Nucleoside production strain as well as construction method and application thereof

Abstract

The invention relates to the technical field of microbial fermentation, in particular to a nucleoside production strain as well as a construction method and application thereof, and particularly relates to a recombinant microorganism with DNA mismatch repair protein mutation and application thereof in nucleoside production. By strengthening the DNA mismatch repair protein or the coding gene thereof, the nucleoside production capacity and production efficiency of microorganisms are remarkably improved, and a new modification target and strategy are provided for construction of nucleoside production strains. The DNA mismatch repair protein variant provided by the invention can effectively promote microorganisms to accumulate nucleoside and remarkably improve the nucleoside production capacity of the microorganisms. According to the method for improving the nucleoside production capacity and the recombinant microorganism constructed by the DNA mismatch repair protein variant provided by the invention, nucleoside can be more efficiently accumulated, and the nucleoside yield is remarkably improved.

Description

Technical Field

[0001] The invention relates to the fields of bioengineering and microbial fermentation, and in particular to a nucleoside production strain and a construction method and application thereof. Background Art

[0002] Nucleoside is a general term for a class of glycosides. Nucleoside is a component of nucleic acid and nucleotide. Nucleoside is formed by the condensation of D-ribose or DZ-deoxyribose with pyrimidine base or purine base. Nucleoside is generally a colorless crystal, insoluble in common organic solvents, easily soluble in hot water, with a melting point of 160-240°C. Nucleosides generated from D-ribose are called ribonucleosides, which participate in the composition of RNA, and nucleosides generated from D-α-deoxyribose are called deoxyribonucleosides, which participate in the composition of DNA. D-ribose condenses with adenine, guanine, cytosine, thymine or uracil to generate the corresponding adenine ribonucleoside, guanine ribonucleoside, cytosine ribonucleoside, thymine ribonucleoside and uracil ribonucleoside, which are respectively referred to as adenosine (A), guanosine (G), cytidine (C), thymidine (T) and uridine (U).

[0003] Guanosine (guanosine) and inosine (inosine) play a wide range of roles in the food and pharmaceutical industries. In the food field, guanosine and inosine are important precursors of disodium guanylate and disodium inosinate, respectively. Disodium guanylate and disodium inosinate are used in combination as food flavor enhancers, and are widely used in condiments such as chicken essence and soy sauce. In the pharmaceutical field, guanosine and inosine can be used as pharmaceutical intermediates for a variety of antiviral drugs, such as acyclovir, triazole nucleoside, and sodium guanosine triphosphate, which all require guanosine as a synthetic raw material. Inosine is an important precursor of inosinic acid, and inosinic acid can be used as a precursor for the synthesis of adenosine (AMP) and guanylate (GMP), which is suitable for leukopenia, thrombocytopenia, various heart diseases, acute and chronic hepatitis, cirrhosis, etc. caused by various reasons. In addition, it can also treat central retinitis and optic atrophy.

[0004] Adenosine is adenine nucleoside, and its chemical name is 6-amino-9-β-D-ribofuranosyl-9-hydrogen purine. It is the product of adenine nucleotide dephosphorylation and is an important nucleotide derivative. Adenosine is an endogenous nucleoside that is found throughout human cells. It can directly enter the myocardium and generate adenosine acid through phosphorylation, and participate in myocardial energy metabolism. It also participates in dilating coronary vessels and increasing blood flow. Adenosine has physiological effects on the cardiovascular system and many other systems and tissues of the body. In addition to being used as a specific drug for treating the heart, adenosine is also an important intermediate for the synthesis of adenosine triphosphate (ATP), adenine, adenosine acid, and adenosine arabinoside, and is widely used in the pharmaceutical and other industries.

[0005] At present, microbial fermentation is the main method for producing nucleosides, and the main microorganisms used include Bacillus subtilis, Bacillus amyloliquefaciens or Bacillus pumilus. In the process of selecting and transforming the growing strains, ultraviolet mutagenesis and diethyl sulfate mutagenesis breeding are used to selectively select high-yielding strains of nucleosides; or according to the metabolic pathways and regulatory mechanisms of nucleotides in bacteria, the genetic background and characteristics of the strains are deeply understood, and the strains are purposefully transformed through metabolic engineering methods to obtain production strains with excellent traits and high nucleoside production. However, the fermentation performance of nucleoside strains is still poor, and the conversion rate of nucleosides is still low, which cannot meet the needs of large-scale industrial production. Summary of the invention

[0006] The purpose of the present invention is to provide a nucleoside production strain and a construction method and application thereof.

[0007] To achieve the purpose of the present invention, in a first aspect, the present invention provides a modified microorganism, wherein the activity of a DNA mismatch repair protein is enhanced compared to an unmodified microorganism, and the microorganism has an enhanced nucleoside production capacity compared to an unmodified microorganism.

[0008] In the present invention, the reference sequence number of the DNA mismatch repair protein in NCBI is CBI42903.1.

[0009] Furthermore, the activity enhancement method of the DNA mismatch repair protein in the microorganism is selected from the following 1) and / or 2):

[0010] 1) Enhanced by changing the amino acid sequence of the DNA mismatch repair protein;

[0011] 2) Enhanced by changing the nucleotide sequence encoding the DNA mismatch repair protein.

[0012] Furthermore, methods such as mutagenesis, site-directed mutagenesis or homologous recombination can be used to enhance the expression of the gene encoding the DNA mismatch repair protein.

[0013] In a specific embodiment of the present invention, the enhancement of DNA mismatch repair protein activity is achieved by the following A and / or B:

[0014] A. strengthening the start codon of the gene encoding the DNA mismatch repair protein to ATG;

[0015] B. Mutating the 201st amino acid of the DNA mismatch repair protein from N to K, H or R.

[0016] The microorganism can be Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus pumilus or Escherichia coli, etc. For example, the starting strain is B.subtilis A5 (the construction method of strain B.subtilis A5 is shown in CN110257315B), Bacillus amyloliquefaciens B.s833 and B.a836. Strains B.s833 and B.a836 can be found in CN112574934A.

[0017] In a second aspect, the present invention provides a method for constructing a nucleoside-producing strain, the method comprising: utilizing genetic engineering means to enhance the coding gene of the DNA mismatch repair protein in a microorganism having the ability to produce nucleosides.

[0018] The reinforcement method can be selected from the following a) and / or b):

[0019] a) enhancing by changing the amino acid sequence of the DNA mismatch repair protein;

[0020] b) enhancing by changing the nucleotide sequence encoding the DNA mismatch repair protein.

[0021] The enhancement method can be selected from at least one of mutagenesis, site-directed mutagenesis, homologous recombination, and the like.

[0022] Preferably, strengthening is achieved by the following ① and / or ②:

[0023] ① Strengthening the start codon of the gene encoding the DNA mismatch repair protein to ATG;

[0024] ② The 201st amino acid of the DNA mismatch repair protein is mutated from N to K, H or R.

[0025] In a third aspect, the present invention provides a nucleoside-producing strain constructed according to the method.

[0026] In a fourth aspect, the present invention provides the use of the microorganism or the nucleoside production strain constructed according to the method in the fermentation production of nucleosides or nucleoside derivatives or in increasing the fermentation yield of nucleosides or nucleoside derivatives.

[0027] The nucleoside derivatives of the present invention include but are not limited to:

[0028] (1) Guanosine or guanosine-related derivatives: guanine, guanylic acid, riboflavin, diacetylguanylic acid, etc.;

[0029] (2) Inosine or inosine-related derivatives: inosinic acid, guanylic acid, adenylic acid, etc.;

[0030] (3) Adenosine or adenosine-related derivatives, adenosine triphosphate (ATP), adenine, adenylic acid, adenosine, etc.

[0031] In a fifth aspect, the present invention provides a method for producing nucleosides, the method comprising the steps of:

[0032] i) culturing the microorganism or the nucleoside-producing strain constructed according to the method to obtain a culture;

[0033] ii) collecting the produced nucleosides from the culture obtained in step i).

[0034] By means of the above technical solution, the present invention has at least the following advantages and beneficial effects:

[0035] The present invention provides a Bacillus subtilis or Bacillus amyloliquefaciens, wherein the gene encoding the DNA mismatch repair protein is modified (enhanced) so that the ability of the strain to produce nucleosides is enhanced compared with that of the unmodified strain, providing a new transformation target and strategy for the construction of nucleoside production strains. The DNA mismatch repair protein variant provided by the present invention can effectively promote the accumulation of nucleosides by microorganisms and significantly improve the nucleoside production capacity of microorganisms. The recombinant microorganism constructed by the method for improving nucleoside production capacity provided by the present invention and the DNA mismatch repair protein can accumulate nucleosides more efficiently, and its nucleoside yield is significantly improved. DETAILED DESCRIPTION

[0036] The present invention aims to provide a new microorganism capable of efficiently producing purine nucleosides by means of genetic engineering. Starting from the genome level of Bacillus subtilis or Bacillus amyloliquefaciens, the present invention strengthens the DNA mismatch repair protein MutL to improve the nucleoside production ability of the strain.

[0037] The present invention adopts the following technical solution:

[0038] The present invention provides a genetically engineered strain of Bacillus amyloliquefaciens or Bacillus subtilis. The engineered strain mutates a DNA mismatch repair protein (encoded by a mutL gene) to enhance the activity of the mutL protein, thereby ensuring the DNA mismatch repair system, enabling the microorganism to efficiently and stably generate guanosine, adenine nucleotides or inosine, and successfully creating a new microorganism capable of efficiently producing nucleosides.

[0039] The present invention also provides a method for constructing the genetically engineered strain of Bacillus amyloliquefaciens or Bacillus subtilis, including: in wild-type or nucleoside-producing Bacillus amyloliquefaciens or Bacillus subtilis, by mutating the N at the 201st amino acid site of mutL to K and the like H and R, so that the amino acid sequence of the mismatch repair protein is changed, and / or the start codon is strengthened to ATG.

[0040] The present invention also provides use of the Bacillus amyloliquefaciens or Bacillus subtilis genetic engineering strain in high-production of nucleosides.

[0041] The mutL gene-enhanced strains were constructed based on Bacillus amyloliquefaciens B.s833 and B.a836 (which have certain guanosine or inosine production capabilities), respectively, and the enhancement method was point mutation of the mutL gene and / or enhancement of the start codon. The nucleoside production capabilities of the constructed strains were improved to varying degrees, and the specific improvement effects are shown in Table 2 below.

[0042] Starting from Bacillus subtilis A5 (which has a certain adenosine or inosine production capacity), strains with mutL mutation and / or start codon enhancement were also constructed. The engineered strains obtained have a certain improvement in the ability to produce inosine or adenosine, and the specific improvement effect is shown in Table 2.

[0043] The above-mentioned transformation can be applied to Bacillus amyloliquefaciens and Bacillus subtilis, but is not limited to the above two strains. It can also be applied to host bacteria such as Bacillus pumilus and Escherichia coli to produce nucleosides such as inosine, guanosine, adenosine, etc. or corresponding nucleoside derivatives such as hypoxanthine, inosinic acid, guanine, guanylic acid, riboflavin, diacetylguanylic acid, etc.

[0044] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Unless otherwise specified, the examples are all based on conventional experimental conditions, such as Sambrook et al. Molecular Cloning Laboratory Manual (Sambrook J & Russell DW, Molecular Cloning: a Laboratory Manual, 2001), or the conditions recommended by the manufacturer's instructions.

[0045] Table 1 Primer names and sequence information used in the examples of the present invention

[0046]

[0047]

[0048] Example 1 mutL in Bacillus subtilis N201K Construction of point mutation strains

[0049] The genome of the adenosine-producing strain B. subtilis A5 (strain B. subtilis A5, see CN110257315B) constructed in the laboratory was used as a template, and the left and right homologous arms were amplified using the primer pairs A5-mutLN201K-1f / 1r and A5-mutLN201K-2f / 2r, and then fused to obtain A5-mutL N201KThe full-length fragment (the sequence information of the corresponding ORF frame is shown in SEQ ID No: 1, and the amino acid sequence information is shown in SEQ ID No: 2). The pKSU plasmid (pKSU plasmid was kindly donated by Professor Wang Shufang of Nankai University, see A markerless gene replacement method for B. amyloliquefaciens LL3 and its use in genome reduction and improvement of poly-γ-glutamic acid production [J], Applied Microbiology and Biotechnology, 2014, 98 (21): 8963-8973. Zhang W, Gao W, Feng J, et al DOI: 10.1007 / s00253-014-5824-2) was double-digested with XbaI / PstI and recovered by gel. The linearized plasmid and A5-mutL were assembled using an assembly kit. N201K The fragments were assembled and transformed into TransT1 competent cells, and then the recombinant plasmid pKSU-A5-mutL was obtained by identification and screening. N201K . . and transformed them into wild bacteria 168 and B. subtilis A5 strains, respectively, to obtain A5-mutL N201K strains, and the strains were named B. subtilis A0069 and B. subtilis A0070, respectively.

[0050] Example 2 mutL in Bacillus subtilis N201H Construction of point mutation strains

[0051] The genome of the adenosine-producing strain B. subtilis A5 (strain B. subtilis A5, see CN110257315B) constructed in the laboratory was used as a template, and the left and right homologous arms were amplified using the primer pairs A5-mutLN201H-1f / 1r and A5-mutLN201H-2f / 2r, and then fused to obtain A5-mutL N201H The full-length fragment (the sequence information of the corresponding ORF frame is shown in SEQ ID No: 3, and the amino acid sequence information is shown in SEQ ID No: 4). The recombinant plasmid pKSU-A5-mutL was obtained according to the construction method in Example 1. N201H . They were transformed into wild bacteria 168 and B. subtilis A5 strains, and mutL N201H strains, and the strains were named B. subtilis A0071 and B. subtilis A0072, respectively.

[0052] Example 3 mutL in Bacillus subtilis N201R Construction of point mutation strains

[0053] The genome of the adenosine-producing strain B. subtilis A5 (strain B. subtilis A5, see CN110257315B) constructed in the laboratory was used as a template, and the left and right homologous arms were amplified using the primer pairs A5-mutLN201R-1f / 1r and A5-mutLN201R-2f / 2r, and then fused to obtain A5-mutL N201R The full-length fragment (the corresponding ORF sequence information is shown in SEQ ID No: 5, and the amino acid sequence information is shown in SEQ ID No: 6). The recombinant plasmid pKSU-A5-mutL was obtained according to the construction method in Example 1. N201R . They were transformed into wild bacteria 168 and B. subtilis A5 strains, and A5-mutL was obtained by screening. N201R strains, and the strains were named B. subtilis A0073 and B. subtilis A0074, respectively.

[0054] Example 4 mutL in Bacillus subtilis V1M Construction of point mutation strains

[0055] The genome of the adenosine-producing strain B. subtilis A5 (strain B. subtilis A5, see CN110257315B) constructed in the laboratory was used as a template and A5-mutL V1M -1f / 1r,A5-mutL V1M -2f / 2r primer pair amplified the left and right homology arms and fused them to obtain A5-mutL V1M The full-length fragment (the corresponding ORF sequence information is shown in SEQ ID No: 7, and the amino acid sequence information is shown in SEQ ID No: 8). The recombinant plasmid pKSU-A5-mutL was obtained according to the construction method in Example 1. 1GTG -ATG . They were transformed into wild bacteria 168 and B. subtilis A5 strains, and A5-s mutL was obtained by screening. 1GTG-ATG strains, and the strains were named B. subtilis A0075 and B. subtilis A0076, respectively.

[0056] Example 5 mutL in Bacillus amyloliquefaciens N201K Point mutation strain construction

[0057] Using the genome of DSM7 strain as template, the left and right homology arms were amplified using the primer pairs mutL-1f / mutLN201K-1r and mutLN201K-2f / mutL-2r, and mutL was fused to obtain N201K The full-length fragment (the corresponding ORF sequence information is shown in SEQ ID No: 9, and the amino acid sequence information is shown in SEQ ID No: 10). The recombinant plasmid pKSU-mutL was obtained according to the construction method in Example 1. N201K and transformed it into the DSM7 model strain and two guanosine-producing strains B.s833 and Ba 836 constructed in the laboratory. The obtained strains were named B.a8435, B.s8436, and B.a8437.

[0058] Example 6 mutL in Bacillus amyloliquefaciens N201H Point mutation strain construction

[0059] Using the genome of DSM7 strain as template, the left and right homology arms were amplified using the primer pairs mutL-1f / mutLN201H-1r and mutLN201H-2f / mutL-2r, and mutL was fused to obtain N201H The full-length fragment (the corresponding ORF sequence information is shown in SEQ ID No: 11, and the amino acid sequence information is shown in SEQ ID No: 12). The recombinant plasmid pKSU-mutL was obtained according to the construction method in Example 1. N201H and transformed it into the DSM7 model strain and two guanosine-producing strains B.s833 and Ba 836 constructed in the laboratory. The obtained strains were named B.a8438, B.s8439, and B.a8440.

[0060] Example 7 mutL in Bacillus amyloliquefaciens N201R Point mutation strain construction

[0061] Using the genome of DSM7 strain as template, the left and right homology arms were amplified using the primer pairs mutL-1f / mutLN201R-1r and mutLN201R-2f / mutL-2r, and mutL was fused to obtain N201R The full-length fragment (the corresponding ORF sequence information is shown in SEQ ID No: 13, and the amino acid sequence information is shown in SEQ ID No: 14). The recombinant plasmid pKSU-mutL was obtained according to the construction method in Example 1. N201R and transformed it into the DSM7 model strain and two guanosine-producing strains B.s833 and Ba 836 constructed in the laboratory. The obtained strains were named B.a8441, B.s8442, and B.a8443.

[0062] Example 8 mutL in Bacillus amyloliquefaciensL1M Construction of point mutation strains

[0063] Using the DSM7 strain genome as a template, mutL L1M -1f / 1r,mutL L1M -2f / 2r primer pair amplified the left and right homology arms and fused them to obtain mutL L1M The full-length fragment (the corresponding ORF sequence information is shown in SEQ ID No: 15, and the amino acid sequence information is shown in SEQ ID No: 16). The recombinant plasmid pKSU-mutL was obtained according to the construction method in Example 1. 1TTG-ATG and transformed it into the DSM7 model strain and two guanosine-producing strains B.s833 and Ba 836 constructed in the laboratory. The obtained strains were named B.a8444, B.s8445, and B.a8446.

[0064] Example 9 Real-time quantitative fluorescence PCR verification of mutL expression level in Bacillus subtilis engineered strains

[0065] All argC mutant engineered bacteria and control strains B.subtilis168, B.subtilis A5 (control strains corresponding to Bacillus subtilis mutant strains) and DSM7, B.s833, B.a836 (control strains corresponding to Bacillus amyloliquefaciens mutant strains) were cultured in LB medium until the logarithmic growth phase, 1 mL of bacterial solution was treated with an appropriate amount of lysozyme, and total RNA was extracted for reverse transcription, and real-time quantitative PCR reaction was performed using cDNA as a template. Reaction conditions: 95℃ pre-denaturation for 10min; 95℃15s, 55℃1min, 40 cycles. After the reaction, the bacterial 16S rRNA was used as a reference, and the transcription level of the relevant gene was calculated according to the 2-ΔΔCT method. The results are shown in Table 2:

[0066] Table 2. Transcription level of strains

[0067] strains Transcription level (relative value) Improvement ratio (%) Ba 833 1 - Bs 8436 1.25 25 Bs 8439 1.24 24 Bs 8442 1.27 27 Bs 8443 1.35 35 Ba 836 1 - Ba 8437 1.19 19 Ba 8440 1.23 23 Ba 8443 1.27 27 Ba 8446 1.38 38 B. subtilis 168 1 - B. subtilis A0069 1.28 28 B. subtilis A0071 1.33 33 B. subtilis A0073 1.29 29 B. subtilis A0075 1.37 37 B. subtilis A5 1 - B. subtilis A0070 1.25 25 B. subtilis A0072 1.27 27 B. subtilis A0074 1.19 19 B. subtilis A0076 1.32 32 DSM7 1 - Bs 8435 1.17 17 Bs 8438 1.19 19 Bs 8441 1.18 18 Bs 8444 1.29 29

[0068] Example 10 Verification of the nucleoside production performance of mutant strains

[0069] 1. Culture the bacteria stored in glycerol overnight at 37°C and isolate a single colony.

[0070] 2. Pick a single colony and inoculate it into 30 mL of seed culture medium (20 g / L glucose, 5 g / L yeast powder, 5 g / L corn steep liquor powder, 3 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate, 0.02 g / L ferrous sulfate, 0.01 g / L manganese sulfate, pH 7.0-7.2, sterilize at 121°C for 20 min. Cultivate at 110 rpm and 37°C for 7-8 h).

[0071] 3. Transfer the inoculum to 30 ml fermentation medium (120 g / L glucose, 3.5 g / L yeast powder, 3 g / L potassium dihydrogen phosphate, 25 g / L ammonium sulfate, 0.01 g / L manganese sulfate, 5 g / L magnesium sulfate, 10 g / L sodium glutamate, 15 g / L corn steep liquor powder, 25 g / L calcium carbonate, pH 7.0-7.2, sterilize at 121°C for 20 min) at a 10% v / v inoculum volume, shake at 130 rpm, and culture at 35°C for 70 h (Bs / a8435-8446 strain fermentation for 72 h; B. subtilis A0069-0076 strain fermentation for 48 h).

[0072] 4. Use liquid chromatography to detect the glycosides produced in the fermentation broth (Table 3).

[0073] Table 3 Evaluation results of mutant strains producing guanosine, inosine and adenosine by shake flask fermentation (mean of three replicates)

[0074]

[0075]

[0076] As can be seen from Table 3, when the mutL 201 position N is mutated to K, and H and R, which are similar to amino acids, are introduced into different starting strains, the corresponding nucleoside production is improved to varying degrees. This shows that this site is effective in improving the nucleoside production capacity of the strain. At the same time, the start codon of the mutL wild-type protein is strengthened in different starting strains, and the nucleoside production capacity of the strain is also improved to varying degrees. This shows that the strengthening of mutL including the expression of the mutated protein has a positive effect on improving the production of nucleosides by the strain.

[0077] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A modified microorganism, characterized in that The microorganism has enhanced activity of a DNA mismatch repair protein compared to an unmodified microorganism, and the microorganism has enhanced nucleoside production capacity compared to an unmodified microorganism; The reference sequence number of the DNA mismatch repair protein on NCBI is CBI42903.

1.

2. The microorganism according to claim 1, characterized in that The activity enhancement method of the DNA mismatch repair protein in the microorganism is selected from the following 1) and / or 2): 1) Enhanced by changing the amino acid sequence of the DNA mismatch repair protein; 2) Enhanced by changing the nucleotide sequence encoding the DNA mismatch repair protein.

3. The microorganism according to claim 2, characterized in that The expression of the gene encoding the DNA mismatch repair protein is enhanced by using mutagenesis, site-directed mutagenesis or homologous recombination.

4. The microorganism according to claim 1, characterized in that The enhancement of DNA mismatch repair protein activity is achieved by A and / or B as follows: A. strengthening the start codon of the gene encoding the DNA mismatch repair protein to ATG; B. Mutating the 201st amino acid of the DNA mismatch repair protein from N to K, H or R.

5. The microorganism according to any one of claims 1 to 4, characterized in that The microorganism is Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus pumilus or Escherichia coli.

6. A method for constructing a nucleoside-producing strain, characterized in that: The method comprises: using genetic engineering means to strengthen the coding gene of the DNA mismatch repair protein in the microorganism having the ability to produce nucleosides; The strengthening method is selected from the following a) and / or b): a) enhancing by changing the amino acid sequence of the DNA mismatch repair protein; b) enhancing by changing the nucleotide sequence encoding the DNA mismatch repair protein; The reference sequence number of the DNA mismatch repair protein on NCBI is CBI42903.

1.

7. The method according to claim 6, characterized in that The enhancement method is selected from at least one of mutagenesis, site-directed mutagenesis, and homologous recombination; Preferably, strengthening is achieved by the following ① and / or ②: ① Strengthening the start codon of the gene encoding the DNA mismatch repair protein to ATG; ② Mutating the 201st amino acid of the DNA mismatch repair protein from N to K, H or R; The microorganism is Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus pumilus or Escherichia coli.

8. A nucleoside producing strain constructed according to the method of claim 6 or 7.

9. Use of the microorganism according to any one of claims 1 to 4 or the nucleoside-producing strain according to claim 8 in the fermentation production of nucleosides or nucleoside derivatives or in increasing the fermentation yield of nucleosides or nucleoside derivatives; The nucleoside or nucleoside derivative includes: (1) Guanosine or guanosine-related derivatives: guanine, guanylic acid, riboflavin, diacetylguanylic acid; (2) Inosine or inosine-related derivatives: inosinic acid, guanylic acid, adenylic acid; (3) Adenosine or adenosine-related derivatives, adenosine triphosphate, adenine, adenylic acid, and adenosine arabinoside.

10. A method for producing nucleosides, characterized in that: The method comprises the following steps: i) culturing the microorganism according to any one of claims 1 to 4 or the nucleoside-producing strain according to claim 8 to obtain a culture; ii) collecting the produced nucleosides from the culture obtained in step i).

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