Patent Application
20180327707
The present invention relates to a stirring device for stirring of a bioreactor according to the preamble of the independent claim, as well as a process of stirring a bioreactor.
For production of culture media for microorganisms or cell cultures, or for controlled biotechnological processes such as cultivation of cells, the stirring or circulating of the bioreactor plays a particularly important role. Due to the different starting concentrations of substances and the metabolism of microorganisms and cells, respectively, during cultivation, there are local changes in concentrations of various chemical components in the media preparation or of nutrients, oxygen and the generated metabolites during cultivation. In order to allow for the same or at least controlled concentration conditions throughout the entire bioreactor, it is required to stir or circulate the fluid or suspension in the container during the entire process.
The use of flexible single-use bioreactors made of plastic foil plays a steadily growing role as compared to rigid containers composed of glass or stainless steel, in particular with regard to the continuously growing requirements for sterility of processes in biotechnology. in addition to their good suitability for sterilization, foil bags offer further advantages such as cost-efficient production, simple and space-saving storage, safety against contamination, and they make tedious purification after usage dispensable.
Devices for stirring of such bioreactors are also known as rockers, platform shakers, wobbling mixers, rotation shakers, vibration shakers, horizontal shakers, orbital shakers, and are described, for example, in patent applications DE3248543A1, CH697035A5 or EP1778828B1.
Such stirring devices are distributed, for example, by the company Sartorius under the brand name BIOSTAT® RM. With this device, the entire bioreactor is moved in such a way that the movement leads to mixing of the reactor content.
These devices are often comprising sensors for surveillance and control of the cultivation processes. These can be arranged inside and outside of the bioreactors.
It may occur that the sensor signal is compromised by the fluctuating fluid level inside of the bioreactor, which can lead to high signal fluctuations or erroneous measurements.
Such a disturbance can be induced, for example, by the sensor signal of a sensor which is arranged inside the bioreactor being influenced by the temporally varying fluid level. The sensor can be temporarilly exposed and temporarilly covered by liquid, or the fluid column above the sensor can be subject to fluctuations in height.
This is the case, e.g., for impedance sensors, by use of which, for example, the biomass of living cells in a culture broth can be determined.
This also occurs, for example, with conductivity sensors, by use of which the conductivity and thus a measure for dissolved substances in a cell suspension can be determined.
In both cases a reproducable result of the measurement can only be obtained when said sensors are ideally permanently covered by the same height of liquid column, or at least covered by a minimum liquid column, respectively.
It is therefore an object of the present invention to provide a stirring device for stirring of a bioreactor, as well as a process of stirring a bioreactor, which do not feature the disadvantages set forth above.
It is another object of the present invention to provide a stirring device for stirring of a bioreactor, as well as a process of stirring a bioreactor, which allow for a reproducable surveillance and control of the cultivation process.
These and other objects are solved by the processes and devices, respectively, set forth in the independent claims of the present invention. The dependent claims are describing preferred embodiments. Value ranges which are limited by numerical values are always meant to encompass said limiting numerical values.
Before the invention is described in detail, it is to be understood that this invention is not limited to particular components of said devices, or of said described process steps, as these processes and devices, respectively, may vary. It is further to be understood that the terminology is used herein only for the purpose of particular described embodiments, and is not intended to be limiting on purpose.
It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an”, and “the” include singular and/or plural referents unless the context clearly dictates otherwise. It is moreover to be understood that, in case parameter ranges are given which are delimited by numeric values, the ranges are deemed to include these limiting values.
According to the present invention, a system is provided comprising a stirring device for stirring of a bioreactor, comprising at least one movement mechanism for inducing a stirring motion in the bioreactor or in a holder of a bioreactor, at least one sensor attached to or in the bioreactor for monitoring at least one physiological or physical readout, wherein the stirring device or the bioreactor further comprise a sensor or transmitter for generating a synchronization readout.
Preferably it is provided that the system further comprises a synchronization mechanism for
Preferably it is further provided that the system comprises an evaluation device for displaying, recording and/or evaluating the at least one physiological or physical readout.
Such stirring devices are usually comprising a plate-shaped or b-shaped holder for a single-use reactor, for example a bioreactor.
The bioreactors are being mounted on said holder, wherein they are fixed by use of clamps or hooks or other reversible fixing materials. The holder is being propelled and generates the stirring movement of the bioreactor's content. The holder hereby executes for example a rocking movement alone a horizontal axis. The bioreactors can feature volumes of between 0.5 and 1000 liters.
Preferably it is provided that the synchronization readout is synchronized or synchronizable with the movement of the stirring device or the stirring movement in the bioreactor.
The term “synchronized” or “adapted to synchronization” (“synchronizable”) as used herein encompasses in particular all such approaches wherein the synchronization readout is selected in such a way that the same picks up a clock pulse or rhythm of the stirring movement or a generated clock pulse or rhythm of an artefact generated directly or indirectly by the stirring movement.
In a prefered embodiment it is provided that the sensor for monitoring a physiological or physical readout and the sensor or transmitter for generating a synchronization readout are identical.
In such an embodiment, for example the physiological or physical readout can be discontinuously recorded, for example with a certain sampling frequency. By using an evaluation algorithm it can then be accomplished, e.g., that in cases when the physiological or physical readout exceeds or goes below a certain threshold value, the following or preceeding measured value is taken.
Such an embodiment can, e.g., be calibrated or taught in advance as the user experiments with various threshold values.
In another prefered embodiment it is provided that a sensor for monitoring of a physiological or physical readout and a sensor or transmitter for generating a synchronization readout are different from one another.
Preferably it is further provided that the sensor for monitoring of a physiological or physical readout is arranged for recording a time series of a physiological or physical readout.
Preferably it is further provided that the sensor or transmitter for generating a synchronization measured value is arranged for generating a time series of a synchronization measured value.
Preferably it is further provided that the bioreactor is mounted on a holder in which the stirring movement can be induced.
Preferably the system herein is designed in such a way that it can induce at least one of the stirring movements selected from the group consisting of
The frequencies of the stirring movements herein are preferably within a range between ≥5 and ≤200 min−1 (i.e., ≥0.083 and ≤3.33 Hz). For a rocking movement the angle is preferably in a range between +/−3° and +/−15°.
Preferably it is further provided that the sensor for monitoring of at least one physiological or physical readout is selected from the group consisting of a
It is important herein that the data recording with regard to the physiological or physical readout can take different times depending on the sensor type, and that signal processing times of variable durations are required between successive measurements, respectively, which has an impact on the frequency of data recording that can be achieved.
Sensors which are amenable to a high frequency of read-out are particularly suited for a continuous or pseudo continuous data recording, respectively (i.e., with a high sampling frequency), whereas sensors which are only amenable to a low frequency of read-out are suited for a discontinuous data recording (i.e., for example, triggered by the synchronization readout).
Preferably it is further provided that the physiological or physical readout to be monitored is selected from the group consisting of
These readouts individually or in combination allow for a statement on (i) the cultivation process (growth of the amount of cells, cell viability etc.), (ii) the quality of the cultivation conditions as well as the media and alike.
Preferably it is further provided that the sensor or transmit for generating a synchronization readout is selected from the group consisting of a
Herein it also holds true that sensors which are amenable to a high frequency of read-out are suited for a continuous or pseudo continuous generation of the synchronization readout (i.e., with a high sampling frequency), whereas sensors which are only amenable to a low frequency of read-out are suited for a discontinuous generation of the synchronization readout (for example, by operating a switch or alike).
It is also important in this context that in the case of
According to the present invention a transmitter creates a trigger signal or a digital signal (digital in the sense of on/off or high/low) for generating a synchronization readout. To this end, the transmitter can comprise, e.g., a switch which is for example operated always when the rocker or platform shaker is reaching its maximum deflection and is changing its direction of movement. At this moment of operating the switch, however, the wave in the culture fluid in the bioreactor that is induced by the movement has not yet reached the respective end of the vessel; this happens with a certain time lag. At this moment of operating the switch, therefore, a liquid column standing above a sensor positioned at the respective end of the vessel is not yet at its maximum—its maximum height is lagging behind the stirring movement with a phase shift.
Therefore it can make sense to take said phase shift into account with regard to triggering a measurement of at least one physiological or physical readout or the selection of at least one recorded value of at least one physiological or physical readout, respectively.
Preferably it is further provided that the synchronization mechanism is a component of evaluation device,
Preferably it is furthermore provided that the bioreactor is a flexible single-use bioreactor made of a foil material.
The use of flexible single-use bioreactors made of plastic foil plays a steadily growing role as compared to rigid containers composed of glass or stainless steel, in particular with regard to the continuously growing requirements for sterility of processes in biotechnology. In addition to their good suitability for sterilization, foil bags offer further advantages such as cost-efficient production, simple and space-saving storage, best-possible safety against contamination, and they make tedious purification after usage dispensable.
Such flexible single-use bioreactors are being distributed for example by the company Sartorius under the trade name “CultiBags ® RM” and “Flexsafe ® RM”. They are available for example in volumes of 2 L, 10 L, 20 L, 50 L, 100 L and 200 L.
According to the present invention, furthermore, a stirring device for stirring of a bioreactor is provided, wherein said stirring device is arranged for use in a system according to the description set forth above. The stirring device is comprising at least one movement mechanism for inducing a stirring movement in the bioreactor or in a holder of a bioreactor.
According to the present invention, furthermore a process is provided for stirring of a bioreactor, wherein by use of a movement mechanism a stirring motion in a bioreactor is induced, at least one physiological or physical readout is monitored by use of a sensor attached to or in the bioreactor, by use of an evaluation device the at least one physiological or physical readout is displayed, recorded and/or evaluated, a synchronization readout is generated by use of a sensor or transmitter for generation of a synchronization readout, and wherein by use of a synchronization device
With regard to the device according to the present invention and the process according to the present invention, respectively, it has to be distinguished between continuously (or pseudo continuously in the case of digital data recording, respectively, sampled) and discontinuously monitored physiological or physical readouts and synchronization readouts.
For example, the synchronization readout can be recorded continuously or pseudo continuously. When a certain criterion is fulfilled, for example when a given threshold is exceeded or undercut, at zero crossing, with reaching a local maximum or local minimum, then measurement of a physiological or physical readout can be triggered. In this case the physiological or physical readout is being discontinuously recorded.
For example, the synchronization readout can be discontinuously recorded, for example by operating a switch at all times when the stirring device is moving through a certain position. These discontinuously recorded synchronization readout can then trigger measurement of a physiological or physical readout (discontinuous) or select in a continuously or pseudo continuously recorded physiological or physical readout certain values.
Quite as well can the discontinuously or continuously or pseudo continuously, respectively, recorded synchronization readout be set off with the discontinuously or continuously or pseudo continuously, respectively, recorded physiological or physical readout.
According to the present invention it is further provided a process for determination of at least one optimal time point of measurement or time period of measurement for the recording of at least one physiological or physical readout by use of a sensor positioned in or at a bioreactor, wherein by use of a stirring device a stirring movement is induced in the bioreactor, wherein by use of a sensor or transmitter a synchronization readout is generated, and wherein by use of a synchronization device
Preferably the stirring movement herein is at least one selected from the group comprising
In a particularly prefered embodiment of the present invention it is provided that a frequency spectrum is gone through for recording of the physiological or physical readout and/or the physiological or physical readout of a frequency spectrum consists.
Some measure processes are using a modulated readout which is dynamically modified in its frequency. In the process a frequency spectrum is gone through for each measurement (a so-called sweep). This method is used with many spectroscopic processes, for example, in impedance spectroscopy as well as optical spectroscopy procedures such as UV-, IR, or Raman spectroscopy and FTIR. Especially physiological or physical readouts generated that way usually need to be discontinuously recorded.
In doing so it may happen that the selection frequency concerning the physiological or physical readout is lower than or in a comparable range as the frequency of the stirring movement. In other words: the time period required for running through the frequency spectrum (“sweep period”) cannot be neglected against the change of the fluid level in the reactor.
Particularly preferably it is provided that the frequency spectrum is discretely and discontinuously recorded in dependency of the synchronization readout.
That way it can be ensured that the different frequencies or wave lengths of the spectrum, respectively, are each measured at a time point when the fluid level at the measure position is identical, so that a spectrum can be recorded that is reproducible and not influenced by fluid fluctuations.
According to the present invention, furthermore, a system or a device is provided according to the description above for use in a process as described above.
According to the present invention, furthermore, the use of a system, a device or a process according to the description above is provided for cultivation of microorganisms and/or
This concerns in particular the cultivation of mammalian cells, plant cells, insect cells, stem cells and microorganisms.
The cultivation of said microorganisms and/or cells is preferably performed for amplifying the same and/or for production of biomolecules, such as proteins, in particular for industrial or pharmaceutical purposes.
Said proteins can be, for example, antibodies, hormones, enzymes, growth factors, cytokines and the like.
Furthermore, according to the present invention, a process for teaching or calibrating a system as described above is provided, wherein in a test run a threshold value concerning (a) the physiological or physical readout or (b) the synchronization readout is defined or determined, that, when it is exceeded or underrun, triggers selection of a measured value of the physiological or physical readout that stands in a timely connection with said exceeding or underrun of the threshold value.
By this process, the best-suited measure time point is thus determined in an upstream procedure.
The present invention is further described by the drawings and examples shown and discussed in the following. It is to be understood that the drawings and examples are for illustration purposes only and are not intended to limit the scope of the invention in any way.
If a slower conductivity detector is used in this system, which for example provides measure values only every three seconds, measure signals are derived as shown by the data points of the data series in
However, if the slow sensor, which takes at least three seconds between two measurements, thus having a maximum frequency of measurements of 0.333 Hz, is synchronized with the wave movement, the measurement can always be triggered at the relevant time point of maximal sensor coverage. This situation is depicted in
The advantage of synchronization is particularly visible if the physiological readout, i.e., the conductivity, is changing over time and the changes are occurring in similar time periods as the overlapping frequency fluctuations between slow sensor detection and stirring movement. Such an example is summarized in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 119 756.1 | Nov 2015 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/077880 | 11/16/2016 | WO | 00 |
