Application of Streptomyces microflavus strain SaTC2601 in promoting conversion of straw by Protaetia brevitabula

Abstract

The present application relates to the application of Streptomyces microflavus strain SaTC2601 in promoting the conversion of straw by Protaetia brevitarsis. The present application finds that the use of Streptomyces microflavus to treat straw can promote the conversion rate of straw by Protaetia brevitarsis larvae and promote the increase of Protaetia brevitarsis larvae, which is not only beneficial to the consumption of straw non-point source pollution, but also the increase of the body weight of Protaetia brevitarsis larvae can increase the protein yield, thereby providing a more favorable channel to guarantee the national food security.

Description

Technical Field

[0001] This invention relates to the field of microorganisms, and in particular to a Streptomyces that promotes weight gain and / or promotes straw conversion in white-spotted beetles. Background Technology

[0002] With the continuous advancement of agricultural modernization, the issue of resource utilization of crop straw has become increasingly prominent. According to incomplete statistics, China produces more than 700 million tons of crop straw annually. How to scientifically and efficiently treat these agricultural wastes and realize their resource utilization has become an important issue for the sustainable development of agriculture.

[0003] White-spotted Flower Beetle ( Protaetia brevitarsis The larvae of the White Spotted Flower Chafer (WSFC) are saprophytic and do not harm plants. They are a resource insect that can convert agricultural waste into high-quality insect protein. They have been domesticated as "micro-livestock," and their dung has a good growth-promoting effect on plants, thus making them highly valuable. Summary of the Invention

[0004] This invention provides *Streptomyces whitworthii*. Streptomyces albidoflavus Application in promoting the conversion of straw by the white-spotted flower beetle and / or promoting the weight gain of the white-spotted flower beetle.

[0005] In one specific embodiment, the strain of *Streptomyces microcyticus* is strain SaTC2601.

[0006] In one specific embodiment, the white-spotted flower beetle is the larva of the white-spotted flower beetle.

[0007] In one specific embodiment, the straw is corn straw.

[0008] In one specific embodiment, the straw is treated with Streptomyces microcyticum strain SaTC2601 for 3 to 10 days before being fed to the white-spotted beetle, for example, for 5 to 7 days.

[0009] In one specific embodiment, the straw is treated with Streptomyces microcyticum SaTC2601 strain at a temperature of 25 to 37 degrees Celsius.

[0010] In one specific embodiment, the straw is treated with Streptomyces microcyticum SaTC2601 strain at a temperature of 28 to 30 degrees Celsius.

[0011] The beneficial effects of this invention are as follows: This invention has found that treating straw with Streptomyces microcytogenes can promote the straw conversion rate of white-spotted beetle larvae and increase the number of white-spotted beetle larvae. This not only helps to eliminate straw non-point source pollution, but also the increased weight of white-spotted beetle larvae can increase their protein production, thus providing a more effective way to ensure national food security. Attached Figure Description

[0012] Figure 1 The image shows photos of SaTC2601 treating corn stalks for 3 days. Detailed Implementation

[0013] The present invention will be further described in detail below through preferred embodiments, but these embodiments do not constitute a limitation thereof.

[0014] Unless otherwise specified, the reagents and other materials used in the embodiments of this invention can be purchased commercially.

[0015] The *Streptomyces whitworthii* used in this invention Streptomyces albidoflavus The SaTC2601 strain was first disclosed in CN202510827215.9. It is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 33741, deposited on March 7, 2025, at the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0016] 1. Preparation of Streptomyces whitworthii spores

[0017] Extraction of soluble insect excrement: Take 100 g of dried larval excrement of white star flower beetle (WSFC) (moisture content below 3%) and add it to a 1L conical flask. Make up the volume to 1L with water and extract at 80 degrees Celsius for 2 hours. Centrifuge to remove insoluble matter to obtain water extract. Spray dry the water extract to obtain water-extracted powder.

[0018] WSFC insect excrement water extract solid culture medium: Weigh 10g of WSFC larval excrement water extract powder, add 15g of agar powder, and bring the volume to 1L. Autoclave at 121°C for 20 min to prepare a 1% WSFC insect excrement water extract solid culture medium. Pour the above 1% WSFC insect excrement water extract solid culture medium into 90mm diameter petri dishes, 20ml per dish, to obtain the WSFC insect excrement water extract solid culture medium.

[0019] The *Streptomyces microcyticus* strains SaTC2601 and X14 were propagated using WSFC insect excrement aqueous extract solid medium. The strains were cultured at 28°C for 7 days on WSFC insect excrement aqueous extract solid medium to produce spores. The spores were collected by suspension in sterile water and prepared into spore suspensions of 1×10⁸ CFU / ml for each strain.

[0020] 2. Processing corn stalks

[0021] After harvesting corn, the corn stalks were air-dried to a moisture content below 3%, and then extruded and granulated into straw feed pellets (meeting the quality requirements of the national standard GB / T 35835-2018 Corn Stalk Pellets). 150 ml of the above-mentioned SaTC2601 or X14 spore suspension was added to 100 g of straw feed pellets, serving as the *Streptomyces microcyticum* SaTC2601 treatment group and the *Streptomyces microcyticum* X14 treatment group, respectively. A 150 ml suspension of 1×10⁸ CFU / ml of live bacteria was prepared using a commercially available straw decomposing agent and added to 100 g of straw feed pellets, serving as the commercially available straw decomposing agent treatment group. 150 ml of sterile water was added to 100 g of straw feed pellets, serving as the control group. The straw from each treatment group and the control group was placed in an incubator at 30°C for static fermentation for 3 days. The results are shown in the table below. Figure 1 .

[0022] from Figure 1 As can be seen, actinomycete spores and actinomycete hyphae can be observed on the straw of the treatment group.

[0023] 3. Effects of SaTC2601 on the body weight of white-spotted flower beetle larvae and its promoting effect on straw conversion in white-spotted flower beetle larvae.

[0024] Take 60g of straw feed pellets from each treatment group and the control group after 3 days of fermentation and place them in rearing boxes. The SaTC2601 treatment group, X14 treatment group, and commercially available straw decomposing agent treatment group all produced white actinomycete mycelia and spores. Weigh and record the body weight of early third instar larvae of the white-spotted flower beetle. Select larvae of similar weight and place them in rearing boxes for each group, with one rearing box constituting one replicate. Each replicate contains 10 larvae, and each treatment group has 3 replicates. Rearing is carried out in an incubator at 30°C for 2 days. Collect and record the larvae, frass, and remaining straw feed pellets from each group. Calculate the larval weight gain, feed intake (initial straw feed pellet weight in each rearing box minus the remaining straw feed pellets after 2 days of feeding), straw conversion rate, and straw conversion efficiency. The straw conversion rate was characterized by the daily feed intake of each kilogram of white-spotted beetle larvae, as shown in formula (1); the straw conversion efficiency was the efficiency of converting straw into insect weight, calculated by the ratio of insect body weight gain to straw consumption, as shown in formula (2). The difference between the SaTC2601 treatment group and the control group was analyzed using a t-test. The results are shown in Table 1.

[0025] Straw conversion rate = ((feeding amount / feeding time) / initial insect weight) × 1000g Formula (1).

[0026] Straw conversion efficiency = (insect body weight gain / food intake) × 100% Formula (2).

[0027] Table 1

[0028] The results in Table 1 show that, compared with the control group, the conversion rate and conversion efficiency of straw in the SaTC2601 treatment group, the X14 treatment group, and the commercially available straw decomposing agent treatment group were significantly higher than those in the control group (p<0.01), indicating that the addition of microbial agents can promote the conversion of straw by *Streptomyces chrysogenum*. Compared with the *Streptomyces microcytogenes* X14 treatment group, the conversion rate and conversion efficiency of straw in the commercially available straw decomposing agent treatment group were significantly higher than those in the *Streptomyces microcytogenes* X14 treatment group (p<0.01), indicating that although conventional *Streptomyces microcytogenes* can promote conversion, its effect is not as good as the synergistic effect of multiple strains in the commercially available compound microbial agents. The straw conversion rate of the SaTC2601 treatment group was 417.93 g, significantly higher than that of the control group (342.39 g) (p<0.01), which was 1.22 times that of the control group. This indicates that the larvae preferred to feed on the straw treated with SaTC2601, which may be related to the special odor produced by the fermentation of this strain. The body weight gain of the insects in the SaTC2601 treatment group was 2.66 g, significantly higher than that of other treatment groups (p<0.01). The straw conversion efficiency of the SaTC2601 treatment group was 20.90%, significantly higher than that of other treatment groups (p<0.01), indicating that the fermentation of straw by this strain can produce more absorbable nutrients.

Claims

1. Streptomyces whitworthii Streptomyces albidoflavus Applications in promoting the conversion of straw by the white-spotted flower beetle and / or promoting weight gain in the white-spotted flower beetle, wherein... The strain of Streptomyces microcytogenes is SaTC2601. The straw is fermented with Streptomyces microcytogenes SaTC2601 for 3 to 10 days and then fed to the white-spotted beetle.

2. The application according to claim 1, characterized in that, The white-spotted flower beetle is the larva of the white-spotted flower beetle.

3. The application according to claim 1, characterized in that, The straw in question is corn stalks.

4. The application according to claim 1, characterized in that, The straw was fermented with Streptomyces microcyticum strain SaTC2601 for 3 days and then fed to the white-spotted flower beetle.

5. The application according to claim 1, characterized in that, The straw was fermented using Streptomyces microcyticum strain SaTC2601 at a temperature of 25 to 37 degrees Celsius.

6. The application according to claim 1, characterized in that, The straw was fermented using Streptomyces microcyticum strain SaTC2601 at a temperature of 28 to 30 degrees Celsius.

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