Gas carbon source converted single-cell protein and preparation method thereof

Abstract

The invention discloses a gas carbon source converted single-cell protein and a preparation method thereof, particularly relates to the technical field of biology, and relates to a gas carbon source converted single-cell protein and a preparation method thereof. The gas carbon source converted single-cell protein is prepared from methane, carbon dioxide mixed gas, a mixed microbial system and a basic culture medium; the volume ratio of methane to carbon dioxide in the mixed gas of methane and carbon dioxide is (1-7): (1-3); according to the method, biogas is converted into single-cell protein by utilizing a mixed microbial system, and in the mixed microbial system, a carbon source is converted into energy and biomass by candida utilis through glycolysis and tricarboxylic acid circulation processes; the rhodopseudomonas palustris absorbs light energy by using the photosynthetic pigment of the rhodopseudomonas palustris; methanophilic bacteria oxidize methane into methanol through a methane oxidase system of the methanophilic bacteria, and further oxidize the methanol into formaldehyde; the three bacteria interact with each other, and different components in the biogas are jointly utilized, so that efficient utilization of resources is realized.

Description

Technical Field

[0001] The present invention relates to the field of biotechnology, and more specifically to a gaseous carbon source conversion single cell protein and a preparation method thereof. Background Art

[0002] Single-cell protein is an important source of microbial protein, with high protein content, complete amino acid composition, and rich nutrients such as vitamins and inorganic salts. At present, the production of single-cell protein mainly relies on the large-scale cultivation of bacteria, yeast, mold and other microorganisms in various matrices. Therefore, it is particularly important to find new and sustainable carbon sources for the production of single-cell protein.

[0003] The preparation of single-cell protein in related technologies mainly includes sugars, straw, industrial wastewater, methanol, and carbon dioxide; sugars provide energy for the growth and reproduction of microorganisms and promote the synthesis of protein in bacterial cells; straw contains certain components such as cellulose, hemicellulose and lignin, which can be used as a carbon source and energy source for microbial growth; industrial wastewater contains rich organic matter and nutrients, which can provide the necessary nutritional conditions for the production of single-cell protein; methanol is used as a carbon source to produce single-cell protein; carbon dioxide is used as the only carbon source for growth and reproduction to synthesize single-cell protein.

[0004] However, there are still some shortcomings in its actual use, such as the limited source of raw materials. The traditional source of raw materials for preparing single-cell protein is limited. Agricultural waste, industrial wastewater and waste residue have certain difficulties in collection, transportation and storage, and are greatly affected by geographical and seasonal factors; product quality is unstable. Due to the unstable composition and quality of raw materials and different control conditions in the production process, the quality of single-cell protein products produced by traditional methods fluctuates; energy consumption is high. In the traditional single-cell protein production process, a large amount of energy is consumed for heating, stirring, and ventilation operations of the fermentation tank, as well as subsequent bacterial separation and drying processes, resulting in high energy costs. Summary of the invention

[0005] In order to improve the above problems and reduce the problems of limited raw material sources, unstable product quality and low conversion efficiency in single-cell protein production, the present invention provides a gas carbon source conversion single-cell protein and a preparation method thereof to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A gas carbon source conversion single cell protein, prepared by methane, carbon dioxide mixed gas, mixed microbial system, and basic culture medium;

[0008] The specific preparation steps are as follows:

[0009] A1. First, the mixed microbial system is inoculated into a reactor containing a basic culture medium according to 10% of the effective volume of the reactor;

[0010] A2, continuously introduce methane and carbon dioxide mixed gas into the reactor, react for 72-120h under the conditions of ventilation volume of 0.5-1.5vvm, pressure in the reactor of 0.1-0.3MPa, reaction temperature of 30-35°C, stirring speed of 100-150r / min, pH of 6-7.5, to obtain fermentation liquid;

[0011] A3. Pour the fermentation liquid obtained in A2 into a centrifuge, centrifuge at a speed of 3000 r / min, take the precipitate, and then wash the precipitate twice with sterile saline, centrifuge again under the same conditions, take the precipitate, and obtain the gas carbon source converted single cell protein.

[0012] Preferably, the volume ratio of methane to carbon dioxide in the methane and carbon dioxide mixed gas is (1-7): (1-3).

[0013] Preferably, the preparation steps of the methanotrophic bacteria are as follows:

[0014] C1. Inoculate the utilis Candida into 10 times the volume of YEPD liquid culture medium, and culture for 24-48 hours at a temperature of 28-32° C. and a rotation speed of 150-200 r / min to obtain a utilis Candida flora liquid;

[0015] C2. The palustris Rhodopseudomonas was inoculated into 10 times the volume of RCVBN liquid culture medium, and cultured at a light intensity of 2000-3000 lx and a temperature of 25-35°C for 48-72 hours to obtain a palustris Rhodopseudomonas swarm liquid;

[0016] C3, inoculating the methanogens into 10 volumes of an inorganic salt culture medium, culturing for 3-5 days at a temperature of 25-35° C. and a methane gas ventilation rate of 0.1-0.3 vvm, to obtain a methanogen group liquid;

[0017] C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

[0018] Preferably, the raw material components and volume ratios of the mixed microbial system are as follows: Candida utilis liquid (1-4) parts, Rhodopseudomonas palustris liquid (1-3 parts), and methanophilic bacteria liquid (1-2 parts).

[0019] Preferably, the basal culture medium consists of potassium nitrate, disodium hydrogen phosphate, magnesium sulfate, ferrous sulfate, glucose, and yeast extract in a weight ratio of 2:1.5:0.6:0.02:10:3:1000 or consists of potassium dihydrogen phosphate, magnesium sulfate, calcium chloride, ferrous sulfate, and ammonium sulfate in a weight ratio of 2.5:0.8:0.2:0.02:1.5:1000.

[0020] Preferably, the YEPD liquid culture medium is composed of glucose, peptone, yeast extract powder and water in a weight ratio of 2:2:1:100 or is composed of sucrose, ammonium chloride, yeast powder and water in a weight ratio of 3:0.5:1.5:100.

[0021] Preferably, the RCVBN liquid culture medium consists of sodium succinate, ammonium chloride, dipotassium hydrogen phosphate, magnesium sulfate, calcium chloride, yeast extract, and water in a weight ratio of 4:1:0.5:0.2:0.05:0.5:1000 or consists of sodium malate, potassium nitrate, dipotassium hydrogen phosphate, ferrous sulfate, and water in a weight ratio of 4:1.5:0.8:0.05:1000.

[0022] Preferably, the inorganic salt culture medium is composed of potassium nitrate, potassium dihydrogen phosphate, magnesium sulfate, calcium chloride, ferrous sulfate, manganese sulfate, copper sulfate, and water in a weight ratio of 1:0.5:0.2:0.05:0.05:0.01:0.005:1000 or is composed of potassium chloride, disodium hydrogen phosphate, urea, manganese sulfate, ferric chloride, and water in a weight ratio of 0.8:0.4g:0.3:0.02:0.01:100.

[0023] Technical effects and advantages of the present invention:

[0024] 1. The present invention utilizes a mixed microbial system to convert biogas into single-cell protein. In the mixed microbial system, Candida utilis converts carbon sources into energy and biomass through glycolysis and tricarboxylic acid cycle processes; Rhodopseudomonas palustris utilizes its photosynthetic pigments to absorb light energy; and Methanophilus oxidizes methane into methanol through its methane oxidase system, and further oxidizes it into formaldehyde. The three bacteria interact with each other and jointly utilize different components in biogas, thereby realizing efficient utilization of resources.

[0025] 2. The single-cell protein produced by the mixed microbial system of the present invention has stable product quality. Since the composition of biogas is relatively fixed, the growth environment and metabolic process of microorganisms are easier to control, thereby improving the safety of the product and reducing the generation of harmful substances.

[0026] 3. The present invention utilizes biogas as energy, reduces energy consumption and production costs, and uses biogas for the production of single-cell protein, which can achieve energy self-sufficiency and reduce dependence on external energy. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the embodiments of the present invention. The raw materials used in the examples and embodiments of the present invention are all commercially available common materials unless otherwise specified below.

[0028] Preparation Example 1-5

[0029] A mixed microbial system, the preparation components and their corresponding proportions are shown in the following table, and is prepared by the following preparation method:

[0030] C1. Inoculate the utilis Candida into 10 times the volume of YEPD liquid culture medium, and culture for 36 hours at a temperature of 30° C. and a rotation speed of 175 r / min to obtain a utilis Candida flora liquid;

[0031] The YEPD liquid medium is composed of glucose, peptone, yeast extract powder, and water in a weight ratio of 2:2:1:100;

[0032] C2, Rhodopseudomonas palustris was inoculated into 10 volumes of RCVBN liquid culture medium, and cultured at a light intensity of 2500 lx and a temperature of 30°C for 60 hours to obtain a Rhodopseudomonas palustris swarm liquid;

[0033] The RCVBN liquid culture medium is composed of sodium succinate, ammonium chloride, dipotassium hydrogen phosphate, magnesium sulfate, calcium chloride, yeast extract powder, and water in a weight ratio of 4:1:0.5:0.2:0.05:0.5:1000;

[0034] C3, inoculating the methanogens into 10 times the volume of the inorganic salt culture medium, culturing for 4 days at a temperature of 30°C and a methane gas ventilation rate of 0.2 vvm, to obtain a methanogen group liquid;

[0035] The inorganic salt medium is composed of potassium nitrate, potassium dihydrogen phosphate, magnesium sulfate, calcium chloride, ferrous sulfate, manganese sulfate, copper sulfate, and water in a weight ratio of 1:0.5:0.2:0.05:0.05:0.01:0.005:1000;

[0036] C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

[0037] Table: Raw material components and their volume ratios in Preparation Examples 1-5

[0038]

[0039] Preparation Example 6

[0040] A mixed microbial system, which is different from Preparation Example 1 in that the specific preparation steps are as follows:

[0041] C1. Inoculate the utilis yeast into 10 times the volume of YEPD liquid culture medium, and culture it at a temperature of 28° C. and a rotation speed of 150 r / min for 24 hours to obtain a utilis yeast flora liquid;

[0042] C2, Rhodopseudomonas palustris was inoculated into 10 volumes of RCVBN liquid culture medium, and cultured at a light intensity of 2500 lx and a temperature of 30°C for 60 hours to obtain a Rhodopseudomonas palustris swarm liquid;

[0043] C3, inoculating the methanogens into 10 times the volume of the inorganic salt culture medium, culturing for 4 days at a temperature of 30°C and a methane gas ventilation rate of 0.2 vvm, to obtain a methanogen group liquid;

[0044] C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

[0045] Preparation Example 7

[0046] A mixed microbial system, which is different from Preparation Example 1 in that the specific preparation steps are as follows:

[0047] C1. Inoculate the utilis yeast into 10 times the volume of YEPD liquid culture medium, and culture it at a temperature of 32° C. and a rotation speed of 200 r / min for 48 hours to obtain a utilis yeast flora liquid;

[0048] C2, Rhodopseudomonas palustris was inoculated into 10 volumes of RCVBN liquid culture medium, and cultured at a light intensity of 2500 lx and a temperature of 30°C for 60 hours to obtain a Rhodopseudomonas palustris swarm liquid;

[0049] C3, inoculating the methanogens into 10 times the volume of the inorganic salt culture medium, culturing for 4 days at a temperature of 30°C and a methane gas ventilation rate of 0.2 vvm, to obtain a methanogen group liquid;

[0050] C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

[0051] Preparation Example 8

[0052] A mixed microbial system, which is different from Preparation Example 1 in that the specific preparation steps are as follows:

[0053] C1. Inoculate the utilis Candida into 10 times the volume of YEPD liquid culture medium, and culture for 36 hours at a temperature of 30° C. and a rotation speed of 175 r / min to obtain a utilis Candida flora liquid;

[0054] C2, Rhodopseudomonas palustris was inoculated into 10 volumes of RCVBN liquid culture medium, and cultured at a light intensity of 2000 lx and a temperature of 25°C for 48 hours to obtain a Rhodopseudomonas palustris swarm liquid;

[0055] C3, inoculating the methanogens into 10 times the volume of the inorganic salt culture medium, culturing for 4 days at a temperature of 30°C and a methane gas ventilation rate of 0.2 vvm, to obtain a methanogen group liquid;

[0056] C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

[0057] Preparation Example 9

[0058] A mixed microbial system, which is different from Preparation Example 1 in that the specific preparation steps are as follows:

[0059] C1. Inoculate the utilis Candida into 10 times the volume of YEPD liquid culture medium, and culture for 36 hours at a temperature of 30° C. and a rotation speed of 175 r / min to obtain a utilis Candida flora liquid;

[0060] C2. Rhodopseudomonas palustris was inoculated into 10 times the volume of RCVBN liquid culture medium, and cultured for 72 hours at a light intensity of 3000 lx and a temperature of 35°C to obtain a Rhodopseudomonas palustris swarm liquid;

[0061] C3, inoculating the methanogens into 10 times the volume of the inorganic salt culture medium, culturing for 4 days at a temperature of 30°C and a methane gas ventilation rate of 0.2 vvm, to obtain a methanogen group liquid;

[0062] C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

[0063] Preparation Example 10

[0064] A mixed microbial system, which is different from Preparation Example 1 in that the specific preparation steps are as follows:

[0065] C1. Inoculate the utilis Candida into 10 times the volume of YEPD liquid culture medium, and culture for 36 hours at a temperature of 30° C. and a rotation speed of 175 r / min to obtain a utilis Candida flora liquid;

[0066] C2, Rhodopseudomonas palustris was inoculated into 10 volumes of RCVBN liquid culture medium, and cultured at a light intensity of 2500 lx and a temperature of 30°C for 60 hours to obtain a Rhodopseudomonas palustris swarm liquid;

[0067] C3, inoculating the methanogens into 10 volumes of inorganic salt culture medium, culturing at a temperature of 25°C and a methane gas ventilation rate of 0.1 vvm for 3 days to obtain a methanogen group liquid;

[0068] C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

[0069] Preparation Example 11

[0070] A mixed microbial system, which is different from Preparation Example 1 in that the specific preparation steps are as follows:

[0071] C1. Inoculate the utilis Candida into 10 times the volume of YEPD liquid culture medium, and culture for 36 hours at a temperature of 30° C. and a rotation speed of 175 r / min to obtain a utilis Candida flora liquid;

[0072] C2, Rhodopseudomonas palustris was inoculated into 10 volumes of RCVBN liquid culture medium, and cultured at a light intensity of 2500 lx and a temperature of 30°C for 60 hours to obtain a Rhodopseudomonas palustris swarm liquid;

[0073] C3, inoculating the methanogens into 10 volumes of inorganic salt culture medium, culturing at a temperature of 35° C. and a methane gas ventilation rate of 0.3 vvm for 5 days to obtain a methanogen group liquid;

[0074] C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

[0075] Preparation Example 12

[0076] A mixed microbial system, which is different from Preparation Example 1 in that the YEPD liquid culture medium is composed of sucrose, ammonium chloride, yeast powder and water in a weight ratio of 3:0.5:1.5:100.

[0077] Preparation Example 13

[0078] A mixed microbial system, which is different from Preparation Example 1 in that the RCVBN liquid culture medium is composed of sodium malate, potassium nitrate, dipotassium hydrogen phosphate, ferrous sulfate, and water in a weight ratio of 4:1.5:0.8:0.05:1000;

[0079] Preparation Example 14

[0080] A mixed microbial system, which is different from Preparation Example 1 in that the inorganic salt culture medium is composed of potassium chloride, disodium hydrogen phosphate, urea, manganese sulfate, ferric chloride, and water in a weight ratio of 0.8:0.4g:0.3:0.02:0.01:100;

[0081] Preparation Examples 15-19

[0082] A gaseous carbon source conversion single cell protein, the preparation components and their corresponding proportions are shown in the following table, and the protein is prepared by the following preparation method:

[0083] A1. First, the mixed microbial system is inoculated into a reactor containing a basic culture medium according to 10% of the effective volume of the reactor;

[0084] The mixed microbial system was prepared by Preparation Example 1;

[0085] The basic culture medium is composed of potassium dihydrogen phosphate, magnesium sulfate, calcium chloride, ferrous sulfate, and ammonium sulfate in a weight ratio of 2.5:0.8:0.2:0.02:1.5:1000;

[0086] A2. A mixed gas of methane and carbon dioxide is continuously introduced into the reactor, and the reaction is carried out for 72 hours under the conditions of a ventilation volume of 0.5 vvm, a pressure in the reactor of 0.1 MPa, a reaction temperature of 30° C., a stirring speed of 100 r / min, and a pH of 6 to obtain a fermentation liquid;

[0087] A3. Pour the fermentation liquid obtained in A2 into a centrifuge, centrifuge at a speed of 3000 r / min, take the precipitate, and then wash the precipitate twice with sterile saline, centrifuge again under the same conditions, take the precipitate, and obtain the gas carbon source converted single cell protein.

[0088] Table: Components and volume ratios of mixed gases in Preparation Examples 15-19

[0089]

[0090] Preparation Example 20

[0091] A gaseous carbon source conversion single cell protein, which is different from Preparation Example 15 in that the preparation method is as follows:

[0092] A1. First, the mixed microbial system is inoculated into a reactor containing a basic culture medium according to 10% of the effective volume of the reactor;

[0093] A2. A mixed gas of methane and carbon dioxide was continuously introduced into the reactor, and the reaction was carried out for 80 hours under the conditions of a ventilation volume of 0.7 vvm, an internal pressure of 0.15 MPa, a reaction temperature of 31° C., a stirring speed of 110 r / min, and a pH of 6.5 to obtain a fermentation liquid;

[0094] A3. Pour the fermentation liquid obtained in A2 into a centrifuge, centrifuge at a speed of 3000 r / min, take the precipitate, and then wash the precipitate twice with sterile saline, centrifuge again under the same conditions, take the precipitate, and obtain the gas carbon source converted single cell protein.

[0095] Preparation Example 21

[0096] A gaseous carbon source conversion single cell protein, which is different from Preparation Example 15 in that the preparation method is as follows:

[0097] A1. First, the mixed microbial system is inoculated into a reactor containing a basic culture medium according to 10% of the effective volume of the reactor;

[0098] A2. A mixed gas of methane and carbon dioxide is continuously introduced into the reactor, and the reaction is carried out for 90 hours under the conditions of a ventilation volume of 0.9 vvm, a pressure in the reactor of 0.2 MPa, a reaction temperature of 32° C., a stirring speed of 120 r / min, and a pH of 7 to obtain a fermentation liquid;

[0099] A3. Pour the fermentation liquid obtained in A2 into a centrifuge, centrifuge at a speed of 3000 r / min, take the precipitate, and then wash the precipitate twice with sterile saline, centrifuge again under the same conditions, take the precipitate, and obtain the gas carbon source converted single cell protein.

[0100] Preparation Example 22

[0101] A gaseous carbon source conversion single cell protein, which is different from Preparation Example 15 in that the preparation method is as follows:

[0102] A1. First, the mixed microbial system is inoculated into a reactor containing a basic culture medium according to 10% of the effective volume of the reactor;

[0103] A2. A mixed gas of methane and carbon dioxide is continuously introduced into the reactor, and the reaction is carried out for 100 hours under the conditions of a ventilation volume of 1.1 vvm, a pressure in the reactor of 0.2 MPa, a reaction temperature of 33° C., a stirring speed of 130 r / min, and a pH of 7 to obtain a fermentation liquid;

[0104] A3. Pour the fermentation liquid obtained in A2 into a centrifuge, centrifuge at a speed of 3000 r / min, take the precipitate, and then wash the precipitate twice with sterile saline, centrifuge again under the same conditions, take the precipitate, and obtain the gas carbon source converted single cell protein.

[0105] Preparation Example 23

[0106] A gaseous carbon source conversion single cell protein, which is different from Preparation Example 15 in that the preparation method is as follows:

[0107] A1. First, the mixed microbial system is inoculated into a reactor containing a basic culture medium according to 10% of the effective volume of the reactor;

[0108] A2. A mixed gas of methane and carbon dioxide was continuously introduced into the reactor, and the reaction was carried out for 110 hours under the conditions of a ventilation volume of 1.3 vvm, an internal pressure of 0.25 MPa, a reaction temperature of 34° C., a stirring speed of 140 r / min, and a pH of 7.5 to obtain a fermentation liquid;

[0109] A3. Pour the fermentation liquid obtained in A2 into a centrifuge, centrifuge at a speed of 3000 r / min, take the precipitate, and then wash the precipitate twice with sterile saline, centrifuge again under the same conditions, take the precipitate, and obtain the gas carbon source converted single cell protein.

[0110] Preparation Example 24

[0111] A gaseous carbon source conversion single cell protein, which is different from Preparation Example 15 in that the preparation method is as follows:

[0112] A1. First, the mixed microbial system is inoculated into a reactor containing a basic culture medium according to 10% of the effective volume of the reactor;

[0113] A2. A mixed gas of methane and carbon dioxide is continuously introduced into the reactor, and the reaction is carried out for 120 hours under the conditions of a ventilation volume of 1.5 vvm, a pressure in the reactor of 0.3 MPa, a reaction temperature of 35° C., a stirring speed of 150 r / min, and a pH of 7.5 to obtain a fermentation liquid;

[0114] A3. Pour the fermentation liquid obtained in A2 into a centrifuge, centrifuge at a speed of 3000 r / min, take the precipitate, and then wash the precipitate twice with sterile saline, centrifuge again under the same conditions, take the precipitate, and obtain the gas carbon source converted single cell protein.

[0115] Preparation Example 25

[0116] A gas carbon source conversion single cell protein, which is different from Preparation Example 15 in that the basic culture medium consists of potassium nitrate, disodium hydrogen phosphate, magnesium sulfate, ferrous sulfate, glucose, and yeast extract in a weight ratio of 2:1.5:0.6:0.02:10:3:1000.

[0117] Preparation Examples 26-37

[0118] A gas carbon source conversion single cell protein, which is different from Preparation Example 15 in that the use of the mixed microbial system used in its components is different, and the specific corresponding relationship is shown in the following table.

[0119] Table: Comparison of the use of mixed microbial systems in preparation examples 26-29

[0120] Group Mixed microbial system Preparation Example 26 Prepared from Preparation Example 2 Preparation Example 27 Prepared from Preparation Example 3 Preparation Example 28 Prepared by Preparation Example 4 Preparation Example 29 Prepared from Preparation Example 5 Preparation Example 30 Prepared from Preparation Example 6 Preparation Example 31 Prepared from Preparation Example 7 Preparation Example 32 Prepared from Preparation Example 8 Preparation Example 33 Prepared from Preparation Example 9 Preparation Example 34 Prepared from Preparation Example 10 Preparation Example 35 Prepared from Preparation Example 11 Preparation Example 36 Prepared from Preparation Example 12 Preparation Example 37 Prepared from Preparation Example 13 Preparation Example 38 Prepared from Preparation Example 14

[0121] Performance testing

[0122] The gas carbon source conversion single cell protein prepared in each embodiment was selected for testing, and the test object was 240 portions of gas carbon source conversion single cell protein, 10 portions in each group; the protein content and microbial content of the product were detected, and the specific detection steps were as follows:

[0123] Crude protein content:

[0124] First, the gaseous carbon source converted single cell protein obtained in the embodiment was sampled, and the crude protein content of the single cell protein was determined by the Kjeldahl method, and the preparation effect of the gaseous carbon source converted single cell protein was characterized based on the data; the test results and evaluation criteria are as follows:

[0125] :60<crude protein content value (considered to have significant production effect);

[0126] :30<crude protein content<60 (considered as general production effect);

[0127] : Crude protein content value <30 (considered as low production effect).

[0128] Biogas and CO2 conversion efficiency:

[0129] First, the mixed gas before and after the reaction in the embodiment is sampled, and the changes in the methane and carbon dioxide content in the biogas before the reaction are detected by gas chromatography. The retention time of the chromatographic peak is used to qualitatively identify the methane and carbon dioxide. The external standard method or the internal standard method is used for quantitative analysis according to the peak area, and the biogas and carbon dioxide conversion efficiency is calculated. The data are used to characterize the biogas and carbon dioxide conversion effect in the process of gas carbon source conversion to single-cell protein. The detection results and evaluation criteria are as follows:

[0130] :65<biogas conversion efficiency (considered to have significant conversion effect);

[0131] :45<biogas conversion efficiency<65(considered as average conversion effect);

[0132] :Methane conversion efficiency <45 (considered as low conversion effect).

[0133] : 50<CO2 conversion efficiency (considered to have significant conversion effect);

[0134] :30<CO2 conversion efficiency<50 (considered as average conversion effect);

[0135] : Carbon dioxide conversion efficiency <30 (considered as low conversion effect).

[0136] It should be specifically noted that the gas carbon source converted single-cell protein obtained above is the gas carbon source converted single-cell protein produced in a normal production method, and the data of the defective gas carbon source converted single-cell protein produced is discarded.

[0137] Examples 1-5

[0138] A gaseous carbon source is used to convert a single-cell protein, and the corresponding relationship of the preparation method used is shown in the following table.

[0139] Table: Comparison of the usage of gaseous carbon sources in converting single cell protein in Examples 1-5

[0140] Group Conversion of single cell protein by gaseous carbon sources Example 1 Prepared from Preparation Example 15 Example 2 Prepared from Preparation Example 16 Example 3 Prepared from Preparation Example 17 Example 4 Prepared from Preparation Example 18 Example 5 Prepared from Preparation Example 19

[0141] The single cell protein converted from the gaseous carbon source in the above Examples 1-5 was extracted, and its crude protein content, biogas conversion efficiency, and carbon dioxide conversion efficiency were tested according to the above measurement steps and measurement standards. The average values ​​of the test results were recorded in the following table.

[0142] Table: Performance test results of crude protein content, biogas and carbon dioxide conversion efficiency of Examples 1-5

[0143]

[0144] As can be seen from the above table, in the gas carbon source conversion single cell protein preparation process in Examples 1-5, all have a good effect of improving the gas carbon source conversion single cell protein production effect. Candida utilis can use part of the organic components in the biogas and the nutrients in the basal culture medium for growth metabolism, and convert the carbon source into energy and biomass through glycolysis and tricarboxylic acid cycle processes; Rhodopseudomonas palustris uses its photosynthetic pigments to absorb light energy, stimulate the electron transport chain, and produce ATP and NADPH; these energies and reducing power are used to fix carbon dioxide through the Calvin cycle and other pathways, and then synthesize organic matter; Methanophiles oxidize methane to methanol through their methane oxidase system, and further oxidize it to formaldehyde; the formaldehyde then enters the metabolic pathway in the cell, and is converted into organic matter through the serine pathway and other pathways, which is used to synthesize bacterial proteins and other biomacromolecules; the three bacteria interact with each other and jointly utilize different components in the biogas to achieve efficient utilization of resources, thereby achieving the purpose of improving the gas carbon source conversion single cell protein production effect;

[0145] Its crude protein content is 68.3% to 71.9%, which is considered to have significant production effect; its biogas conversion efficiency is 65.3% to 68.2%, which is considered to have significant conversion efficiency; its carbon dioxide conversion efficiency is 50.3% to 52.2%, which is considered to have significant conversion efficiency;

[0146] It can be seen that when the production raw materials are certain, the production effect of gas carbon source conversion of single-cell protein can be increased by adjusting the proportion of mixed gas components introduced into the mixed microbial system. Combined with the data in the above table, it is not difficult to see that when culturing single-cell protein, when the volume ratio of methane and carbon dioxide in the methane and carbon dioxide mixed gas is 1:1, the production effect of gas carbon source conversion of single-cell protein is best. The reason for this is that a relatively balanced ratio is used, and the three microorganisms can play a role to a certain extent; methanophiles have enough methane for metabolic conversion, Rhodopseudomonas palustris can also use carbon dioxide for photosynthesis, and Candida utilis can also obtain nutrition from the metabolites of the two gases, as obtained from Examples 1-5.

[0147] Embodiment 6-11

[0148] A gaseous carbon source is used to convert a single-cell protein, and the corresponding relationship of the preparation method used is shown in the following table.

[0149] Table: Comparison of the usage of gaseous carbon sources in converting single cell protein in Examples 6-11

[0150]

[0151]

[0152] The single cell protein converted from the gaseous carbon source in the above Examples 6-11 was extracted, and its crude protein content, biogas conversion efficiency, and carbon dioxide conversion efficiency were tested according to the above measurement steps and measurement standards. The average values ​​of the test results were recorded in the following table.

[0153] Table: Performance test results of crude protein content, biogas and carbon dioxide conversion efficiency of Examples 1, 6-11

[0154]

[0155] As can be seen from the above table, in the gas carbon source conversion single cell protein preparation process in Examples 1-5, all have a good effect of improving the gas carbon source conversion single cell protein production effect. Candida utilis can use part of the organic components in the biogas and the nutrients in the basal culture medium for growth metabolism, and convert the carbon source into energy and biomass through glycolysis and tricarboxylic acid cycle processes; Rhodopseudomonas palustris uses its photosynthetic pigments to absorb light energy, stimulate the electron transport chain, and produce ATP and NADPH; these energies and reducing power are used to fix carbon dioxide through the Calvin cycle and other pathways, and then synthesize organic matter; Methanophiles oxidize methane to methanol through their methane oxidase system, and further oxidize it to formaldehyde; the formaldehyde then enters the metabolic pathway in the cell, and is converted into organic matter through the serine pathway and other pathways, which is used to synthesize bacterial proteins and other biomacromolecules; the three bacteria interact with each other and jointly utilize different components in the biogas to achieve efficient utilization of resources, thereby achieving the purpose of improving the gas carbon source conversion single cell protein production effect;

[0156] Its crude protein content is 71.9% to 74.3%, which is considered to have significant production effect; its biogas conversion efficiency is 68.1% to 71.2%, which is considered to have significant conversion efficiency; its carbon dioxide conversion efficiency is 52.1% to 55.0%, which is considered to have significant conversion efficiency;

[0157] It can be seen that when the production raw materials are certain, the production effect of gas carbon source conversion to single-cell protein can be increased by adjusting the process conditions of culturing single-cell protein. It is not difficult to see from the data in the above table that when culturing single-cell protein, increasing the ventilation volume, pressure in the reactor, reaction temperature, and stirring speed during the culture process can improve the production effect of single-cell protein, and then tend to be stable. The reason for this is that the increase in ventilation volume means that more biogas is introduced into the reactor. For methanophiles, more methane is available for them to use, and methane is converted into methanol and formaldehyde through the methane oxidase system, and then organic matter and bacterial protein are synthesized; increasing the pressure in the reactor can increase the solubility of methane and carbon dioxide in the biogas in the culture medium; increasing the temperature can increase the activity of enzymes in microorganisms and accelerate the speed of various metabolic reactions; stirring can fully mix the culture medium and microorganisms in the reactor to ensure that the microorganisms can evenly contact nutrients and gas carbon sources; but with the continuous increase in ventilation volume, the utilization of gas by microorganisms gradually reaches saturation, as shown in Examples 1, 6-10;

[0158] It can be seen that when the production raw materials are certain, the production effect of gas carbon source conversion of single-cell protein can be changed by adjusting the components of the basic culture medium. Combined with the data in the above table, it is not difficult to see that the culture effects of the two prepared oxidizing bacteria culture media are not much different. The gas conversion efficiency of single-cell protein cultured using a basic culture medium composed of potassium nitrate, disodium hydrogen phosphate, magnesium sulfate, ferrous sulfate, glucose, and yeast extract is slightly lower, as obtained from Examples 1 and 11.

[0159] Examples 12-15

[0160] A gaseous carbon source is used to convert a single-cell protein, and the corresponding relationship of the preparation method used is shown in the following table.

[0161] Table: Comparison of the usage of gaseous carbon sources in converting single cell protein in Examples 12-15

[0162] Group Conversion of single cell protein by gaseous carbon sources Example 12 Prepared from Preparation Example 26 Example 13 Prepared from Preparation Example 27 Embodiment 14 Prepared from Preparation Example 28 Embodiment 15 Prepared from Preparation Example 29

[0163] The single cell protein converted from the gaseous carbon source in the above Examples 12-15 was extracted, and its crude protein content, biogas conversion efficiency, and carbon dioxide conversion efficiency were tested according to the above measurement steps and measurement standards. The average values ​​of the test results were recorded in the following table.

[0164] Table: Performance test results of crude protein content, biogas and carbon dioxide conversion efficiency of Examples 1, 12-15

[0165]

[0166] As can be seen from the above table, in the gas carbon source conversion single-cell protein preparation process in Examples 12-15, all have a good effect of improving the gas carbon source conversion single-cell protein production effect. Candida utilis can use part of the organic components in the biogas and the nutrients in the basal culture medium for growth metabolism, and convert the carbon source into energy and biomass through glycolysis and tricarboxylic acid cycle processes; Rhodopseudomonas palustris uses its photosynthetic pigments to absorb light energy, stimulate the electron transport chain, and produce ATP and NADPH; these energies and reducing power are used to fix carbon dioxide through the Calvin cycle and other pathways, and then synthesize organic matter; Methanophiles oxidize methane to methanol through their methane oxidase system, and further oxidize it to formaldehyde; the formaldehyde then enters the metabolic pathway in the cell, and is converted into organic matter through the serine pathway and other pathways, which is used to synthesize bacterial proteins and other biomacromolecules; the three bacteria interact with each other and jointly utilize different components in the biogas to achieve efficient utilization of resources, thereby achieving the purpose of improving the gas carbon source conversion single-cell protein production effect;

[0167] Its crude protein content is 71.9% to 74.1%, which is considered to have significant production effect; its biogas conversion efficiency is 68.2% to 70.4%, which is considered to have significant conversion efficiency; its carbon dioxide conversion efficiency is 52.2% to 54.1%, which is considered to have significant conversion efficiency;

[0168] It can be seen that when the production raw materials are certain, the production effect of gas carbon source conversion to single-cell protein can be increased by adjusting the proportion of each component in the mixed microbial system. Combined with the data in the above table, it is not difficult to see that when the mixed microbial system is prepared, when the ratio of the Candida utilis group liquid, the palustrine red Pseudomonas group liquid, and the methanophilic group liquid reaches 3:1:2, the production effect of gas carbon source conversion to single-cell protein is the best. The reason for this is that as the reaction proceeds, methanophilic bacteria utilize methane, and the palustrine red Pseudomonas utilizes carbon dioxide and the like for metabolic activities. Their synergistic effect enables the material and energy circulation of the entire system to proceed efficiently. The amino acids, vitamins and other substances produced by Candida utilis can be used by the other two bacteria. At the same time, the conversion products of the other two bacteria to the substrate can also be used for the growth of Candida utilis, forming a good interactive relationship, so it performs well in improving the biogas conversion efficiency and single-cell protein yield, as shown in Examples 1 and 12-15.

[0169] Examples 16-24

[0170] A gaseous carbon source is used to convert a single-cell protein, and the corresponding relationship of the preparation method used is shown in the following table.

[0171] Table: Comparison of the usage of gaseous carbon sources in converting single cell protein in Examples 16-24

[0172]

[0173]

[0174] The single cell protein converted from the gaseous carbon source in the above Examples 16-24 was extracted, and its crude protein content, biogas conversion efficiency, and carbon dioxide conversion efficiency were tested according to the above measurement steps and measurement standards. The average values ​​of the test results were recorded in the following table.

[0175] Table: Performance test results of crude protein content, biogas and carbon dioxide conversion efficiency of Examples 1, 16-24

[0176]

[0177]

[0178] As can be seen from the above table, in the gas carbon source conversion single-cell protein preparation process in Examples 16-23, all have a good effect of improving the gas carbon source conversion single-cell protein production effect. Candida utilis can use part of the organic components in the biogas and the nutrients in the basal culture medium for growth metabolism, and convert the carbon source into energy and biomass through glycolysis and tricarboxylic acid cycle processes; Rhodopseudomonas palustris uses its photosynthetic pigments to absorb light energy, stimulate the electron transport chain, and produce ATP and NADPH; these energies and reducing power are used to fix carbon dioxide through the Calvin cycle and other pathways, and then synthesize organic matter; Methanophiles oxidize methane to methanol through their methane oxidase system, and further oxidize it to formaldehyde; the formaldehyde then enters the metabolic pathway in the cell, and is converted into organic matter through the serine pathway and other pathways, which is used to synthesize bacterial proteins and other biomacromolecules; the three bacteria interact with each other and jointly utilize different components in the biogas to achieve efficient utilization of resources, thereby achieving the purpose of improving the gas carbon source conversion single-cell protein production effect;

[0179] Its crude protein content is 70.2% to 71.9%, which is considered to have significant production effect; its biogas conversion efficiency is 67.1% to 68.2%, which is considered to have significant conversion efficiency; its carbon dioxide conversion efficiency is 51.2% to 52.2%, which is considered to have significant conversion efficiency;

[0180] It can be seen that when the production raw materials are certain, the production effect of gas carbon source conversion to single-cell protein can be increased by adjusting the preparation conditions of each component in the mixed microbial system. It is not difficult to see from the data in the above table that when Candida utilis is cultured at a temperature of 30°C and a rotation speed of 175r / min for 36h; Rhodopseudomonas palustris is cultured at a light intensity of 2500lx and a temperature of 30°C for 60h; Methanophilus is cultured at a temperature of 30°C and a methane gas ventilation rate of 0.2vvm for 4 days. The three bacteria have the best quality, which are obtained from Examples 1 and 16-21;

[0181] It can be seen that when the production raw materials are certain, the production effect of gas carbon source conversion to single-cell protein can be increased by adjusting the preparation conditions of each component in the mixed microbial system. It is not difficult to see from the data in the above table that the YEPD liquid culture medium prepared from glucose, peptone, yeast extract powder and water; the RCVBN liquid culture medium prepared from sodium succinate, ammonium chloride, dipotassium hydrogen phosphate, magnesium sulfate, calcium chloride, yeast extract powder and water; and the inorganic salt culture medium prepared from potassium nitrate, potassium dihydrogen phosphate, magnesium sulfate, calcium chloride, ferrous sulfate, manganese sulfate, copper sulfate and water have the best culture effect, which is obtained from Examples 1 and 22-24.

[0182] This specific embodiment is only an explanation of the present invention, not a limitation of the present invention. After reading this specification, those skilled in the art can make non-creative modifications to this embodiment as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A formula for converting a gaseous carbon source into a single cell protein, characterized in that: The mixed microbial system is placed in a basic culture medium, and then placed in a reactor for fermentation, during which a mixed gas of methane and carbon dioxide is continuously introduced; The components and volume ratios of the raw materials for preparing the mixed microbial system are as follows: 1-4 parts of Candida utilis group liquid, 1-3 parts of Rhodopseudomonas palustris group liquid, and 1-2 parts of methanophilic bacteria group liquid; The volume ratio of methane to carbon dioxide in the methane and carbon dioxide mixed gas is (1-7):(1-3).

2. A gaseous carbon source conversion single cell protein formula according to any one of claim 1, characterized in that: The method for preparing single cell protein by converting gaseous carbon source comprises the following steps: A1. First, the mixed microbial system is inoculated into a reactor containing a basic culture medium according to 10% of the effective volume of the reactor; A2, continuously introduce methane and carbon dioxide mixed gas into the reactor, react for 72-120h under the conditions of ventilation volume of 0.5-1.5vvm, pressure in the reactor of 0.1-0.3MPa, reaction temperature of 30-35°C, stirring speed of 100-150r / min, pH of 6-7.5, to obtain fermentation liquid; A3. Pour the fermentation liquid obtained in A2 into a centrifuge, centrifuge at a speed of 3000 r / min, take the precipitate, and then wash the precipitate twice with sterile saline, centrifuge again under the same conditions, take the precipitate, and obtain the gas carbon source converted single cell protein.

3. A gaseous carbon source conversion single cell protein formula according to claim 1, characterized in that: The preparation steps of the mixed microbial system are as follows: C1. Inoculate the utilis Candida into 10 times the volume of YEPD liquid culture medium, and culture for 24-48 hours at a temperature of 28-32° C. and a rotation speed of 150-200 r / min to obtain a utilis Candida flora liquid; C2. The palustris Rhodopseudomonas was inoculated into 10 times the volume of RCVBN liquid culture medium, and cultured at a light intensity of 2000-3000 lx and a temperature of 25-35°C for 48-72 hours to obtain a palustris Rhodopseudomonas swarm liquid; C3, inoculating the methanogens into 10 volumes of an inorganic salt culture medium, culturing for 3-5 days at a temperature of 25-35° C. and a methane gas ventilation rate of 0.1-0.3 vvm, to obtain a methanogen group liquid; C4, mixing the Candida utilis flora obtained in C1, the Rhodopseudomonas palustris flora obtained in C2, and the methanophilic flora obtained in C3 to obtain a mixed microbial system.

4. A gaseous carbon source conversion single cell protein formula according to claim 1, characterized in that: The basic culture medium is composed of potassium nitrate, disodium hydrogen phosphate, magnesium sulfate, ferrous sulfate, glucose and yeast extract in a weight ratio of 2:1.5:0.6:0.02:10:3:1000 or is composed of potassium dihydrogen phosphate, magnesium sulfate, calcium chloride, ferrous sulfate and ammonium sulfate in a weight ratio of 2.5:0.8:0.2:0.02:1.5:1000.

5. A gaseous carbon source conversion single cell protein formula according to claim 3, characterized in that: The YEPD liquid culture medium is composed of glucose, peptone, yeast extract powder and water in a weight ratio of 2:2:1:100 or is composed of sucrose, ammonium chloride, yeast powder and water in a weight ratio of 3:0.5:1.5:

100.

6. A gaseous carbon source conversion single cell protein formula according to claim 3, characterized in that: The RCVBN liquid culture medium is composed of sodium succinate, ammonium chloride, dipotassium hydrogen phosphate, magnesium sulfate, calcium chloride, yeast extract and water in a weight ratio of 4:1:0.5:0.2:0.05:0.5:1000 or is composed of sodium malate, potassium nitrate, dipotassium hydrogen phosphate, ferrous sulfate and water in a weight ratio of 4:1.5:0.8:0.05:1000.

7. A gaseous carbon source conversion single cell protein formula according to claim 3, characterized in that: The inorganic salt culture medium is composed of potassium nitrate, potassium dihydrogen phosphate, magnesium sulfate, calcium chloride, ferrous sulfate, manganese sulfate, copper sulfate, and water in a weight ratio of 1:0.5:0.2:0.05:0.05:0.01:0.005:1000 or is composed of potassium chloride, disodium hydrogen phosphate, urea, manganese sulfate, ferric chloride, and water in a weight ratio of 0.8:0.4g:0.3:0.02:0.01:100.

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