Application of pythium oligandrum strain emf915 in preparing biological antiseptic preservative

Abstract

A Pythium oligandrum strain EMF915 is preserved in China Center for Type Culture Collection of Wuhan University on May 24, 2022, with a preservation number of CCTCC NO: M 2022710 and an address of Wuhan University, Hubei Province, China, and a nucleotide sequence as shown in the sequence table SEQ ID NO: 1. The strain is used for preparing a Prunus domestica, Fragaria ananassa, Prunus cerasus, Actinidia deliciosa biological preservative. Compared with general storage, the biological preservative treatment reduces the rot rate of Prunus domestica by 65-75%, reduces the rot rate of Fragaria ananassa by 20-30%, reduces the rot rate of Prunus cerasus by 40-50%, reduces the rot rate of Actinidia deliciosa by 50-60%, and reduces the rot rate of Lycopersicon lycopersicum by 80-90%. The biological preservative prepared by the Pythium oligandrum strain EMF915 can be used for postharvest preservation of fruits and vegetables and prolongs the shelf life.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of microbial technology application, and particularly relates to a biological preservative. BACKGROUND

[0002] China is a large country of fruit and vegetable production, and the yield of fruits and vegetables ranks first in the world for many years. According to relevant statistics, the rot loss rate of fresh fruits and vegetables in China at present is between 30% and 50%, it is necessary to speed up the development of new fruit and vegetable preservation technology, and to strengthen its application, which has important significance for China's fruit and vegetable industry, and is also conducive to the healthy development of China's agriculture.

[0003] The existing low-temperature storage and chemical preservation are two main technical means for fruit and vegetable preservation in China, and the technology is relatively mature, but there are some obvious shortcomings. The main shortcomings of low-temperature storage are high cost, large energy consumption, and unstable product quality after preservation. The main shortcomings of chemical preservation are chemical residues, certain safety hazards, and resistance of preserved fruits and vegetables after long-term use.

[0004] In the field of fruit and vegetable preservation technology, one of the technical problems to be urgently solved at present is to provide a biological preservative for fruits and vegetables, which has long preservation time, stable performance, and no harm to human body. SUMMARY

[0005] One of the technical problems solved by the application is to provide a new use of Pythium oligandrum strain EMF915.

[0006] The technical scheme adopted to solve the above technical problems is that Pythium oligandrum strain EMF915 is used in the preparation of prune biological preservative.

[0007] The Pythium oligandrum strain EMF915 is preserved in the China Center for Type Culture Collection of Wuhan University on May 24, 2022, with the preservation number CCTCC NO:M 2022710, the preservation address is Wuhan University, Hubei Province, Wuhan City, and the active ingredients include oospores, zoospores and part of the living mycelium prepared from the strain, and the nucleotide sequence is as follows:

[0008]

[0009]

[0010] 1. A separation method of Pythium oligandrum strain EMF915

[0011] Sampling: The conventional five-point sampling method was used to collect rhizosphere soil from various mountainous areas in Donggang Village, Donghui Town, Lancang Lahu Autonomous County, Pu'er City, Yunnan Province in July 2019. 10-15 g of soil was taken and placed in a sterile distillate water containing 100 mL of sterilized glass beads. The mixture was shaken at 180 rpm and 28°C for 40-60 minutes. The supernatant was collected and stored in a refrigerator at 0±1°C for future use.

[0012] Strain isolation: The bacterial solution was diluted with distilled water to 10 -6 ~10 -7 μL, and 100 μL of each was taken and spread on PDA plates. The plates were incubated at 28°C for 3 days, and the strains were separated and purified according to the characteristics of the oospores. The Pythium oligandrum strain EMF915 was obtained.

[0013] 2. Identification of Pythium oligandrum strain EMF915

[0014] (1) Morphological characteristics

[0015] The mycelium of Pythium oligandrum strain EMF915 on PDA plates was aerial, with white, round, and occasionally long to the top of the plate. The mycelium was colorless, fluffy, and non-septate (multinucleated). The results are shown in Figure 1 . In Figure 1 , Figure A is a front view of the mycelium of Pythium oligandrum strain EMF915 on PDA plates, Figure B is a rear view of the mycelium of Pythium oligandrum strain EMF915 on PDA plates, Figure C is a 10x magnification of the mycelium of Pythium oligandrum strain EMF915 on PDA plates, and Figure D is a 40x magnification of the mycelium of Pythium oligandrum strain EMF915 on PDA plates.

[0016] (2) Molecular development analysis

[0017] PCR amplification of ITS sequence

[0018] According to the ITS region of fungal rRNA, the universal upstream primer ITS1

[0019] 5'-TCCGTAGGTGAACCTGCGG-3' and the downstream primer ITS4

[0020] 5'-TCCTCCGCTTATTGATATGC-3' were used for PCR amplification reaction under the following reaction system:

[0021] 2x Taq PCR Master MIX II 10 μL, 10 μM of ITS1 primer 1 μL, 10 μM of ITS4 primer 1 μL, template DNA 1 μL, and distilled water to 20 μL. The PCR reaction program is as follows:

[0022] 94℃ denaturation 3 minutes, 36 cycles of 98℃ denaturation 10 seconds, 52℃ annealing 30 seconds, 72℃ recombination 1 minute, 72℃ extension 2 minutes. After 1% agarose gel electrophoresis detection, it is sent to Shanghai Shenguo Bioengineering Company for sequencing, the similar sequences of the obtained sequences are searched by BLAST, and a phylogenetic tree is constructed in MEGA 7.0 software by using the neighbor-joining method, and the results are as follows Figure 2 After preliminary classification and identification, the isolated fungus (Pythium oligandrum) is strain EMF915.

[0023] The nucleotide sequence sequencing results are as follows:

[0024]

[0025] The plum biological preservative is prepared in a liquid form, and in 1 mL of the liquid biological preservative, the number of Pythium oligandrum strain EMF915 oospores is 1x10 6 CFU / mL~4x10 6 CFU / mL, and the Pythium oligandrum strain EMF915 fermentation broth is used in preparation of the liquid biological preservative.

[0026] The preparation method is as follows:

[0027] 100g of tomatoes, 100g of lettuce, 100g of spinach, 100g of parsley, 100g of celery are taken, and the extract liquid is added to 1L of water, 10g of yeast powder, 8g of sodium chloride, 1g of Vc, 1g of citric acid, 0.1mL of glycerol, 1g of calcium carbonate, 0.6g of dipotassium hydrogen phosphate, 0.125g of potassium dihydrogen phosphate, and the Pythium oligandrum strain EMF915 liquid culture is inoculated at an inoculation amount of 5%, and fermentation is carried out at 28℃, 160rpm for 7~15 days to prepare the Pythium oligandrum strain EMF915 fermentation broth, the Pythium oligandrum strain EMF915 fermentation broth is added to a homogenizer for homogenization to obtain the Pythium oligandrum fermentation broth, and the plum biological preservative is prepared.

[0028] The use method of the plum biological preservative is as follows:

[0029] 1kg of plums and 100mL of the plum biological preservative are taken, the plum biological preservative is diluted with water when used, the volume ratio of the plum biological preservative to water is 1:500, the biological preservative spraying liquid is prepared, the biological preservative spraying liquid is uniformly sprayed on the surface of the plums by using a sprayer, the plums are dried at room temperature, and the plums are stored in a 4℃ refrigerator.

[0030] The Pythium oligandrum strain EMF915 of the application is used in preparation of a strawberry biological preservative.

[0031] The strawberry biological preservative is prepared in liquid form, and 1 mL of the liquid strawberry biological preservative contains 1x10 6 CFU / mL~4x10 6 CFU / mL.

[0032] The preparation method is as follows:

[0033] 100g of tomato, 100g of lettuce, 100g of spinach, 100g of parsley, and 100g of celery are taken, and the extraction liquid is added into 1L of water, 10g of yeast powder, 8g of sodium chloride, 1g of Vc, 1g of citric acid, 0.1mL of glycerol, 1g of calcium carbonate, 0.6g of dipotassium hydrogen phosphate, 0.125g of potassium dihydrogen phosphate, and the liquid culture of the Pythium oligandrum strain EMF915 is added, the inoculation amount is 5%, and fermentation is carried out at 28℃ and 160rpm for 7-15 days to prepare the fermentation liquor of the Pythium oligandrum strain EMF915, the fermentation liquor is added into a homogenizer to be homogenized to obtain the fermentation liquor of the Pythium oligandrum, and the strawberry biological preservative is prepared.

[0034] The use method of the strawberry biological preservative is as follows:

[0035] 1kg of strawberries is taken, 100mL of the strawberry biological preservative is used, the strawberry biological preservative spraying liquid is uniformly sprayed on the surface of the strawberries by using a sprayer, the strawberries are dried at room temperature, and the strawberries are stored in ventilation at room temperature of 25℃.

[0036] The Pythium oligandrum strain EMF915 is used in the preparation of the cherry biological preservative.

[0037] The cherry biological preservative is prepared in liquid form, and 1 mL of the liquid cherry biological preservative contains 1x10 6 CFU / mL~4x10 6 CFU / mL.

[0038] The preparation method is as follows:

[0039] Take 100 g of tomato, 100 g of lettuce, 100 g of spinach, 100 g of parsley, 100 g of celery extract liquid into 1 L of water, add 10 g of yeast powder, 8 g of sodium chloride, 1 g of Vc, 1 g of citric acid, 0.1 mL of glycerol, 1 g of calcium carbonate, 0.6 g of dipotassium hydrogen phosphate, 0.125 g of potassium dihydrogen phosphate, add Pythium oligandrum strain EMF915 liquid culture, the inoculation amount is 5%, 28℃, 160rpm fermentation for 7-15 days, to prepare Pythium oligandrum strain EMF915 fermentation broth, add homogenizer to homogenize, get Pythium oligandrum fermentation liquor, prepare cherry biological preservative.

[0040] The use method of the cherry biological preservative is as follows:

[0041] Take 1 kg of cherry, 100 mL of cherry biological preservative, when used, dilute the cherry biological preservative with water, the volume ratio of the cherry biological preservative to water is 1:100, prepare cherry biological preservative spraying liquid, uniformly spray the cherry biological preservative spraying liquid on the surface of the cherry with a sprayer, air dry at room temperature, and store at room temperature 28℃.

[0042] The application of Pythium oligandrum strain EMF915 in preparing kiwi biological preservative.

[0043] The kiwi biological preservative is prepared in liquid form, 1 mL of the liquid kiwi biological preservative contains 1×10 6 CFU / mL-4×10 6 CFU / mL of Pythium oligandrum strain EMF915, and the Pythium oligandrum strain EMF915 fermentation liquor is used in preparing the liquid kiwi biological preservative.

[0044] The preparation method is as follows:

[0045] Take 100 g of tomato, 100 g of lettuce, 100 g of spinach, 100 g of parsley, 100 g of celery extract liquid into 1 L of water, add 10 g of yeast powder, 8 g of sodium chloride, 1 g of Vc, 1 g of citric acid, 0.1 mL of glycerol, 1 g of calcium carbonate, 0.6 g of dipotassium hydrogen phosphate, 0.125 g of potassium dihydrogen phosphate, add Pythium oligandrum strain EMF915 liquid culture, the inoculation amount is 5%, 28℃, 160rpm fermentation for 7-15 days, to prepare Pythium oligandrum strain EMF915 fermentation broth, add homogenizer to homogenize, get Pythium oligandrum fermentation liquor, prepare cherry biological preservative.

[0046] The use method of the cherry biological preservative is as follows:

[0047] Take 1 kg of kiwi, 100 mL of kiwi biological preservative, when using kiwi biological preservative dilution, the volume ratio of kiwi biological preservative to water is 1:100, prepare kiwi biological preservative spray liquid, use the sprayer to evenly spray kiwi biological preservative spray liquid on the surface of kiwi, dry at room temperature, and store in a 4℃ refrigerator.

[0048] The use of the Pythium oligandrum strain EMF915 in the preparation of a tomato biological preservative.

[0049] The tomato biological preservative is prepared in liquid form, and in 1 mL of liquid tomato biological preservative, the number of Pythium oligandrum strain EMF915 oospores is 1×10 6 CFU / mL~4×10 6 CFU / mL, and the Pythium oligandrum strain EMF915 fermentation broth is used in the preparation of the liquid tomato biological preservative.

[0050] The preparation method is as follows:

[0051] Take 100 g of tomato, 100 g of lettuce, 100 g of spinach, 100 g of parsley, and 100 g of celery extract, add 1 L of water, add 10 g of yeast powder, 8 g of sodium chloride, 1 g of Vc, 1 g of citric acid, 0.1 mL of glycerol, 1 g of calcium carbonate, 0.6 g of dipotassium hydrogen phosphate, 0.125 g of potassium dihydrogen phosphate, add Pythium oligandrum strain EMF915 liquid culture, inoculation amount is 5%, 28℃, 160 rpm fermentation for 7-15 days, prepare Pythium oligandrum strain EMF915 fermentation broth, add homogenizer, get Pythium oligandrum fermentation broth, prepare tomato biological preservative.

[0052] The use method of the tomato biological preservative is as follows:

[0053] Take 1 kg of kiwi, 100 mL of kiwi biological preservative, when using kiwi biological preservative dilution, the volume ratio of kiwi biological preservative to water is 1:100, prepare kiwi biological preservative spray liquid, use the sprayer to evenly spray kiwi biological preservative spray liquid on the surface of kiwi, dry at room temperature, and store in a 4℃ refrigerator.

[0054] A biological preservative prepared using the *Pythium oligandrum* strain EMF915 was used in experiments. Compared with general storage, when stored in a 4℃ cold storage for 60 days, the biological preservative reduced the spoilage rate of plums by 65%–75%; when strawberries were stored at 25℃ at room temperature, the preservation rate was measured every day, and after 4 days, the biological preservative reduced the spoilage rate of strawberries by 20%–30%; when cherries were stored at 28℃ indoors, the preservation rate was measured every 3 days, and after 12 days, the spoilage rate of cherries was reduced by 40%–50%; when kiwifruit were stored in a 4℃ cold storage, the preservation rate was measured on the 90th day, and the spoilage rate of kiwifruit was reduced by 50%–60%; when tomatoes were stored in a 4℃ cold storage, the preservation rate was measured on the 30th day, and the spoilage rate of tomatoes was reduced by 80%–90%. A biological preservative prepared using the strain EMF915 of *Pythium oligandrum* can be used to preserve fruits and vegetables. Attached Figure Description

[0055] Figure 1 This is a diagram showing the growth morphology of Oligocytophyte EMF915.

[0056] Figure 2 This is a diagram showing the tree establishment results of Oligocytophyte EMF915.

[0057] Figure 3 The graph shows the rot rate of plums stored in a 4℃ cold storage for 60 days using EMF915, a biological preservative of Pythium oligandii strain.

[0058] Figure 4 The graph shows the rot rate of strawberries after being stored at room temperature (25℃) for 4 days using the Oligopyrophyte strain EMF915 as a biological preservative.

[0059] Figure 5 The graph shows the rot rate of cherries stored at 28°C for 12 days using the Oligopyrophyte strain EMF915 as a biological preservative.

[0060] Figure 6 The graph shows the rot rate of kiwifruit stored in a 4℃ cold storage for 90 days using the EMF915 strain of *Pythium oligandrum* as a biological preservative.

[0061] Figure 7 The graph shows the rot rate of tomatoes stored in a 4℃ cold storage for 30 days using EMF915 strain of Pythium oligandrum as a biological preservative. Detailed Implementation

[0062] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the present invention is not limited to these embodiments.

[0063] Example 1

[0064] The use of Pythium oligandrum strain EMF915 in the preparation of a plum biological preservative.

[0065] The Pythium oligandrum strain EMF915 was preserved in the China Center for Type Culture Collection of Wuhan University on May 31, 2022, with a preservation number of CCTCC NO: M 2022710 and a preservation address of Wuhan University, Hubei Province, Wuhan City. The active ingredients include oospores, zoospores and part of the living mycelium prepared from the strain, and the nucleotide sequence is as follows:

[0066]

[0067] The plum biological preservative is prepared in liquid form. In 1 mL of the liquid biological preservative, the number of oospores of the Pythium oligandrum strain EMF915 is 1×10 6 CFU / mL~4×10 6 CFU / mL, and the fermentation broth of the Pythium oligandrum strain EMF915 is used in the preparation of the liquid biological preservative.

[0068] The preparation method is as follows:

[0069] Take 100 g of tomato, 100 g of lettuce, 100 g of spinach, 100 g of parsley, and 100 g of celery extract, add 1 L of water, add 10 g of yeast powder, 8 g of sodium chloride, 1 g of Vc, 1 g of citric acid, 0.1 mL of glycerol, 1 g of calcium carbonate, 0.6 g of dipotassium hydrogen phosphate, 0.125 g of potassium dihydrogen phosphate, add Pythium oligandrum strain EMF915 liquid culture, inoculation amount is 5%, 28℃, 160 rpm fermentation for 7~15 days, prepare Pythium oligandrum strain EMF915 fermentation broth, add homogenizer, get Pythium oligandrum fermentation broth, prepare plum biological preservative.

[0070] The use method of the plum biological preservative is as follows:

[0071] Take 1 kg of plum, 100 mL of plum biological preservative, dilute the plum biological preservative with water, the volume ratio of plum biological preservative to water is 1:500, prepare biological preservative spraying liquid, evenly spray the biological preservative spraying liquid on the surface of the plum with a sprayer, dry at room temperature, and store in a 4℃ refrigerator.

[0072] In the laboratory experiment, 2 kg of plums, 100 mL of plum biological preservative, and 100 mL of tap water were divided into an experimental group and a control group, with 1 kg of plums in each group. The experimental group was treated with the plum biological preservative according to the use method of the present embodiment, and the control group was treated with tap water for comparison of the preservative function. The blackening and shrinkage of the plum stems were used as the standard for judging the preservation, and the plum rot rate was calculated every 10 days according to the formula:

[0073] Rot rate % = plum rot number / total plum number x 100%

[0074] In the experiment, the plums were stored in a 4°C refrigerator. There were 10 plums in each group, and the experiment was repeated twice. The preservation rate was calculated every 10 days, and the total calculation time was 60 days. The experimental results are shown in Table 1 Figure 3 .

[0075] Table 1: Number of rotten plums in the experimental group and the control group stored in the refrigerator for 60 days

[0076]

[0077] According to Table 1 and Figure 3 It can be seen that when stored in a 4°C refrigerator for 60 days, the rot rate of plums is 10%, and the rot rate of the control group is 80%. Compared with the control group, the rot rate of the experimental group is reduced by 70%.

[0078] Example 2

[0079] The nucleotide sequence of Pythium oligandrum strain EMF915 is the same as that of Example 1.

[0080] The use of Pythium oligandrum strain EMF915 in the preparation of a strawberry biological preservative. The strawberry biological preservative is prepared in liquid form, and in 1 mL of the liquid strawberry biological preservative, the number of Pythium oligandrum strain EMF915 oospores is 1 x 10 6 CFU / mL ~ 4 x 10 6 CFU / mL. In the preparation of the liquid strawberry biological preservative, the fermentation broth of Pythium oligandrum strain EMF915 is used.

[0081] The raw materials and preparation method for preparing the strawberry biological preservative of Pythium oligandrum strain EMF915 are the same as those of Example 1.

[0082] The use method of the strawberry biological preservative is as follows:

[0083] Take 1 kg of strawberries and 100 mL of strawberry biological preservative, and prepare a biological preservative spray liquid. Use a sprayer to evenly spray the strawberry biological preservative spray liquid on the surface of the strawberries, dry at room temperature, and store in a ventilated place.

[0084] The inventors used the strawberry bio-preservation preservative prepared in this example as an experimental group and compared it with tap water as a control group. In the laboratory experiment, 6 kg of strawberries, 600 mL of strawberry bio-preservation preservative, and 300 mL of tap water were divided into an experimental group and a control group. The experimental group had 3 kg of strawberries, and the control group had 3 kg of strawberries. The experimental group used the strawberry bio-preservation preservative, and the control group used tap water to compare the preservation function. The rotten standard was based on the surface rotting, wrinkling, and winding of the mycelium of the strawberries. The preservation rate was calculated every other day by detecting the rotting rate of the strawberries according to the following formula:

[0085] Rotten rate % = number of rotten strawberries / total number of strawberries x 100%.

[0086] In the experiment, the strawberries were stored at room temperature of 25°C. There were 15 strawberries in each group, and the experiment was repeated three times. The preservation rate was calculated every other day. The experimental results are shown in Table 2 and Figure 4 .

[0087] Table 2 Number of rotten strawberries in the experimental group and the control group at room temperature of 25°C for 4 days

[0088]

[0089] As shown in Table 2 and Figure 4 , the rotting rate of the experimental group was 40.00%, and the rotting rate of the control group was 64.44%. Compared with the control group, the rotting rate of the experimental group was reduced by 24.44%.

[0090] Example 3

[0091] The nucleotide sequence of the Pythium oligandrum strain EMF915 is the same as that of Example 1.

[0092] Use of the Pythium oligandrum strain EMF915 in the preparation of a cherry bio-preservation preservative.

[0093] The cherry bio-preservation preservative is prepared in liquid form. In 1 mL of liquid cherry bio-preservation preservative, the number of Pythium oligandrum strain EMF915 oospores is 1 x 10 6 CFU / mL to 4 x 10 6 CFU / mL. In the preparation of the liquid cherry bio-preservation preservative, the fermentation broth of the Pythium oligandrum strain EMF915 is used.

[0094] The raw materials and preparation method for preparing the Pythium oligandrum strain EMF915 cherry bio-preservation preservative are the same as those of Example 1.

[0095] The use method of the cherry bio-preservation preservative is as follows:

[0096] The method for using and the dosage of the cherry bio-preservation preservative are the same as those in Example 1.

[0097] In the laboratory experiment, 6 kg of cherries, 300 mL of cherry bio-preservation preservative, and 300 mL of tap water were divided into an experimental group and a control group. The experimental group had 3 kg of cherries, and the control group had 3 kg of cherries. The experimental group used the cherry bio-preservation preservative according to the method of the present embodiment, and the control group used tap water for comparison of the preservation function test. The preservation rate was calculated according to the cherry surface rotting, wrinkling, and winding mycelium as the rotting standard. The cherry rotting rate was detected every 3 days, and the rotting rate was calculated according to the following formula:

[0098] Rotten rate % = number of rotten cherries / total number of cherries x 100%.

[0099] In the experiment, the cherries were stored at room temperature of 28°C. The control group and the experimental group each had 20 cherries, and the experiment was repeated twice. The preservation rate was calculated every 3 days, and the experimental results are shown in Table 3 and Figure 5 .

[0100] Table 3: Rotting rate of cherries in the experimental group and the control group stored at room temperature of 28°C for 12 days

[0101]

[0102] As shown in Table 3 and Figure 5 , the rotting rate of the blank group was 72.5% on the 12th day, and the rotting rate of the experimental group was 27.5%. Compared with the control group, the rotting rate of the experimental group was reduced by 45.0%.

[0103] Example 4

[0104] The nucleotide sequence of the Pythium oligandrum strain EMF915 is the same as that in Example 1.

[0105] The use of the Pythium oligandrum strain EMF915 in the preparation of a kiwifruit bio-preservation preservative.

[0106] The kiwifruit bio-preservation preservative is prepared in liquid form. In 1 mL of the liquid kiwifruit bio-preservation preservative, the number of Pythium oligandrum strain EMF915 oospores is 1 x 10 6 CFU / mL to 4 x 10 6 CFU / mL. In the preparation of the liquid kiwifruit bio-preservation preservative, the fermentation broth of the Pythium oligandrum strain EMF915 is used.

[0107] The raw materials and preparation method for preparing the kiwifruit bio-preservation preservative of the Pythium oligandrum strain EMF915 are the same as those in Example 1.

[0108] The method for using the kiwifruit bio-preservation preservative is as follows:

[0109] Take 1 kg of kiwi, 100 mL of kiwi biological preservative, when using, dilute the kiwi biological preservative with water, the volume ratio of kiwi biological preservative to water is 1:50, prepare kiwi biological preservative spraying liquid, use a sprayer to evenly spray kiwi biological preservative spraying liquid on the surface of kiwi, dry at room temperature, and store in a 4°C refrigerator.

[0110] Take 6 kg of kiwi, 300 mL of kiwi biological preservative, and 300 mL of tap water for laboratory experiments, and divide them into an experimental group and a control group. The experimental group has 3 kg of kiwi and the control group has 3 kg of kiwi. According to the use method of this embodiment, the experimental group uses kiwi biological preservative, and the control group uses tap water for comparison of preservative function test. During the experiment, the kiwi is stored in a 4°C refrigerator, and the rot rate of the kiwi is detected on the 90th day. The rot rate is calculated according to the formula:

[0111] Rot rate % = number of rotten kiwis / total number of kiwis x 100%.

[0112] The experimental results are shown in Table 4, Figure 6 .

[0113] Table 4 Rot rate of kiwi in 4°C refrigerator for 90 days in the experimental group and the control group

[0114] Time (days) Rot rate (%) of control group Rot rate (%) of experimental group 90 71.67 15.00

[0115] As shown in Table 4, Figure 6 , on the 90th day, the rot rate of the experimental group was 15.00%, and the rot rate of the control group was 71.67%. Compared with the control group, the experimental group decreased by 56.67%.

[0116] Example 5

[0117] The nucleotide sequence of Pythium oligandrum strain EMF915 is the same as that of Example 1.

[0118] The tomato biological preservative is prepared in liquid form. In 1 mL of liquid tomato biological preservative, the number of Pythium oligandrum strain EMF915 oospores is 1 x 10 6 CFU / mL ~ 4 x 10 6 CFU / mL. In the preparation of liquid tomato biological preservative, Pythium oligandrum strain EMF915 fermentation broth is used.

[0119] The raw materials and preparation method for preparing Pythium oligandrum strain EMF915 tomato biological preservative are the same as those of Example 1.

[0120] The use method of the tomato biological preservative is the same as that of Example 1.

[0121] In the laboratory experiment, 4 kg of tomatoes, 200 mL of tomato biological preservative, and 200 mL of tap water were divided into an experimental group and a control group. The experimental group used 2 kg of tomatoes and the control group used 2 kg of tomatoes. The experimental group used the tomato biological preservative according to the usage method of the present embodiment, and the control group used tap water for comparison of the preservative function test. According to the standard of surface rotting, wrinkling, and winding mycelium, the preservation rate was calculated. The rotting rate of tomatoes was detected on the 30th day, and the rotting rate was calculated according to the formula:

[0122] Rotting rate % = number of rotting / total number of rotting x 100%.

[0123] In the experiment, the tomatoes were stored in a 4°C refrigerator. The preservation rate was calculated on the 30th day. The experimental results are shown in Table 5 and Figure 7 .

[0124] Table 5: Statistics of rotting rate of tomatoes stored in a 4°C refrigerator on the 30th day

[0125] Time (days) Rot rate (%) of control group Rot rate (%) of experimental group 30 100 12.5

[0126] As shown in Table 5, on the 30th day, the rotting rate of the experimental group was 12.5%, and the rotting rate of the control group was 100%. Compared with the control group, the rotting rate of the experimental group was reduced by 87.5%.

Claims

1. Use of Pythium oligandrum strain EMF915 in the preparation of a plum biological preservative; The Pythium oligandrum strain EMF915 was deposited at the China Center for Type Culture Collection of Wuhan University on May 24, 2022, with the accession number CCTCC NO: M 2022710, and the address is Wuhan University, Wuhan, Hubei Province, China, and its nucleotide sequence is shown in the sequence table SEQ ID NO: 1; The Prunus domestica biological preservative is prepared in liquid form, and 1 mL of the liquid biological preservative contains 1×10 6 CFU / mL to 4×10 6 CFU / mL of spores of the Pythium oligandrum strain EMF915, and the fermentation broth of the Pythium oligandrum strain EMF915 is used in preparation of the liquid biological preservative. The preparation method is as follows: Take 100g of tomato, 100g of lettuce, 100g of spinach, 100g of parsley, 100g of celery, and add 1L of water, add 10g of yeast powder, 8g of sodium chloride, 1g of Vc, 1g of citric acid, 0.1mL of glycerol, 1g of calcium carbonate, 0.6g of dipotassium hydrogen phosphate, 0.125g of potassium dihydrogen phosphate, add Pythium oligandrum strain EMF915 liquid culture, inoculation amount is 5%, 28℃, 160rpm fermentation for 7-15 days, to prepare Pythium oligandrum strain EMF915 fermentation broth, add homogenizer to homogenize, to prepare plum biological preservative; The use method of plum biological preservative is as follows: Take 1kg of plum, 100mL of plum biological preservative, dilute the plum biological preservative with water when using, the volume ratio of plum biological preservative to water is 1:500, prepare biological preservative spraying liquid, use a sprayer to evenly spray the biological preservative spraying liquid on the surface of the plum, air dry at room temperature, and store in a 4℃ refrigerator.

2. Use of Pythium oligandrum strain EMF915 in the preparation of a strawberry biological preservative; The strawberry biological preservative is prepared in liquid form, and 1 mL of the liquid strawberry biological preservative contains 1×10 6 CFU / mL~4×10 6 CFU / mL, and the fermentation liquor of the Pythium aphanidermatum strain EMF915 is used in preparation of the liquid strawberry biological preservative. The preparation method is as follows: Take 100g of tomato, 100g of lettuce, 100g of spinach, 100g of parsley, 100g of celery, and add 1L of water, add 10g of yeast powder, 8g of sodium chloride, 1g of Vc, 1g of citric acid, 0.1mL of glycerol, 1g of calcium carbonate, 0.6g of dipotassium hydrogen phosphate, 0.125g of potassium dihydrogen phosphate, add Pythium oligandrum strain EMF915 liquid culture, inoculation amount is 5%, 28℃, 160rpm fermentation for 7-15 days, to prepare Pythium oligandrum strain EMF915 fermentation broth, add homogenizer to homogenize, to prepare plum biological preservative; The use method of plum biological preservative is as follows: Take 1kg of plum, 100mL of plum biological preservative, dilute the plum biological preservative with water when using, the volume ratio of plum biological preservative to water is 1:500, prepare biological preservative spraying liquid, use a sprayer to evenly spray the biological preservative spraying liquid on the surface of the plum, air dry at room temperature, and store in a 4℃ refrigerator.

3. Use of Pythium oligandrum strain EMF915 in the preparation of a cherry biological preservative; The cherry biological preservative is prepared in liquid form, and 1 mL of the liquid cherry biological preservative contains 1×10 6 CFU / mL~4×10 6 CFU / mL, and the fermentation liquor of the Pythium aphanidermatum strain EMF915 is used in preparation of the liquid cherry biological preservative. The preparation method is as follows: Take 100 g of tomato, 100 g of lettuce, 100 g of spinach, 100 g of parsley, 100 g of celery extract liquid into 1 L of water, add 10 g of yeast powder, 8 g of sodium chloride, 1 g of Vc, 1 g of citric acid, 0.1 mL of glycerol, 1 g of calcium carbonate, 0.6 g of dipotassium hydrogen phosphate, 0.125 g of potassium dihydrogen phosphate, add oligophagous pythium strain EMF915 liquid culture, inoculation amount is 5%, 28℃, 160 rpm fermentation 7-15 days, preparation oligophagous pythium strain EMF915 fermentation broth, add homogenizer homogenization, get oligophagous pythium fermentation broth, preparation cherry biological preservative; The use method of cherry biological preservative is as follows: Take 1 kg of cherry, 100 mL of cherry biological preservative, when using, dilute cherry biological preservative with water, the volume ratio of cherry biological preservative to water is 1:100, preparation cherry biological preservative spraying liquid, use sprayer to evenly spray cherry biological preservative spraying liquid on the surface of cherry, dry at room temperature, store at room temperature 28℃.

4. The use of oligophagous pythium strain EMF915 of claim 1 in the preparation of kiwi biological preservative; The prepared kiwi biological preservative is in liquid form, and 1 mL of the liquid kiwi biological preservative contains 1×10 6 CFU / mL to 4×10 6 CFU / mL of Pythium oligandrum strain EMF915 spores, and the fermentation liquor of the Pythium oligandrum strain EMF915 is used in preparation of the liquid kiwi biological preservative. Its preparation method is as follows: Take 100 g of tomato, 100 g of lettuce, 100 g of spinach, 100 g of parsley, 100 g of celery extract liquid into 1 L of water, add 10 g of yeast powder, 8 g of sodium chloride, 1 g of Vc, 1 g of citric acid, 0.1 mL of glycerol, 1 g of calcium carbonate, 0.6 g of dipotassium hydrogen phosphate, 0.125 g of potassium dihydrogen phosphate, add oligophagous pythium strain EMF915 liquid culture, inoculation amount is 5%, 28℃, 160 rpm fermentation 7-15 days, preparation oligophagous pythium strain EMF915 fermentation broth, add homogenizer homogenization, get oligophagous pythium fermentation broth, preparation cherry biological preservative; The use method of cherry biological preservative is as follows: Take 1 kg of cherry, 100 mL of cherry biological preservative, when using, dilute cherry biological preservative with water, the volume ratio of cherry biological preservative to water is 1:100, preparation cherry biological preservative spraying liquid, use sprayer to evenly spray cherry biological preservative spraying liquid on the surface of cherry, dry at room temperature, store at room temperature 28℃.

5. The use of oligophagous pythium strain EMF915 of claim 1 in the preparation of tomato biological preservative; The tomato biological preservative is prepared in liquid form, and 1 mL of the liquid tomato biological preservative contains 1×10 6 CFU / mL~4×10 6 CFU / mL, and the fermentation liquor of the Pythium oligandrum strain EMF915 is used in the preparation of the liquid tomato biological preservative. Its preparation method is as follows: Take 100 g of tomato, 100 g of lettuce, 100 g of spinach, 100 g of parsley, 100 g of celery extract liquid into 1 L of water, add 10 g of yeast powder, 8 g of sodium chloride, 1 g of Vc, 1 g of citric acid, 0.1 mL of glycerol, 1 g of calcium carbonate, 0.6 g of dipotassium hydrogen phosphate, 0.125 g of potassium dihydrogen phosphate, add oligophagous pythium strain EMF915 liquid culture, inoculation amount is 5%, 28℃, 160 rpm fermentation 7-15 days, preparation oligophagous pythium strain EMF915 fermentation broth, add homogenizer homogenization, get oligophagous pythium fermentation broth, preparation cherry biological preservative; The use method of the tomato biological preservative is as follows: 1 kg of tomatoes, 100 mL of tomato biological preservative, when in use, the tomato biological preservative is diluted with water, the volume ratio of the tomato biological preservative to water is 1:100, a tomato biological preservative spraying solution is prepared, the tomato biological preservative spraying solution is uniformly sprayed on the surface of the tomatoes by a sprayer, and the tomatoes are dried at room temperature and stored in a 4℃ refrigerator.

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