EP3861095A1

EP3861095A1 - Method for stimulating the growth of biomass in a liquid inside a bioreactor

Info

Publication number: EP3861095A1
Application number: EP19783990.5A
Authority: EP
Inventors: Volker Kirchhoff; André Weidauer; Jessy Schönfelder; Gaby GOTZMANN; Christiane Wetzel; Jörg KUBUSCH
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2018-10-05
Filing date: 2019-09-25
Publication date: 2021-08-11
Also published as: US20210380964A1; DE102018124666A1; CN112789349A; KR20210072052A; WO2020069944A1; BR112021006089A2

Abstract

The invention relates to a method for stimulating the growth of a biomass, which is mixed with a liquid inside a bioreactor (11; 21), by means of ionising radiation. The following method steps are used: a) exposing a first partial volume (15; 25) of the liquid in the bioreactor (11; 21) to ionising radiation, the first partial volume (15; 25) comprising at most 10% of the liquid volume (12; 22) in the bioreactor (11; 21); b) mixing the first partial liquid volume (15; 25), which has been exposed to ionising radiation, with the second partial liquid volume, which has not been exposed to ionising radiation, in the bioreactor (11; 21); c) repeating method steps a) and b) multiple times, each partial volume of the liquid in the bioreactor (11; 21) being exposed to a total radiation dose of at most 50 Gy on statistical average.

Description

Method for stimulating the growth of biomass contained in a liquid within a bioreactor

description

The invention relates to a method for stimulating the growth of components contained in a liquid nutrient medium, which are to be cultivated in a bioreactor, by means of ionizing radiation.

Bioreactors are becoming increasingly important in energy generation, wastewater treatment and also in the production of vaccines, to name just a few examples. A bioreactor is to be understood in the following as a container in which specially grown microorganisms, cells or other constituents are cultivated under the best possible conditions in a liquid nutrient medium, in order to either the microorganisms or cells themselves, parts of them or one of them

Ways to gain substance or to break down chemical compounds. The term biomass is to be taken to mean the sum of those microorganisms, cells and / or other constituents that are cultivated in a bioreactor. As already explained, biomass is usually mixed with a liquid that also functions as a nutrient medium within a bioreactor.

In order to promote the growth of the biomass cultivated in a bioreactor, the environmental conditions within the bioreactor, such as temperature, pressure, supply and exhaust air, and the nutrient conditions for the components to be cultivated are primarily optimized.

Various methods are known to grow biomass in one

Promote and stimulate bioreactor. In WO 201 1/1 1 6969 A1, to promote the growth of algae or cyanobacteria in a container filled with an aqueous solution, it is proposed to remove a side stream of the aqueous solution from the container, to saturate it with carbon dioxide and to return it to the container near the bottom . The disadvantage here is that this procedure can only be used with a few types of microorganisms.

The term "hormesis" is a hypothesis known according to which harmful or toxic substances, administered in very low doses, have a positive effect Can have organisms. Such a positive effect has already been demonstrated for various substances, such as digitalis, colchin or opium. Out

It is also known in laboratory tests that ionizing radiation, administered in very low doses, has a so-called biopositive effect on viruses, bacteria, fungi and algae [E. Lengfelder, "Is there also a biopositive effect of ionizing radiation?", "Low-dose radiation and health", pages 97-102], which is also referred to as "radiation hormesis". For example, algae were able to accelerate growth after X-ray radiation and in bacteria and amoeba an increase in the division activity after administration of a low radiation dose is also found. Also in MG Vicker et al., "Hormesis and the biological effect of ionizing radiation: experiments with lung fibroblasts", "The effect is lower

Radiation doses ", page 243 ff., This radiation hormesis is named, whereby reference is made to the fact that ionizing radiation stimulates the DNA repair systems in E. coli. Concrete process steps, such as radiation treatment with a low radiation dose outside of laboratory conditions on a larger biomass can be made, but are not known from the latter two writings.

The invention is therefore based on the technical problem of creating a method for stimulating the growth of biomass within a bioreactor, by means of which the disadvantages of the prior art can be overcome. In particular, it should be possible with the method according to the invention to also stimulate larger volumes of biomass in a bioreactor with regard to growth, the method being intended to enable homogeneous treatment of the entire biomass.

The technical problem is solved by objects with the features of patent claim 1. Further advantageous embodiments of the invention result from the dependent claims.

In the method according to the invention, the growth of biomass, which is mixed with a liquid within a bioreactor, is stimulated by the application of ionizing radiation. The ionizing radiation used here is preferably electron-generated and accelerated low-energy electrons and / or X-rays generated by the electron source. As low-energy electrons in the sense of the invention there are electrons with a

Accelerating voltage from 25 keV to 300 keV can be seen. As previously mentioned, the biomass within a bioreactor is usually mixed with a liquid. If subsequently a liquid or a

If partial liquid volume is named within a bioreactor, the named liquid also includes the biomass contained in the liquid or so the named partial liquid volume also includes the partial amount of biomass mixed in the partial liquid volume.

While methods from the prior art often attempt to complete the treatment of a batch of material with ionizing radiation in one radiation pass, high-energy, accelerated electrons being used when using electron beams, the method according to the invention is based on only partial volumes of a batch of material with ionizing radiation

act, but several times and with very low doses of ionizing

Radiation.

Therefore, in the method according to the invention, only a first partial volume of a liquid located in a bioreactor is exposed to ionizing radiation, the first partial volume comprising a maximum of 10% of the liquid volume in the bioreactor. Then the first partial volume of the liquid which is exposed to ionizing radiation is mixed with the second partial volume of liquid in the bioreactor which has not been exposed to ionizing radiation. The process steps of irradiating a first one

Partial volume of the liquid in the bioreactor with ionizing radiation and the mixing of the first partial volume with the second partial volume

then repeated several times. It is known that for the stimulation of the growth of biomass, depending on the type of constituents of a biomass, different total doses of ionizing radiation can be optimal for a stimulation process. In the method according to the invention, the repetition of the two

Process steps of the application of a first partial volume with ionizing radiation and the mixing of the first partial volume exposed to ionizing radiation with the second partial volume are completed at the latest when each partial volume of the liquid in the bioreactor has been subjected to a statistical mean value of a total radiation dose of 50 Gy. The total radiation dose can, however, also be selected to be less than 50 Gy, depending on the type of components of a biomass. Which The total radiation dose for a type of the components of a biomass is optimal for stimulating the growth of the biomass, can be determined on the basis of laboratory tests.

The application of only a relatively small first partial volume of a liquid in a bioreactor with ionizing radiation; The irradiation of the first partial volume during a radiation passage with a radiation dose that is relatively small in relation to the total radiation dose and the frequent mixing of the liquid in the bioreactor mean that the entire liquid in the bioreactor and thus also the entire biomass in the bioreactor are given a statistical average with a homogeneous total dose ionizing radiation is applied, which, viewed across the total volume of the biomass, is accompanied by a homogeneous stimulation of the growth of the biomass. The smaller the first partial volume of the liquid in the bioreactor, the more advantageous it is. In one embodiment, a first partial volume is therefore selected which comprises a maximum of 5% of the total volume of the liquid in the bioreactor.

It is known that the mean depth of penetration of low-energy electrons into a medium and the distribution of the energy introduced into the medium considered via the depth of penetration can be calculated. Depending on this, it is possible for a person skilled in the art to set the electrical parameters of an electron source in such a way that the low-energy electrons generated by the electron source are only subjected to a maximum of 10% and preferably a maximum of 5% of the total volume of a liquid located in a bioreactor. According to the invention, a partial volume is considered to be charged with the low-energy electrons of an electron source if at least 90% of the energy of the low-energy electrons generated by the electron source is entered in this partial volume.

As previously noted, it is also advantageous if one

Irradiation passage of a first partial volume even a small dose of ionizing radiation is entered in the first partial volume. In a further embodiment, therefore, a first partial volume of the liquid in the bioreactor is exposed to only 1% of the total dose of ionizing radiation which is required for stimulating the growth of the partial amount of biomass contained in the first partial volume of the liquid. The application of such a low dose of ionizing radiation to a relatively small first partial volume to be irradiated requires that in order to stimulate the growth of the entire biomass in the bioreactor, multiple irradiation of the first partial volume and multiple mixing of a currently irradiated first partial volume with a currently relevant one second partial volume that is not irradiated is required, but this has the advantage already mentioned that all particles in the bioreactor are subjected to the same total dose of ionizing radiation on a statistical average.

The method according to the invention is therefore also particularly suitable if larger volumes of a biomass are to be stimulated with regard to growth, for example in the case of bioreactors with a capacity of several hundred or even several thousand liters.

In one embodiment of the method according to the invention, a partial area of a wall of the bioreactor is formed as an electron exit window of the electron source, through which low-energy electrons penetrate into the first partial volume of the liquid inside the bioreactor, with means for mixing the liquid in the bioreactor having the effect that the composition of the first Partial volume of the liquid changed in the bioreactor.

Alternatively, the first partial volume of the liquid volume can also be obtained from the

Removed bioreactor, charged with low-energy electrons outside the bioreactor and then mixed with the second liquid volume remaining in the bioreactor.

As previously described, the growth of a biomass can be stimulated according to the invention by entering the energy of low-energy electrons from an electron source and / or X-rays generated by the electron source in the first partial volume. As is known, when generating accelerated electrons using an electron source, X-rays are also always generated. The type of material and / or the thickness of that belonging to an electron source

Electron exit window is the ratio of those entered in a medium

low-energy electrons and the X-ray radiation entered into the medium can be adjusted. If the thickness of an electron exit window remains the same

Electron exit window material increases, then the ratio described above shifted in favor of the X-rays entered in the medium. Because on the one hand there are biomass particles in which the growth is preferred by the

Application of low-energy electrons is stimulated and on the other hand biomass particles, in which the growth is preferred by the application of

X-ray radiation can be stimulated by suitable choice of the material for the electron exit window and / or by suitable choice of the thickness of the

Electron exit window can be set whether more low-energy electrons or X-rays should be added to a biomass.

In one embodiment, the stimulation process for the growth of biomass is carried out only once after the liquid mixed with biomass has been filled into the associated bioreactor. Alternatively, the stimulation process can be repeated at intervals of a few minutes to a few months.

The present invention is explained in more detail below on the basis of exemplary embodiments. The figures show:

1 shows a device suitable for carrying out the method according to the invention in a schematic sectional illustration;

2 shows an alternative which is suitable for carrying out the method according to the invention

Device in a schematic sectional view.

In Fig. 1, a device is shown schematically in a section, which for

Execution of the method according to the invention is suitable. A liquid volume 12 of a liquid mixed with a biomass is first introduced into a bioreactor 11. A wall of the bioreactor 1 1 is in one area as

Electron exit window 13 of an electron source 14 is formed. The electron exit window 13 is used to stimulate the growth of the biomass

low-energy electrons with an acceleration voltage of 25 keV to 300 keV in a first partial volume 15 of the liquid volume 12. Since, as already mentioned, the penetration depth of accelerated electrons and the distribution of the energy introduced into the liquid can be calculated, a person skilled in the art can According to the invention, set the electrical parameters of the electron source 14 in such a way that the

low-energy electrons of the electron source 14 acted on first partial volumes 15 accounts for a maximum of 10% and preferably a maximum of 5% of the liquid volume 12 and that at least 90% of the energy of the low-energy electrons is introduced into this first partial volume 15.

Preferably, the first partial volume 15 of the liquid during a

Irradiation time period with a maximum of 1% of the total amount of low-energy electrons, which is required to stimulate the biomass particles mixed with the first partial volume 15. Laboratory experiments can determine which dose of low-energy electrons is required to make up all of the biomass particles

To stimulate partial volume 1 5. Depending on this, a person skilled in the art can also set the electrical parameters of the electron source 14 in such a way that a maximum of 1% of the total amount occurs during an irradiation period

low-energy electrons penetrate into the sub-volume 1 5, which are required to stimulate all biomass particles within the sub-volume 1 5.

Means 1 6 ensure that a first partial volume 1 5 charged with low-energy electrons is mixed with the second partial volume not charged with low-energy electrons, as a result of which the composition of the first partial volume 1 5 also changes and thus a new first partial volume 1 5 is continuously formed.

The application of the first partial volume 1 5 with low-energy electrons and the mixing of the liquid in the bioreactor 1 1 continue until all biomass particles have been subjected to the statistical average of the total dose of low-energy electrons required for stimulation. According to the invention, each partial volume of the liquid in the bioreactor 1 1 is loaded with a dose of a maximum of 50 Gy on average.

In one embodiment, the electron source 14 is operated continuously and with constant power throughout the process of stimulating all biomass particles in the bioreactor 11. Alternatively, the electron source 14 can also be activated only periodically at time intervals, the periods of the activation of the

Electron source can be the same length or different lengths.

In a further embodiment, the liquid in the bioreactor 1 1 during the entire stimulation process of all biomass particles within the liquid volume 12 in the bioreactor 1 1 continuously mixed with the agents 1 6. Alternatively, the liquid in the bioreactor 11 can also be mixed only periodically at time intervals, it being possible for the time intervals to be of the same length or of different lengths.

An alternative device for carrying out the method according to the invention is shown schematically in a section in FIG. 2. In a bioreactor 21 is first a

Liquid volume 22 of a liquid mixed with biomass, in which the growth of the biomass particles are to be stimulated. A continuous flow of the liquid located in the bioreactor 21 is branched off by means of at least one pump device 27, conveyed through a pipeline 28 and then returned to the bioreactor 21.

One wall of the pipeline 28 is formed in one area as an electron exit window 23 of an electron source 24. Low-energy electrons with an acceleration voltage of 25 keV to 300 keV enter a first partial volume 25 of the liquid volume 22 through the electron exit window 23. The pipeline 28 and the electron source 24 are dimensioned such that the low-energy electrons generated by the electron source 24 each have only a first one Apply partial volume 25, which is a maximum of 10% and preferably a maximum of 5% from

Liquid volume 22 makes up, with at least 90% of the energy of

low-energy electrons is entered into the first partial volume 25.

With this procedure, the flow velocity of the liquid in the pipeline 28 and the electrical parameters of the electron source 24 are set in such a way that in a first partial volume 25 during one pass (that is, when it is once

Electron exit window 25 flows past) a maximum of 1% of the total amount

penetrate low-energy electrons, which are required to stimulate all biomass particles within the first partial volume 25.

The application of first partial volume 25 with low-energy electrons and the mixing of the liquid in the bioreactor 21 continue until a previously calculated total dose of low-energy electrons has been entered into the liquid volume 22. If, as shown in FIG. 2, the continuous flow of the liquid in the bioreactor 21 is branched off in a lower region of the bioreactor 21 and reintroduced in an upper region of the bioreactor 21, then this process alone ensures constant mixing liquid located in the bioreactor 21. In addition, the liquid in the bioreactor 21 can also be mixed continuously or at intervals by means of means 26.

The procedures according to the invention described for FIGS. 1 and 2 ensure the application of a continuously homogeneous dose of accelerated electrons based on the total liquid volume in a bioreactor and are therefore suitable for stimulating the growth of a biomass. The method according to the invention can be used, for example, in bioreactors for producing vaccines or else in wastewater treatment. In the exemplary embodiments described for FIGS. 1 and 2, at least one sensor can also be arranged within the regions of the first partial volumes 15 and 25, respectively, with which the intensity of the current of accelerated, low-energy electrons; their distribution in partial volume 15 or 25 and / or the dose of the low-energy electrons applied in partial volume 15 or 25 can be detected and controlled by means of an evaluation device.

Claims

1 . Method for stimulating the growth of a biomass which is mixed with a liquid within a bioreactor (1 1; 21) by means of ionizing radiation, characterized by the following method steps:

a) loading a first partial volume (15; 25) of the liquid in the bioreactor (115; 21) with ionizing radiation, the first partial volume (15; 25) not exceeding 10% of the liquid volume (12; 22) in the bioreactor (1 1; 21) includes;

b) mixing the first partial volume (1 5;

25) the liquid with the second partial liquid volume in the bioreactor (1 1; 21) which has not been exposed to ionizing radiation;

c) repeating process steps a) and b) several times, each partial volume of the liquid in the bioreactor (1 1; 21) with a statistical average

Total radiation dose of a maximum of 50 Gy is applied.

2. The method according to claim 1, characterized in that accelerated,

low-energy electrons with an acceleration voltage of 25 keV to 300 keV and / or X-rays are used as ionizing radiation.

3. The method according to claim 1 or 2, characterized in that a portion of a wall of the bioreactor (1 1) as an electron exit window (13)

Electron source (14) is formed, through which low-energy electrons and / or X-rays penetrate into the first partial volume (1 5) of the liquid within the bioreactor (1 1), means for mixing the liquid in the

Bioreactor (1 1) cause the composition of the first partial volume (1 5) of the liquid in the bioreactor (1 1) to change.

4. The method according to claim 3, characterized in that the electron source (14) is operated continuously during the stimulation process of the entire biomass in the bioreactor (1 1).

5. The method according to claim 3, characterized in that the electron source (14) is periodically activated.

6. The method according to any one of claims 1 to 5, characterized in that the liquid in the bioreactor (1 1) is continuously mixed during the stimulation process of the entire biomass in the bioreactor (1 1).

7. The method according to any one of claims 1 to 5, characterized in that the

Liquid in the bioreactor (1 1) is mixed periodically.

8. The method according to claim 1 or 2, characterized in that the first

Partial volume (25) of the liquid is removed from the bioreactor (21), exposed to low-energy electrons and / or X-rays outside the bioreactor (21) and then with the second one remaining in the bioreactor (21)

Volume of liquid is mixed.

9. The method according to claim 8, characterized in that a continuous

flowing liquid stream branched out of the bioreactor (21), outside the

Bioreactor is guided past an electron exit window (23) of the electron source (24), subjected to low-energy electrons and / or X-rays there, and is then reintroduced into the bioreactor (21).

10. The method according to claim 8 or 9, characterized in that the liquid in

Bioreactor (21) is continuously mixed.

1 1. Method according to one of the preceding claims, characterized in that a first partial volume (1 5; 25) is used, which comprises a maximum of 5% of the liquid volume (12; 22) in the bioreactor (1 1; 21).

12. The method according to any one of claims 2 to 1 1, characterized in that at least 90% of the energy of the low-energy electrons is entered in the first partial volume (1 5; 25)