BIOREACTOR COMPRISING A FILTER POCKET, AND METHOD FOR PRODUCING SAME

Abstract

A bioreactor for cultivating microorganisms and cells of animal or plant origin includes a filter pocket which is arranged on the inner surface of a flexible wall of the bioreactor and which is delimited on the outside by the wall of the bioreactor and on the inside by a filter pocket wall. The inside filter pocket wall is formed at least partially by a filter medium. A spacer is arranged in the filter pocket between the wall of the bioreactor and the filter medium. The spacer has at least one through opening. A connecting portion of the filter medium protrudes through the through opening and is directly connected to the wall of the bioreactor. A method of manufacturing a filter pocket in a bioreactor for cultivating microorganisms and cells of animal or plant origin is also provided herein.

Claims

1. A bioreactor for cultivating microorganisms and cells of animal or plant origin, comprising a filter pocket which is arranged on an inner surface of a flexible wall of the bioreactor and which is delimited on an outside by the wall of the bioreactor and on an inside by a filter pocket wall, wherein the filter pocket wall is formed at least partially by a filter medium, and wherein a spacer is arranged in the filter pocket between the flexible wall of the bioreactor and the filter medium, characterized in that the spacer has at least one through opening and in that a connecting portion of the filter medium protrudes through the through opening and is directly connected to the wall of the bioreactor.

2. The bioreactor according to claim 1, characterized in that a plurality of through openings, which are arranged so as to be regularly distributed over the spacer, is provided, and in that a plurality of connecting portions of the filter medium protrude through the through opening and are directly connected to the wall of the bioreactor.

3. The bioreactor according to claim 1, characterized in that the filter pocket is free of completely or partially separated chambers.

4. The bioreactor according to claim 1, characterized in that the wall of the bioreactor is at least partially formed of polyethylene.

5. The bioreactor according to claim 1, characterized in that the spacer is at least partially formed of polyethylene terephthalate.

6. The bioreactor according to claim 1, characterized in that the filter medium is a microfiltration membrane which is at least partially formed of polyethersulfone.

7. The bioreactor according to claim 6, characterized in that at least one of two sides of the microfiltration membrane is connected to a porous planar structure.

8. The bioreactor according to claim 1, characterized in that a connecting piece to which a hose line can be coupled is inserted into the filter medium.

9. The bioreactor according to claim 1, characterized in that the bioreactor has a maximum total volume of at least 50 liters.

10. A method of manufacturing a filter pocket in a bioreactor for cultivating microorganisms and cells of animal or plant origin, comprising the following steps: providing a flexible wall for forming a bioreactor, a spacer, and a filter pocket wall formed at least partially by a filter medium, wherein the filter pocket wall has a greater superficial extent than the spacer; forming at least one through opening in the spacer which completely penetrates the spacer; placing the spacer on an inner surface of the flexible wall of the bioreactor; placing the filter pocket wall on the spacer; circumferentially fixing an edge of the filter pocket projecting beyond the spacer to the wall of the bioreactor; passing a connecting portion of the filter medium through the through opening; and fixing the connecting portion of the filter medium directly to the wall of the bioreactor.

11. The method according to claim 10, characterized in that the fixing of the at least one connecting portion of the filter medium to the wall of the bioreactor is performed by spot welding.

12. The method according to claim 10, characterized in that the fixing of the at least one connecting portion of the filter medium to the wall of the bioreactor is performed by bonding.

13. The bioreactor according to claim 7, wherein the porous planar structure is a polypropylene/polyethylene-polyethylene terephthalate-polypropylene/polyethylene laminate.

14. The bioreactor according to claim 9, wherein the maximum total volume is at least 100 liters.

15. The bioreactor according to claim 9, wherein the maximum total volume is at least 200 liters.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further features and advantages of the invention will become apparent from the description below and from the accompanying drawings to which reference is made and in which:

[0021] FIG. 1 shows a spacer for a filter pocket in a bioreactor according to the invention in a first embodiment;

[0022] FIG. 2 shows a filter medium for forming a filter pocket in a bioreactor according to the invention in accordance with the first embodiment;

[0023] FIG. 3 shows a finished filter pocket in a bioreactor according to the invention in accordance with the first embodiment;

[0024] FIG. 4 shows a spacer for a filter pocket in a bioreactor according to the invention in a second embodiment;

[0025] FIG. 5 shows a filter medium for forming a filter pocket in a bioreactor according to the invention in accordance with the second embodiment; and

[0026] FIG. 6 shows a finished filter pocket in a bioreactor according to the invention in accordance with the second embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0027] The figures exemplarily show how a filter pocket can be formed in a large bioreactor. More specifically, FIGS. 1 to 3 refer to a first embodiment of a bioreactor having a total volume of 100 liters (recommended working volume: 50 liters), FIGS. 4 to 6 to a second embodiment of a bioreactor having a total volume of 200 liters (recommended working volume: 100 liters). The description below basically applies to both embodiments. The differences between the two embodiments are explained separately at the end.

[0028] FIGS. 1 and 4 each show a blank of a wide-meshed technical textile which serves as a spacer 10 in the finished filter pocket. Preferably, the textile is made of PET-fibers (polyethylene terephthalate), but may also be formed in any other way and/or in any other flexible, break-proof and non-buckling material. It is important that the spacer 10 can be passed through by the filtrated (cell-free) medium in the filter pocket—i.e., is in particular not solid—but is however stable enough to prevent the space defined in the filter pocket from collapsing. Furthermore, it must be ensured that specific areas can be separated out of the spacer 10. This characteristic of the spacer 10 will be discussed in more detail later.

[0029] FIGS. 2 and 5 each show a filter medium 12 by means of which the inner wall of the filter pocket in the bioreactor is formed. The filter medium 12 is impermeable to cells, but well permeable to other ingredients of the cell suspension. To this end, microfiltration membranes (only referred to as membranes below) having an effective pore size of 10 μm at maximum are suitable for this purpose, for example a hydrophilic polyethersulfone membrane (PESU) which does not swell upon wetting, having a pore size of 1.2 μm. In any case, the pores are smaller than the meshes of the spacer 10.

[0030] One or both sides of the membrane may be adhesively connected to a porous planar structure, such as a stable core shroud nonwoven having a PP/PE-PET-PP/PE layered structure (polypropylene/polyethylene-polyethylene terephthalate-polypropylene/polyethylene laminate).

[0031] A connecting piece 14 is incorporated in the filter medium 12, for example a hose olive which completely penetrates the filter medium 12. A hose line 16 can be connected to the connecting piece 14 at least on one side of the filter medium 12.

[0032] In the following, the manufacture of a filter pocket by means of the filter medium 12 serving as a filter pocket wall and the spacer 10 inside a flexible single-use bioreactor is described by way of example, the wall 18 of which is preferably formed from PE (polyethylene).

[0033] The spacer 10 is “perforated” at predetermined locations, i.e., through openings 20 which completely penetrate the spacer 10 are formed at these locations. The through openings 20 can be made in various ways, for example by punching, and in basically any shape, but preferably with a circular circumference. In FIGS. 1 and 4, the spacer 10 is already provided with four and six through openings 20, respectively.

[0034] Before the bioreactor is completed, the spacer 10 is first placed on the inner side of the bioreactor wall 18 which faces the culture medium when the bioreactor is in use, at the location where the filter pocket is to be formed, and the larger filter medium 12, which projects beyond the spacer 10 on all sides, is placed thereover.

[0035] Subsequently, the edge of the filter pocket wall, which in the example embodiment described here is formed solely from the filter medium 12, is connected to the bioreactor wall 18 in a completely circumferentially fluid-tight manner, in particular by welding. Such a fluid-tight connection is also to be understood as an indirect attachment of the filter pocket wall or the filter medium 12 to the bioreactor wall 18 with material arranged therebetween. An indirect fluid-tight connection may be advantageous, where appropriate, if improved adhesion and/or tightness can be achieved compared to a direct connection. The filter pocket formed in this way, which is not yet finished, is thus delimited on the outside by the bioreactor wall 18 and on the inside (at least partially) by the filter medium 12. The spacer 10 is not involved in this connection step, except that due to the fixing of the edge of the filter medium 12 to the bioreactor wall 18, it is “trapped” in the filter pocket thus formed.

[0036] Thereafter, in a further connection step, additional point-like connections are made between the filter medium 12 and the bioreactor wall 18. For this purpose, corresponding connecting portions 22 of the filter medium 12 are pressed through the through openings 20 of the spacer 10 and fixed directly to the bioreactor wall 18. This is possible, for example, by bonding or local heating and fusing, in particular using a spot-welding system. The spacer 10 is not directly involved in this connection step either, i.e., the spacer 10 itself does not form a connection with either the filter medium 12 or the bioreactor wall 18. However, the mobility of the spacer 10 in the filter pocket is severely limited or completely prevented by the point connections, which is advantageous and therefore desirable.

[0037] In case of a relatively thick spacer 10 and/or a relatively inflexible filter medium 12, protruding nipples may be provided on the side of the filter medium 12 associated with the bioreactor wall 18, the arrangement of which is adapted to the arrangement of the through openings 20 in the spacer 10. The filter medium 12 is then placed on the spacer 10 prior to fixation such that the nipples extend into or through the through openings 20 to facilitate fixation of the filter medium 12 at these locations. Such nipples may also be provided on the bioreactor wall 18 in addition to, or in place of, the nipples on the filter medium.

[0038] The exact shape of the point connections is not of particular importance. For example, annular fastening points can be formed with a heated cylindrical tube.

[0039] It is however important that the point connections are not arranged in the edge region, but in a central region of the filter medium 12. This not only ensures that the connection between the filter medium 12 and the bioreactor wall 18 is significantly strengthened, but also that the spacer 10 is fixed in position without being directly involved in the connection between the filter medium 12 and the bioreactor wall 18. The individual point connections also ensure that no chambers or other dead spaces are separated or delimited within the filter pocket. Rather, the medium can reach any region of the filter pocket.

[0040] As shown in FIGS. 3 and 6, after completion of the two connection steps described above, which in principle can also be carried out in reverse order, a filter pocket suitable for perfusion which is extremely robust is formed in the bioreactor. The bioreactor is then completed in a manner known per se.

[0041] The inner filter pocket wall may also be formed only partially of the filter medium 12, i.e., it need not necessarily be formed entirely of the filter medium 12.

[0042] The different materials of the filter medium 12, of the spacer 10 and of the bioreactor wall 18 are selected such that the spacer 10—in particular during use of the bioreactor—does not stick either to the filter medium 12 or to the bioreactor wall 18.

[0043] A hose line 16 which can be led out of the bioreactor and is provided in particular for discharging medium from the filter pocket can be connected to the connecting piece 14 in the filter medium 12 which faces away from the filter pocket. In principle, other designs are also possible. It is essential that the filter pocket has at least one fluid connection via which a separate flow connection can be realized, which is isolated from the medium in the bioreactor outside the filter pocket, so that the medium to be discharged from the filter pocket does not mix with the remaining medium in the bioreactor.

[0044] As mentioned above, FIGS. 1 to 3 refer to a first embodiment of a bioreactor having a total volume of 100 liters, and FIGS. 4 to 6 refer to a second embodiment of a bioreactor having a total volume of 200 liters. In contrast to the first embodiment, not four but six regularly arranged point connections are provided in the second embodiment. However, the specific number, arrangement, shape and size of the point connections are not to be understood as limiting either the embodiments described above or other embodiments, but are in principle variable.

[0045] The size, shape and position of the filter pocket in the bioreactor can be largely selected in an arbitrary manner depending on the application. For example, a very elongated filter pocket or even a filter pocket running completely around the inner circumference of the bioreactor are conceivable. In the latter case, a “circumferential” edge connection of the filter pocket wall would be understood as a connection of the two longitudinal edges of the annular filter pocket wall to the bioreactor wall 18.

[0046] In general, the specific design of the filter pocket should meet the following requirements and criteria:

[0047] On the one hand, the stability of the filter pocket for the respective intended use must be ensured at any time. On the other hand, however, the membrane surface of the filter medium 12 that can be used by flow should be restricted as little as possible, i.e., the filter surface that cannot be used due to the point connections should be as small as possible. In addition, the point connections should impair the distribution of the medium in the filter pocket as little as possible. The function of the connecting piece 14 must also be ensured.

[0048] The described concept of manufacturing robust filter pockets has already been successfully tested for bioreactors of the sizes 100 liters and 200 liters for use on a tilting device, but can also be used for bioreactors of other sizes, in particular for even larger bioreactors.

LIST OF REFERENCE NUMERALS

[0049] 10 spacer [0050] 12 filter medium [0051] 14 connecting piece [0052] 16 hose line [0053] 18 bioreactor wall [0054] 20 through opening [0055] 22 connecting portion