Method for promoting degradation of waste feather by feather powder

Abstract

The application provides a method for promoting degradation of waste feather by feather powder. The method is characterized in that feather powder is added to an inorganic salt culture medium containing waste feather as the only carbon and nitrogen source, and then microorganisms with the function of degrading keratin are inoculated to degrade the waste feather. The method has the advantages of short degradation time of waste feather, significantly improved degradation rate and keratinase activity, low cost and easy operation. The application can accelerate the green transformation and high-value application of waste feather, and can screen and enrich germplasm resources for degrading keratin, thereby helping to realize the green and circular high-quality development of the livestock and poultry breeding industry.

Description

Technical Field

[0001] This invention belongs to the field of resource utilization of livestock and poultry breeding waste, and specifically relates to a method for promoting the degradation of waste feathers by feather powder. Background Technology

[0002] Waste feathers are a byproduct of livestock and poultry farming, with a global annual production exceeding 10 million tons and my country's annual production around 4 million tons. Rich in keratin (over 90%), feathers are an important source of protein, bioactive peptides, amino acids, and minerals, and are widely used in feed, fertilizers, medical materials, daily chemical products, and agriculture. Due to the high concentration of disulfide and hydrogen bonds in feathers, they are difficult to degrade in the natural environment. Improper handling can easily lead to environmental pollution, resource waste, and health threats.

[0003] Generally, physical, chemical, and enzymatic methods for processing feathers can damage their nutritional components, pollute the environment, or be costly. Currently, feather meal obtained through extrusion is widely used in the feed industry and in the screening of feather-degrading microorganisms; however, this method destroys certain amino acids in the feathers, and animal digestibility is low (<30%). In recent years, biomanufacturing and green manufacturing have become the mainstream directions for the comprehensive utilization of low-value biomass to achieve high value. Utilizing microbial methods to biotransform waste feathers into high-nutrient products or functional materials such as amino acids and bioactive peptides has become a research hotspot.

[0004] However, due to the dense structure of feathers, the time required for microbial degradation of feathers is generally more than 5 days, and even more than 10 days. Studies have reported that keratinase plays a crucial role in the feather degradation process. Researchers have enhanced the enzyme activity and thermostability of keratinase by optimizing its promoter, gene expression, and thermal stability, thereby improving the performance of microorganisms in degrading feathers. These measures can improve keratinase activity at the gene level. However, the expression of keratinase (protease) is largely constrained and induced by the environment, resulting in low degradation efficiency and long time consumption. Therefore, improving the environment for microbial feather degradation can also induce efficient keratinase expression in cells. Although there are many studies on using feather powder for preliminary screening of microorganisms that degrade feathers, there are no studies or reports on whether it can promote the degradation of waste feathers. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for promoting the degradation of waste feathers using feather powder. This invention addresses the limitations of feather powder derived from feather puffing and the low efficiency of microbial feather degradation by adding feather powder to an inorganic salt culture medium containing waste feathers. This enhances the activity of microorganisms producing keratinase, thereby improving the feather degradation efficiency.

[0006] The present invention relates to a method for promoting the degradation of waste feathers using feather powder, which involves adding feather powder to an inorganic salt culture medium containing waste feathers, inoculating microorganisms to ferment and degrade the waste feathers, wherein the microorganisms are bacteria or fungi with the function of degrading keratin.

[0007] Preferably, S1: streak microbial cells on LB or PDA solid medium and incubate at 30-40℃ for 24-48h to obtain cells; S2: pick cells and place them in the corresponding liquid medium, incubate at 30-40℃ and 180-250rpm for 12-48h to prepare seed culture; S3: add feather powder to inorganic salt medium containing waste feathers and sterilize; S4: inoculate the seed culture into inorganic salt medium and degrade at 30-40℃ and 160-250rpm for 20-48h; 4) detect the degradation rate of feather powder and waste feathers by microorganisms and the activity of keratinase produced.

[0008] Preferably, the discarded feathers are discarded chicken feathers, duck feathers, or goose feathers.

[0009] Preferably, the feather powder is obtained by puffing chicken feathers, duck feathers, or goose feathers.

[0010] Preferably, the microorganism is Bacillus cereus. More preferably, it is Bacillus cereus C3752.

[0011] The inorganic salt culture medium can be a conventional inorganic salt culture medium, preferably comprising, by mass fraction, 0.01–0.10% NaCl, 0.01–0.12% KH₂PO₄, and 0.02–0.09% K₂HPO₄, with a pH of 7.0–10. More preferably, the inorganic salt culture medium comprises, by mass fraction, 0.04% NaCl, 0.06% KH₂PO₄, and 0.09% K₂HPO₄, with a pH of 9.5.

[0012] Preferably, the amount of feather meal added is 0.1-0.3% (w / v, g / ml) of the culture medium by volume. More preferably, the amount of feather meal added is 0.15% (w / v, g / ml).

[0013] Preferably, the waste feathers are present in an inorganic salt culture medium at a concentration of 1% w / v g / ml.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. Adding a small amount of feather powder directly to an inorganic salt culture medium containing waste feathers can improve the degradation efficiency of waste feathers. This method is low-cost and simple to operate.

[0016] 2. Adding feather powder can significantly increase keratinase activity by about 40% and increase the degradation rate of feathers by about 14%.

[0017] 3. In addition to improving the degradation rate of waste feathers, this invention also has the function of screening microorganisms that produce keratinase and / or degrade feathers, thus enriching the germplasm resources of microorganisms that produce keratinase and / or degrade keratin. Attached Figure Description

[0018] Figure 1 This is a comparison of the efficiency of Bacillus in degrading feather powder and waste feathers;

[0019] Figure 2 It is the effect of feather powder on the degradation of waste feathers by Bacillus subtilis;

[0020] Figure 3 This describes the relationship between the changes in keratinase produced by Bacillus over time and the amount of feather meal added. Detailed Implementation

[0021] The following embodiments are further explanations and illustrations of the present invention, but not limitations thereof.

[0022] Example 1: Adding feather powder promotes the degradation of waste feathers by Bacillus subtilis.

[0023] This embodiment uses Bacillus as an example for illustration. Bacillus refers to common Bacillus species, such as Bacillus cereus and Bacillus licheniformis. This embodiment selects Bacillus cereus C3752, disclosed in NCBI, GenBank: OM368754.1. The applicant also holds this strain and guarantees its availability to the public for 20 years from the application date.

[0024] (1) Comparison of feather meal and feather degradation by Bacillus cereus strain C3752

[0025] Bacillus cereus C3752 was streaked onto LB solid medium and incubated statically at 37°C for 24 hours. Colonies were picked and placed on LB liquid medium, and incubated at 37°C and 200 rpm for approximately 14 hours to obtain a seed culture. The seed culture was inoculated at approximately 5% (v / v) into inorganic salt medium using chicken feather meal (1%, w / v, g / ml) as the sole carbon and nitrogen source and inorganic salt medium using waste chicken feathers (1%, w / v, g / ml) as the sole carbon and nitrogen source, and incubated at 37°C and 200 rpm for 36 hours. Figure 1 As shown, differential gravimetric analysis revealed that the degradation rate of chicken feather powder by Bacillus cereus strain C3752 was over 87.6%, while the degradation efficiency of waste chicken feathers was around 64%. This indicates that feather powder can be efficiently degraded by microorganisms, and its degradation rate is significantly better than that of feathers.

[0026] The inorganic salt culture medium, by mass fraction, comprises 0.04% NaCl, 0.06% KH₂PO₄, and 0.09% K₂HPO₄. It is prepared by mixing all components thoroughly, adjusting the pH to 9.5, and sterilizing at 121°C for 20 minutes. If chicken feather powder or waste chicken feathers are to be added, the same method applies: mix all components thoroughly, adjust the pH to 9.5, and sterilize at 121°C for 20 minutes.

[0027] (2) Effect of feather meal addition on feather degradation by Bacillus cereus C3752 strain

[0028] Relative to the volume of the inorganic salt culture medium, 0.1%, 0.15%, 0.2%, 0.25%, and 0.3% (w / v, g / ml) chicken feather powder were added to an inorganic salt culture medium (50 mL) containing waste chicken feathers (1%, w / v, g / ml), respectively. A 5% seed culture was then inoculated at a volume ratio (same as step (1)). The mixture was cultured at 37℃ and 200 rpm for 36 h, and the degradation rate of the waste chicken feathers was then detected. Figure 2 As shown, with increasing feather meal addition, the degradation of waste chicken feathers by Bacillus cereus strain C3752 initially increased and then decreased, reaching its highest degradation rate (~73%) at a feather meal addition of 0.15%. This was compared to the control group without added feather meal (…). Figure 1 The efficiency of strain C3752 in degrading waste chicken feathers was enhanced by approximately 14%. The results indicate that adding approximately 0.15% feather powder can promote the degradation of waste feathers.

[0029] To further explore the reasons why feather meal promotes feather degradation, spectrophotometry was used to detect changes in keratinase activity during feather degradation. Figure 3 As shown, with the increase of feather meal addition, keratinase activity first increased and then decreased, with a significant increase in keratinase activity in the 0.15% feather meal group. Simultaneously, in the initial stage of waste chicken feather degradation (0–4 h), except for the 0.3% feather meal group, the changes in keratinase activity in the other groups were not significant. From 4 to 24 h, keratinase activity continuously increased, reaching its peak at 24 h (332 U / mL), at which point it was 39.8% higher than the control group without feather meal. After 24 h, the enzyme activity gradually decreased. However, throughout the entire waste feather degradation process, the keratinase activity in the 0.15% feather meal group was higher than that in the other groups.

[0030] In conclusion, feather meal enhances the activity of keratinase produced by Bacillus cereus C3752, thereby improving its efficiency in degrading waste chicken feathers.

[0031] The above embodiments are merely illustrative examples of the present invention, and the scope of protection of the present invention is not limited thereto. Any simple changes or combinations of the formula, simple changes or equivalent substitutions of the technical solutions obtained by those skilled in the art within the scope of the technology disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for promoting the degradation of waste feathers using feather powder, characterized in that, Feather powder is added to an inorganic salt culture medium containing waste feathers, and microorganisms are inoculated to ferment and degrade the waste feathers. The microorganisms are bacteria or fungi with the function of degrading keratin. The inorganic salt culture medium comprises, by mass fraction, 0.04% NaCl, 0.06% KH₂PO₄, and 0.09% K₂HPO₄, with a pH of 9.5; The amount of feather meal added is 0.15% (w / v) g / ml. The waste feathers mentioned above have a content of 1% (w / v) g / ml in the inorganic salt culture medium. The microorganism mentioned is Bacillus cereus C3752.

2. The method according to claim 1, characterized in that, S1: Strand the microbial cells onto LB or PDA solid medium and incubate them at 30-40℃ for 24-48 hours to obtain the cells; S2: Pick bacterial cells and place them in the appropriate liquid culture medium. Incubate at 30-40℃ and 180-250rpm for 12-48h to prepare seed culture; S3: Add feather powder to an inorganic salt culture medium containing waste feathers and sterilize. S4: The seed culture was inoculated into an inorganic salt culture medium and degraded at 30–40℃ and 160–250 rpm for 20–48 h. The degradation rate of the waste feathers was then measured.

3. The method according to claim 1 or 2, characterized in that, The discarded feathers mentioned are discarded chicken feathers, duck feathers, or goose feathers.

4. The method according to claim 1 or 2, characterized in that, The feather powder mentioned is derived from chicken feathers, duck feathers, or goose feathers through puffing.

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