Streptomyces jute and application thereof

Abstract

The invention belongs to the technical field of microorganisms, and particularly relates to streptomyces jute and application thereof. The streptomyces corchorusii is classified and named as streptomyces corchorusii, and is preserved in the China General Microbiological Culture Collection Center (CGMCC), and the preservation number is CGMCC No.33658. The streptomyces corchorusii is named as streptomyces corchorusii and is preserved in the China General Microbiological Culture Collection Center (CGMCC). The streptomyces corchorusii can antagonize various plant pathogenic fungi or oomycetes, volatile matters generated on a solid culture medium plate, extracellular proteins obtained by ammonium sulfate precipitation during liquid culture, organic phase extraction and concentration compounds and the like can inhibit the growth of the pathogenic fungi or oomycetes, and the streptomyces corchorusii can rapidly grow and propagate by taking colloidal chitin as a unique carbon source; chitosan oligosaccharide is efficiently produced, plants can be stimulated to enhance immunity, healthy growth of the plants is guaranteed, and the streptomyces corchorusii provided by the invention has important agricultural application value.

Description

Technical Field

[0001] The present application relates to a Streptomyces corchorusii and its application, belonging to the field of microbial technology. Background Art

[0002] Plant pathogens have caused great harm to food production. There are more than 10,000 plant diseases caused by plant pathogens, accounting for 10-30% of the total annual crop losses. Plant diseases are an important factor affecting the yield and quality of global crops, and the annual global crop yield reduction caused by plant diseases is as high as 30-50%. The pathogens causing plant diseases mainly include fungi, oomycetes, viruses, bacteria, nematodes, etc., among which plant fungal diseases account for 70-80% of plant diseases. Alternaria solani Alternaria solani ), Fusarium oxysporum Fusarium oxysporum Schltdl ), Fusarium graminearum Fusarium graminearum Schwabe ), Colletotrichum gloeosporioides Colletotrichum gloeosporioides Penz.&Sacc are common plant pathogenic fungi in China. Fusarium oxysporum, Fusarium graminearum, and Colletotrichum gloeosporioides have been rated as the top ten pathogenic fungi in molecular plant pathology by the international famous journal Molecular Plant Pathology. Phytophthora nicotianae in oomycetes is also one of the top ten pathogenic oomycetes in molecular plant pathology.

[0003] Although using traditional chemical pesticides to control plant diseases is simple and quick to take effect, due to the long-term unreasonable use of chemical fungicides, it has brought serious disasters to the ecological environment and human health. Therefore, it is urgent to adopt green and scientific prevention and control means. Streptomyces Streptomyces ) belongs to the order Actinomycetales and is a Gram-positive bacterium with highly branched vegetative hyphae. At present, about 40% of the reported bioactive substances of microbial origin are from Streptomyces, including various antibiotics, herbicides, and other bioactive substances. With the development and improvement of science and technology, sequencing technology has brought a revolutionary breakthrough to the research of genomics. Through in-depth research on Streptomyces genomic data, it is found that the genomic size of Streptomyces is relatively large and the GC content is generally high. After further exploring the Streptomyces genome, many antibiotics that have been widely used subsequently have been discovered. At the same time, Streptomyces also has high application value in agriculture. For example, using Streptomyces agricultural antibiotics, live bacterial agents, etc. to control plant diseases.

[0004] The genome of Streptomyces is more than twice that of ordinary bacteria. In addition to producing a variety of antibiotics, it also has the ability to degrade complex organic substances, such as chitin. Chitin, also known as chitose, is very abundant in nature. Chitin is a polysaccharide abundant in nature, insoluble in water, often discarded as waste, causing waste of resources and environmental pollution. Chitin is the second largest carbohydrate and the second largest nitrogen-containing compound, a polymer second only to cellulose and hemicellulose, and is one of the components of insect exoskeletons, animal shells or fungal cell walls.

[0005] Chitooligosaccharides (abbreviated as CHOS, also known as chitosan oligosaccharides) are a class of weak polysaccharides composed of 2-10 monosaccharides linked by glycosidic bonds, which can be formed during the decomposition of chitin. Chitooligosaccharides can play a very good role in cultivating beneficial bacteria, enabling beneficial bacteria to secrete resistant enzymes chitinase and antibiotic substances to directly dissolve the egg body wall, and at the same time can also inhibit the growth and reproduction of harmful bacteria. The market demand for chitin hydrolysis products is large, and they can be applied in many fields, with important research prospects and market value. The enzymatic degradation method of chitin has the advantages of environmental protection, mild conditions, high product purity, etc., and has great development potential. At the same time, chitosan and its oligosaccharides have also begun to attract the attention of the agricultural sector. In the context of organic agriculture, they do not cause harm to the environment, and the absorption efficiency of plants for fertilizers is greatly increased, which can promote the growth of agricultural plants and also play a role in disease prevention and control.

[0006] Therefore, it is necessary to provide a Streptomyces strain that antagonizes various plant pathogenic fungi or oomycetes and efficiently degrades chitin, thus contributing to the application of Streptomyces in the prevention and control of plant diseases. Summary of the Invention

[0007] To solve the above problems, the present application provides a Streptomyces corchorusii and its application. The Streptomyces corchorusii ChiF can grow and reproduce under the condition of using chitin as the sole carbon source, can efficiently degrade chitin, and the supernatant protein of the fermentation broth of this strain can be used for the enzymatic production of chitooligosaccharides using colloidal chitin. It helps plants resist the invasion of pathogenic bacteria in the soil where this strain is inoculated, improves the immune ability of plants, and ensures the healthy growth of plants, with important agricultural application value.

[0008] The present application provides a Streptomyces corchorusii ( Streptomyces corchorusii ), and the Streptomyces corchorusii is selected from any one of the following: 1) The isolated Streptomyces corchorusii was deposited with the China General Microbiological Culture Collection Center CGMCC on February 26, 2025, with the deposit number CGMCC No. 33658, and the address of the deposit unit is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing; 2) The isolated offspring, mutants or derivatives of the isolated Streptomyces corchorusii as described in 1).

[0009] Optionally, the nucleotide sequence of the 16S rDNA of the Streptomyces corchorusii is as shown in SEQ ID No.1.

[0010] Optionally, the Streptomyces corchorusii can inhibit Alternaria brassicae ( Alternaria raphani Groves ), Fusarium moniliforme ( Fusarium moniliforme Sheld ), Fusarium oxysporum f. sp. lycopersici ( Fusarium oxysporum ) and Phytophthora parasitica ( Hytophthora nicotianae ) in the growth of one or more of the bacteria.

[0011] Optionally, the Streptomyces corchorusii can grow using chitin as the sole carbon source.

[0012] Optionally, the Streptomyces corchorusii can grow at 25 - 40 °C, pH 6 - 10, and 3 - 7% sodium chloride environment.

[0013] Optionally, the Streptomyces corchorusii can express chitin-degrading enzymes without the need to add colloidal chitin for induction.

[0014] Optionally, the Streptomyces corchorusii contains at least 10 chitin hydrolase genes of the GH18 family and at least 2 chitin hydrolase genes of the GH19 family.

[0015] This application provides the above-mentioned Streptomyces corchorusii in the application of producing chitooligosaccharides using chitin, enhancing plant immunity or resisting plant diseases.

[0016] This application provides a product, and the product is selected from any one of the following: a) A product containing the above-mentioned Streptomyces corchorusii; b) A product containing the lysate of the above-mentioned Streptomyces corchorusii; c) A product containing the culture of the above-mentioned Streptomyces corchorusii.

[0017] This application provides the above-mentioned product in the application of producing chitooligosaccharides using chitin, enhancing plant immunity or resisting plant diseases.

[0018] The beneficial effects of this application include but are not limited to: 1. According to the Streptomyces corchorusii and its application of this application, the Streptomyces corchorusii can antagonize various plant pathogenic fungi or oomycetes, and the volatiles produced on the solid medium plate, extracellular proteins obtained by ammonium sulfate precipitation during liquid culture, and organic phase extraction and concentration compounds can inhibit the growth of pathogenic fungi or oomycetes. Specifically, it inhibits Alternaria brassicae ( Alternaria raphani Groves ) on the solid plate, Fusarium moniliforme ( Fusarium moniliforme Sheld ), Fusarium oxysporum f. sp. lycopersici (Fusarium oxysporum ) and the growth of Phytophthora nicotianae Hytophthora nicotianae .

[0019] 2. The Streptomyces corchorusii according to the present application and its application. The Streptomyces corchorusii can grow using any one of glucose, cellobiose, sucrose, starch, colloidal chitin, and chitin powder as a carbon source, and can grow rapidly especially under the condition of using colloidal chitin as the sole carbon source. And it can grow in an environment of 25~40°C and pH 6~10, without adding colloidal chitin for induction, and can produce chitin-degrading enzymes. Through genome and transcriptome sequencing, it is found that this bacterium not only has endochitinase and exochitinase for hydrolyzing chitin, but also has enzymes for oxidative cleavage of chitin. The synergistic action of these enzymes enables the Streptomyces corchorusii to efficiently degrade chitin into oligosaccharides.

[0020] 3. The Streptomyces corchorusii according to the present application and its application. The Streptomyces corchorusii not only has differences in biological species identification from the previously reported chitinase-producing Streptomyces, but also has significant differences in physiological and biochemical characteristics. By studying the genomic information of the Streptomyces corchorusii of the present invention and using transcriptome sequencing to analyze the division of labor and functions of endochitinase and exochitinase in the process of using chitin, it provides theoretical guiding significance for better utilization of this bacterium.

[0021] 4. The Streptomyces corchorusii according to the present application and its application. Using the Streptomyces corchorusii and its fermentation broth to produce chitooligosaccharides and improve plant immune resistance and antagonize plant diseases has good application prospects, and can also make full use of chitin resources. The Streptomyces corchorusii has important agricultural application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings: Figure 1 It is the comparison result of the clear zone (A) of each isolated strain in the chitin solid medium and the hydrolysis degree in the liquid medium (B) involved in Example 1 of the present application; Figure 2 It is the result diagram of the antagonistic effect of the strain ChiF involved in Example 2 of the present application on four plant pathogens on the plate (A. Chinese cabbage pathogen; B. Rice pathogen; C. Tomato pathogen; D. Black shank pathogen); Figure 3 It is the result diagram of the antagonistic effect of the volatile substances of the strain ChiF involved in Example 2 of the present application on four plant pathogens; Figure 4 It is the result diagram of the construction of the phylogenetic tree of the strain ChiF involved in Example 4 of the present application based on the whole gene map; Figure 5 This is a statistical result diagram of the carbohydrate-degrading enzyme system in the whole-genome sequencing map of strain ChiF involved in Example 4 of this application; Figure 6 This is the result diagram of Venn analysis (A) and PCA analysis (B) of the expression level analysis among samples involved in Example 5 of this application; Figure 7 This is the volcano plot of the transcriptome sequencing of strain ChiF involved in Example 5 of this application; Figure 8 This is the cluster analysis diagram of each gene in the transcriptome sequencing of strain ChiF involved in Example 5 of this application; Figure 9 This is the result diagram of the KEGG pathway enrichment analysis of the transcriptome of strain ChiF involved in Example 5 of this application. Detailed implementation mode

[0023] The following describes this application in detail with reference to the examples. However, this application is not limited to these examples. Unless otherwise specified, the raw materials and reagents in the examples of this application are purchased through commercial channels.

[0024] Example 1 Isolation, screening and identification of strains 1) Isolation and screening of strains The tobacco rhizosphere soil collected from the Qingdao farmland of the CAS Tobacco Research Institute was continuously diluted with sterile 0.9% saline to 10 -4 、10 -5 、10 -6 , and then spread on an agar plate containing 1% colloidal chitin, 0.3% KH2PO4, 0.2% NH4NO3, 0.15% K2HPO4, 0.01% MgSO4•7H2O, 0.001% CaCl2, 0.001% ethylenediaminetetraacetic acid and 1.5% agar powder (pH 7). The plate was incubated at 30 °C for 6 days. The colonies growing on the plate with a clear zone were transferred to a new plate to purify the microorganisms and check the range of the clear zone. Then, in a shaking flask at 30 °C, the microorganisms were subcultured in a liquid medium (containing 1% colloidal chitin, 0.3% KH2PO4, 0.2% NH4NO3, 0.15% K2HPO4, 0.01% MgSO4•7H2O, 0.001% CaCl2, 0.001% EDTA) on a rotary shaker (180 rpm, Shanghai Zhichu). After culturing for 3 days, the culture solution was centrifuged (4 °C, 12000×g, 20 minutes), and the supernatant was collected for measuring the chitinase activity (the results are as Figure 1 shown).

[0025] Using morphological, physiological and biochemical parameters, as well as 16S rDNA-based sequence analysis, bacterial strains with clear transparent zones were identified after PCR amplification with specific primers 16S-27F and 16S-1492R. The nucleotide bases of the obtained DNA sequences were assembled and compared with the sequences in the EzBioCloud database to identify the bacterial strains. Through 16S sequence identification, colony ABC was identified as Achromobacter, with the highest similarity to Achromobacter xylosoxidans JCM 9787. Colonies ChiD to ChiS were all Streptomyces, with the highest similarity to Streptomyces corchorusii DSM 40340, Streptomyces misionensis JCM 4497, Streptomyces glaucescens DSM 40155 respectively. Colonies ChiD to ChiS were all Streptomyces, belonging to the group of Gram-positive Streptomyces that can produce spores with strong stress resistance. After that, a secondary screening was carried out through the antagonistic test of plant pathogens. Strain ChiF was the dominant strain in agricultural production. It could not only produce spores with strong stress resistance, but also had strong extracellular enzyme activity in the mycelial stage. The whole genome sequence was used to further identify strain ChiF.

[0026] 2) Taxonomic identification of strain ChiF PCR sequence determination was carried out using the universal primers 16S rDNA-27F / 16S rDNA-1492R. Among them, the 16S RDNA sequence primers were: 16S-27F: AGAGTTTGATCMTGGCTCAG; 16S-1492R: TACGGYTACCTTGTTACGACTT.

[0027] The PCR reaction system was as follows: 2×PCR Master Mix: 25 μl; Primer 1 (10µM): 1 μl; Primer 2 (10µM): 1 μl; Template: 1 μl; ddH2O: 22 μl; The PCR reaction program was as follows: Pre-denaturation at 94°C for 5 min; Denaturation at 94°C for 30 s, annealing at 55°C for 30 s, extension at 72°C for 90 s, repeated for 30 cycles; Final extension at 72°C. The PCR products were recovered by gel and sent to a sequencing company for sequencing.

[0028] The 16S rDNA fragment sequence of the said CHiF strain is shown in SEQ ID NO.1.

[0029] As shown in Table 1, after comparison with the NCBI database, the strain to be detected, CHiF, was identical to Streptomyces corchorusii Streptomyces corchorusiiDSM40340 (T) has the highest similarity, with its serial number KQ948396 reaching 99.93%. Its similarities with Streptomyces spinosisporus NBRC13431(T), Streptomyces olivaceoviridis NBRC13066(T), and Streptomyces nishiyamaensis JCM4734 (T) all exceed 99.50%. Its similarities with Streptomyces gilvosporeus DSM40089 (T), Streptomyces longwoodensis DSM41677 (T), and Streptomyces lasaliensis ATCC 31180 (T) all reach 99.42%. Its similarities with Streptomyces sisomicini K04-0144 (T), Streptomyces bungoensis DSM 41781(T), and Streptomyces chromogenes MK-45 (T) are 99.35%, 99.28%, and 98.99% respectively. These streptomycetes either produce pigments or antibiotic compounds. This group has a strong ability to produce secondary metabolites, which can not only inhibit plant pathogens but also produce chitinase to stimulate plants to enhance their immune resistance against pathogen invasion.

[0030] Streptomyces corchorusii ChiF is Gram-positive. After one week of cultivation on ISP2 plates, the colony diameter reaches 2 mm. The colony edge is relatively regular, the surface is opaque, and it is milky white. The strain is oxidase-negative, and the hydrolysis of starch and casein is determined on starch agar and skim milk agar plates. By placing overnight cultures on agar plates and then incubating the plates at 5, 10, 15, 20, 25, 30, 40, 45, and 55 °C to evaluate the growth temperature range, the strain grows between 10 and 40 °C. The optimal growth temperature is 35 °C. The sodium tolerance is evaluated by inoculating the strain into tryptic soy broth (TSB) containing 2, 5, 7, 8, 9, or 10% (w / v) NaCl and then incubating at 30 °C for two days. It is found that the strain can grow at NaCl concentrations up to 5%. The growth in pH-adjusted TSB incubated at 30 °C for two days shows that the strain can grow at pH 5 - 10.

[0031] Characterize the acids produced by carbohydrate catabolism using the API CH50 kit; incubate at 30 °C for 48 hours, and it can utilize (acids produced by catabolism) d-ribose, d-glucose, d-fructose, d-xylose, d-fructose, d-fructose, L-rhamnose, mannitol, inositol, raffinose, melibiose, cellobiose, maltose, trehalose, amide, and glycogen. The API 20E kit was used for testing, and after incubating at 30 °C for 48 hours, strain acetoin produced a positive Voges-Proskauer (VP) reaction and gelatinase activity. It can reduce nitrate to nitrite. It can utilize L-aspartic acid, L-threonine, glycine, L-phenylalanine, L-arginine, L-methionine, L-ornithine as the sole nitrogen source, and cannot utilize D-valine as the sole nitrogen source. This bacterium can produce acid phosphatase, alkaline phosphatase, fructase, α-galactosidase, α-fucosidase, α-mannosidase, arginine dihydrolase, β-glucosidase, β-galactosidase, and does not produce α-chymotrypsin.

[0032] The jute Streptomyces ChiF strain screened in the present invention was preserved. The preservation unit: General Microbiology Center of the China Committee for Culture Collection of Microorganisms; Preservation date: February 26, 2025, Streptomyces jute Streptomyces corchorusii The preservation number of ChiF is CGMCC No. 33658.

[0033] Table 1 Alignment results of the 16S rDNA sequences of the strain ChiF of the present invention

[0034] Example 2 Antagonistic effect of Streptomyces ChiF against plant pathogens First, take out about 50 or more strains from the strains screened for chitin degradation for the first time, including Achromobacter, Bacillus, and Streptomyces.

[0035] Then conduct a secondary screening: use the plate to spot plant pathogens for the antibacterial test between bacteria (the results are as Figure 2 shown), and two strains of Streptomyces ChiF and ChiG were screened. Finally, chiF was selected for the next test. At the same time, genomic sequencing and transcriptome sequencing analysis were carried out.

[0036] Furthermore, use Alternaria brassicae ( Alternaria raphani Groves), Gibberella fujikuroi ([[]] Fusarium moniliforme Sheld), Fusarium oxysporum f. sp. lycopersici ([[]] Fusarium oxysporum ) and Phytophthora nicotianae for the antibacterial test against plant pathogens (the results are as Figure 3 shown).

[0037] The antagonistic mechanism was analyzed from the following three aspects: 1) The crude extract obtained by extracting metabolites with ethyl acetate was spotted on a plate; 2) The protein precipitated by ammonium sulfate extraction from the fermentation broth was spotted on a plate; 3) The antibacterial effect of volatile substances was verified by the method of sandwiching two plates. The results are shown in Table 2 below.

[0038] Table 2 Inhibitory effects on four plant pathogenic bacteria

[0039] According to the results in Table 2, except for the black shank pathogen, the other three pathogens are sensitive to the volatile substances of this strain, and the inhibition rates are all between 57% and 75%. The substances obtained by protein precipitation and extraction with ethyl acetate have a relatively high inhibition rate against the black shank pathogen. The inhibition rate of protein precipitation is 64%, and the inhibition rate of ethyl acetate is 75%.

[0040] Example 3 Determination of the growth conditions of Streptomyces ChiF For the analysis and determination method of the growth conditions and growth curve of the bacteria, ISP2 liquid medium was used, which contained 4 g of glucose, 4 g of yeast powder, 10 g of malt extract powder, and 2 g of calcium carbonate per liter of water. A pre-inoculum was prepared in ISP2 and incubated overnight at 30 °C. The pre-inoculum on the ISP2 solid medium was used to inoculate 100 ml of LB medium, and it was found that after three or four days, it grew into a thick millet porridge-like state, indicating that the stationary phase had been reached. The growth curve was analyzed at 10 - 50 °C, and it was found that the strain grew vigorously in the range of 25 - 40 °C, and the optimal growth temperature was 30 °C. Then, under the culture conditions of 30 °C, the optimal growth pH value was determined, and it was found that it could grow between pH 6.0 and 10.0, and the highest growth rate could be achieved at pH 7.0. ChiF can grow using any one of glucose, cellobiose, sucrose, starch, colloidal chitin, and chitin powder as the carbon source.

[0041] Example 4 Whole-genome sequencing of Streptomyces and analysis of chitin degradation genes and secondary metabolite gene clusters 1) Genomic DNA extraction The strain ChiF was streaked on an ISP2 solid medium and cultured overnight at 30 °C. Next, the bacterial plaque on the solid medium was inoculated into 200 mL of ISP2 liquid medium and cultured at 30 °C at 180 rpm for about 48 hours. The cell biomass was harvested after centrifugation at 12000×g for 10 minutes. The genomic DNA of ChiF was extracted using a Bacterial / Fungal DNA Extraction Kit (Magnetic Beads) (Majorbio, Shanghai, China). The purified genomic DNA was quantified and high-quality DNA was used for further research.

[0042] 2) Library construction and genome sequencing The genomic sequence analysis of the ChiF strain was performed using the Illumina sequencing platform (MajorBio Co., Shanghai, China). The DNA sample was sheared into fragments of about 400 bp using a Covaris M220 focused acoustic shearing machine. Then the prepared library was used for Illumina Novaseq 6000 on-machine sequencing.

[0043] 3) Genome assembly and annotation The data generated by the Illumina platform were used for bioinformatics analysis. All analyses were performed using the Majorbio Cloud Platform (www.Majorbio.com), an online platform of Shanghai Majorbio Bio-pharm Technology Co., Ltd. The raw reads obtained after sequencing were filtered using the fastp software (version 0.19.6) and then assembled using the SOPA de novo version 2.04.

[0044] The total length of the genome of this bacterium was 10,171,291 bp, approximately 10.17 Mb, with a total of 123 scaffolds. There were 103 larger scaffolds, and the total length of the larger scaffolds was 10.16 Mb. The largest scaffold had a base number of 7.67 Mb. The Scaf N50 (bp) and Scaf N90 (bp) were 317,629 bp and 62,758 bp respectively. The genomic G+C (%) was 72.095, and the N Rate (%) was 0.123. The sequencing depth was Depth 109.83. A phylogenetic tree of this genome was constructed using housekeeping genes, and it was found that this bacterium belongs to the Streptomyces group (the results are as Figure 4 shown).

[0045] Glimmer was used for CDS prediction and 9,036 genes were obtained. tRNAscan-SE was used for tRNA prediction and 83 tRNAs were obtained. Barrnap was used for rRNA prediction and 2 rRNAs were predicted. Sequence alignment tools such as BLASTP, Diamond, and HMMER were used to annotate the predicted CDS from the NR, Swiss-Prot, Pfam, GO, COG, KEGG, and CAZY databases. Briefly, each set of query proteins was aligned with the database, and the best-matching subjects were obtained (e-value < 10 -5)for gene annotation. The biosynthetic gene clusters (BGCs) of secondary metabolites were identified by antiSMASH v5.1.2 software, with a total of 44, including fourteen NRPS synthetic gene clusters, nine PKS synthetic gene clusters, three RiPP-like synthetic gene clusters, six terpene synthetic gene clusters, and four siderophore synthetic gene clusters, for a total of 44 secondary metabolic gene clusters. Through CAZy software, it was identified that there were 42 AA families, 8 CBM families, 85 esterases, 154 glycoside hydrolases, 5 polysaccharide lyases of the PL family, and 77 glycosyltransferases (the results are as Figure 5 shown).

[0046] Among them, there were chitin hydrolases of the GH18 family and the GH19 family, as well as 3 LPMO oxidative cleavage enzyme genes, and the results are shown in Table 3 below.

[0047] Table 3 Metabolic prediction of secondary metabolic gene clusters of strain ChiF

[0048] Example 5 Transcriptome sequencing of Streptomyces ChiF Total RNA was extracted from bacteria using the CTAB method, and genomic DNA was removed. Only high-quality RNA samples were used to construct the sequencing library. The mRNA was purified by depleting ribosomal RNA (rRNA) using the RiboCop rRNA Depletion Kit, and then all the mRNA was fragmented into short fragments (200 nt) by adding lysis buffer. Secondly, double-stranded cDNA was synthesized using random hexamer primers (Illumina). When synthesizing the second strand of cDNA, dUTP was incorporated instead of dTTP. Then, according to the Illumina library construction protocol, the synthesized cDNA was subjected to end repair, phosphorylation, and "A" base addition. The RNA-seq transcriptome library was prepared after ligation using the Illumina® Stranded mRNA Prep with total RNA. The paired-end RNA-seq library was sequenced using the Illumina Novaseq 6000 (Illumina, Inc.). Clean reads were achieved by deleting low-quality sequences, reads with more than 10% N bases (unknown bases), and reads containing adapter sequences. The data generated by the Illumina platform was used for bioinformatics analysis. All analyses were performed using the online platform of the Majorbio Cloud Platform (www.Majorbio.com) of Shanghai Majorbio Bio-pharm Technology Co., Ltd.

[0049] Using ISP2 liquid medium as the transcriptome control and inorganic salt colloidal chitin medium as the experimental group, the analysis of expression levels between samples: Venn analysis and PCA analysis (results as shown in Figure 6 indicated) showed significant differences between the two samples. Through transcriptome differential analysis, 1760 transcriptionally upregulated genes and 3583 transcriptionally downregulated genes were found (results as shown in Figure 7 indicated), and 4422 genes with no significant changes were identified, and cluster analysis of individual genes was performed (results as shown in Figure 8 indicated). In the presence of chitin medium, KEGG metabolic pathway analysis found significant differences in genes related to ABC transporters and ribosome synthesis proteins ( Figure 9 ).

[0050] The genes related to carbohydrate degradation and their expression levels are shown in Table 4 below.

[0051] Table 4 Gene expression of carbohydrate hydrolase GH18 and GH19 families

[0052] According to the results in Table 4, in this Streptomyces, some chitin-hydrolyzing enzymes can be secreted and expressed at a high level regardless of the inducer. For example, gene5957 of the GH18 family was 11352 before induction and 15178 after induction, showing an increase after induction, but the number of its transcripts remained at a very good level before and after induction.

[0053] In summary, the Streptomyces provided in this application can efficiently utilize chitin resources, efficiently produce chitooligosaccharides, and antagonize various plant pathogenic fungi or oomycetes. It can be predicted that the Streptomyces corchorusii provided in this application has important agricultural application value.

[0054] The above is only an example of this application. The protection scope of this application is not limited by these specific examples, but is determined by the claims of this application. For those skilled in the art, various changes and modifications can be made to this application. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of this application shall be included within the protection scope of this application.

Claims

1. A strain of Streptomyces corchorusii( Streptomyces corchorusii) , characterized in that The Streptomyces corchorusii is selected from any one of the following: 1) The isolated Streptomyces corchorusii was deposited with the China General Microbiological Culture Collection Center (CGMCC) on February 26, 2025, with the deposit number CGMCC No. 33658, and the address of the depositary institution is No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing; 2) The isolated progeny, mutants or derivatives of the isolated Streptomyces corchorusii as described in 1).

2. The Streptomyces corchorusii according to claim 1, characterized in that, The nucleotide sequence of the 16s rDNA of the Streptomyces corchorusii is as shown in SEQ ID No.

1.

3. The Streptomyces corchorusii according to claim 1, wherein The Streptomyces corchorusii can inhibit the growth of one or more of the following bacteria: Alternaria brassicae Alternaria raphani Groves ), Gibberella fujikuroi Fusarium moniliforme Sheld ), Fusarium oxysporum f. sp. lycopersici Fusarium oxysporum ) and Phytophthora parasitica Hytophthora nicotianae ).

4. The Streptomyces corchorusii according to claim 1, characterized in that, The Streptomyces corchorusii can grow using chitin as the sole carbon source.

5. The Streptomyces corchorus according to claim 1, characterized in that, The Streptomyces corchorusii can grow under the conditions of 25-40 °C, pH 6-10, and 3-7% sodium chloride.

6. The Streptomyces corchorusii according to claim 1, characterized in that, The Streptomyces corchorusii can express chitin-degrading enzymes without the need for induction by adding colloidal chitin.

7. The Streptomyces corchorusii according to claim 1, characterized in that, The Streptomyces corchorusii contains at least 10 chitin hydrolase genes of the GH18 family and at least 2 chitin hydrolase genes of the GH19 family.

8. The application of the Streptomyces corchorusii according to any one of claims 1-7 in the production of chito-oligosaccharides using chitin, enhancing plant immunity or resisting plant diseases.

9. A product, characterized in that, The product is selected from any one of the following: a) A product containing the Streptomyces corchorusii according to any one of claims 1-7; b) A product containing the lysate of the Streptomyces corchorusii according to any one of claims 1-7; c) A product containing the culture of the Streptomyces corchorusii according to any one of claims 1-7.

10. The application of the product according to claim 9 in the production of chito-oligosaccharides using chitin, enhancing plant immunity or resisting plant diseases.

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