Abstract:
An improved system and method for dispensing dehydrated culture media (DCM) powder into containers for preparation as a culture media. The manual and automated systems and methods operate to dispense DCM powder, as well as liquid, into vessels or media preparation instruments in a manner to avoid DCM dust inhalation by persons in the surrounding area and contamination of equipment and surfaces in the surrounding area.

Description:
[0001]    This is a divisional application of U.S. patent application Ser. No. 11/119,792, filed on May 3, 2005, the entire content of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention provides an improved system and method for dispensing dehydrated culture media (DCM) powder into containers for preparation of culture media. More particularly, the present invention relates to improved manual and automated systems and methods for dispensing DCM powder into vessels or media preparation instruments in a sanitary manner to avoid contamination by DCM powder dust to the surrounding area. 
         [0004]    2. Description of the Related Art 
         [0005]    Microbiology laboratories are required to produce large quantities of agar based growth media to use in the growth of bacteria and other microorganisms. Regardless of the specific agar media formulation used, most media are prepared by mixing powdered dehydrated culture media (DCM) with water and then sterilizing the mixture in an autoclave to insure the growth media is free of contamination. The dehydrated media powder, which is ground very fine, is typically delivered to the laboratory in plastic containers of varying sizes. A laboratory technician will typically scoop or pour out and weigh the required amount of DCM powder, add the appropriate amount of water, and mix and warm the mixture using, for example, a magnetic stirring motor with stir bar. Once the DCM and water have been completely mixed, the mixture is sterilized by autoclave or media preparator. 
         [0006]    As used in most laboratories, DCM is a very light and fine powder. Some DCM formulations are highly toxic and all are irritants to some degree. When poured, DCM often forms a cloud of dust that rises above and around the technician who is dispensing the powder. This “media cloud” or “dusting” causes several problems. Often the technician will inhale DCM dust, which can be a health hazard. Additionally, as the dust settles it leaves a film of agar on surrounding laboratory surfaces. Because DCM typically is used in areas that tend to be warm and moist due to the close proximity of steam-producing autoclaves, the media dust leaves a sticky film that is difficult to clean and that increases the likelihood of surface contamination. Moreover, because the DCM is a fine powder, it tends to penetrate into very small spaces in the laboratory, including the inside surfaces of scientific instruments where the resulting film can cause damage and excess wear over time. 
         [0007]    Another problem is that the process of dispensing DCM is time consuming since a precise quantity should first be weighed prior to adding water. A further problem is that mixing large batches of DCM with water, e.g., batches of certain types of media larger than 10 liters, often requires DCM and water to be added alternately in limited quantities each time to avoid clumping of the media. This increases the time needed to create the media, contributes to inaccuracies and errors and increases the likelihood of DCM dusting. A further problem is that technicians sometimes are imprecise in their measurements of DCM or water. It is also important for technicians to be able to readily identify different containers including different types of media cultures without close inspection, to thus increase the efficiency of the dispensing process. 
         [0008]    Accordingly, a need exists for an improved system and method for dispensing DCM in a sanitary manner to avoid contamination to surrounding areas and minimize exposure to technicians and other personnel. 
       SUMMARY OF THE INVENTION 
       [0009]    An embodiment of the present invention provides an automated or manual system for delivering DCM powder to a preparation instrument or a container in a sanitary manner to prevent media dusting by eliminating or substantially reducing the formation of the DCM media cloud during the preparation process. An embodiment of the present invention further provides a method for a convenient, rapid, exact and reproducible dispensing of DCM into either flasks or automated media sterilizers or other instruments. 
         [0010]    The embodiments of the present invention further are capable of dispensing an appropriate amount of water or liquid into a media sterilizer or other instrument or container while simultaneously dispensing DCM powder in the proper amount and in a manner so as to avoid clumping. The metering device can be programmable to dispense the appropriate admixture of water and DCM depending on the concentration desired. The embodiments of the present invention are also able to prevent or minimize laboratory errors by applying color coding or other identification indicia to the DCM containers to indicate specific media formulations, thereby reducing the likelihood that the incorrect DCM formulation will be used by a technician. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    These and other objects, advantages and novel features of the invention will be more readily appreciated from the following detailed description when read in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a conceptual block diagram illustrating an example of an automated system for dispensing DCM powder into a media preparation instrument according to an embodiment of the present invention; 
           [0013]      FIG. 2  is an example of a container which stores the DCM powder according to an embodiment of the present invention; 
           [0014]      FIG. 3  is a top view of the container as shown in  FIG. 2 ; 
           [0015]      FIG. 4  illustrates an example of an adapter according to an embodiment of the present invention, that can be used with the container shown in  FIG. 2 ; 
           [0016]      FIG. 5  is a detailed top view of the portion of the motorized valve assembly of the system shown in  FIG. 1  that receives the mouth of the DCM container according to the embodiment of the present invention; 
           [0017]      FIG. 6  illustrates an example of the features of the rotatable valve of the valve assembly shown in  FIG. 1  for dispensing the DCM powder in a measured fashion according to an embodiment of the present invention; and 
           [0018]      FIG. 7  illustrates an example of another system for dispensing DCM powder into a flask in a measured manner according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]      FIG. 1  illustrates an automated system  100  for dispensing DCM powder according to an embodiment of the present invention. As illustrated, the automated system  100  includes a motorized valve assembly  102  that is connected via a conduit  104  to a media preparation instrument  106 . The media preparation instrument can be any type of instrument such as the MediaPrep line from Systec Gmbh, Wettenberg, Germany, Masterclave line from AES Laboratoire, Rennes, France, or MediaClave line from Integra Biosciences, Chur, Switzerland, each of which are commercially available. 
         [0020]    As further illustrated, the system further includes a flow meter  108 . The flow meter is electronically controlled with a digital or analog input and output for communication with a secondary device used to inject the DCM powder into the system. The flow meter can work on the basis of peristaltic action or other common commercial methodologies such as magnetic, ultrasonic, positive displacement or differential pressure. The flow meter instrument can be any type of instrument such as the AES PM05 from AES Laoratoire, Rennes, France, or the Perimatic GP or Perimatic Premier from Jencons Scientific, Inc., Bridgeville, Pa., that is connected to a water supply  110  or other liquid supply and provides water or other liquid to the media preparation instrument  106  in a regulated manner via flexible tube  112  as discussed in more detail below. The tube  112  is connected to a rigid tube  113  made of, for example, stainless steel or any other suitable material, and which extends near the bottom of the interior of the media preparation instrument  106  to minimize clumping of the DCM powder  120  and to improve mixing. The rigid tube  113  allows water to be added below the surface line of the DCM mixture to prevent or decrease the incidence of splashing or bubbling to prevent or substantially prevent, or at least minimize, the contact of water with the media entry port. A flexible tube may be utilized in place of the rigid tube  113 ; provided such flexible tube is configured so as to prevent or decrease the incidence of splashing or bubbling in the media preparation device. In practice, the tube  113  can be of any suitable material, such as rigid plastic, flexible plastic, bendable metal, a flexible hose, and so on, as long as it is positioned to prevent or substantially prevent the incidence of splashing or bubbling and its opening is at a sufficient distance from the media entry port. The motorized valve assembly  102  and flow meter  108  are connected by a communication cable  114  so that the rate at which the DCM powder is dispensed by the motorized valve  102  is coordinated with the rate at which liquid is dispensed into the media preparation instrument  106  by the flow meter  108  under the control of a controller  116 , which can be a processor or any type of computer as can be appreciated by one skilled in the art. The controller  116  can be programmable by the technician or other suitable personnel as desired and with ease to control the desired dispensing rate of the DCM powder and liquid as discussed in more detail below. As further illustrated, the motorized valve  102  receives a container  118  in which the DCM powder is stored. 
         [0021]    An example of a container for storing the DCM powder is shown in  FIG. 2 . In particular, the container  118  includes a container portion  120  and a cap  122 . The container portion  120  can be any shape, although according to an embodiment of the present invention, it is advantageous for stacking purposes for the container to be shaped in the form of a rectangle or square having flat or substantially flat sides as shown in  FIG. 2  and in the top view of  FIG. 3 . As further illustrated in  FIG. 3 , the cap  122  is preferably square shaped and has a flat or substantially flat top surface to allow the containers to be stacked vertically. The width and length of the cap  122  can correspond to the width and length of the container portion  120  as shown, or can be less than or greater than the width and length of the container portion  120 , as deemed suitable for storage and stacking purposes. 
         [0022]    In addition, for identification purposes, the container portion  120  and the cap  122  can be coded with a color or other indicator representing the contents of the container  118 . For instance, this identification can be a color coding (e.g., red, green, blue, etc.) that is present on portions or the entirety of the container portion  120  and cap  122 , a type of indicia (e.g., numbers, letters or alphanumeric symbols) on the container portion  120  and cap  122  representing the content of the container, and/or a bar code representing the content of the container  118 . Various safety warnings and other relevant information can also be present on the container portion  120 , cap  122  or both. Also, the container portion  120  and cap  122  can be made of any suitable material, such as plastic or various polymers, and can be opaque, or can be translucent so that a technician can readily determine the amount of DCM powder remaining in the container. Furthermore, the mouth of the container portion  120  is tapered or conical in shape so as to allow the DCM powder to readily flow from the container portion  120  when the container portion  120  is set in an upside down position with the cap  122  removed, and includes threads  121  as indicated. The mouth of the container portion  120  and the cap  122  can have threads  123  so that the cap  122  can be screwed onto exterior threads on the container portion  120 . The container portion  120  can also be configured to include threads  121  on its interior wall near its opening. In this event, the container portion  120  can be screwed onto the motorized valve assembly  102  of  FIG. 1  or the valve assembly  146  of  FIG. 6 , or directly onto the inlet of the media preparation instrument  106 , regardless of whether the motorized valve assembly  102 , valve assembly  146  or the inlet of the media preparation instrument  106 , has interior or exterior threads. Alternatively, the cap  122  can be snap-fit onto the container portion  120 , and the container portion  120  can simply be placed in an inverted manner so that its opening is received into the opening in the motorized valve assembly  102 , valve assembly  146  or the inlet of the media preparation instrument  106 . 
         [0023]    In addition, it should be noted that the container portion  120  can have a volume that contains a pre-measured, pre-packaged quantity of DCM powder for a single-use, so that the container  118  can be discarded after its DCM powder contents has been dispensed as discussed in more detail below. It should be further noted that the container  118  can alternatively be configured as a burstable pouch or bag, for example, that contains a pre-measured, pre-packaged amount that can be dispensed directly into the media preparation instrument  106 , into the media preparation instrument  106  via an adapter  125  as shown in  FIG. 4 , or into the motorized valve assembly  102  when pressure is applied to the container portion  120  to burst the container  120 , and then the container portion  120  can be discarded. Concerning the adapter  125 , as indicated in  FIG. 4 , the adapter  125  can be shaped at an angle, or can include a lancet  127 , such that when the container portion  120  is mated with the adapter  125 , the lancet  127  or angled portion of the adapter  125  pierces a membrane (e.g., a rupturable membrane) present at the mouth of the container portion  120 . Furthermore, the adapter can have threads  129  that mate with the threads  123  on the outside of the container portion  120  so that the container portion  120  can be screwed onto the adapter  125 . It is further noted that the threads  123  can also be present on the outside of the adapter  125  as indicated, to mate with interior threads of the container portion  120  should such an arrangement be necessary. The other end of the adapter  125  can include threads  133  that can be on the exterior surface of the adapter  125 , the interior surface of the adapter  125  (as indicated by the breakaway section), or both, to allow the adapter  125  to mate with the motorized valve assembly  102 , valve assembly  146  or the inlet of the media preparation instrument  106 , regardless of whether the threads of the valves  102  or  146 , or at the inlet of the media preparation instrument  106 , are exterior or interior. 
         [0024]    An example of the operation of the automated system  100  will now be described with reference to  FIG. 1 . As indicated, the cap  122  is removed from the container  118  and the container portion  120  is placed in an upside-down vertical or substantially vertical position on the top of the motorized valve assembly  102 . As shown in  FIG. 5 , the mouth  124  of the motorized valve assembly  102  can have a lancet  126  or other suitable puncturing mechanism for puncturing any membrane (e.g., a rupturable membrane) that may be present at the mouth of the container portion  120 , so that the DCM powder can be gravity-fed into the motorized valve assembly  102 . The inner surface of the mouth  124  of the motorized valve assembly  102  can also include threads  131  that can mate with the threads  123  at the outside mouth of the container portion  120  as the container portion  120  is mated with the motorized valve assembly  102 . Alternatively, the mouth of the container portion  120  can simply mate with the mouth  124  of the motorized valve assembly  102  in any suitable manner. As noted above, the adapter  125  can be used to couple the container portion  120  to the mouth  124  of the motorized valve assembly  102 . In this regard, the adapter can have threads  133  that mate with the threads  131  on the inner surface of the mouth  124  of the motorized valve assembly  102 . In any event, the mating of the container portion  120  and the mouth  124  of the motorized valve assembly  102 , either directly or via the adapter  125 , as well as the mating of the container portion  120  with the media preparation instrument  106  directly or via the adapter  125 , form a closed or substantially closed system that eliminates or at least substantially eliminates DCM dust formation outside of the media preparation instrument  106 . The mouth  124  of the motorized valve assembly  102  can alternatively be configured to mate with a container  118  that is configured as a burstable pouch or bag as discussed above, either directly or via the adapter  125  in any of the manners described above, so that when pressure is applied to the container portion  120 , the pre-measured amount of DCM powder is dispensed into the motorized valve assembly  102  while maintaining the closed system to eliminate or at least substantially eliminate DCM dusting, and then the container portion  120  and cap  122  can be discarded. 
         [0025]    As further illustrated in  FIG. 5 , the motorized valve assembly  102  can include a motor  128 , such as a DC servo motor, a stepper motor, or any other suitable motor, that can be controlled by the controller  116  to rotate a rotatable valve  130  of the motorized valve assembly  102  that is shown in  FIG. 1  and in more detail in  FIG. 6 . As indicated, the rotatable valve  130  includes wells  132  having a volume corresponding to a desired volume or mass of DCM powder (e.g., 15 grams) that is to be dispensed into the media preparation instrument  106 . That is, the rotatable valve  130  is rotated at a desired rate as controlled by the controller  116  to periodically dispense the appropriate amount of DCM powder into the media preparation instrument  106  via the conduit  104 . In addition, as the rotatable valve  130  is being rotated under the control of the controller  116 , the flow meter  108  is controlled by the controller  116  to dispense an appropriate amount of liquid into the medium preparation assembly  106  via the tube  112 . The ratio of dehydrated media to liquid is user controllable. For example, in a 100 liter preparation, one-fifth of the total DCM to be solubilized is added with every 20 liters of water. The user is able to define any ratio of total DCM to water, e.g., ¼ DCM combined incrementally with ¼ water or ⅓ DCM combined incrementally with ⅓ water. Accordingly, the rotatable valve  130  can be rotated more rapidly to dispense the DCM powder into the media preparation instrument  106  at a faster rate, while the controller  116  can proportionately control the flow meter  108  to increase the flow of liquid into the media preparation instrument  106 . The motorized valve assembly  102  can further include a counter  135 , such as a mechanical or digital counter as known in the art, that counts the number of rotations of the rotatable valve  130 , and can be automatically or manually reset to zero after the desired amount of DCM powder has been dispensed. 
         [0026]    It should be also noted that the rotatable valve  130  can be removed and replaced with another rotatable valve having wells of a different volume which thus feed a greater amount or lesser amount of DCM powder into the media preparation instrument  106  per each rotation. Furthermore, as shown in  FIG. 5 , the motorized valve assembly  102  can include an agitator  134 , such as a vibrating coil or any other suitable component, to shake or vibrate the motorized valve assembly  102  to allow the DCM powder to more freely flow through the motorized valve assembly  102  and conduit  104  into the media preparation instrument  106 . 
         [0027]    It should also be noted that the rotatable valve  130  can include a handle  138  that can be turned manually if is desired to operate the rotatable valve  130  manually. The flow meter  108  can also be operated manually if desired. As further indicated, the media preparation instrument  106  includes a stirrer magnet  136  as known in the art which can provide further stirring and agitation of the powder and liquid mixture in the media preparation instrument  106 . It can be further noted that the controller  116  can be connected by any suitable means to the controller (not shown) of the media preparation instrument  106  to increase or decrease the rate of stirring by the stirring magnet  138  depending on the rate of deposit of DCM powder and liquid by the motorized valve assembly  102  and flow meter  108 . Accordingly, this system  100  allows for the accurate dispensing of DCM powder and liquid into the media preparation instrument  106  in a clean and sanitary manner, with little or no waste of the DCM powder, minimal contamination of the surrounding areas due to dusting, and minimal exposure to the lab technician and other personnel due to dusting. 
         [0028]    Although  FIG. 1  and its related figures illustrate an automated system  100  for dispensing DCM powder into a media preparation instrument  106 , the automated system  100 , or a manual system, can be used to dispense the powder into another vessel or flask  140 , such as an Erlenmeyer flask, as illustrated in  FIG. 7 . As indicated in  FIG. 7 , the system includes a ring stand  142  having a support  144  for supporting the container portion  120  in an upside down vertical or substantially vertical manner so that the DCM powder can flow by gravity into the valve assembly  146 . The valve assembly  146  can include threads that mate with threads  123  on the outside of the mouth of the container portion  120 , or the container portion  120  can simply be received into an opening in the valve assembly  146 . Alternatively, the container portion  120  can be mated with the valve assembly  146  via the adapter  125  in the manner discussed above with regard to the motorized valve assembly  102 , so as to form a closed or substantially closed system. Accordingly, the mating of the container portion  120  and the valve assembly  146 , either directly or via the adapter  125 , form a closed or substantially closed system that eliminates or at least substantially eliminates DCM dust formation outside of the vessel  140 . The valve assembly  146  can alternatively be configured to mate, either directly or via the adapter  125 , with a container  118  that is configured as a burstable pouch or bag as discussed above, so that when pressure is applied to the container  118 , the pre-measured amount of DCM powder is dispensed into the valve assembly  146  when pressure is applied to the container  118  while maintaining the closed or substantially closed system to eliminate or at least substantially eliminate DCM dusting, and then the container  118  can be discarded. Furthermore, as can be appreciated from the above, the vessel  140  can be configured to mate with any of the types of container portion  120  directly or via the adapter  125  without using the valve assembly  146 , and can have threads that mate with the threads  129  on the adapter  125  to facilitate the mating. 
         [0029]    Also, the mouth of the valve assembly  146  can include a lancet similar to lancet  126  (see  FIG. 5 ) to puncture any sealable membrane covering the mouth of the container portion  120 . The valve assembly  146  further can be configured similar to the automated valve assembly  102 , or can be configured solely as a manual valve assembly in which a user such as lab technician rotates the rotatable valve  130  of the valve assembly  146  by turning a knob  150  or by any other suitable mechanism. As with the motorized valve assembly  102 , the rotatable valve  130  of the valve assembly  146  can be removed and replaced with a rotatable valve having different size wells to dispense a different amount of DCM powder into the flask  142  per each rotation. The valve assembly  146  can further include a counter  147 , such as a mechanical or digital counter as known in the art, that counts the number of rotations of the rotatable valve  130 , and can be automatically or manually reset to zero after the desired amount of DCM powder has been dispensed. 
         [0030]    As further shown, the valve assembly  146  can include a non-porous rubber or plastic sleeve  148  to allow for mating with the mouth of the flask  142 . Furthermore, the valve assembly  146  or the sleeve  148  can include an inlet tube  152  to allow water or other liquid to be manually or automatically fed into the flask  142  as the rotatable valve  148  is being manually or automatically rotated. The valve assembly  146  and the system in general can be automatically or manually agitated to allow the DCM powder to more freely fall into the valve assembly  146 , and thus more freely into the flask  142 . Accordingly, the system shown in  FIG. 7  also provides an efficient and sanitary system for dispensing DCM powder into a container while avoiding waste and contamination of the surrounding area due to dusting and exposure to DCM powder inhalation due to dusting. 
         [0031]    While this invention has been particularly shown and described with reference to preferred embodiments thereof the preferred embodiments described above are merely illustrative and are not intended to limit the scope of the invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.