Method for increasing fermentation speed

Abstract

The invention relates to the field of biological fermentation, and discloses a method for increasing fermentation speed, which comprises the following steps: adding an organic gas-liquid mass transfer enhancer and zymophyte into fermentation liquor, introducing gas with specified flow, and stirring at specified rotating speed at specified temperature to carry out fermentation reaction; wherein the addition amount of the organic gas-liquid mass transfer enhancer is a first addition amount, and the addition amount of the zymophyte is a second addition amount. The gas-liquid mass transfer condition of the fermentation reaction can be improved, and the fermentation speed is increased.

Description

Technical Field

[0001] The invention relates to the field of biological fermentation, and in particular to a method for increasing fermentation speed. Background Art

[0002] The gas-liquid mass transfer coefficient (K L a) refers to the rate coefficient at which the effective components in the gas (such as oxygen, carbon dioxide, carbon monoxide, hydrogen, etc.) dissolve and transfer (transport) to the liquid when the gas is introduced into the fermentation device. The higher the gas-liquid mass transfer coefficient, the more effective components are dissolved and transferred to the liquid per unit time. These effective components can be further utilized by microorganisms (such as bacteria, yeast) dispersed in the liquid to generate target products. Therefore, the gas-liquid mass transfer coefficient is a very critical quantity in the fermentation process, which is affected by multiple factors such as the shape of the fermenter, the air intake method, temperature, pH, the viscosity of the fermentation liquid, and solutes. In particular, the strains need to consume a large amount of synthetic gas (such as carbon dioxide and hydrogen) during the fermentation reaction. The fermentation rate is highly correlated with the reactor.

[0003] At present, common reactors in industrial fermentation equipment include: mechanical stirring reactor, tower reactor, fixed bed reactor, membrane reactor, airlift reactor, etc. These reactors generally have the problems of poor gas-liquid mass transfer effect and low gas utilization efficiency, which forms one of the main bottlenecks for increasing the fermentation speed. Summary of the invention

[0004] In view of the bottleneck of fermentation technology in the prior art, the present invention provides a method for increasing the fermentation speed, so as to further improve the gas-liquid mass transfer coefficient of the fermentation reaction and increase the fermentation speed.

[0005] The present invention provides a method for increasing fermentation speed, comprising:

[0006] An organic gas-liquid mass transfer enhancer and fermentation bacteria are added to the fermentation liquid, a gas of a specified flow rate is introduced, and the liquid is stirred at a specified temperature and a specified speed to carry out a fermentation reaction;

[0007] Wherein, the addition amount of the organic gas-liquid mass transfer enhancer is a first addition amount, and the addition amount of the fermentation bacteria is a second addition amount.

[0008] Optionally, the organic gas-liquid mass transfer enhancer includes hemoglobin;

[0009] The first addition amount includes 0.1g / L to 0.3g / L;

[0010] The specified rotation speed includes 50 rpm to 200 rpm.

[0011] Optionally, if the fermentation reaction is an aerobic reaction, the pH value of the fermentation broth is 7±0.5; the fermentation broth further comprises:

[0012] Peptone: 0.8g / L~1.5g / L;

[0013] Yeast extract: 0.8g / L~1.5g / L;

[0014] Potassium dihydrogen phosphate: 5g / L~15g / L;

[0015] Ammonium sulfate: 10g / L~20g / L;

[0016] Glucose: 30g / L~80g / L.

[0017] Optionally, the gas is air, and the specified flow rate includes 150 sccm to 300 sccm.

[0018] Optionally, the specified temperature includes 25°C to 35°C;

[0019] The fermentation bacteria include yeast Yarrowia Lipolytica;

[0020] The second addition amount includes 30 ml / L to 100 mL / L.

[0021] Optionally, when the designated temperature is 30°C, the gas-liquid mass transfer coefficient of the fermentation liquid added with 0.1% organic gas-liquid mass transfer enhancer is more than 2.8 times the gas-liquid mass transfer coefficient of the blank fermentation liquid; the gas-liquid mass transfer coefficient of the fermentation liquid added with 0.3% organic gas-liquid mass transfer enhancer is more than 8.3 times the gas-liquid mass transfer coefficient of the blank fermentation liquid.

[0022] Optionally, if the fermentation reaction is an anaerobic reaction, the pH value of the fermentation liquid is 7±0.5;

[0023] The fermentation broth comprises:

[0024] Peptone: 0.8g / L~1.5g / L;

[0025] Yeast extract: 0.8g / L~1.5g / L.

[0026] Optionally, the gas includes CO;

[0027] The specified flow rate includes 150 sccm to 300 sccm.

[0028] Optionally, the designated temperature includes 50°C to 60°C.

[0029] Optionally, the fermentation bacteria include anaerobic acetic acid Clostridium Moorella thermoacetica;

[0030] The second addition amount includes 30 ml / L to 100 mL / L.

[0031] On the one hand, the present invention improves the gas-liquid mass transfer coefficient by adding an organic gas-liquid mass transfer enhancer, which is beneficial to the growth of fermentation bacteria. On the other hand, by finely adjusting the reaction conditions of multiple dimensions of the fermentation reaction, a good growth environment is provided for the fermentation bacteria. After the improvement, the acetic acid production rate of the present invention can be increased by more than 2 times, indicating that the fermentation rate can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 This is the bacterial concentration-time curve of the fermentation reaction 1 in the embodiment of the present invention;

[0034] Figure 2 This is the acetic acid concentration-time curve of the fermentation reaction 1 in the embodiment of the present invention;

[0035] Figure 3 This is the bacterial concentration-time curve of fermentation reaction 2 in the embodiment of the present invention;

[0036] Figure 4 The acetic acid concentration-time curve of fermentation reaction 2 in the embodiment of the present invention;

[0037] Figure 5 This is the bacterial concentration-time curve of fermentation reaction 3 in the embodiment of the present invention;

[0038] Figure 6 The acetic acid concentration-time curve of the fermentation reaction 3 in the embodiment of the present invention;

[0039] Figure 7 4 is a bacterial concentration-time curve of fermentation reaction 4 in an embodiment of the present invention.

[0040] Figure 8 1 is a bacterial concentration-time curve of fermentation reaction 5 in an embodiment of the present invention.

[0041] Fig. 9 1 is the bacterial concentration-time curve of fermentation reaction 6 in the embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] An embodiment of the present invention provides a method for increasing fermentation speed, comprising:

[0044] An organic gas-liquid mass transfer enhancer and fermentation bacteria are added to the fermentation liquid, a gas of a specified flow rate is introduced, and the fermentation liquid is stirred at a specified temperature and a specified speed;

[0045] Wherein, the addition amount of the organic gas-liquid mass transfer enhancer is a first addition amount, and the addition amount of the fermentation bacteria is a second addition amount.

[0046] Understandably, an organic gas-liquid mass transfer enhancer is a substance that can combine with a reaction gas to increase the saturated dissolved concentration of the reaction gas in the fermentation liquid. Here, the organic gas-liquid mass transfer enhancer can be hemoglobin. The selection of fermentation bacteria is related to the fermentation product. Suitable fermentation bacteria can be selected according to the fermentation product. Fermentation liquid refers to a solution with added nutrient elements. The corresponding fermentation liquid can be prepared according to the growth requirements of the strain.

[0047] During the fermentation reaction, a specified flow of gas needs to be introduced into the fermentation liquid. The specified flow is comprehensively considered and optimized based on factors such as the type of fermentation bacteria, the metabolic characteristics during the fermentation process, and the properties of the fermentation materials. The gas can be selected according to actual needs.

[0048] In the fermentation reaction, the growth and metabolic rate of the fermentation bacteria are affected by temperature. Too high or too low temperature will have an adverse effect on the growth and metabolism of the fermentation bacteria, and ultimately affect the quality and yield of the fermentation product. Here, the fermentation reaction is carried out at a specified temperature. The specified temperature is generally selected as the most suitable growth temperature for the fermentation bacteria. The specified speed needs to be adjusted according to the fermentation bacteria and fermentation conditions.

[0049] The first addition amount of the organic gas-liquid mass transfer enhancer can be adjusted according to actual needs. In some examples, the addition amount of the organic gas-liquid mass transfer enhancer and the gas-liquid mass transfer enhancement effect can be linearly or nonlinearly related. The second addition amount of the fermentation bacteria can be adjusted according to actual needs.

[0050] In some examples, the fermentation reaction needs to be carried out under "sterile" conditions to exclude contamination of the fermenting bacteria by other bacterial species.

[0051] In this embodiment, on the one hand, by adding an organic gas-liquid mass transfer enhancer, the gas-liquid mass transfer coefficient is improved, which is beneficial to the growth of fermentation bacteria. On the other hand, by finely adjusting the reaction conditions in multiple dimensions of the fermentation reaction, a good growth environment is provided for the fermentation bacteria.

[0052] Optionally, the organic gas-liquid mass transfer enhancer includes hemoglobin;

[0053] The first addition amount includes 0.1g / L to 0.3g / L;

[0054] The specified rotation speed includes 50 rpm to 200 rpm.

[0055] It is understandable that the organic gas-liquid mass transfer enhancer can be hemoglobin. The molecular formula of hemoglobin is C 40 H 54 FeN4O6, molecular weight is about 64,500g / mol. Hemoglobin is an iron-rich protein composed of four subunits, each of which contains an iron ion that can bind and release gases such as oxygen, carbon monoxide and carbon dioxide. Hemoglobin binds with oxygen to form oxyhemoglobin (HbO2), and its binding constant (P50 value of the oxygen dissociation curve) is about 26-27mmHg. Hemoglobin binds with carbon monoxide to form carboxyhemoglobin (HbCO), and its binding constant is about 200-250 times higher than that of hemoglobin binding with oxygen. Hemoglobin can bind with carbon dioxide to form carbonated hemoglobin (HbCO2), but the binding capacity is much lower than that of oxygen and carbon monoxide. Hemoglobin has a low binding capacity for nitrogen and hydrogen, which can usually be ignored.

[0056] Hemoglobin contains iron ions in its structure, which can form complexes with oxygen, carbon dioxide, and carbon monoxide. By adding hemoglobin to the fermentation broth, the concentration of the reaction gas in the liquid phase can be increased, thereby promoting gas-liquid mass transfer. Hemoglobin increases the solubility of the reaction gas in the fermentation broth, and through combining and separating with the reaction gas, it plays a role in dynamic balance between the supply and consumption of the reaction gas. Therefore, adding hemoglobin can increase the gas-liquid mass transfer coefficient in the fermentation broth and improve the gas-liquid mass transfer effect.

[0057] The first addition amount of hemoglobin can be set according to actual needs, such as 0.1 g / L to 0.3 g / L.

[0058] In fermentation reactions, the specified speed is an important parameter that can affect the mixing uniformity of the fermentation liquid, the reaction gas transfer efficiency and the growth and reproduction of the fermentation bacteria. Usually, the specified speed needs to be adjusted according to different reaction types and experimental conditions.

[0059] Generally speaking, a lower specified speed can reduce bubble generation and shear force, thereby reducing microbial damage and product loss; while a higher stirring speed can improve gas transfer efficiency and mass transfer rate, thereby accelerating the reaction rate and increasing product yield. However, due to the limited tolerance of fermentation bacteria to stirring speed, too high or too low stirring speed will affect the growth and metabolic activity of fermentation bacteria, resulting in a decrease in the quality and yield of metabolites. In some examples, the specified speed includes 50rpm to 200rpm. Preferably, the specified speed includes 100rpm.

[0060] Optionally, if the fermentation reaction is an aerobic reaction, the pH value of the fermentation broth is 7±0.5; the fermentation broth further comprises:

[0061] Peptone: 0.8g / L~1.5g / L;

[0062] Yeast extract: 0.8g / L~1.5g / L;

[0063] Potassium dihydrogen phosphate: 5g / L~15g / L;

[0064] Ammonium sulfate: 10g / L~20g / L;

[0065] Glucose: 30g / L~80g / L.

[0066] Understandably, in aerobic fermentation reactions, pH regulation is very important because it can affect factors such as the activity of aerobic fermentation bacteria, the generation and purity of metabolites, etc. Preferably, the pH value of the fermentation broth is 7±0.5.

[0067] The fermentation broth can contain a variety of nutrients, such as peptone, yeast extract, potassium dihydrogen phosphate, ammonium sulfate, and glucose.

[0068] Among them, peptone is a high-quality nitrogen source, which can provide the nitrogen required by aerobic fermentation bacteria and promote the growth of aerobic fermentation bacteria and the production of metabolites. The role of peptone in aerobic fermentation reactions includes: 1. Providing nitrogen source: Peptone is rich in compounds such as amino acids and peptides, which can provide the necessary nitrogen source for aerobic fermentation bacteria. 2. Promoting the growth of aerobic fermentation bacteria: Nitrogen is one of the nutrients necessary for the growth of aerobic fermentation bacteria. Peptone can provide sufficient nitrogen source, thereby promoting the growth of aerobic fermentation bacteria. 3. Increasing the yield of fermentation products: Peptone can provide a rich nitrogen source and other nutrients, which helps aerobic fermentation bacteria synthesize more metabolites. 4. Improving the purity of fermentation products: Peptone can provide a higher nitrogen source, which makes it unnecessary for aerobic fermentation bacteria to use other proteins to obtain nitrogen during the growth process, thereby reducing the generation of impurities and improving the purity of fermentation products.

[0069] Yeast extract is a nutrient-rich mixture extracted from yeast cells and is an important fermentation auxiliary material. The role of yeast extract in aerobic fermentation reactions includes: 1. Providing nitrogen source: Yeast extract can provide aerobic fermentation bacteria with the necessary nitrogen source, promoting the growth of aerobic fermentation bacteria and the production of metabolites. 2. Promoting the growth of aerobic fermentation bacteria: Yeast extract contains a large amount of nutrients such as complex vitamins, amino acids, proteins, etc. These nutrients can provide sufficient nutritional conditions for aerobic fermentation bacteria, thereby promoting the growth of aerobic fermentation bacteria. 3. Promoting the metabolism of acid-producing bacteria: Yeast extract contains a higher number of certain types of amino acids (such as lysine), which can promote the metabolism and growth of acid-producing bacteria (such as lactic acid bacteria), thereby increasing the yield of the product. 4. Improving the quality of fermentation products: Polysaccharides and other bioactive substances in yeast extract can affect the quality of the product by acting together with aerobic fermentation bacteria. 5. Reducing production costs: Compared with other nitrogen sources, yeast extract is relatively cheap, which can help manufacturers reduce production costs.

[0070] Potassium dihydrogen phosphate (KH2PO4) is a colorless crystalline powder. The role of potassium dihydrogen phosphate in aerobic fermentation reactions includes: 1. Providing phosphorus for aerobic fermentation bacteria: Potassium dihydrogen phosphate is one of the sources of phosphorus necessary for the growth and metabolism of aerobic fermentation bacteria, and can be used as one of the nutrients in the fermentation liquid. 2. Regulating pH value: Potassium dihydrogen phosphate will produce acidity when dissolved in water, which can neutralize the alkaline substances produced during the fermentation process, thereby maintaining a suitable pH range. 3. Promoting the growth of aerobic fermentation bacteria: As one of the components of the fermentation liquid, potassium dihydrogen phosphate can provide essential nutrients and promote the growth and metabolism of aerobic fermentation bacteria. 4. Regulating the metabolism of aerobic fermentation bacteria: Potassium dihydrogen phosphate can also regulate the metabolism of aerobic fermentation bacteria, affecting the utilization of different nutrients and the generation of metabolites by aerobic fermentation bacteria. 5. Increasing product yield: In some cases, an appropriate amount of potassium dihydrogen phosphate can increase the yield of certain products.

[0071] Ammonium sulfate is often used to supplement nitrogen sources and adjust pH in aerobic fermentation reactions. When the pH is high and nitrogen supplementation is needed, ammonium sulfate can provide nitrogen sources as a physiological acidic substance and can also lower the pH value. As a supplement to inorganic nitrogen sources, ammonium sulfate can increase the yield of fermentation products.

[0072] Glucose is a monosaccharide. As one of the substrates in aerobic fermentation reactions, glucose can provide energy and carbon sources for microorganisms, and it can also affect the type and amount of organic compounds produced during the fermentation process.

[0073] Optionally, the gas is air, and the specified flow rate includes 150 sccm to 300 sccm.

[0074] Understandably, during aerobic fermentation, the gas introduced is air. Airflow control is one of the most important factors. By controlling the specified flow rate of air, the dissolved oxygen concentration in the fermentation liquid can be adjusted, the appropriate pH value can be maintained, and the mass transfer and mixing of substances can be promoted, thereby improving the product quality and yield of the aerobic fermentation reaction.

[0075] Normally, the air flow rate is determined based on the amount of oxygen required by the aerobic fermentation bacteria in the fermentation broth. At the beginning of the process, the gas flow rate is usually set to a lower value to avoid the oxygen being consumed too quickly. When the number of aerobic fermentation bacteria increases and the metabolism accelerates, the air flow rate can be gradually increased to meet the active oxygen content required by the aerobic fermentation bacteria. At the same time, it is also necessary to keep the fermentation broth and air mixed evenly to prevent uneven oxygen distribution and localized liquid accumulation.

[0076] Optionally, the specified temperature includes 25°C to 35°C;

[0077] The fermentation bacteria include yeast Yarrowia Lipolytica;

[0078] The second addition amount includes 30 ml / L to 100 mL / L.

[0079] Understandably, temperature is another important factor that affects aerobic fermentation reactions. In aerobic fermentation reactions, the activity of aerobic fermentation bacteria is greatly affected by the ambient temperature. Different types of aerobic fermentation bacteria have different adaptability ranges to temperature. Therefore, the most suitable temperature range can be determined based on the characteristics of aerobic fermentation bacteria and the needs of the product.

[0080] Generally speaking, lower temperatures can slow down the metabolic rate of microorganisms, thereby reducing energy consumption and product losses; while higher temperatures can increase the metabolic rate and reaction speed of microorganisms, thereby accelerating the reaction process and increasing product yields. However, due to the limited sensitivity and resistance of aerobic fermentation bacteria to temperature, excessively high or low temperatures will affect the growth and metabolic activity of aerobic fermentation bacteria, resulting in decreased product quality and yield. In some examples, the specified temperature includes 25°C to 35°C. Preferably, the specified temperature includes 30°C.

[0081] Appropriate aerobic fermentation bacteria can be selected based on the metabolites. Common aerobic fermentation bacteria include:

[0082] 1. Lactobacillus: It can metabolize monosaccharides such as glucose and produce lactic acid and other organic acids. It is usually used to make foods such as yogurt, pickles and sauerkraut.

[0083] 2. Acetic acid bacteria: can oxidize ethanol in alcoholic fermentation broth into acetic acid, usually used to make vinegar and table vinegar;

[0084] 3. Brewer's yeast: It can metabolize fructose, glucose, maltose and other substances to produce alcohol and carbon dioxide. It is usually used to make alcoholic beverages such as beer, wine and liquor.

[0085] 4. Pyruvic acid bacteria: can metabolize a variety of sugars and produce pyruvic acid, butyric acid and other acids, usually used to make foods such as sodium acetate and meat products;

[0086] 5. Cellulolytic bacteria: They can decompose difficult-to-degrade substances such as cellulose and lignin, and are usually used to make feed, biofuels and biomass materials.

[0087] Here, yeast Yarrowia Lipolytica can be used. Yarrowia Lipolytica is a common fungal microorganism belonging to single-cell yeast. It has diverse metabolic pathways and high tolerance, and can grow and metabolize using various wastes and cheap raw materials. Yarrowia Lipolytica can metabolize using a variety of substrates such as glucose, glycerol, fatty acids and agar, and produce a variety of organic substances.

[0088] The amount of aerobic fermentation bacteria added is the second amount. The amount of fermentation bacteria added in the fermentation reaction depends on multiple factors, including the strain used, fermentation conditions and the type of fermentation product. Here, yeast Yarrowia Lipolytica is selected, and its second amount includes 30ml / L to 100mL / L. Preferably, the second amount includes 50ml / L.

[0089] Optionally, when the designated temperature is 30°C, the gas-liquid mass transfer coefficient of the fermentation liquid added with 0.1% organic gas-liquid mass transfer enhancer is more than 2.8 times the gas-liquid mass transfer coefficient of the blank fermentation liquid; the gas-liquid mass transfer coefficient of the fermentation liquid added with 0.3% organic gas-liquid mass transfer enhancer is more than 8.3 times the gas-liquid mass transfer coefficient of the blank fermentation liquid.

[0090] Understandably, the gas-liquid mass transfer coefficient of the same gas in the fermentation liquid at different temperatures. The mass transfer enhancement effect produced by adding the gas-liquid mass transfer enhancer is also different. According to the test, at 30°C, the gas-liquid mass transfer coefficient of the fermentation liquid with 0.1% hemoglobin added is more than 2.8 times that of the blank fermentation liquid; the gas-liquid mass transfer coefficient of the fermentation liquid with 0.1% hemoglobin added is more than 8.3 times that of the blank fermentation liquid.

[0091] Optionally, if the fermentation reaction is an anaerobic reaction, the pH value of the fermentation liquid is 7±0.5;

[0092] The fermentation broth comprises:

[0093] Peptone: 0.8g / L~1.5g / L;

[0094] Yeast extract: 0.8g / L~1.5g / L.

[0095] Understandably, in the fermentation reaction, the regulation of pH is very important because it can affect factors such as the activity of the fermenting bacteria, the generation and purity of metabolites. Preferably, the pH value of the fermentation broth is 7±0.5. The fermentation broth can contain a variety of nutrients, such as peptone and yeast extract. The role of peptone and yeast extract in anaerobic reactions is similar to that in aerobic reactions, and will not be repeated here.

[0096] Optionally, the gas includes CO;

[0097] The specified flow rate includes 150 sccm to 300 sccm;

[0098] Understandably, when an anaerobic reaction occurs, the gas introduced may be carbon monoxide. Carbon monoxide provides energy and a carbon source for anaerobic bacteria. In some cases, carbon monoxide may also affect the metabolic pathways in anaerobic fermentation reactions through the activity of specific enzymes. It may have a direct or indirect effect on the activity of certain enzymes, thereby regulating the metabolic process of microorganisms and the generation of reaction products.

[0099] In fermentation reactions, airflow control is one of the most important factors. By controlling the specified flow rate of CO, the dissolved gas concentration in the fermentation broth can be adjusted, the appropriate pH value can be maintained, and the mass transfer and mixing of substances can be promoted, thereby improving the product quality and yield of the fermentation reaction.

[0100] Normally, the gas flow rate is determined based on the amount of carbon monoxide required by the fermentation bacteria in the fermentation broth. At the beginning of the process, the gas flow rate is usually set to a lower value to avoid the carbon monoxide being consumed too quickly. As the number of fermentation bacteria increases and metabolism accelerates, the carbon monoxide flow rate can be gradually increased to meet the active oxygen content required by the fermentation bacteria. At the same time, it is also necessary to keep the fermentation broth and carbon monoxide mixed evenly to prevent uneven distribution of carbon monoxide and local accumulation of liquid.

[0101] Optionally, the designated temperature includes 50°C to 60°C.

[0102] Understandably, temperature is another important factor that affects the fermentation reaction. In the fermentation reaction, the activity of the fermentation bacteria is greatly affected by the ambient temperature. Different types of fermentation bacteria have different adaptability to temperature. Therefore, the most suitable temperature range can be determined according to the characteristics of the fermentation bacteria and the needs of the product.

[0103] Generally speaking, lower temperatures can slow down the metabolic rate of microorganisms, thereby reducing energy consumption and product loss; while higher temperatures can increase the metabolic rate and reaction speed of microorganisms, thereby accelerating the reaction process and increasing product yield. However, due to the limited sensitivity and resistance of fermentation bacteria to temperature, too high or too low temperatures will affect the growth and metabolic activity of fermentation bacteria, resulting in decreased product quality and yield. In some examples, the specified temperature includes 50°C to 60°C. Preferably, the specified temperature includes 55°C.

[0104] Optionally, the fermentation bacteria include anaerobic Clostridium Moorellathermoacetica;

[0105] The second addition amount includes 30 ml / L to 100 mL / L.

[0106] Understandably, suitable fermentation bacteria can be selected based on the metabolites. Fermentation bacteria include species such as Moorella thermoacetica, Clostridium, Bacteroides, Acetobacterium, and Methanobacterium. These bacterial communities complete different metabolic reactions during the fermentation process and produce different metabolites. For example, Clostridium bacteria mainly produce acetic acid and hydrogen by fermenting organic matter, while Methanobacterium bacteria use CO2 and hydrogen to produce methane. These fermentation bacteria are interdependent in the anaerobic digestion system, following the laws of material conservation and energy conservation, while also performing complementary or alternative metabolic activities.

[0107] Here, anaerobic clostridium thermoacetica can be used. Anaerobic clostridium thermoacetica is an anaerobic acetogenic bacterium belonging to the Bacillota phylum. It can grow under strict anaerobic conditions and produce acetic acid by consuming CO.

[0108] The amount of fermentation bacteria added is the second amount. The amount of fermentation bacteria added in the fermentation reaction depends on multiple factors, including the strain used, fermentation conditions and the type of fermentation product. Here, anaerobic acetic clostridium Moorellathermoacetica is selected, and its second amount includes 30ml / L to 100mL / L. Preferably, the second amount includes 50ml / L.

[0109] Anaerobic fermentation reaction 1 (no addition control group)

[0110] A 2L stirred fermentation apparatus was used, in which the liquid volume was 1L, and the fermentation liquid contained 1g / L peptone and 1g / L yeast extract.

[0111] Other control conditions include: fermentation liquid temperature of 55° C., stirring speed of 100 rpm, flow rate of synthesis gas of 150 sccm (standard cubic centimeters per minute), and composition of CO.

[0112] 50 mL of Moorella thermoacetica was used as inoculum and the pH was controlled at 7 ± 0.5.

[0113] The bacterial concentration, i.e., OD (Optical Density), was measured during the 120-hour fermentation period, and the acetic acid production was also measured.

[0114] Anaerobic acetic acid clostridium Moorella thermoacetica can use CO for cell growth and produce acetic acid. The reaction formula is as follows:

[0115] 4CO+2H2O===C2H4O2+2CO2

[0116] The reaction results are as follows Figure 1 and Figure 2 shown. Figure 1 This is the bacterial concentration-time curve, the unit of the ordinate is OD, and the unit of the abscissa is hr (hour). Figure 2 This is an acetic acid concentration-time curve, the unit of the ordinate is acetic acid concentration (g / L), and the unit of the abscissa is hr (hour).

[0117] After 108 hours, both cell growth and acetate production reached a plateau, with the highest cell concentration being around OD 14.6. The average acetate production rate from 24 hours to 108 hours was calculated as:

[0118] R1=(20.6-2.02) / (108-24)=0.27g·L -1 ·hr -1 .

[0119] Anaerobic fermentation reaction 2 (adding 0.1% hemoglobin)

[0120] A 2L stirred fermentation apparatus was used, in which the liquid volume was 1L, and the fermentation liquid contained 1g / L peptone and 1g / L yeast extract.

[0121] Other control conditions include: fermentation liquid temperature of 55°C, stirring speed of 100 rpm, synthesis gas flow rate of 150 sccm (standard cubic centimeters per minute), and composition of CO. In addition, 1 g of hemoglobin was added, that is, the addition amount of hemoglobin was 0.1%.

[0122] 50 mL of Moorella thermoacetica was used as inoculum and the pH was controlled at 7 ± 0.5.

[0123] The bacterial concentration, i.e., OD (Optical Density), was measured during the 120-hour fermentation period, and the acetic acid production was also measured.

[0124] The reaction results are as follows Figure 3 and Figure 4 shown. Figure 3 This is the bacterial concentration-time curve, the unit of the ordinate is OD, and the unit of the abscissa is hr (hour). Figure 4 This is an acetic acid concentration-time curve, the unit of the ordinate is acetic acid concentration (g / L), and the unit of the abscissa is hr (hour).

[0125] After 72 hours, both cell growth and acetate production reached a plateau, with the highest cell concentration being around OD 18. The average acetate production rate from 24 hours to 72 hours was calculated as:

[0126] R2=(23.2-0.44) / (72-24)=0.47g·L -1 ·hr -1 .

[0127] Anaerobic fermentation reaction 3 (adding 0.3% hemoglobin)

[0128] A 2L stirred fermentation apparatus was used, in which the liquid volume was 1L, and the fermentation liquid contained 1g / L peptone and 1g / L yeast extract.

[0129] Other control conditions include: fermentation liquid temperature of 55°C, stirring speed of 100 rpm, synthesis gas flow rate of 150 sccm (standard cubic centimeters per minute), and composition of CO. In addition, 3 g of hemoglobin was added, that is, the addition amount of hemoglobin was 0.3%.

[0130] 50 mL of Moorella thermoacetica was used as inoculum and the pH was controlled at 7 ± 0.5.

[0131] The bacterial concentration, i.e., OD (Optical Density), was measured during the 120-hour fermentation period, and the acetic acid production was also measured.

[0132] The reaction results are as follows Figure 5 and Figure 6 shown. Figure 5 This is the bacterial concentration-time curve, the unit of the ordinate is OD, and the unit of the abscissa is hr (hour). Figure 6 This is an acetic acid concentration-time curve, the unit of the ordinate is acetic acid concentration (g / L), and the unit of the abscissa is hr (hour).

[0133] After 60 hours, both cell growth and acetate production reached a plateau, with the highest cell concentration being around OD 16. The acetate production rate from 24 hours to 60 hours was calculated as:

[0134] R3=(26.4-2.5) / (60-24)=0.66g·L -1 ·hr -1 .

[0135] The results of fermentation reactions 1 to 3 are shown in Table 1.

[0136] Table 1 Anaerobic fermentation reactions using CO as substrate

[0137] Reaction number <![CDATA[OD max ]]> <![CDATA[Acetic acid max (g / L)]]> Acetic acid speed R Acetic acid production speed multiple Fermentation reaction 1 14.6 20.8 0.27 1 Fermentation reaction 2 18 26 0.47 1.74 Fermentation reaction 3 16 26 0.66 2.44

[0138] As can be seen from Table 1, in the anaerobic fermentation of carbon monoxide, adding different amounts of hemoglobin can indeed have a significant effect on the production rate of acetic acid. The experimental results show that adding 0.1% and 0.3% hemoglobin can increase the production rate of acetic acid by 1.74 times and 2.44 times, respectively. This result may be due to the positive role of hemoglobin in the absorption and utilization of carbon monoxide. Carbon monoxide is one of the key components in syngas and is essential for microbial metabolism during the anaerobic fermentation of carbon monoxide. The addition of hemoglobin can increase the effective solubility and utilization rate of carbon monoxide in the liquid phase, and promote the absorption and utilization ability of microorganisms for carbon monoxide.

[0139] By improving the absorption and utilization efficiency of carbon monoxide, the addition of hemoglobin increases the speed and efficiency of microbial metabolism to produce acetic acid, thereby increasing the production rate of acetic acid. This phenomenon may be related to the binding ability between iron ions in the hemoglobin molecular structure and carbon monoxide, which enables carbon monoxide to be converted into acetic acid more efficiently.

[0140] Aerobic fermentation reaction 4 (no addition control group)

[0141] A 2L stirred fermentation apparatus was used, in which the liquid volume was 1L. The fermentation liquid contained 1g / L peptone, 1g / L yeast extract, 10g / L potassium dihydrogen phosphate, 15g / L ammonium sulfate, and 50g / L glucose.

[0142] Other controlled conditions include: fermentation liquid temperature of 30° C., stirring speed of 100 rpm, and air flow rate of 150 sccm (standard cubic centimeters per minute).

[0143] 50 mL of yeast Yarrowia Lipolytica was used as inoculum. The pH was controlled at 7 ± 0.5.

[0144] The bacterial concentration during the 72-hour fermentation period was measured, i.e., OD (Optical Density). Figure 7 shown. Figure 7 This is the bacterial concentration-time curve, the unit of the ordinate is OD, and the unit of the abscissa is hr (hour).

[0145] After 56 hours, the growth of yeast Yarrowia Lipolytica reached the plateau phase. The average growth rate from 8 hours to 56 hours was calculated as:

[0146] R4=(64.5-1.24) / (56-8)=1.3OD / hr.

[0147] Aerobic fermentation reaction 5 (adding 0.1% hemoglobin)

[0148] A 2L stirred fermentation apparatus was used, in which the liquid volume was 1L, and the fermentation liquid contained 1g / L peptone, 1g / L yeast extract, 10g / L potassium dihydrogen phosphate, 15g / L ammonium sulfate, and 50g / L glucose. In addition, 1g of hemoglobin was added.

[0149] Other controlled conditions include: fermentation liquid temperature of 30° C., stirring speed of 100 rpm, and air flow rate of 150 sccm (standard cubic centimeters per minute).

[0150] 50 mL of yeast Yarrowia Lipolytica was used as inoculum. The pH was controlled at 7 ± 0.5.

[0151] The bacterial concentration during the 72-hour fermentation period was measured, i.e., OD (Optical Density). Figure 8 shown.

[0152] After 40 hours, the growth of yeast Yarrowia Lipolytica reached the plateau phase. The average growth rate from 8 hours to 40 hours was calculated as:

[0153] R5=(88-1.8) / (40-8)=2.7OD / hr.

[0154] Aerobic fermentation reaction 6 (adding 0.3% hemoglobin)

[0155] A 2L stirred fermentation apparatus was used, in which the liquid volume was 1L, and the fermentation liquid contained 1g / L peptone, 1g / L yeast extract, 10g / L potassium dihydrogen phosphate, 15g / L ammonium sulfate, and 50g / L glucose. In addition, 3g of hemoglobin was added.

[0156] Other controlled conditions include: fermentation liquid temperature of 30° C., stirring speed of 100 rpm, and air flow rate of 150 sccm (standard cubic centimeters per minute).

[0157] 50 mL of yeast Yarrowia Lipolytica was used as inoculum. The pH was controlled at 7 ± 0.5.

[0158] The bacterial concentration during the 72-hour fermentation period was measured, i.e., OD (Optical Density). Fig. 9 shown.

[0159] After 40 hours, the growth of yeast Yarrowia Lipolytica reached the plateau phase, and the average growth rate from 8 hours to 48 hours was calculated as:

[0160] R6=(168-1.44) / (40-8)=4.2OD / hr.

[0161] By comparing their respective gas-liquid mass transfer coefficients and the growth rates of microbial cells, the results are shown in Table 2.

[0162] Table 2 Aerobic fermentation reactions using air as substrate

[0163] Reaction number <![CDATA[K L a(min) -1 )]]> Mass transfer increase times Cell growth rate R Growth rate multiple Fermentation reaction 4 0.0293 1 1.3 1 Fermentation reaction 5 0.0822 2.8 2.7 2.1 Fermentation reaction 6 0.2431 8.3 4.2 3.2

[0164] It can be seen from Table 2 that as the gas-liquid transfer coefficient K La As the amount of hemoglobin increases, the corresponding cell growth rate of each aerobic fermentation also increases. It should be noted that although the cell growth rate has increased, it is not completely proportional. When 0.1% hemoglobin was added, the mass transfer coefficient increased by 2.8 times and the growth rate increased by 2.1 times. As for the group with 0.3% hemoglobin added, although the mass transfer coefficient increased by 8.3 times, the cell growth rate in aerobic fermentation only increased by 3.2 times, which was not a proportional increase. It can be seen that the rate-limiting step of aerobic fermentation is not entirely determined by gas-liquid mass transfer, and there are other factors that also affect the rate of cell growth.

[0165] This example shows that adding a certain amount of hemoglobin can increase the mass transfer coefficient of aerobic fermentation, thereby increasing the cell growth rate in aerobic fermentation.

[0166] Mass transfer coefficient measurement test

[0167] A 2L stirred fermentation apparatus was used, in which the liquid volume was 1L, pure water was used instead of fermentation liquid, and 0g, 1g, and 3g of hemoglobin were added respectively, that is, the amount of hemoglobin added was 0.1%; other control parameters included fermentation liquid temperature of 30°C, stirring speed of 100rpm, and air flow rate of 150sccm (standard cubic centimeters per minute). The results are shown in Table 3.

[0168] Table 3 Mass transfer coefficient measurement test

[0169] test <![CDATA[K L a(min) -1 )]]> Increase multiple Blank control group 0.0293 1 0.1% hemoglobin 0.0822 2.8 0.3% hemoglobin 0.2431 8.3

[0170] As can be seen from Table 4, adding 0.1% or 0.3% hemoglobin can greatly increase the gas-liquid mass transfer coefficient of the fermenter, which increases by 2.8 times and 8.3 times respectively.

[0171] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for increasing fermentation speed, characterized in that: include: An organic gas-liquid mass transfer enhancer and fermentation bacteria are added to the fermentation liquid, a gas of a specified flow rate is introduced, and the liquid is stirred at a specified temperature and a specified speed to carry out a fermentation reaction; Wherein, the addition amount of the organic gas-liquid mass transfer enhancer is a first addition amount, and the addition amount of the fermentation bacteria is a second addition amount.

2. The method for increasing the fermentation speed according to claim 1, characterized in that: The organic gas-liquid mass transfer enhancer includes hemoglobin; The first addition amount includes 0.1g / L to 0.3g / L; The specified rotation speed includes 50 rpm to 200 rpm.

3. The method for increasing the fermentation speed according to claim 1, characterized in that: If the fermentation reaction is an aerobic reaction, the pH value of the fermentation liquid is 7±0.5; the fermentation liquid also includes: Peptone: 0.8g / L~1.5g / L; Yeast extract: 0.8g / L~1.5g / L; Potassium dihydrogen phosphate: 5g / L~15g / L; Ammonium sulfate: 10g / L~20g / L; Glucose: 30g / L~80g / L.

4. The method for increasing the fermentation speed according to claim 3, characterized in that: The gas is air, and the specified flow rate includes 150 sccm to 300 sccm.

5. The method for increasing fermentation speed according to claim 3, characterized in that: The specified temperature includes 25°C to 35°C; The fermentation bacteria include yeast Yarrowia Lipolytica; The second addition amount includes 30 ml / L to 100 mL / L.

6. The method for increasing fermentation speed according to claim 1, characterized in that: When the specified temperature is 30°C, the gas-liquid mass transfer coefficient of the fermentation liquid added with 0.1% organic gas-liquid mass transfer enhancer is more than 2.8 times that of the blank fermentation liquid; the gas-liquid mass transfer coefficient of the fermentation liquid added with 0.3% organic gas-liquid mass transfer enhancer is more than 8.3 times that of the blank fermentation liquid.

7. The method for increasing fermentation speed according to claim 1, characterized in that: If the fermentation reaction is an anaerobic reaction, the pH value of the fermentation liquid is 7±0.5; The fermentation broth comprises: Peptone: 0.8g / L~1.5g / L; Yeast extract: 0.8g / L~1.5g / L.

8. The method for increasing fermentation speed according to claim 7, characterized in that: The gas includes CO; The specified flow rate includes 150 sccm to 300 sccm.

9. The method for increasing fermentation speed according to claim 7, characterized in that: The specified temperature includes 50°C to 60°C.

10. The method for increasing fermentation speed according to claim 7, characterized in that: The fermentation bacteria include anaerobic acetic Clostridium Moorellathermoacetica; The second addition amount includes 30 ml / L to 100 mL / L.

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