SYSTEM AND METHOD FOR MEASURING MICROBIAL ACTIVITY

Abstract

SYSTEM AND METHOD FOR MEASURING MICROBIAL ACTIVITY A microbial activity measurement system comprising a support with a plurality of slots, each slot configured to accommodate the cap of at least one reactor, a stirring device positioned below the support, a transducer positioned above the support, and a displacement device configured to move the transducer. Abstract figure: Fig. 2

Description

Title of the invention: SYSTEM AND METHOD FOR MEASURING MICROBIAL ACTIVITY FIELD OF INVENTION

[0001] The present invention relates to a system for measuring microbial activity and more specifically for measuring biodegradability. STATE OF THE ART

[0002] One of the major industrial challenges is to produce safe substances with a good environmental profile. Professionals in the chemical, food, cosmetic, and medical sectors must therefore assess the environmental risks that may arise from their substances, particularly by measuring microbial activity. These measurements are further defined by standards.

[0003] However, known systems and procedures for measuring microbial activity are not satisfactory.

[0004] Indeed, most microbial activity measurements are carried out manually with bulky and expensive devices.

[0005] Some systems offer automated measurement procedures. However, these systems require human intervention for certain steps in the process. Furthermore, these processes necessitate opening the reactors to allow the sensors to perform measurements. This creates exchanges between the outside air and the air inside the reactor, which fundamentally alters the kinetics of microbial activity and introduces measurement biases. Finally, known systems do not necessarily comply with the testing standards imposed by regulations.

[0006] There is therefore a need for an automated system and method for measuring microbial activity in order to increase the speed of testing and to allow for reliable and accurate measurement of microbial activity without altering its kinetics. Furthermore, the method must comply with applicable regulations.

[0007] The object of the invention is therefore to provide a microbial activity measurement system comprising: at least one support, each support comprising a plurality of locations configured to accommodate a reactor, at least one stirring device, at least one transducer configured to interact with a point sensor positioned inside a reactor and a device for moving at least one transducer. SUMMARY

[0008] To this end, the present invention relates to a microbial activity measurement system comprising: - At least one support, each support comprising a plurality of upward-opening slots, each slot being configured to accommodate a reactor plug, each reactor being capable of hermetically containing a sample, each slot comprising a center defining a measurement axis perpendicular to the support; - At least one stirring device positioned under the support, each stirring device being capable of stirring the sample in a reactor; - At least one transducer positioned above the support, each transducer being configured, when aligned with the measurement axis of one of the support's locations, to interact with a point sensor positioned inside a reactor placed in said location, the point sensor then being aligned with the measurement axis, the point sensor being configured to measure at least one marker of microbial activity; and - A displacement device configured to move at least one transducer in order to align it successively with the measurement axis from several locations on the support.

[0009] Indeed, this system allows for the measurement of microbial activity without removing the reactor cap. Thus, the reactor remains airtight throughout the incubation period. Consequently, the kinetics of microbial activity are not altered during measurement, which reduces measurement bias.

[0010] Furthermore, the reactor plug does not need to be modified to allow the insertion of measuring instruments inside the reactor. The cost of implementing the system is therefore reduced, and the reactor remains perfectly airtight and safe because the absence of modification to the plug also reduces the risk of damage to the plug or the reactor.

[0011] Furthermore, incubation and microbial activity measurements can take place in a single system without the need for handling or logistics to transport reactors from an incubation system to a measurement system.

[0012] The positioning of the stirring devices under the support and of the transducer above the support allows the transducer to be moved in a two-dimensional plane without being hindered by the presence of the stirring devices.

[0013] Finally, the positioning of the plugs in the upward-opening support means that the reactors have their bottoms facing upwards. Thus, the transducer can be moved as close as possible to the point sensor of each reactor while remaining in a plane, without the need for complex three-dimensional movements – for example, raising and lowering the transducer for each reactor to avoid the reactor plugs with each movement.

[0014] This therefore implies a reduction in the cost of the system, which is all the greater the more automated the system is. Thus, a system comprising a single transducer only requires a displacement device in one plane (in two dimensions).

[0015] According to one embodiment, each stirring device includes a movable magnetic attractor positioned under a location and capable of cooperating with a magnetic agitator disposed inside the reactor placed in that location, the mobilization of the magnetic attractor enabling the magnetic agitator to be mobilized in the reactor.

[0016] Positioning the stirring device under the support and the cap of each reactor downwards allows, in the case of stirring by magnetization, for the magnetic stirrer to be positioned totally in the liquid and as close as possible to the magnetic attractor.

[0017] According to one embodiment, the transducer allows interaction by fluorescence.

[0018] According to one embodiment, at least one of the markers of microbial activity is chosen from among the quantity of oxygen, the quantity of carbon dioxide, the quantity of methane, the concentration of a predetermined chemical molecule, and / or the pressure inside the reactor.

[0019] According to one embodiment, the microbial activity measurement system further includes an enclosure configured to protect at least one transducer from external disturbances.

[0020] According to one embodiment, the microbial activity measurement system further includes a fluid recovery tank between the support and the stirring device.

[0021] Thus, the stirring device is protected in the event of a leak from one or more reactors.

[0022] The present invention also relates to a reactor suitable for hermetically containing a sample, the reactor having a side wall, a bottom and a ring onto which a plug fits, the ring having an alignment axis, a point sensor being disposed inside the reactor, on the bottom of the reactor and placed on the alignment axis, the point sensor being configured to measure at least one marker of microbial activity, the reactor being suitable for being accommodated in a location of a support of the system described above so that the plug fits into the location and the alignment axis overlaps with the measurement axis of said location.

[0023] Indeed, the reactor that can be used in the system of the invention is advantageously a commercially available reactor that requires no structural adaptation. Only the point sensor needs to be fixed to the bottom of the reactor. This results in a less expensive and easier-to-use system compared to known systems.

[0024] The point sensor can for example be pre-calibrated, which makes it possible to avoid a calibration step of the sensor before using the reactor.

[0025] According to one embodiment, the base has a thickness between 2 mm and 6 mm.

[0026] According to one embodiment, the bottom has a curvature between 600 mm and 3000 mm.

[0027] The present invention also relates to an applicator allowing the placement of a point sensor on the bottom of a reactor in order to prepare a reactor as described above, the applicator comprising a centering element adjustable on the ring of the reactor and a positioning element allowing the point sensor to be placed on the bottom of the reactor and on the alignment axis.

[0028] The present invention also relates to a method of using a microbial activity measurement system as described above, the method comprising the steps of: - Supply of at least one reactor, the reactor having a wall comprising a side wall, a bottom and a ring onto which a plug is fitted, the ring having an alignment axis; - For each reactor: • Placement of at least one point sensor configured to measure at least one marker of microbial activity inside the reactor, on the bottom of the reactor and on the alignment axis; • Introduction of a sample into the reactor; • Closing the reactor with a cap; • Place the reactor in the holder by adjusting the cap in one of the locations of the support, such that the alignment axis overlaps with the measurement axis of said location, the bottom of the reactor being positioned above the ring; - Agitation of the sample using the agitation device; - Alignment of at least one of the transducers with at least one of the measurement axes using the displacement device; - Interaction of said transducer with the point sensor in order to measure at least one marker of microbial activity.

[0029] According to one embodiment, the alignment and interaction steps are repeated at predetermined time intervals for at least one reactor.

[0030] According to one embodiment, the process further includes, before the sample is placed in the reactor, a calibration step of the point sensor.

[0031] According to one embodiment, the method of use allows the measurement of the biodegradability of the sample, the sample comprising a microbial inoculum.

[0032] According to one embodiment of the method of use, the point sensor is configured to measure the amount of oxygen inside the reactor.

[0033] According to one embodiment of the method of use, the transducer interacts with the point sensor by fluorescence. DEFINITIONS

[0034] In the present invention, the terms below are defined as follows:

[0035] “Sample” refers to a liquid comprising at least one substance for which a measurement of microbial activity – for example, a measurement of biodegradability or biodegradation – is performed. This substance may be soluble in the liquid, dispersed in the liquid, or volatile.

[0036] “Substance” refers to any molecule, polymer or mixture of molecules and polymer. DESCRIPTION OF THE FIGURES

[0037] Other features and advantages of the present invention will become apparent from the description given below, with reference to the attached drawings which illustrate examples of embodiment without any limiting character.

[0038] [Fig.1] represents the microbial activity measurement system according to one embodiment.

[0039] [Fig.2] shows the system in use. The transducer is successively positioned above each reactor by means of the displacement device in order to interact with the corresponding point sensor.

[0040] [Fig.3] shows the reactor support according to an embodiment comprising six locations.

[0041] [Fig.4] shows a set of eight reactor supports according to a mode of A design in which each support comprises six slots. Reactors are placed in six of the eight supports.

[0042] [Fig.5] shows a reactor and its stopper according to one embodiment. A point sensor is placed at the bottom of the reactor.

[0043] [Fig.6] shows an applicator according to one embodiment.

[0044] [Fig.7] shows the application of the point sensor in the bottom of the reactor using the applicator of the [Fig.6].

[0045] [Fig.8] shows the agitation according to one embodiment.

[0046] [Fig.9] shows a set of stirring devices according to one embodiment.

[0047] [Fig. 10] shows a reactor placed in a location, the plug being in low, just above a stirring device.

[0048] [Fig. 11] shows the evolution of the oxygen C level (in percent) over time T (in days) for each of the six reactors in the example. DETAILED DESCRIPTION

[0049] The present invention relates to a microbial activity measurement system 100. The system 100 is suitable for measuring any type of microbial activity in a sample. For example, the system 100 can determine the biodegradability of certain chemical substances by measuring the oxygen consumption of the microbial inoculum present in the sample. In another example, the system 100 can determine the activity of starter cultures for fermentation, enabling the acceleration of fermentation processes in the food, pharmaceutical, biotechnological, and renewable energy sectors. In yet another example, the system 100 can measure the effect of an active ingredient—for example, an antibiotic—or a molecule on the growth of bacteria or fungi in medicine or cosmetics.

[0050] System 100 allows, in particular, the implementation of the 301 AF methods for easy biodegradability measurement according to the OECD guidelines for testing chemicals (adopted in 1992 and amended in 2013). In these methods, the sample is placed in a filled and hermetically sealed vial. The vials are incubated at a constant temperature and in the dark for 28 days. A marker of microbial activity is measured, for example, dissolved organic carbon (301 A and 301 E), CO2 released (301 B), oxygen consumption (301 C and 301 F), or dissolved oxygen (301 D), allowing estimation of the biodegradation that has occurred in the sample. The measurement can also be based on a quantity derived from or correlated with one of these markers.

[0051] In order to be able to carry out microbial activity measurements, particularly in the case of OECD 301 AF method tests, the system 100, shown in Figures 1 and 2, comprises: - At least one 120 support; - At least one stirring device 140 positioned under the support 120; - At least one 160 transducer positioned above the 120 support; and - A displacement device 165 configured to move at least one transducer 160.

[0052] Each support 120 comprises a plurality of upward-opening slots 125 as shown in [Fig. 3]. Preferably, each support 120 comprises 2x3 slots 125. Each slot 125 comprises a center defining a measurement axis Al perpendicular to the support 120.

[0053] Each location 125 is configured to accommodate a reactor 180 as shown in [Fig. 4]. This [Fig. 4] represents a system 100 comprising eight supports 125, each support comprising 2x3 slots 125 allowing automatic measurement of up to 48 reactors 180.

[0054] The reactors 180 that can be used in the system 100 can be of any type. For example, the reactors 180 can be round laboratory bottles with screw caps from the Duran Schott brand (registered trademark) with a volume between 50 mL and 1 L. Preferably, the reactors 180 have a volume between 100 mL and 250 mL. The volume of 133 mL is a good compromise between the space required for 48 tests and the volume of air needed for microbial activity.

[0055] A reactor 180, by definition, has a wall and a ring onto which a plug 182 is fitted. The ring is the upper part of the reactor 180 onto which the plug 182 is positioned. The ring may include a thread onto which the plug 182 screws or a ring onto which the plug 182 clips. When the plug 182 is not positioned on the ring, the latter allows access to the interior of the reactor 180. An example of the shape of a reactor 180 is shown in [Fig. 5]. However, the morphology of the wall of the reactor 180 is of little importance. The wall may be transparent, preferably made of glass, for example, borosilicate glass. Glass ensures sufficient sealing against gas diffusion. The wall comprises a side wall 184a and a bottom 184b. The 184b base can have a thickness between 2 mm and 6 mm, preferably between 3.5 mm and 4.5 mm.The bottom 184b, even if it can be flat, can also have a radius of curvature between 600 mm and 3000 mm, preferably between 900 mm and 1250 mm. The ring includes a center defining an alignment axis A2 extending between the ring and the bottom 184b.

[0056] More precisely, each location 125 is configured to accommodate a plug 182. Preferably, each location 125 is configured so that its shape is adjusted to the shape of the plug 182 that will be accommodated. By "adjusted," it should be understood that the plug can be inserted into the location but is positioned in such a way as to prevent any movement and therefore any change in the position of the reactor 180. Alternatively, the reactors 180 are chosen so that their plugs fit into the locations 125. This allows the reactor 180 to be held vertically "upside down" so that the plug 182 is positioned under the bottom 184b. Preferably, the plug 182 is adjusted in the location 125 so that the alignment axis A2 coincides with the measuring axis A1 of said location 125.

[0057] Each reactor 180 is capable of hermetically sealing a sample. The sample preferably contains a microbial inoculum, that is, a collection of microorganisms (for example, bacteria, fungi, or protists) whose activity will be measured over time. But the system 100 It can also use a single species of microorganism. The activity of the microbial inoculum is measured by a spot sensor 150 located inside the reactor 180, on the bottom 184b of the reactor 180. The spot sensor 150 is preferably positioned on the alignment axis A2. Thus, when the plug 182 is inserted into the slot 125, the spot sensor 150 is aligned with the measurement axis AL

[0058] To facilitate the repeatability of the alignment of the point sensor on the alignment axis A2, an applicator 190 can be used. An example of an applicator is shown in [Fig. 6]. The applicator 190 includes a centering element 192 that is adjustable on the ring of the reactor 180. For example, if the ring has a thread for screwing on the plug 182, the centering element 192 can also have a thread for screwing onto the ring in the same way as the plug 182. The applicator 190 further includes a positioning element 194 for placing the point sensor 150 on the bottom 184b of the reactor 180 and on the alignment axis A2.

[0059] The application of the point sensor 150 using this applicator 190 is shown in [Fig. 7]. The centering element 192 is fitted onto the ring, and the positioning element 194 is long enough to secure the point sensor 150 to the base 184b. The point sensor 150 can, for example, be secured by gluing. After securing the sensor 150, the applicator 190 is removed from the reactor. The applicator 190 can advantageously be reused for all reactors of the same size.

[0060] The point sensor 150 is preferably configured to measure at least one marker of microbial activity, for example, the level or quantity of carbon dioxide (CO2), the level or quantity of methane (CH4), the pressure, the concentration of a predetermined chemical molecule, and / or the temperature in the reactor 180. Preferably, the marker of microbial activity is the level or quantity of dissolved oxygen (OECD method 301 D). Indeed, during the biodegradation of substances, the microbial inoculum consumes oxygen to oxidize said substances. Thus, the quantity of dissolved oxygen consumed, also called biochemical oxygen demand (BOD), makes it possible to quantify the quantity of material that can be degraded and therefore the biodegradability of the sample.

[0061] These markers of microbial activity can be measured directly in the sample. These markers of microbial activity are preferably measured in the atmosphere of reactor 180, i.e., above the surface of the sample. The point sensor 150 can advantageously be pre-calibrated. This eliminates the need for a calibration step of the point sensor 150 before using each reactor 180.

[0062] Each stirring device 140 of the system 100 is capable of stirring (mixing) the sample in a reactor 180. Mixing the sample is advantageous because it ensures homogeneous activity of the microbial inoculum throughout the sample. The stirring device 140 is preferably configured to stir the sample without opening the stopper 182 of the reactor 180.

[0063] The stirring device can, for example, be a vibrating or rotating platform on which the support(s) are placed.

[0064] Preferably, each stirring device 140 comprises a movable magnetic attractor 144 positioned under a location 125 and capable of cooperating with a magnetic agitator 148 disposed inside the reactor 180 housed in this location 125. The magnetic agitator 148 may, for example, be a magnetic bar. Mobilizing the magnetic attractor 144 thus allows the magnetic agitator 148 to be moved within the reactor 180. For example, mobilizing the magnetic attractor 144 is an actuation or movement of this attractor 144, for example, by means of an actuator 146 such as a motor. In [Fig.8], the motor 146 allows, for example, a propeller 142 comprising two magnets forming the magnetic attractor 144 to be rotated in a direction Fl. The rotation of the two magnets implies the rotation in the direction F2 of the magnetic agitator 148 thanks to the force of magnetic attraction.The movement of the magnetic stirrer 148 allows the sample contained in the reactor 180 to be agitated. An example of a set of magnetic attractors 144 is shown in [Fig.9]. In this figure, the magnetic attractors 144 are positioned in a base which advantageously allows the position of the magnetic attractors 144 to correspond with the support locations 125 120 as shown in [Fig.3].

[0065] Positioning the reactor 180 "upside down" advantageously allows the movement of the magnetic stirrer 148, which settles into the stopper 182 due to gravitational attraction, without risk of damage to the point sensor 150 fixed to the bottom 184b. Furthermore, in this configuration, the magnetic stirrer 148 can be fully immersed in the sample, resulting in improved mixing efficiency. Finally, positioning the magnetic stirrer 148 in the stopper of the reactor 180 brings it closer to the magnetic attractor 144, further enhancing mixing thanks to the greater magnetic attraction between these two elements.

[0066] Advantageously, the system 100 may further include a fluid recovery tank positioned between the support 120 and the stirring devices 140. This allows the fluid (sample) to be recovered in the event of a leak from the reactors 180 and prevents damage to the actuators 146.

[0067] Each transducer 160 of the system 100 is configured, when aligned with the measuring axis A1 of one of the locations 125, to interact with a point sensor 150 of a reactor 180 housed in that location 125. This interaction allows the transmission of the measurement performed by the point sensor 150 to the transducer 160 and / or the sending of an instruction signal from the transducer 160 to the point sensor 150. Thus, the measurement performed in situ is read through the wall of each reactor 180 without opening the cap 182. The reactor 180 therefore remains hermetically sealed throughout the incubation and measurement periods, which prevents any alteration of the kinetics of microbial activity. Similarly, this avoids modifying the cap or the wall of the reactors 180 to insert measuring elements. Thus, the 180 reactors, which are consumables, can be 180 reactors commonly found in commerce and therefore cheaper.Furthermore, the absence of modification to the plug or the wall maintains the safe operation of reactors 180.

[0068] The glass wall of the reactor 180 advantageously allows the transmission of the measurement or instruction signal using a wavelength between 0.38 pm and 0.78 pm. For example, the interaction between the transducer 160 and the point sensor 150 is achieved by fluorescence. For example, the transducer 160 used is the Presens Electro-Optical Module E0M-02-F0M combined with Presens PSt3 point sensors 150.

[0069] In the context of a fluorescence measurement, the point sensor 150 contains a fluorescent marker whose fluorescence yield is linked to the concentration of a molecule in the sample. Thus, after equilibrium has been reached between the sample and the point sensor 150—this equilibrium being rapid compared to the characteristic evolution time of the sample—the fluorescence intensity of the point sensor is an indirect measure of the concentration of said molecule, for example, a marker of microbial activity. It should be noted that the measurement can be very indirect. Thus, the point sensor 150 can be sensitive to the oxygen concentration in the reactor headspace, this gaseous oxygen concentration being itself in equilibrium with the dissolved oxygen whose concentration is to be measured.

[0070] An example of a system 100 configuration in which a single location 125 is represented is shown in [Fig. 10] with the magnetic attractor 144 positioned under the location closest to the plug of the reactor 180 and the transducer 160 positioned above the bottom 184b of the reactor 180 closest to the point sensor 150. The measuring axis Al is then aligned with the alignment axis A2.

[0071] In order to align the transducer 160 with the measuring axis A1, the system 100 includes a displacement device 165. Positioning the reactor 180 "upside down" and fixing the point sensor 150 to the bottom 184b allows It is advantageous to successively position the transducer 160 as close as possible to each of the sensors 150 in a simple movement within a plane. The displacement device 165 thus does not necessarily need to be configured to perform an up-and-down movement each time it passes from one reactor 180 to the other. The positioning accuracy of the transducer 160 is preferably on the order of a millimeter. To achieve such accuracy, CNC (Computer Numerical Control) based technology can be used.

[0072] Advantageously, the system 100 may further include an enclosure configured to protect at least one transducer from external disturbances.

[0073] The system described above advantageously reduces measurement bias.

[0074] The invention also relates to a method of using the microbial activity measurement system described above. The method comprises the steps of: - Supply of at least one reactor 180; - For each reactor 180: • Placement of at least one point sensor 150 inside reactor 180, on the bottom 184b of reactor 180 and on the alignment axis A2; • Introduction of a sample into reactor 180; • Closing reactor 180 with plug 182; • Placement of reactor 180 in one of the 125 slots of the support, such that the alignment axis A2 overlaps with the measurement axis Al of location 125, the bottom 184b of reactor 180 being positioned above the ring; - Agitation of the sample using the stirring device 140; - Alignment of at least one of the transducers 160 with at least one of the measurement axes Al using the displacement device 165; - Interaction of transducer 160 with point sensor 150.

[0075] The alignment and interaction steps can be repeated at predetermined time intervals for at least one reactor 180.

[0076] The method may further include, before the sample is placed in the reactor 180, a calibration step of the point sensor 150. The calibration may include a calibration step of the signal as a function of the material, the thickness and the curvature of the bottom 184b of the reactor 180. The calibration may include, alternatively or in combination, a calibration step of the point sensor 150 itself, for example if this point sensor 150 is not pre-calibrated. Examples

[0077] The present invention will be better understood by reading the following example which illustrates, without limitation, the use of the system.

[0078] In this example, the system 100 includes a support 120 comprising 2x3 locations 125, six magnetic stirring devices 140 positioned under the support 120, a transducer 160 positioned above the support 120 and a displacement device 165.

[0079] Each location 125 accommodates a reactor 180. The reactors 180 are round borosilicate glass laboratory bottles with screw caps, manufactured by Duran Schott (registered trademark), with a volume of 133 mL. The reactors 180 are positioned vertically "upside down" so that the cap 182 is positioned below the base 184b.

[0080] Three test reactors 180 (RI, R2, R3) are filled with a sample containing a microbial inoculum and sodium acetate. The other three reactors 180 serve as controls. Two of them (R4, R5) contain only the same microbial inoculum as the test reactors 180, while the third (R6) contains only sodium acetate (in the same quantity and concentration as RI, R2, and R3) in an abiotic medium.

[0081] The point sensor 150 present in each of the reactors 180 is configured to measure the oxygen O2 level.

[0082] The interaction between the transducer 160 and the point sensor 150 is achieved by fluorescence. The transducer 160 used is the Presens Electro-Optical Module E0M-02-F0M, while the point sensor 150 is the Presens PSt3, whose fluorescence intensity is related to the dissolved oxygen concentration.

[0083] The alignment of the transducer 160 and the reading of the oxygen level by fluorescence for each of the reactors 180 are carried out at regular intervals for approximately 4 days.

[0084] Fig. 11 shows the evolution of the oxygen level C (in percent) in the sample over time T (in days) for each of the reactors 180 (R1-R6).

[0085] First, it is noted that the oxygen level in the control reactors 180 (R4, R5, R6) remains stable (variation less than 2%) during the measurements. This clearly shows that the system exhibits high stability, which reduces measurement bias.

[0086] Secondly, it is observed that the oxygen concentration (¹³C) decreases in the three test reactors 180 (RI, R2, R3) at approximately 1.5 days, 1.7 days, and 2.3 days, respectively. This decrease lasts between 0.2 and 0.3 days. Afterward, the oxygen concentration remains stable. This demonstrates that sodium acetate is rapidly degraded, and the system according to the invention allows for a precise and reliable measurement of the evolution of the oxygen concentration and for accurately determining the biodegradability of the sodium acetate sample. DIGITAL REFERENCES

[0087] 100 - System / / 120 - Support / / 125 - Location / / 140 - Device agitation / / 142 - Propeller / / 144 - Magnetic attractor / / 146 - Actuator / / 148 - Magnetic agitator / / 150 - Point sensor / / 160 - Transducer / / 165 - Displacement device / / 180 - Reactor / / 182 - Plug / / 184a - Side wall / / 184b - Bottom / / 190 - Applicator / / 192 - Centering element / / 194 - Positioning element / / Fl - Propeller rotation / / F2 - Magnetic attractor rotation / / Al - Measurement axis / / A2 - Alignment axis IIC- Oxygen content / / R1-R6 - Six different reactors for biodegradability measurement / / T - Time.

Claims

Demands

1. A microbial activity measurement system (100) comprising: - At least one support (120), each support (120) comprising a plurality of slots (125), each slot (125) being configured to accommodate a reactor (180), each reactor (180) comprising a plug (182) suitable for being disposed in the slot (125), preferably each slot (125) being open upwards so as to position the bottom (184b) of the reactor (180) above the plug (182) of the reactor (180), each reactor (180) being suitable for hermetically containing a sample, each slot (125) comprising a center defining a measurement axis (A1) perpendicular to the support; - At least one stirring device (140) positioned under the support (120), each stirring device (140) being suitable for stirring the sample in a reactor (180);- At least one transducer (160) positioned above the support (120), each transducer (160) being configured, when aligned with the measurement axis (Al) of one of the locations (125) of the support, to interact with a point sensor (150) positioned inside a reactor (180) placed in said location (125), the point sensor (150) then being aligned with the measurement axis (Al), the point sensor (150) being configured to measure at least one marker of microbial activity; and - A displacement device (165) configured to move the at least one transducer (160) in order to align it successively with the measurement axis (Al) of several locations (125) of the support.

2. The microbial activity measurement system (100) according to claim 1, wherein each stirring device (140) comprises a movable magnetic attractor (144) positioned under a location (125) and capable of cooperating with a magnetic stirrer (148) disposed inside the reactor (180) placed in that location (125), the mobilization of the magnetic attractor (144) allowing the magnetic stirrer (148) to be mobilized in the reactor (180).

3. The microbial activity measurement system (100) according to any one of claims 1 to 2, wherein the transducer (160) enables interaction by fluorescence.

4. The microbial activity measurement system (100) according to any one of claims 1 to 3, wherein at least one of the markers of microbial activity is selected from the amount of oxygen, the amount of carbon dioxide, the amount of methane, the concentration of a predetermined chemical molecule, and / or the pressure inside the reactor (180).

5. A reactor (180) capable of hermetically containing a sample, the reactor (180) having a side wall (184a), a bottom (184b) and a ring in the upper part of the reactor (180) onto which a plug (182) fits, the ring having an alignment axis (A2), a point sensor (150) being disposed inside the reactor (180), on the bottom (184b) of the reactor (180) and positioned on the alignment axis (A2), the point sensor (150) being configured to measure at least one marker of microbial activity, the reactor (180) being capable of being accommodated in a slot (125) of a support of the system (100) according to any one of claims 1 to 4 such that the plug (182) fits into the slot (125) and the alignment axis (A2) overlaps with the measurement axis (Al) of said location (125).

6. The reactor (180) according to claim 5, wherein the bottom (184b) has a thickness between 2 mm and 6 mm.

7. The reactor (180) according to any one of claims 5 to 6, wherein the bottom (184b) has a curvature between 600 mm and 3000 mm.

8. An applicator (190) allowing the placement of a point sensor (150) on the bottom (184b) of a reactor (180) in order to prepare a reactor (180) according to any one of claims 5 to 7, the applicator (190) comprising a centering element (192) adjustable on the ring of the reactor (180) and a positioning element (194) allowing the point sensor (150) to be placed on the bottom (184b) of the reactor (180) and on the alignment axis (A2).

9. A method of using a microbial activity measurement system (100) according to any one of claims 1 to 4, the method comprising the steps of: - Providing at least one reactor (180), the reactor (180) having a wall comprising a side wall (184a), a bottom (184b) and a ring in the upper part of the reactor (180) onto which a plug (182) is fitted, the ring having an alignment axis (A2); - For each reactor (180): • Placing at least one point sensor (150) configured to measure at least one marker of microbial activity inside the reactor (180), on the bottom (184b) of the reactor and on the alignment axis (A2); • Introducing a sample into the reactor (180); • Closing the reactor (180) with a plug (182);• Placement of the reactor (180) in the support (120) by adjusting the plug (182) in one of the slots (125) of the support, such that the alignment axis (A2) overlaps with the measurement axis (A1) of said slot (125), the bottom (184b) of the reactor (180) being positioned above the ring; - Agitation of the sample using the stirring device (140); - Alignment of at least one of the transducers (160) with at least one of the measurement axes (A1) using the displacement device (165); - Interaction of said transducer (160) with the point sensor (150) in order to measure at least one marker of microbial activity.

10. The method of use according to claim 9, wherein the alignment and interaction steps are repeated at predetermined time intervals for at least one reactor (180).

11. The method of use according to claim 9 or 10, further comprising, before the disposition of the sample in the reactor (180), a calibration step of the point sensor (150).

12. The method of use according to any one of claims 9 to 11 allowing the measurement of the biodegradability of the sample, the sample comprising a microbial inoculum.

13. The method of use according to claim 12, wherein the point sensor (150) is configured to measure the amount of oxygen inside the reactor (180).

14. The method of use according to claim 12 or 13, wherein the transducer (160) interacts with the point sensor (150) by fluorescence.

Images