CN-121975667-A - Acid-resistant and high-temperature-resistant cellulose degrading bacterium and application thereof in silage

Abstract

The invention discloses an acid-resistant and high-temperature-resistant cellulose degrading bacterium and application thereof in silage, and belongs to the technical field of functional microorganism screening and application. The strain is bacillus CYC6, and the preservation number is CGMCC No.36210. The strain has excellent high temperature resistance and acid resistance, can still keep good growth and cellulase activity under the high temperature of 40-50 ℃ and the acidic environment of pH 3.0-4.0, and simultaneously has high-efficiency cellulose degradation capability, and the carboxymethyl cellulase activity reaches 17.209 +/-0.472U/mL. The invention also provides a method for applying the CYC6 strain to silage, and the inoculation amount is 1 multiplied by 10 8 CFU per gram of silage raw material. The CYC6 strain can obviously reduce the content of neutral washing fibers and acidic washing fibers of silage, simultaneously improve the content of crude protein and fermentation quality, reduce the pH value to 3.98 and improve the content of lactic acid to 12.03 percent. The invention solves the technical problem that the existing cellulose degrading bacteria are easy to inactivate in the high-temperature acidic environment in the silage process, and provides an effective solution for improving the silage quality.

Inventors

• YAO BO
• CHEN JISHAN
• ZHU RUIFEN
• LIU CHANG
• FAN YAN

Assignees

• 重庆市畜牧科学院

Dates

Publication Date

20260505

Application Date

20251221

Claims (9)

1. 1. A cellulose degrading bacterium is characterized in that the cellulose degrading bacterium is bacillus CYC6, and is preserved in China general microbiological culture collection center (CGMCC) No. 36210 in the year 2025 and the month 9, and the bacillus CYC6 has acid resistance and high temperature resistance.
2. 2. The cellulose degrading bacterium according to claim 1, wherein the 16s rDNA sequence of Bacillus CYC6 is shown in SEQ ID NO. 1.
3. 3. The cellulose degrading bacterium according to claim 1, wherein the bacillus CYC6 is isolated from fresh rumen fluid of adult beef cattle.
4. 4. Use of the bacillus CYC6 according to any one of claims 1-3 for silage preparation.
5. 5. The use according to claim 4, characterized in that it is a bacillus CYC6 suspension sprayed in silage.
6. 6. A method of preparing silage comprising the steps of: s1, performing activation culture on the bacillus CYC6 according to claim 1 to prepare bacillus CYC6 bacterial suspension; s2, uniformly spraying the bacterial suspension onto silage raw materials for inoculation, and ensuring that the bacterial suspension and the silage raw materials are fully mixed; S3, filling the mixed silage raw materials into silage bags, sealing, and fermenting at room temperature.
7. 7. The method according to claim 6, wherein the medium for the activation culture is LB liquid medium, and the temperature of the activation culture is 37 ℃.
8. 8. The method of claim 6, wherein the silage material is cut hybrid pennisetum.
9. 9. The method of claim 6, wherein the amount of inoculation is 1 x 10 6 CFU/g fresh weight.

Description

Acid-resistant and high-temperature-resistant cellulose degrading bacterium and application thereof in silage Technical Field The invention belongs to the technical field of functional microorganism screening and application, and particularly relates to acid-resistant and high-temperature-resistant cellulose degrading bacteria and application thereof in silage. Background China is the large country of animal husbandry, and the efficient utilization of roughage resources is the key for guaranteeing the sustainable development of animal husbandry. Silage is a feed technology for storing fresh forage grass in an anaerobic environment through lactobacillus fermentation, and can effectively solve the problem of unbalanced seasonal supply of forage grass. However, many important forage grasses, especially warm-season grasses such as hybrid pennisetum, contain significant amounts of structural carbohydrates such as cellulose, hemicellulose, etc. that are difficult to digest directly by ruminants in the cell wall. This results in poor fermentation quality, low nutrient utilization and limited addition ratios in animal diets when silaged directly. Silage inoculation with microbial additives is an effective means of improving silage quality. The cellulose degrading bacteria can secrete cellulase, and partially decompose plant cell walls in the silage process, so that on one hand, the wrapped soluble carbohydrates are released, more fermentation substrates are provided for beneficial microorganisms such as lactic acid bacteria, and the like, the rapid acid production is promoted, the silage success rate is improved, and on the other hand, the fiber content of silage is directly reduced, and the in-vitro dry matter digestibility of the silage is improved, so that the nutritional value of the feed and the feed intake of animals are improved. Currently, there have been studies attempting to apply cellulose-degrading bacteria to silage. However, the actual silage process is a dynamic and complex environment, especially in the early stage of silage, plant cells still breathe, and various microorganisms can generate heat through metabolic activity, so that the temperature in the silage pit can rise to 40-50 ℃ to form a high-temperature environment. At the same time, successful silage processes are accompanied by a rapid drop in pH, which eventually results in an acidic environment, typically below 4.0. Most conventional cellulose degrading bacteria, such as strains derived from fungi of trichoderma, penicillium and the like, or some normal-temperature bacteria are difficult to simultaneously resist the high temperature in the early stage of ensiling and the acid environment in the whole ensiling process, and the enzyme activity and the viability of the bacteria are severely inhibited, so that the effect of the bacteria under the real ensiling condition is unstable and even fails. In addition, many cellulose degrading bacteria screened in the prior art are derived from soil, rotten vegetation and other environments, and the biological characteristics of the cellulose degrading bacteria and the suitability of the specific fermentation system of silage are insufficient. The rumen serves as a natural "fermenter" in which the microbial system has the natural advantage of efficiently degrading cellulose. And the strain which can simultaneously have the characteristics of high-efficiency cellulose degradation capability, high temperature resistance and strong acid resistance is separated from rumen, and the strain is successfully applied to improving the silage quality of warm-season high-fiber pasture in high-temperature and high-humidity areas such as Chongqing and the like, so that the strain has important production significance. Therefore, there is an urgent need in the art to isolate, screen and identify superior cellulose degrading strains from special environments that can accommodate silage and acid stress, to solve the technical bottleneck that the existing silage inoculant has poor effect in a real and severe silage environment, and to develop efficient and stable silage microbial additives. Disclosure of Invention The invention aims to overcome the defect that cellulose degrading bacteria in the prior art are difficult to maintain high activity in the high-temperature and ensilage whole-process acid environment during ensilage, and provides a strain which can simultaneously resist the high-temperature and acid environment and has high-efficiency cellulose degrading capability. In order to achieve the aim of the invention, the invention adopts the following technical scheme: the invention provides a cellulose degrading bacterium, which is bacillus CYC6, and is preserved in China general microbiological culture collection center (CGMCC) No. 36210 in the period of 2025 and 10-9, wherein the bacillus CYC6 has acid resistance and high temperature resistance. Further, the 16s rDNA sequence of the bacillus CYC6 is shown in SE