staphylococcus xylose S3 is as follows: Figure 3 As shown, the strain was in the logarithmic phase from 500 to 2000 min, and reached the plateau phase after 2000 min.

[0038] Example 2: Lipid degradation capacity of Staphylococcus xylose S3

[0039] Strain activation: Staphylococcus xylose S3 was activated and cultured in nutrient broth medium at 37°C for 48 hours.

[0040] Lipid degradation ability of the strain in the culture medium system: The culture medium was prepared according to the glycerol tartrate agar and sterilized at 120℃ for 15 min. The OD value of the activated Staphylococcus xylose S3 bacterial suspension was adjusted to 0.6. 2 μL of bacterial suspension was dropped onto a glycerol tartrate agar plate and incubated at 37℃ for 24 h. The clear zone around the colony was observed and D / d (D: diameter of clear zone; d: diameter of strain) was calculated.

[0041] Lipid degradation ability of the strain in fermented fish: Tilapia fillets were minced into a paste, and deionized water was added in equal proportions and sterilized at 120℃ for 15 min. A strain with an OD value of 0.6 was inoculated into the sterilized fish paste at an inoculum rate of 1% (v / v), and fermented at 34℃ for 48 h. The acid value and TBARS value of the fish paste were determined. The acid value was determined according to the national standard GB5009.229—2025 "Determination of Acid Value in Food". The TBARS value was determined according to GB / T 35252-2017 "Determination of 2-Thiobarbituric Acid Value of Animal and Vegetable Oils".

[0042] Comparative Example 1: Lipid Degradation Capacity of Staphylococcus xylose (Commercial 1)

[0043] The difference between Comparative Example 1 and Example 2 is that Staphylococcus xylose S3 in Example 2 was replaced with Staphylococcus xylose (Commercial 1).

[0044] Comparative Example 2: Lipid Degradation Capacity of Staphylococcus xylose (Commercial 2)

[0045] The difference between Comparative Example 2 and Example 2 is that Staphylococcus xylose S3 in Example 2 was replaced with Staphylococcus xylose (Commercial 2).

[0046] Comparative Example 3: Lipid Degradation Capacity of Staphylococcus xylose YCC3

[0047] The difference between Comparative Example 3 and Example 2 is that Staphylococcus xylose S3 in Example 2 is replaced with Staphylococcus xylose YCC3.

[0048] Comparative Example 4: Lipid Degradation Capacity of Staphylococcus aureus (Commercial)

[0049] The difference between Comparative Example 4 and Example 2 is that Staphylococcus xylose S3 in Example 2 was replaced with Staphylococcus carminans (commercial).

[0050] Comparative Example 5: Lipid Degradation Capacity of Staphylococcus warwick G2

[0051] The difference between Comparative Example 5 and Example 2 is that Staphylococcus xylose S3 in Example 2 was replaced with Staphylococcus wartii G2.

[0052] Comparative Example 6: Lipid Degradation Capacity of Staphylococcus saprophyticus S10

[0053] The difference between Comparative Example 6 and Example 2 is that Staphylococcus xylose S3 in Example 2 is replaced with Staphylococcus saprophyticus S10.

[0054] Comparative Example 7: Unvaccinated Control

[0055] The difference between Comparative Example 7 and Example 2 is that the inoculation of Staphylococcus xylose S3 in Example 2 was replaced with no inoculation of microorganisms.

[0056] 1. Differences in lipid hydrolysis capacity of strains in culture medium.

[0057] Figure 4 The figure shows the lipid hydrolysis clear zones of the strains on tributyrate medium. It can be seen from the figure that except for Staphylococcus aureus (commercial) strain, which does not have a clear zone, the other strains all have clear zones of different sizes. This indicates that Staphylococcus aureus (commercial) strain does not have lipid degradation ability, while the other 6 strains have lipid hydrolysis ability. Figure 5The D / d value reflects the lipid degradation ability of a bacterial strain; a higher D / d value indicates a stronger lipid hydrolysis ability. The figure shows that *Staphylococcus xylose* S3 had the highest D / d value, significantly higher than other inoculation groups (p<0.05), at 1.69. The subsequent values ​​were: *Staphylococcus xylose* (commercial 1) > *Staphylococcus xylose* YCC3 > *Staphylococcus saprophyticus* S10 > *Staphylococcus xylose* (commercial 2) > *Staphylococcus wartii* G2 > *Staphylococcus carinatum* (commercial).

[0058] 2. Differences in lipid hydrolysis capacity of strains in fermented fish paste.

[0059] Figure 6 The acid value of fish paste fermented with different strains was determined. Acid value reflects the content of free fatty acids in the oil; free fatty acids are produced after lipid hydrolysis, thus reflecting the degree of lipid hydrolysis. The figure shows that fish paste inoculated with *Staphylococcus xylose S3* had the highest acid value, increasing by 1.18 times compared to Comparative Example 1 and by 7 times compared to Comparative Example 7, indicating that *Staphylococcus xylose S3* has a higher lipid hydrolysis capacity than the other six strains. This corresponds to the results regarding the size of the clear zone in the culture medium.

[0060] 3. Differences in lipid oxidation capacity of strains in fermented fish paste.

[0061] Figure 7 The TBARS values ​​of fish paste inoculated with different strains after fermentation were calculated. TBARS reflects the degree of lipid oxidation; lipid hydrolysis can produce highly unstable free fatty acids, which (especially unsaturated fatty acids) are easily oxidized. Therefore, TBARS can also reflect the lipid degradation capacity. The figure shows that fish paste inoculated with Staphylococcus xylose S3 had the highest TBARS, indicating that Staphylococcus xylose S3 has a higher lipid degradation capacity than the other six strains. Furthermore, within two days of fermentation, the TBARS value of Example 2 was twice that of Comparative Example 7.

[0062] 4. Evaluation of the fishy aroma of fermented fish paste

[0063] Sensory evaluation of the fishy aroma of fermented fish paste was conducted (Table 1), and the samples were ranked according to their fishy aroma scores from highest to lowest as follows: Example 1 (8.9) > Comparative Example 1 (7.9) > Comparative Example 3 (7.7) > Comparative Example 6 (7.0) > Comparative Example 2 (6.6) > Comparative Example 5 (5.7) > Comparative Example 4 (3.5) > Comparative Example 7 (1.4). This indicates that Staphylococcus xylose S3 is more effective than other strains in enhancing the flavor of fermented fish paste.

[0064] Table 1 Sensory Evaluation Criteria

[0065]

[0066] In summary, the *Staphylococcus xylose* S3 strain of this invention possesses strong lipid degradation capabilities, and this advantage contributes positively to enhancing the flavor of fermented fish paste. Compared to fermented fish paste inoculated with other bacteria or without inoculation, this strain exhibits significant advantages.

[0067] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A strain of Staphylococcus xylitol ( Staphylococcus xylosus The *Staphylococcus xylose* S3 was deposited at the Guangdong Provincial Center for Microbial Culture Collection on February 24, 2025, with accession number GDMCC No: 65894.

2. A microbial preparation containing the Staphylococcus xylose S3 of claim 1.

3. A fermented food containing *Staphylococcus xylose* S3 as described in claim 1 or the microbial preparation as described in claim 2, characterized in that, The fermented food is fermented meat.

4. The fermented food as described in claim 3, characterized in that, The meat is fish, shrimp, or squid.

5. The fermented food as described in claim 4, characterized in that, The fish mentioned are large yellow croaker, golden pomfret, mackerel, tilapia, crucian carp, silver carp, snakehead, grass carp, perch, or black carp.

6. A method for fermenting food, characterized in that, The Staphylococcus xylose S3 of claim 1 or the microbial preparation of claim 2 is added to meat products for fermentation; the meat products include minced meat, meat chunks or meat strips.

7. The method as described in claim 6, characterized in that, Inoculate sterilized fish paste with Staphylococcus xylose S3 seed culture and ferment at 30-37℃ for 36-60 hours.

8. The use of Staphylococcus xylose S3 of claim 1 or the microbial preparation of claim 2 in regulating the degree of lipid oxidation in fermented meat.

9. The use of Staphylococcus xylose S3 of claim 1 or the microbial preparation of claim 2 in improving the flavor of fermented meat.

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