Anti-biofilm bubbling bioreactor, and process based on such a bioreactor

Abstract

The invention relates to a bioreactor, in particular a photobioreactor, comprising: - a chamber (E) comprising a chamber wall, and a lower end (I) comprising a side wall (PP) and a bottom (PD); - at least one gas injector (G) arranged in the lower end (I), characterized in that said gas injector (G) is arranged in the side wall (PP) of the lower end (I), and is positioned so that its gas bubbles rise in the medium while in contact with the chamber wall of the chamber (E). Thus, the gas bubbles prevent biofilm formation. The invention also relates to a method based on such a bioreactor. Abstract figure: Fig. 1

Description

Title of the invention: Anti-biofilm bubbling bioreactor, and method based on such a bioreactor

[0001] The invention relates to the field of bioreactor arrangements, in particular photobioreactors. The invention relates more particularly to limiting the formation of biofilm on the walls of these bioreactors.

[0002] Bioreactors are used to grow cultures of microorganisms in a culture medium.

[0003] Certain strains of microorganisms of interest tend to clump together on the walls of the bioreactor to form a biofilm. This is very problematic in the case of photobioreactors where the biofilm limits the light exposure of the cells inside the bioreactor, which limits the development of the culture and the productivity of the bioreactor.

[0004] Furthermore, this limits visual control of the culture.

[0005] A first objective of the present invention is to propose a solution for li mitation of biofilm formation on the bioreactor enclosure wall.

[0006] A second objective is to propose a solution improving the visual control of cells inside a photobioreactor.

[0007] To achieve these objectives, the invention proposes a bioreactor comprising: - an enclosure which comprises an enclosure wall, and a lower end which comprises a side wall and a bottom; - at least one gas injector arranged in the lower end, characterized in that said gas injector is arranged in the enclosure, in particular in the side wall of the lower end, and is arranged therein such that its gas bubbles rise in the medium while being in contact with the enclosure wall of the enclosure.

[0008] Advantageously, the bubbles continuously occupy enclosure wall surfaces so that they prevent the apposition of cells on the same surfaces. Thus, the cells are unable to create a biofilm on the enclosure wall. On visual inspection, no biofilm is detectable on the wall unlike the bioreactors of the prior art.

[0009] Furthermore, the arrangement of the gas injectors in the side wall makes it possible to limit the space requirement below the lower end. Thus, the bioreactor is more compact below the lower end compared to the bioreactors of the prior art.

[0010] According to a variant, the enclosure comprises several gas injectors arranged at several points on the side wall of the lower end.

[0011] This allows for multiple vertical sections of the enclosure wall where biofilm formation is prevented.

[0012] According to a variant, the enclosure wall has a cylindrical shape and the gas injectors are angularly spaced around the central axis of the cylindrical shape.

[0013] This allows for a cylindrical shape that is easy to manufacture. Furthermore, a cylindrical shape makes it easier to observe the cell culture in several directions in space, compared to a parallelepiped or cubic shape, for example.

[0014] According to one variant, the enclosure wall is arranged in an essentially vertical manner.

[0015] This makes it possible to improve the visibility of the cells by an operator, compared to an oblique wall.

[0016] According to a variant, said gas injector is a gas diffuser.

[0017] This makes it possible to generate very fine bubbles to limit turbulence, and to improve the visibility of the cells and their lighting.

[0018] According to one variant, the bioreactor forms a photobioreactor and the enclosure wall is transparent.

[0019] This makes it possible to cultivate photosynthetic microorganisms such as green, blue or red algae.

[0020] According to a variant, the lower end is in the form of a lower end piece separate from the enclosure, and connected to the enclosure, and the bioreactor further comprises a connecting piece for connecting said lower end piece to the enclosure wall, in a sealed manner.

[0021] This makes it easier to assemble the reactor, to produce an end wall in a specific material which may be different from that of the enclosure, and to produce the reactor more easily in large series.

[0022] According to one variant, the lower end piece is of the metallic type, in particular stainless steel.

[0023] This allows the holes and structures to be put in place by drilling and welding.

[0024] The invention further relates to a kit for mounting a bioreactor according to the invention, comprising: - the transparent enclosure; - the lower end piece; - said connecting piece; and - said gas injector

[0025] Another subject of the invention relates to a method of manufacturing a bioreactor according to one of the preceding claims, comprising the following steps: - set up the enclosure; - arranging at least one gas injector in the enclosure, in particular in the side wall of the lower end, so that its gas bubbles rise in the medium while being in contact with the enclosure wall of the enclosure.

[0026] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating preferred embodiments of the invention, in which: - [Fig.l] schematically illustrates a view in space of a photobioreactor structure according to a preferred embodiment of the invention; - [Fig.2] schematically illustrates a front view of a piece of furniture according to the invention comprising the photobioreactor structure of [Fig.l]; - [Fig.3] schematically illustrates a front view of a lower end piece of the photobioreactor structure of [Fig.l]; - [Fig.4] schematically illustrates a top view of the lower end piece of [Fig.3].

[0027] The invention firstly concerns the general structure of the photobioreactor. The structure comprises a cylindrical enclosure E, the lower base and / or the upper base of which are open. The enclosure E is used in a vertical position so that the main axis of the cylinder is vertical.

[0028] The structure further comprises a lower end piece I configured to be connected to said lower base by means of a lower connecting piece RL

[0029] The structure further comprises an upper end piece S configured to be connected to said upper base by means of an upper connecting piece RS.

[0030] The connection is made with an end piece I / S which can be slightly larger or smaller, or of the same size (here diameter) as the corresponding part of the enclosure E. The connecting piece RI, RS is configured as appropriate for a watertight connection.

[0031] According to the invention, the lower end piece I comprises a proximal portion PP and a distal portion PD better visible in [Fig.3].

[0032] The proximal portion PP is cylindrical in shape. It comprises a connecting part cooperating with said connecting piece RI / RS and the transparent enclosure E to close the corresponding opening of the enclosure E in a sealed manner.

[0033] The distal portion PD is conical in shape. The base of this cone is continuous with the cylindrical proximal portion PP. This cone has a distal end AP, in the form of an apex (better visible in [Fig.3]).

[0034] The lower end piece I may be of metallic type, for example stainless steel. Other materials may of course be considered within the scope of the invention, such as in particular plastic materials or structures made of 3D printing.

[0035] Similarly, the upper end piece S comprises a proximal portion PP and a distal portion PD, preferably with the same characteristics as those detailed above.

[0036] Furthermore, according to the invention, said distal end AP comprises at least one mouthpiece orifice E1, S1 at the apex. The mouthpiece orifice may be equipped with a mouthpiece structure. These are in particular the upper and lower distal ends AP.

[0037] Furthermore, the proximal portion PP comprises at least one bypass orifice D1, D2, D3, D4 in a lateral position, or even several angularly spaced bypass orifices. The bypass orifices D1, D2, D3, D4 are equipped with bypass structures, better visible in figures 3 and 4. Pumps PI, P2 can also be provided.

[0038] In particular, the lower end piece I comprises a first set of several angularly spaced bypass ports, configured to receive gas injectors G inserted into the end piece. In the illustrated variant, there are 4 gas injectors arranged around the photobioreactor structure.

[0039] In addition, a bypass D2 can be provided, connected to a liquid injector, by a sterile circuit allowing liquid to be injected into the medium without opening the reactor, limiting the risk of contamination. The liquid injector can be connected via a solenoid valve EV.

[0040] Furthermore, the lower end piece I comprises at least one bypass orifice configured to receive a probe, for example a pH probe, inserted into the end piece I.

[0041] The invention also relates to a lower end piece I, and an upper end piece S as described above, as well as a corresponding mounting kit.

[0042] In use, the photobioreactor structure is arranged in a specific piece of furniture M, for example a cabinet, equipped with lighting means L, such as light strips comprising LEDs. The piece of furniture M may comprise panels and preferably a door. Thus, the continuous lighting of the photobioreactor can be carried out in the piece of furniture M without interfering with the exterior of the piece of furniture M.

[0043] The cabinet M comprises a speaker support SE making it possible to easily hold the speaker E in the cabinet M; and an end support SI making it possible to hold the end piece, here lower I, in the cabinet M.

[0044] For this purpose, the enclosure support SE comprises a first circular receiving structure, receiving the enclosure E. The first receiving structure can be removable, in two semi-circles for example, with fixing of the parts in semi- circle by a hinge. Thus, this first receiving structure is opened to place the enclosure E within it before closing it.

[0045] Furthermore, the end support SI comprises a second circular receiving structure, receiving the lower end piece I. The lower end piece I can be inserted therein by the tip, and be held there by the weight of the photobioreactor structure and the strength of the second receiving structure.

[0046] This type of furniture M serves as a support for control devices, monitoring devices or others, to participate in the operation of the photobioreactor.

[0047] We can also consider a piece of furniture in the form of strand supports without panels or doors.

[0048] The assembly of the photobioreactor structure is done in two main steps.

[0049] In a first step, the lower end piece I must be connected to said lower base of the enclosure E, by means of said lower connecting piece RI.

[0050] In a second step, the upper end piece S must be connected to the upper base of the enclosure E, by means of said upper connecting piece RS.

[0051] Once the photobioreactor structure is assembled, all that remains is to insert it into the cabinet M. For this purpose, the enclosure support SE can be opened to place the enclosure E there. Then, the apex of the lower end piece I can be placed in the end support SI.

[0052] Now concerning the arrangement, it can be adapted for a photobioreactor described previously, or for a bioreactor in the broad sense.

[0053] Thus, the bioreactor comprises the enclosure E, a recirculation circuit RC, and a recirculation pump PL

[0054] The enclosure E comprises the lower end I having at least one outlet SI for liquids (namely here the mouth SI); and an upper end S having at least one inlet DI for liquids (namely here at the bypass orifice D1).

[0055] In particular, said outlet S1 has a central position at the center of the apex of the lower end I, relative to the gas injectors G which have a peripheral position. The gas injectors G are preferably gas diffusers, diffusing for example bubbles of less than 500 pm. We can speak of microbubbling in the context of this part of the invention.

[0056] In the illustrated variant, the mouth orifice El is used to evacuate the gas injected into the enclosure E, as well as the foam created by microbubbling. The mouth orifice El also allows collection by overflow thanks to the injection of medium via the bypass orifice D2 (continuous collection). The mouth orifice El overflows into a sterilizable container, the gas is evacuated from this container through a filter.

[0057] The enclosure E here having a cylindrical shape, the gas injectors G are angularly spaced in the enclosure E around the central axis of the cylindrical shape. There has at least four G gas injectors. This allows diffusion over the entire bioreactor of, for example, 200mm in diameter. Each diffuser diffuses over a quarter of the surface of revolution of the enclosure.

[0058] It is possible to envisage an individual injector device which can be inserted into the container of the enclosure. The injector and / or the gas inlet of the injector may or may not pass through a wall of the enclosure. Such an injector device may have the shape of a ring or an arc of a circle.

[0059] The recirculation circuit RC is connected to said input DI and to said output SI. It allows liquid to be recirculated in a pipe of small diameter compared to the enclosure E. This pipe measures, for example, 20 mm in diameter.

[0060] The recirculation pump PI is connected to the output SI and to the lower part of the recirculation circuit RC.

[0061] The upper part of the recirculation circuit RC is connected to the DI input at the top of enclosure E.

[0062] According to the invention, the recirculation pump PI is configured to produce a flow of liquid FL from said outlet SI to said inlet DI so that the flow of liquid FL in the enclosure E has an essentially vertical direction from top to bottom.

[0063] Furthermore, the gas injectors G are arranged at several points of the lower end I. Thus, they make it possible to produce a vertical gas flow FG from bottom to top.

[0064] The combination of the downward flow of liquid FL and the upward flow of gas FG makes it possible to achieve a reverse circulation of gas and medium, homogenizing the culture and the distribution of the cells in the enclosure E.

[0065] In the preferred variant, the recirculation circuit RC comprises a transparent control window F. At this location, the wall is preferably entirely transparent over a few centimeters. This window is preferably arranged at human height so that it can be checked without bending down. It is, for example, in a range between 1.60m and 1.75m from the ground.

[0066] The invention also relates to the method of manufacturing a bioreactor as described above.

[0067] In this method, the recirculation pump PI is connected to the output SI of the enclosure E, as well as to the recirculation circuit RC.

[0068] Then, the recirculation circuit RC is connected to the DI input of the enclosure E.

[0069] Pump P2 is a pump used to completely or partially drain the photobioreactor.

[0070] Specifically concerning the arrangement of the gas injectors G (diffusers), it can be adapted for a photobioreactor described previously, or for a bioreactor in the broad sense.

[0071] Thus, the bioreactor comprises the enclosure E which comprises an enclosure wall, and a lower end I (here in the form of a separate end piece).

[0072] The lower end I comprises a side wall (here the proximal portion PP) and a bottom of a given shape (here the distal portion PD of conical shape).

[0073] The bioreactor further comprises the gas injectors G arranged in the side wall PP of the lower end I.

[0074] According to the invention, the gas injectors are arranged therein so that their gas bubbles rise in the medium while being in contact with the enclosure wall of the enclosure E.

[0075] In order to cover the entire enclosure wall, the gas injectors G are arranged at several points on the side wall PP, here at points angularly spaced around the central axis of the cylindrical enclosure wall.

[0076] In the illustrated variant, the enclosure wall is arranged vertically. The gas bubbles are therefore preferably projected there.

[0077] The invention also relates to the method of manufacturing a bioreactor as described above.

[0078] In this method, the gas injectors G are placed in the side wall PP of the lower end I, so that their gas bubbles rise in the medium while being in contact with the enclosure wall of the enclosure E.

Claims

Claims

1. Bioreactor comprising: - an enclosure (E) which comprises an enclosure wall, and a lower end (I) which comprises a side wall (PP) and a bottom (PD); - at least one gas injector (G) arranged in the lower end (I), characterized in that said gas injector (G) is arranged in the enclosure (E), in particular in the side wall (PP) of the lower end (I), and is arranged therein so that its gas bubbles rise in the medium while being in contact with the enclosure wall of the enclosure (E).

2. Bioreactor according to the preceding claim, characterized in that the enclosure (E) comprises several gas injectors (G) arranged at several points on the side wall (PP) of the lower end (I).

3. Bioreactor according to the preceding claim, characterized in that the enclosure wall has a cylindrical shape and the gas injectors (G) are angularly spaced around the central axis of the cylindrical shape.

4. Bioreactor according to one of the preceding claims, characterized in that the enclosure wall is arranged essentially vertically.

5. Bioreactor according to one of the preceding claims, characterized in that said gas injector (G) is a gas diffuser.

6. Bioreactor according to one of the preceding claims, characterized in that it forms a photobioreactor and the enclosure wall is transparent.

7. Bioreactor according to one of the preceding claims, characterized in that the lower end is in the form of a lower end piece separate from the enclosure, and connected to the enclosure, the bioreactor further comprising a connecting piece (RI) for connecting said lower end piece (I) to the enclosure wall, in a sealed manner.

8. Bioreactor according to the preceding claim, characterized in that the lower end piece (I) is of metallic type, in particular stainless steel.

9. A kit for mounting a bioreactor according to claim 7 or 8, comprising: - the transparent enclosure (E); - the lower end piece (I); - said connecting piece (RI); and - said gas injector (G).

10. A method of manufacturing a bioreactor according to one of claims 1 to 8, comprising the following steps: - set up the enclosure (E); - arranging at least one gas injector (G) in the enclosure (E), in particular in the side wall (PP) of the lower end (I), so that its gas bubbles rise in the medium while being in contact with the enclosure wall of the enclosure (E).

Images