Microorganism culture system and method for culturing by recycling waste gas in system

Abstract

The present invention is a microorganism culture system comprising: a culture tank; a recycle gas adjustment unit; one end of the first gas circulation pipeline is connected to the upper part of the culture tank, and the other end of the first gas circulation pipeline is connected to the recycled gas adjusting part; and a second gas circulation line, one end of which is connected to the recirculated gas adjustment unit and the other end of which is connected to the culture tank, and which supplies recirculated gas to the inside thereof. The recycle gas adjustment unit mixes one or more gas components selected from the group consisting of a combustible gas, a combustion-supporting gas, and a non-combustible gas into at least a portion of the exhaust gas discharged from the culture tank such that the concentration of the combustion-supporting gas in the recycle gas is within a predetermined range. In addition, the invention also provides a method for culturing by recycling waste gas in a culture system using microorganisms.

Description

Technical Field

[0001] The invention relates to a microorganism culture system and a method for culture by recycling waste gas in the system. Background Art

[0002] Microorganisms can convert carbon-rich gases such as carbon dioxide, carbon monoxide and methane into various chemical products such as fuels, proteins, alcohols and organic acids through their fermentation, and use them in industrial production. Gas fermentation is one of the technologies that has attracted much attention in achieving a sustainable society because it can utilize a variety of raw materials including household waste, industrial waste and agricultural waste, reduce dependence on fossil carbon sources, and contribute to reducing greenhouse gas emissions.

[0003] The growth of microorganisms is affected by various conditions in the fermenter (such as temperature, pH value, pressure, agitation, ventilation, etc.). There are microorganisms that grow under anaerobic conditions and microorganisms that grow under aerobic conditions. If the microorganisms grow under aerobic conditions, air is generally used as the oxygen source, but oxygen-enriched air or pure oxygen can also be used to promote their growth.

[0004] In order to optimize the productivity of products by fermentation processes using microorganisms that proliferate under aerobic conditions, it is generally preferred to culture at as high an oxygen concentration as possible. In this way, the amount of oxygen dissolved from the gas phase to the liquid phase increases, and the biosynthesis reaction of aerobic microorganisms increases.

[0005] Depending on the type of microorganism used for fermentation, some fermentation substrates may also contain substances that require flammable gases (e.g., hydrogen, etc.). Since flammable gases may cause gas explosions if they are present near a fire source, it is necessary to ensure that no explosion will occur during the implementation of the culture process. However, it is very difficult to completely eliminate fire sources such as static electricity, and the composition of the gas is usually controlled so that it is not within the range of explosive composition, that is, the oxygen concentration in the gas composition is not included in the explosion limit oxygen concentration.

[0006] In a microbial fermentation culture process using combustible gas, a culture system is being developed that can prevent gas explosions while helping to improve the productivity of the final product and reduce operating costs. For example, Patent Document 1 and Non-Patent Document 1 disclose a system that measures the gas composition of waste gas accumulated in the head space of a fermentation culture tank after culture, supplies the waste gas to the fermentation culture tank again, and mixes the components of the gas composition consumed by fermentation (e.g., hydrogen, oxygen, carbon dioxide, etc.) and supplies them to the fermentation culture tank, thereby efficiently performing culture.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1 International Publication No. 2019 / 191767

[0010] Non-patent literature

[0011] Non-patent literature 1Garcia-Gonzalez,L.,et al.,Sustainable autotrophicproduction of polyhydroxybutyrate(PHB) from CO2 using a two-stage cultivationsystem.,Catalysis Today,257(2015),pp.237-245 Summary of the invention

[0012] Issues that the invention needs to solve

[0013] The object of the present invention is to provide a novel microorganism culture system and microorganism culture method capable of performing culture safely and efficiently.

[0014] Solutions to Solve Problems

[0015] In a conventional microbial culture system (such as non-patent document 1), when the waste gas accumulated in the head space of the culture tank is reused, a method is adopted in which the insufficient gas components required for the culture are separately premixed as supplementary gas and supplied to the culture tank. However, if this system is used, when a flammable gas is used, the possibility that the composition of the supplementary gas supplied to the culture tank is within the range of an explosive composition cannot be ruled out. Therefore, we have studied a new microbial culture system and microbial culture method to achieve safer and more efficient fermentation culture.

[0016] In order to solve the above problems, after intensive research, a system and method have been developed, that is, in a microbial culture system, when adjusting the recirculated gas from the exhaust gas, the required gas components are mixed so that the concentration of the combustion-supporting gas in the recirculated gas is within a specified range, thereby enabling safe and efficient fermentation culture. That is, the present invention includes the following inventions.

[0017] [1] A microorganism cultivation system comprising:

[0018] Culture tank;

[0019] Recirculation gas conditioning unit;

[0020] a first gas circulation pipeline, one end of which is connected to the upper part of the culture tank, and the other end of which is connected to the recirculation gas regulating part;

[0021] A second gas circulation line has one end connected to the recirculation gas adjustment unit and the other end connected to the culture tank and supplies the recirculation gas to the interior of the culture tank.

[0022] In which, the recirculating gas regulating unit is connected to one or more gas supply units selected from the group consisting of a combustible gas supply unit, an combustion-supporting gas supply unit and a non-combustible gas supply unit, and the recirculating gas regulating unit mixes one or more gas components selected from the group consisting of a combustible gas, an combustion-supporting gas and a non-combustible gas into at least a part of the exhaust gas discharged from the culture tank so that the concentration of the combustion-supporting gas in the recirculating gas is within a specified range.

[0023] [2] The cultivation system according to item 1, wherein the second gas circulation line further comprises a first gas concentration meter for measuring the concentration of at least the combustion-supporting gas in the recirculating gas,

[0024] The recirculation gas regulator performs feedback regulation based on the concentration of the combustion-supporting gas measured by the first gas concentration meter so that the concentration of the combustion-supporting gas in the recirculation gas is within a predetermined range.

[0025] [3] The culture system according to item 1 or 2, wherein the combustible gas supply unit is independently connected to the recirculating gas adjustment unit.

[0026] [4] The culture system according to any one of items 1 to 3, wherein the recirculating gas regulating unit mixes the gas components so that the concentration of the combustible gas and / or the non-combustible gas in the recirculating gas is within a prescribed range.

[0027] [5] The culture system according to any one of items 1 to 4, wherein a second gas concentration meter for measuring the concentration of at least the combustion-supporting gas in the exhaust gas is further provided on the upper portion of the culture tank and / or on the first gas circulation line.

[0028] [6] A culture system according to any one of items 1 to 5, wherein the combustion-supporting gas supply unit and the non-combustible gas supply unit are connected to the recirculating gas regulating unit so that the combustion-supporting gas and the non-combustible gas are premixed before being mixed with the exhaust gas.

[0029] [7] The culture system according to any one of items 1 to 6, wherein the microorganism is an aerobic fermentation bacterium.

[0030] [8] The culture system according to item 7, wherein the aerobic fermentation bacteria are hydrogen oxidizing bacteria and the combustible gas is hydrogen.

[0031] [9] The culture system according to any one of items 1 to 8, wherein the combustion-supporting gas is oxygen.

[0032]

[10] The culture system according to any one of items 1 to 9, wherein the non-flammable gas is carbon dioxide gas and / or nitrogen gas.

[0033]

[11] The culture system according to any one of items 1 to 10, wherein the internal pressure of the culture tank is equal to or higher than atmospheric pressure.

[0034]

[12] The culture system according to any one of items 1 to 11, wherein a compressor is provided in the first gas circulation line.

[0035]

[13] The culture system according to any one of items 1 to 12, wherein

[0036] The recirculation gas conditioning unit comprises:

[0037] one or more gas mixers;

[0038] a first gas regulating unit for regulating a supply amount of the combustible gas from the combustible gas supply unit;

[0039] a second gas regulating unit, which is used to regulate the supply amount of the combustion-supporting gas from the combustion-supporting gas supply unit;

[0040] The third gas regulating part is used to regulate the supply amount of the non-combustible gas from the non-combustible gas supply part.

[0041] The combustible gas supply unit, the combustion-supporting gas supply unit, and the non-combustible gas supply unit are connected to the gas mixer.

[0042]

[14] A method for culturing microorganisms by recycling waste gas in a culture system, comprising the following steps:

[0043] (1) a step of supplying a supply gas containing a combustible gas, an oxidizing gas, and a non-combustible gas to a culture containing microorganisms and a culture medium supplied to a culture tank of a culture system and culturing the culture;

[0044] (2) a step of mixing one or more gas components selected from the group consisting of the combustible gas, the combustion-supporting gas and the non-combustible gas into at least a portion of the exhaust gas discharged in the step (1) to prepare a recirculating gas, and performing the mixing so that the concentration of the combustion-supporting gas in the recirculating gas is within a predetermined range; and

[0045] (3) A step of carrying out the step (1) and supplying the recirculating gas obtained in the step (2) as the supply gas to the culture.

[0046]

[15] The method according to item 14, wherein after step (2) and before step (3), the method further comprises:

[0047] (2') a step of measuring the concentration of at least the combustion-supporting gas in the recirculating gas,

[0048] Feedback adjustment is performed based on the concentration of the combustion-supporting gas measured in step (2') so that the concentration of the combustion-supporting gas in step (2) is within a specified range.

[0049]

[16] The method according to item 14 or 15, wherein the combustible gas is mixed with the exhaust gas independently.

[0050]

[17] The method according to any one of items 14 to 16, wherein the combustible gas and / or the non-combustible gas is mixed with the gas component in such a manner that a predetermined concentration range is achieved in the recirculating gas.

[0051]

[18] The method according to any one of items 14 to 17, wherein after step (1) and before step (2), the method further comprises:

[0052] (1′) A step of measuring the concentration of at least the combustion-supporting gas in the exhaust gas discharged in the step (1).

[0053]

[19] The method according to any one of items 14 to 18, wherein in the step (2), the combustion-supporting gas and the non-combustible gas are premixed before being mixed with the exhaust gas.

[0054]

[20] The method according to any one of items 14 to 19, wherein the microorganism is an aerobic fermentation bacterium.

[0055]

[21] The method according to item 20, wherein the aerobic fermentation bacteria are hydrogen oxidizing bacteria and the combustible gas is hydrogen.

[0056]

[22] The method according to any one of items 14 to 21, wherein the combustion-supporting gas is oxygen.

[0057]

[23] The method according to any one of items 14 to 22, wherein the non-combustible gas is carbon dioxide gas and / or nitrogen gas.

[0058]

[24] The method according to any one of items 14 to 23, wherein the pressure inside the culture tank is equal to or higher than atmospheric pressure.

[0059] Effects of the Invention

[0060] According to the present invention, a culture system and a culture method can be provided, which have a lower risk of explosion and a higher safety than before when the waste gas is reused to adjust the recirculation gas in the fermentation culture of microorganisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] [ Figure 1 ] Figure 1 It is a schematic diagram of an example of the structure of the culture system of the present invention.

[0062] [ Figure 2 ] Figure 2 It is a schematic diagram of an example of the structure of the culture system of the present invention.

[0063] [ Figure 3 ] Figure 3 It is a schematic diagram of an example of the structure of the culture system of the present invention. DETAILED DESCRIPTION

[0064] The following describes the embodiments of the present invention, but the technical scope of the present invention is not limited to the following. In addition, the prior art documents cited in this specification are incorporated into this specification by reference. As long as it does not depart from the gist of the present invention, the present invention can be changed, for example, the constituent elements of the present invention are added, deleted and replaced.

[0065] In this specification, terms such as "first", "second", "third", etc. are used to distinguish one element from another. For example, the first element can be expressed as the second element, and similarly, the second element can be expressed as the first element, but this will not depart from the scope of the present invention.

[0066] Unless otherwise defined, the terms (technical and scientific terms) used in this specification have the same meanings as those generally understood by those skilled in the art.

[0067] <Microbial culture system>

[0068] Figure 1 to Figure 3It is a schematic diagram for explaining a microorganism culture system (1, 1a, 1b) in one embodiment. However, the structure shown in the drawings of the present application is only an example, and the structure of the culture system of the present invention is not limited to this. In addition, in this specification, the elements marked with the same symbols basically represent the same element. In addition, depending on the purpose and necessity, each element constituting the culture system 1, 1a or 1b may adopt only a part of the elements, or may adopt any combination thereof. In addition, the description of each element of the culture system of the present invention is also applicable to the method of the present invention described later as appropriate.

[0069] In one embodiment, the culture system 1 of the present invention (e.g. Figure 1 )have:

[0070] Culture tank 10;

[0071] Recirculation gas conditioning unit;

[0072] a first gas circulation pipeline 12, one end of which is connected to the upper part of the culture tank, and the other end of which is connected to the recirculation gas regulating part;

[0073] The second gas circulation line 13 has one end connected to the recirculation gas adjustment unit and the other end connected to the culture tank to supply the recirculation gas therein.

[0074] In the culture system 1 of the present invention, a recycling gas regulating unit (for example, a gas mixer 11) is connected to one or more gas supply units selected from the group consisting of a combustible gas supply unit 14, an combustion-supporting gas supply unit 15 and a non-combustible gas supply unit 16, and the recycling gas regulating unit is configured to mix one or more gas components selected from the group consisting of combustible gas, combustion-supporting gas and non-combustible gas (also called inert gas) into at least a part of the exhaust gas discharged from the culture tank 10 so that the concentration of the combustion-supporting gas in the recycling gas is within a specified range.

[0075] The culture tank 10 used in the culture system 1 of the present invention can be a culture tank suitable for achieving the type and purpose of the microorganism to be cultured (for example, the optimal conditions when the microorganism is used to produce the desired substance, etc.). There is no special restriction on the capacity and shape of the culture tank 10, as long as it is selected in combination with the use, purpose, etc. For example, a cylindrical, bag-shaped, spherical, etc. culture tank can be used. The culture tank 10 can be provided with a stirring blade for stirring the culture medium, and the culture medium can also be circulated and stirred by liquid flow, and can also be stirred by shaking the culture tank 10 itself. In addition, the culture tank 10 can also be equipped with a temperature control device (for example, a heater or a cooling coil, etc.) for keeping the temperature of the culture medium at an arbitrary temperature. In addition, the culture tank 10 can also be provided with a pH sensor, a dissolved oxygen (DO) sensor, and / or a pressure sensor, etc., for monitoring the culture medium conditions in the culture tank 10. The known devices and sensors set in the culture tank can be combined to be suitable for different uses and purposes.

[0076] The culture system 1 of the present invention is particularly suitable for fermentation culture using combustible gas. Combustible gases applicable to the culture system 1 of the present invention (and the method of the present invention) include, but are not limited to, gases such as hydrogen, ammonia, hydrogen sulfide, and volatile hydrocarbons (for example, but not limited to, methane or hydrocarbons with a carbon number (C) of 2 or more (for example, C 2-8 Alkanes, C 3-8 Cycloalkanes, C 2-8 Olefins, C 3-8 Cycloolefins, or C 2-8 For example, if the microorganism used in the fermentation is a hydrogen oxidizing bacterium, hydrogen can be used.

[0077] In order to prevent gas explosions in gas compositions containing flammable gases, it is necessary to first (i) not provide a fire source and (ii) ensure that the gas composition is not within the range of explosive compositions. However, it is not easy to eliminate the fire source. For example, static electricity may also cause ignition, so it is difficult to take a foolproof approach. Therefore, the latter countermeasure, i.e., controlling the composition of the gas, is usually given priority. The risk of combustion or explosion of flammable gases themselves is usually very low. If flammable gases are to cause combustion or explosion, they need to be mixed with oxygen and other combustion-supporting gases (combustible components) in a certain proportion, and the temperature (or fire source) and other conditions must be met to trigger combustion and explosion.

[0078] In this specification, "combustible gas" refers to a gas that does not burn alone but has the property of promoting combustion after being mixed with a combustible gas, for example, including gases such as oxygen, ozone, nitrous oxide, nitric oxide, nitrogen dioxide, fluorine, chlorine, chlorine dioxide, nitrogen trifluoride, chlorine trifluoride, silicon tetrachloride, and oxygen difluoride. The combustible gas that can be used in the culture system 1 of the present invention (and the method of the present invention) can use the above-mentioned gases, but considering that it is used to culture microorganisms, it is preferably oxygen-containing or oxygen. As the combustible gas that can be used in the culture system 1 of the present invention (and the method of the present invention), in some cases, air containing oxygen can also be used. When adding air to the exhaust gas to adjust the recirculated gas, it is only necessary to adjust the concentration of other gas components (for example, nitrogen) contained in the air. In addition, in this specification, "single combustion-supporting gas" does not mean that it contains no components other than the combustion-supporting gas, but means that it may contain components other than the combustion-supporting gas, for example, in a ratio of less than 5%, preferably 4%, 3%, 2%, 1%, 0.5%, or less than 0.1%.

[0079] For example, if it is a two-component mixed system of a flammable gas and an oxidizing gas, combustion explosion can be prevented by making the concentration of the flammable gas below the lower explosion limit of the mixed system or above the upper explosion limit. The lower explosion limit refers to the minimum concentration of the flammable gas that can continue to burn, and the upper explosion limit refers to the minimum concentration of the oxidizing gas that can continue to burn. Therefore, in the case where the composition of the upper explosion limit is represented by the concentration of the oxidizing gas, the explosion can be prevented by keeping the concentration of the oxidizing gas in the mixed system below the concentration. In the case where the oxidizing gas is oxygen, the oxygen concentration in the upper explosion limit is particularly referred to as the "explosion limit oxygen concentration" (reference: Shozo Yagyu, "Explosion limit oxygen concentration in inert gas addition", Safety Engineering, Vol.25No.4 (1986)).

[0080] Therefore, in the culture system 1 of the present invention (and the method of the present invention), by adjusting the amount of gas components added by the recirculating gas regulating unit so that the concentration of the oxidizing gas in the recirculating gas is within a specified range, that is, below the explosion limit concentration (for example, below the explosion limit oxygen concentration), it is possible to prevent the explosion of the recirculating gas, and to safely and efficiently carry out fermentation culture. Since the explosion limit concentration varies depending on the gas components that may be contained in the recirculating gas, it can be appropriately set according to the purpose of the fermentation culture and the means of application (for example, the type of microorganisms, the type of combustible gas, the type of non-combustible gas) and based on known information. (For example, refer to Shozo Yagyu, "Explosion Limit Oxygen Concentration in Inert Gas Addition", Safety Engineering, Vol. 25 No. 4 (1986), etc.).

[0081] If the exhaust gas or recirculated gas contains at least three components, that is, in addition to the combustible gas and the combustion-supporting gas, there is also a non-combustible gas, according to known information, it is sufficient to make the mixing ratio of these three components not fall within the range of the explosion limit (for example, see Shozo Yagyu, "Explosion Limit Oxygen Concentration in Inert Gas Addition", Safety Engineering, Vol. 25 No. 4 (1986); Shozo Yagyu, "Explosion Range of Mixed Gas (2)", Safety Engineering, Vol. 1 No. 2 (1962)). Although there is no particular limitation, for example, if the gas components contained in the exhaust gas or recirculated gas are composed of hydrogen (combustible gas), carbon dioxide (non-combustible gas) and oxygen (combustible gas), under normal temperature and pressure conditions, the concentration of oxygen is hardly affected by the ratio of the other two components, and about 5% is its upper explosion limit. In addition, when it is necessary to increase the oxygen concentration, it can be excluded from the explosion range by making the hydrogen concentration less than 8%. In addition, if the concentration of carbon dioxide gas is 80%, the concentrations of hydrogen and carbon dioxide gas can reach 10% respectively. Therefore, according to the type of microorganisms used in the present invention or their growth state, the types of combustible gas and non-combustible gas contained in the exhaust gas or recycled gas, etc., the mixing ratio of each gas component can be adjusted. At least from the perspective of safety, as long as the concentration of the combustion-supporting gas (for example, oxygen) is controlled within a specified range, it is preferably lower than the explosion limit oxygen concentration. For example, when the combustible gas is hydrogen, the oxygen concentration can be preferably adjusted to less than 5%. The concentration of other gas components in the recycled gas is preferably adjusted according to the type of microorganism used, or for the purpose of efficiently producing the required substances, so that it is within a specified range.

[0082] In the culture system 1 of the present invention (and the method of the present invention), for example, helium, nitrogen, water vapor, carbon dioxide, carbon tetrachloride gas, etc. can be used as non-combustible gas, and a plurality of such non-combustible gases can also be used in combination. Since the explosion range can be changed by changing the non-combustible gas, therefore, it is possible to appropriately select according to the purpose. In the culture system 1 of the present invention (and the method of the present invention), carbon dioxide and / or nitrogen can be contained as non-combustible gas. In addition, the non-combustible gas used in the present invention can play the role of the substrate used in the microbial fermentation, and it is also possible to appropriately select according to the type of the microorganism, for example, carbon dioxide can be used as the fermentation substrate of the microorganism.

[0083] In one embodiment, the second gas circulation pipeline 13 may further include a first gas concentration meter 23 (for example, see Figure 2 and Figure 3). Based on the concentration of the combustible gas measured by the first gas concentration meter 23, the recirculating gas regulating unit performs feedback regulation so that the concentration of the combustible gas in the recirculating gas is within a specified range (for example, below the explosion limit concentration). In this way, the concentration of the combustible gas in the recirculating gas introduced into the culture tank can be controlled within a specified concentration range. Therefore, in the culture system (1a, 1b) of the present invention as a whole, the concentration of the combustible gas can be controlled not to exceed the specified concentration, which can further improve safety.

[0084] In one embodiment, the combustible gas supply unit 14 can be independently connected to the recirculating gas regulating unit. Since the combustible gas supply unit 14 contains a single combustible gas and substantially does not contain other components such as an oxidizing gas, the composition of the combustible gas contained therein is not included in the range of the explosive composition. In addition, since the combustible gas supply unit 14 can be independently connected to the recirculating gas regulating unit, the concentration of the oxidizing gas is maintained below the explosion limit concentration even in the pipeline connecting the combustible gas supply unit 14 to the recirculating gas regulating unit, thereby ensuring safety. In addition, in this specification, "single combustible gas" does not mean that it does not contain any components other than the combustible gas at all, but means that it can contain components other than the combustible gas, for example, at a ratio of less than 5%, preferably 4%, 3%, 2%, 1%, 0.5%, or less than 0.1%.

[0085] In one embodiment, the recirculating gas regulating unit may be configured to mix the combustible gas and / or non-combustible gas components in the recirculating gas in such a manner that the concentration of such gas components is within a specified range. The concentration of the combustible gas and / or non-combustible gas is preferably adjusted according to the type of microorganism used or for the purpose of producing substances required for the microorganism so that it is within a specified range. In this way, the concentration of gases other than the combustion-supporting gas in the recirculating gas can also be adjusted, so that the recirculating gas that is more suitable for the microbial fermentation conditions can be supplied to the culture tank, so that the fermentation can be carried out efficiently.

[0086] In one embodiment, a second gas concentration meter 24 (for example, Figure 2 and Figure 3). Thus, for example, even if the culture state of the microorganisms changes dramatically, and the concentration of the combustion-supporting gas (such as oxygen) contained in the exhaust gas deviates from the concentration range assumed during normal culture (for example, when the oxygen concentration in the exhaust gas is not lower than the concentration range assumed during normal culture), the abnormality can be detected in advance. According to the detected abnormality, for example, the amount of gas components added by the recycling gas regulating unit can be adjusted, which can prevent the concentration of the combustion-supporting gas from exceeding the prescribed range, thereby further improving safety. Therefore, in one embodiment, the culture system (1a, 1b) may have a mechanism for performing feedforward regulation, which performs feedforward regulation through the recycling gas regulating unit based on the concentration of the combustion-supporting gas measured by the second gas concentration meter 24, so that the concentration of the combustion-supporting gas in the recycling gas is within the prescribed range.

[0087] The first gas concentration meter 23 and / or the second gas concentration meter 24 may also have a function of measuring the concentration of combustible gas and / or non-combustible gas, thereby confirming that the concentration of combustible gas and / or non-combustible gas contained in the exhaust gas and / or the recirculated gas is within a specified range, especially under culture conditions suitable for microbial culture.

[0088] In one embodiment, the combustion-supporting gas supply unit 15 and the non-combustible gas supply unit 16 may also be connected to the recirculation gas regulator so that the combustion-supporting gas and the non-combustible gas are pre-mixed before mixing with the exhaust gas (e.g. Figure 2 and Figure 3 ). For example, the combustible gas supply line 150 connected to the combustible gas supply unit 15 and the non-combustible gas supply line 160 connected to the non-combustible gas supply unit 16 intersect to form a combustible gas / non-combustible gas supply line 170, and the combustible gas / non-combustible gas supply line 170 can also be connected to the recirculation gas regulating unit (for example, the gas mixer 11, 11b). Therefore, the combustible gas and the non-combustible gas are premixed before mixing with the exhaust gas. By premixing the combustible gas and the non-combustible gas, the concentration of the combustible gas provided at a high concentration can be reduced, the risk of reaching the combustible range and burning when mixed with the exhaust gas is reduced, and the risk of combustion and corrosion of metal materials caused by the combustible gas can be reduced.

[0089] In the culture system 1 (and the method of the present invention), the culturable microorganisms are not particularly limited, and may be, for example, aerobic fermentation bacteria or anaerobic fermentation bacteria. For example, hydrogen oxidizing bacteria may be used as aerobic fermentation bacteria.

[0090] Hydrogen oxidizing bacteria is a general term for bacteria that oxidize free hydrogen and use the energy generated by the reaction to assimilate carbonic acid.

[0091] Hydrogen oxidizing bacteria include, but are not limited to, for example, Achromobacter, Acidithiobacillus, Acidovorax, Alcaligenes, Anabena, Aquifex, Arthrobacter, Azospirillum, Bacillus, Bradyrhizobium, Cupricinus, and avidus), Derxia, Helicobacter, Herbaspirillum, Hydrogenobacter, Hydrogenobaculum, Hydrogenophaga, Hydrogenophilus, Hydrogenothermus, Hydrogenovibrio, Ideonella species O1 lasp.O1), Kyrpidia, Metallosphaera, Methanobrevibacter, Myobacterium, Nocardia, Oligotropha, Paracoccus, Pelomonas, Polaromonas, Pseudomonas, Pseudonocardia onocardia, Rhizobium, Rhodococcus, Rhodopseudomonas, Rhodospirillum, Streptomyces, Thiocapsa, Treponema, Variovorax, Xanthobacter, or Wautersia, or a combination of more than one thereof.

[0092] In the culture system 1 of the present invention (and the method of the present invention) of one embodiment, the internal pressure of the culture tank 10 can be adjusted to be higher than the atmospheric pressure by any pressurizing means (for example, a pump or a compressor). In this way, the recirculated gas supplied to the culture tank 10 can be effectively dissolved in the culture medium, thereby promoting the fermentation culture of the microorganisms. The pressure of the culture tank 10 is a gauge pressure (pressure difference relative to atmospheric pressure), for example, 0.01MPa to 1.0MPa, 0.01MPa to 0.5MPa, 0.01MPa to 0.2MPa or 0.05MPa to 0.2MPa.

[0093] In the culture system 1 of one embodiment, a compressor may be provided in the first gas circulation line to circulate the waste gas. The compressor applicable to the present invention is not particularly limited, and for example, an axial compressor, a centrifugal compressor, a reciprocating compressor, or a rotary compressor may be applicable, and may be appropriately selected in consideration of the purpose or scale of the system, the gas composition of the waste gas and / or the recirculated gas, and the like.

[0094] In the culture system 1 of one embodiment, the recirculating gas regulating unit may be, for example, one or more gas mixers (11, 11a, 11b) (e.g. Figures 1 to 3 ). By the operation of the gas mixer (11, 11a, 11b), the combustible gas, the combustion-supporting gas and / or the non-combustible gas supplied from the combustible gas supply unit 14, the combustion-supporting gas supply unit 15 and / or the non-combustible gas supply unit 16 are mixed with the exhaust gas, and the concentration of the combustion-supporting gas in the recirculated gas is adjusted to be within a specified range (for example, below the explosion limit oxygen concentration). A single gas mixer (11) may be connected to the combustible gas supply unit 14 via a combustible gas supply line 140, to the combustion-supporting gas supply unit 15 via a combustion-supporting gas supply line 150, and to the non-combustible gas supply unit 16 via a non-combustible gas supply line 160. In addition, the combustible gas supply unit 14, the combustion-supporting gas supply unit 15 and the non-combustible gas supply unit 16 may be connected to a plurality of gas mixers (11a, 11b), respectively. For example, the three gas mixers may be connected to the combustible gas supply unit 14, the combustion-supporting gas supply unit 15, and the non-combustible gas supply unit 16. In addition, for example, the combustible gas supply unit 14 may be connected to one of the two gas mixers (11a, 11b), and the combustion-supporting gas supply unit 15 and the non-combustible gas supply unit 16 may be connected to the other gas mixer 11b.

[0095] In a culture system (1a, 1b) of one embodiment (e.g. Figures 2-3 ), the recirculation gas regulating unit may include:

[0096] one or more gas mixers (11, 11a, 11b);

[0097] a first gas regulating unit 141 for regulating the supply amount of the combustible gas from the combustible gas supply unit 14;

[0098] A second gas regulating unit 151, which is used to adjust the supply amount of the combustion-supporting gas from the combustion-supporting gas supply unit 15;

[0099] The third gas regulating unit 161 is used to regulate the supply amount of the non-combustible gas from the non-combustible gas supply unit 16 .

[0100] The first gas regulating unit 141, the second gas regulating unit 151 and / or the third gas regulating unit 161 may be respectively disposed in the middle of the combustible gas supply line 140, the combustion-supporting gas supply line 150 and / or the non-combustible gas supply line 160 (e.g. Figure 2 and Figure 3 ), and may also be set at the gas outlet of the combustible gas supply unit 14, the combustion-supporting gas supply unit 15 and / or the non-combustible gas supply unit 16. The first gas regulating unit 141, the second gas regulating unit 151 and / or the third gas regulating unit 161 may adjust the amount of the supplied gas component by an opening and closing mechanism such as a valve (for example, a solenoid valve). The first gas regulating unit 141, the second gas regulating unit 151 and / or the third gas regulating unit 161 appropriately perform feedback adjustment according to the gas composition of the recirculated gas measured by the first gas concentration meter 23, thereby preventing the gas composition of the recirculated gas from being within the explosion range, thereby further improving safety.

[0101]

[0102] In one embodiment, the method of the present invention may include:

[0103] (1) a step of supplying a supply gas containing a combustible gas, an oxidizing gas, and a non-combustible gas to a culture containing microorganisms and a culture medium supplied to a culture tank of a culture system and culturing the culture;

[0104] (2) a step of mixing one or more gas components selected from the group consisting of the combustible gas, the combustion-supporting gas and the non-combustible gas into at least a portion of the exhaust gas discharged in the step (1) to prepare a recirculating gas, and performing the mixing so that the concentration of the combustion-supporting gas in the recirculating gas is within a predetermined range; and

[0105] (3) A step of carrying out the step (1) and supplying the recirculated gas obtained in the step (2) as the supply gas to the culture. For example, the method of the invention can be implemented by using the culture system, but is not limited to the structure of the culture system as long as the method of the invention can be implemented. In addition, the structure applicable to the method of the invention can also be applied to the components described in the above <Cultivation system for microorganisms>.

[0106] In one embodiment of the method, the culture medium used in the system and method of the present invention is appropriately selected according to the type of microorganism used, is not limited to known culture media, and a culture medium whose composition is appropriately changed according to the purpose can also be used, so there is no particular limitation.

[0107] In one embodiment, in the above step (2), one or more gas components selected from the group consisting of combustible gas, combustion-supporting gas and non-combustible gas are mixed into at least a portion of the waste gas discharged in the step (1) to prepare the recirculating gas. As described above, in the recirculating gas, it is sufficient to control the concentration of the combustion-supporting gas within a prescribed range. From the perspective of safety, it is more preferably controlled to be below the explosion limit concentration. The concentration of other gas components in the recirculating gas is preferably adjusted to be within a prescribed range according to the type of microorganism used or for the purpose of efficiently producing the desired substance.

[0108] In one embodiment, the method of the present invention comprises, after step (2) and before step (3):

[0109] (2') a step of measuring the concentration of at least the combustion-supporting gas in the recirculating gas,

[0110] Feedback adjustment is performed based on the concentration of the oxidizing gas measured in step (2') so that the concentration of the oxidizing gas in step (2) is within a specified range (for example, below the explosion limit concentration). In this way, the concentration of the oxidizing gas in the recirculating gas introduced into the culture tank can be controlled within a specified concentration range. Therefore, in the overall system using the method of the present invention, the concentration of the oxidizing gas can be controlled not to exceed the specified concentration, thereby further improving safety.

[0111] In one embodiment, the combustible gas mixed by the method of the present invention is preferably mixed independently into the exhaust gas. By independently supplying a single combustible gas to the exhaust gas, the concentration of the combustion-supporting gas in the combustible gas can be kept below the explosion limit concentration during the mixing process with the exhaust gas, thereby ensuring safety.

[0112] In one embodiment, the combustible gas and / or non-combustible gas mixed by the method of the present invention is mixed with the gas component to reach a prescribed range in the recirculating gas. The concentration of the combustible gas and / or non-combustible gas is preferably adjusted according to the type of microorganism used or the substance required for its production so that it is within a prescribed range. In this way, the concentration of gases other than the combustion-supporting gas in the recirculating gas can also be adjusted, so that a gas more suitable for the fermentation conditions can be supplied to the culture tank, so that fermentation can be carried out efficiently.

[0113] In one embodiment of the method of the present invention, after step (1) and before step (2), the method further comprises:

[0114] (1') A step of measuring the concentration of at least the combustion-supporting gas in the exhaust gas discharged in the step (1). Thus, for example, even if the culture state of the microorganisms changes drastically and the oxygen concentration contained in the exhaust gas changes drastically (for example, when the oxygen concentration does not decrease), detection can be performed before the recirculation gas is generated, and the concentration of the combustion-supporting gas in the recirculation gas can be prevented from exceeding a prescribed range, thereby further improving safety.

[0115] Therefore, in one embodiment of the method of the present invention, after step (1) and before step (2), the method further includes:

[0116] (1") is a process for measuring the concentration of at least the combustion-supporting gas in the exhaust gas discharged in the process (1), and performing feedforward adjustment based on the concentration of the combustion-supporting gas measured in the process (1") so that the concentration of the combustion-supporting gas in the process (2) is within a specified range.

[0117] In each process of the present invention in one embodiment, the concentration of combustible gas and / or non-combustible gas contained in the exhaust gas and / or the recycled gas is measured, and the concentration of the combustible gas and / or the non-combustible gas is adjusted so that it is within a prescribed range, in particular, culture conditions suitable for the cultivation of microorganisms.

[0118] In the method of the present invention in one embodiment, in step (2), the combustion-supporting gas and the non-combustible gas may be pre-mixed before being mixed with the exhaust gas. In this way, the concentration of the combustion-supporting gas provided at a high concentration can be reduced, the risk of reaching the flammable range and burning when mixed with the exhaust gas can be reduced, and the risk of combustion and corrosion of metal materials caused by the combustion-supporting gas can be reduced.

[0119] Explanation of symbols

[0120] 1. 1a, 1b culture system

[0121] 10 culture tanks

[0122] 11, 11a, 11b Gas mixer

[0123] 12. First gas circulation pipeline

[0124] 13 Second gas circulation pipeline

[0125] 14 Combustible gas supply unit

[0126] 15 Combustion-supporting gas supply unit

[0127] 16 Non-combustible gas supply unit

[0128] 17 Microorganisms

[0129] 18 Culture medium

[0130] 19 Exhaust

[0131] 20 Exhaust gas flow direction

[0132] 21 Flow direction of recirculating gas

[0133] 22 Compressor

[0134] 23. First Gas Concentration Meter

[0135] 24 Second gas concentration meter

[0136] 140 Combustible gas supply line

[0137] 141 First gas regulating unit

[0138] 142 Feedback control signal to the first gas regulating unit

[0139] 150 Combustion-supporting gas supply pipeline

[0140] 151 Second gas regulating unit

[0141] 152 Feedback control signal to the second gas regulating unit

[0142] 160 Non-combustible gas supply line

[0143] 161 Third gas regulating unit

[0144] 162 Feedback control signal to the third gas regulating unit

[0145] 170 Combustible gas / non-combustible gas supply pipeline

Claims

1. A microorganism culture system, comprising: Culture tank; Recirculation gas conditioning unit; a first gas circulation pipeline, one end of which is connected to the upper part of the culture tank, and the other end of which is connected to the recirculation gas regulating part; A second gas circulation pipeline, one end of which is connected to the recirculation gas regulating unit, and the other end of which is connected to the culture tank and supplies the recirculation gas therein, in, The recirculating gas regulating unit is connected to one or more gas supply units selected from the group consisting of a combustible gas supply unit, an combustion-supporting gas supply unit and a non-combustible gas supply unit. The recirculating gas regulating unit mixes one or more gas components selected from the group consisting of a combustible gas, an combustion-supporting gas and a non-combustible gas into at least a part of the exhaust gas discharged from the culture tank so that the concentration of the combustion-supporting gas in the recirculating gas is within a specified range.

2. The culture system according to claim 1, wherein: The second gas circulation line further comprises a first gas concentration meter for measuring the concentration of at least the combustion-supporting gas in the recirculating gas. The recirculation gas regulator performs feedback regulation based on the concentration of the combustion-supporting gas measured by the first gas concentration meter so that the concentration of the combustion-supporting gas in the recirculation gas is within a predetermined range.

3. The culture system according to claim 1 or 2, wherein: The combustible gas supply unit is independently connected to the recirculation gas adjustment unit.

4. The culture system according to any one of claims 1 to 3, wherein: The recirculation gas adjustment unit mixes the gas components so that the concentration of the combustible gas and / or the non-combustible gas in the recirculation gas is within a predetermined range.

5. The culture system according to any one of claims 1 to 4, wherein: The upper portion of the culture tank and / or the first gas circulation line further has a second gas concentration meter for measuring the concentration of at least the combustion-supporting gas in the exhaust gas.

6. The culture system according to any one of claims 1 to 5, wherein: The combustion-supporting gas supply unit and the non-combustible gas supply unit are connected to the recirculation gas adjustment unit so that the combustion-supporting gas and the non-combustible gas are pre-mixed before being mixed with the exhaust gas.

7. The culture system according to any one of claims 1 to 6, wherein: The microorganism is an aerobic fermentation bacterium.

8. The culture system according to claim 7, wherein the aerobic fermentation bacteria are hydrogen oxidizing bacteria, and the combustible gas is hydrogen.

9. The culture system according to any one of claims 1 to 8, wherein: The combustion-supporting gas is oxygen.

10. The culture system according to any one of claims 1 to 9, wherein: The non-combustible gas is carbon dioxide gas and / or nitrogen gas.

11. The culture system according to any one of claims 1 to 10, wherein: The pressure inside the culture tank is equal to or higher than atmospheric pressure.

12. The culture system according to any one of claims 1 to 11, wherein: A compressor is provided in the first gas circulation line.

13. The culture system according to any one of claims 1 to 12, wherein: The recirculation gas conditioning unit has: one or more gas mixers; a first gas regulating unit for regulating a supply amount of the combustible gas from the combustible gas supply unit; a second gas regulating unit, which is used to regulate the supply amount of the combustion-supporting gas from the combustion-supporting gas supply unit; a third gas regulating unit for regulating the supply amount of the non-combustible gas from the non-combustible gas supply unit, The combustible gas supply unit, the combustion-supporting gas supply unit, and the non-combustible gas supply unit are connected to the gas mixer.

14. A method for culturing microorganisms by recycling waste gas in a culture system, wherein: The method includes: (1) a step of supplying a supply gas containing a combustible gas, an oxidizing gas, and a non-combustible gas to a culture containing microorganisms and a culture medium supplied to a culture tank of a culture system and culturing the culture; (2) a step of preparing a recirculating gas by mixing one or more gas components selected from the group consisting of the combustible gas, the combustion-supporting gas and the non-combustible gas into at least a portion of the exhaust gas discharged in the step (1), wherein the concentration of the combustion-supporting gas in the recirculating gas is within a predetermined range by mixing; and (3) A step of carrying out the step (1) and supplying the recirculating gas obtained in the step (2) as the supply gas to the culture.

15. The method according to claim 14, wherein: After step (2) and before step (3), the method comprises: (2') a step of measuring the concentration of at least the combustion-supporting gas in the recirculating gas, Feedback adjustment is performed based on the concentration of the combustion-supporting gas measured in the step (2') so that the concentration of the combustion-supporting gas in the step (2) is within a specified range.

16. The method according to claim 14 or 15, wherein: The combustible gas is independently mixed with at least a portion of the exhaust gas.

17. The method according to any one of claims 14 to 16, wherein: The combustible gas and / or the non-combustible gas is mixed with the gas component in such a manner that a predetermined concentration range is achieved in the recirculation gas.

18. The method according to any one of claims 14 to 17, wherein after step (1) and before step (2), the method comprises: (1′) A step of measuring the concentration of at least the combustion-supporting gas in the exhaust gas discharged in the step (1).

19. The method according to any one of claims 14 to 18, wherein: In the step (2), the combustion-supporting gas and the non-combustible gas are premixed before being mixed with at least a portion of the exhaust gas.

20. The method according to any one of claims 14 to 19, wherein: The microorganism is an aerobic fermentation bacterium.

21. The method according to claim 20, wherein: The aerobic fermentation bacteria are hydrogen oxidizing bacteria, and the combustible gas is hydrogen.

22. The method according to any one of claims 14 to 21, wherein: The combustion-supporting gas is oxygen.

23. The method according to any one of claims 14 to 22, wherein: The non-combustible gas is carbon dioxide gas and / or nitrogen gas.

24. The method according to any one of claims 14 to 23, wherein: The pressure inside the culture tank is equal to or higher than atmospheric pressure.

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