A SYSTEM FOR PREPARING OF A CULTURE MEDIUM FOR BACTERIOLOGICAL USE

Abstract: A method for the preparation of a culture medium for bacteriological employment includes arranging said culture medium in a medium treatment station, hydrating said culture medium, sterilizing said culture medium; said arranging includes packaging said culture medium in hydro-soluble containers; a packaging unit includes a covering containing a culture medium for bacteriological employment; said covering is constituted by hydro-soluble material.

Description: A system for preparing of a culture medium for bacteriological use The invention relates to the preparation of a culture medium suitable for bacteriological research. Such preparation comprises hydration and sterilization of a predetermined amount of culture medium. During weighing of the predetermined amount problems are found deriving from the risk that the operator can inhale particles of volatile toxic substances included in the culture medium. Packages are available on the market containing a standard amount of a culture medium; thus weighing of the culture medium has no longer to be performed by the operator. Nevertheless, the packages must be opened in order to pour the culture medium into a suitable container for the subsequent hydration and sterilization thereof. Therefore, inhalation risk of toxic substances contained in the culture medium is not completely averted, since when the package is opened, paticles of volatile toxic substances may still be inhalated. In order to avoid inhalation risk of toxic volataile particles, culture mediums in granular form have been proposed. This does not eliminate the risk that volatile toxic substances are inhalated, since a certain amount of powder is still produced by friction among the grains, which are caused to slide on each other during various handling steps. Furthermore, it is still necessary to handle the medium manually. Therefore, the operator is not completely safe from contamination by volatile particles of the culture medium. An object of the present invention is to improve the existing systems for prepararing a culture medium for bacteriological use. A further object of the present invention is to provide a method for preparing a culture medium which does not cause the operator being contaminated. In a first aspect of the invention, a method for preparing a In a first aspect of the invention, a method for preparing a culture medium for bacteriological use is provided, comprising: providing said culture medium in a medium treatment station, hydrating said culture medium, sterilizing said culture medium, packaging said culture medium, characterized in that, said packaging comprises packaging said culture medium into hydro-soluble means. In a second aspect of the invention, a packaging unit is provided comprising enclosure means for containing a culture medium for bacteriological use, characterized in that, said enclosure means comprises hydro-soluble material. Owing to these aspects of the invention, the package containing the culture medium does not need to be opened for hydration purposes, because, the package dissolves once immersed into water. To facilitate dissolution of the package, the water temperature is raised, which is also required for sterilisation of the culture medium. In an advantageous version, the package is a bag closed around its periphery. Preferably, the package is obtained from a hydro-soluble film based on polyvinylic alcohol (PVOH) having good physic- mechanical characteristics and optimal impermeability qualities to toxic agents contained in the culture medium. In a further advantageous version, said package is protected by inserting thereof into outer enclosure means, which are preferably water-repellent. The outer enclosure means protect the enclosure means from external agents and, more particularly, from humidity in the ambient air. Otherwise an un-protected package, when left in contact with the air, owing to atmospheric humidity, tends to become partially soluble; therefore the culture medium contained in the package tends to hydrate thus resulting It is to be noted that use of hydro-soluble film based on polyvinylic alcohol (PVOH) is advantageous not only because it is characterized by good physic-mechanical characteristics and optimal impermeability qualities to toxic agents contained in the culture mediums, but also because solubilized molecules of polyvinylic alcohol (PVOH) dissolve into the culture medium considerably improving the fertility thereof. Broth culture mediums, obtained from packages comprising polyvinylic alcohol (PVOH) , partly lose their transparecy and show a slightly cloudy appearance, which however doesen't compromise the functionality of such mediums. Owing to the invention, the preparation of the medium is much quicker, since it is no longer necessary to weight the medium. Furthermore, no toxic waste is originated. The invention could be better understood and carried into practice with reference to some examples which have not to be intended as limitative. A culture medium suitable for being used for bacteriological research is packaged in bags or cases obtained from a particular hydro-soluble film based on polyvinylic alcohol (PVOH) , for example according to IT- 1.140.254. Thickness of the bag walls of 16 μm results particularly advantageous because a relative low amount of material to be used is required while assuring good physic- mechanical characteristics of the bag. The other dimensions of the package depend on the intended use thereof: for a laboratory use, package dimensions to obtain about one liter of culture medium are preferable; for industrial use, such as for use in fermenting units, greater dimensions are preferable, so as to obtain several of medium liters. Various types of materials can be obtained based on PVOH, those materials differring from one another for process parameters, such as in particular the temperature above which the material results completely soluble and the temperature under which the material results completely water inert. For merely purpose of example, the temperatures above which the material results completely soluble and the temperatures under which the material results completely water inert are indicated in the following list. type inert up to soluble above LTF +5°C +15°C LTS +10°C +25°C HT1 +50°C +63°C HT2 +60°C +70°C HT3 +65°C +80°C A range of other types of material exists with intermediate values of inertness and solubility to water temperatures with respect to the values above referenced. It is possible to take advantage of such dependence of the solubility from the temperature in order to vary the material type with the culture medium type used (Agar, Broth, etc.). Nevertheless, a material with inertness temperature of +25°C and solubility temperature of +40 °C constitutes a suitable choice for any type of medium. The culture medium arranged in the bags previously described is then submitted to hydration and sterilization operations. The whole arrangement , obviously, does not result prejudicial for the operator because the toxic substances contained in the medium, which could volatile, stay in any way closed into the packages up to the hydration step. Afterwards some examples, which have not to be intended as limitative, are shown. These examples relate to culture mediums, obtained from packagings comprising enclosure means made of a film of polyvinylic alcohol (PVOH), that produced very good results. Various tests have been carried out about colonies morphology and dimension, hemolysis, H2S formation, selectivity and also tests about culture mediums containing MUG (4- METHYLU BELLIFERIL-BETA-D-GLUCURONIDE) . The tests produced similar and in many cases better results than that obtained without the use of the PVOH-hydro-soluble package. The PH of the culture medium remains unchanged if compared with conventional culture mediums. The transparency of the culture medium is acceptable. Culture medium Control stocks Results with packaging units MUELLER HINTO Escherichia coli ATCC 25922 _ _ ^ Good growth and inhibition zone AGAR Staphilococcus aureus ATCC 6538 Good growth and inhibition zone Pseudomonas aeruginpsa ATCC 7853 Good growth and inhibition zone S.S.AGAR Salmonella typhimurium Wildstamm Growths and H2S formation Shigella flexneri Atcc 12022 Growth and colourless colony Escherichia coli ATCC 25922 Good inhibition BISMUTH SULPHITE Salmonella typhi Wildstmann Growth with black colonies with black halo AGAR with metallic brightness Salmonella flexneri ATCC 12022 Growth with brown colonies Enterococcus faecalis ATCC 51299 Growth inhibition, very small green-brown colonies Klebisella pneumonia Wildstamm Growth inhibition, green-brown colonies XLT4-AGAR Escherichia coli ATCC 25922 Yellow colonies Proteus mirabilis ATCC 14153 Inhibition Salmonella typhimurium Wildstamm Yellow-red colonies with black centre Staphilococcus aureus ATCC 6538 Inhibition VRB MUG Escherichia coli ATCC 25922 Good growth, good fluorescence Citrobacter freundii Wildstamm Good growth, without fluorescence COLUMBIA AGAR Streptococcus pneumoniae ATCC 49619 Good growth, a-hemolysis, morphology, colour, recovery Streptococcus pyogenes Good growth, b-hemolysis, morphology, colour, recovery Staphilococcus aureus ATCC 6538 Good growth, morphology, colour, recovery Escherichia coli ATCC 25922 Good growth, morphology, colour, recovery Enterococcus faecalis ATCC 51299 Good growth, morphology, colour, recovery MAC CONKEY AGAR Escherichia coli ATCC 25922 Red colonies, good morphology, recovery Salmonelja senftenberg Wildstamm Colourless colonies, good growth. norphology, recovery Proteus mirabilis ATCC 14153 Colourless colonies, good growth, morphology, recovery Enterococcus faecalis ATCC 51299 Inhibition Candida albicans ATCC 10321 Good growth, morphology, colour, recovery Aspergillus niger ATCC 16404 Good growth, moφholog.y L colour L recovery VRBD AGAR Escherichia coli ATCC 25922 Good inhibition Red-violet colonies, good growth, morphology, cojour, recovery _ , Staphilococcus aureus ATCC 6538 Good inhibition

Claims: CLAIMS 1. A method for preparing a culture medium for bacteriological use, comprising: packaging said culture medium, providing said culture medium in a medium treatment station, hydrating said culture medium, sterilizing said culture medium, characterized in that, said packaging comprises packaging said culture medium into hydro-soluble package means. 2. A method according to claim 1, wherein said packaging comprises packaging said culture medium into bag means closed around its periphery. 3. A method accoring ot claim 1, or 2, wherein said packaging comprises providing film means based on hydro- soluble polymer means. 4. A method according to any preceding claims, wherein said hydro-soluble means comprises polyvinylic alcohol. 5. A method according to any one of claims 3 to 4, wherein said providing comprises providing bags having a wall- thickness of around 16 μm. 6. A method according to any one of claims 3 to 5, wherein said providing includes providing bags inert to water up to a lower temperature and soluble in water at a higher temperature. 7. A method according to any preceding claims, wherein said packaging comprises further packaging said culture medium and said hydro-soluble package means into further package means. 8. A packaging unit including package means containing a culture medium for bacteriological use, characterized in that said package means comprises hydro-soluble package means. 9. A packaging unit according to claim 8, wherein said hydro-soluble package means comprises hydro-soluble polymer means . 10. A packaging unit according to claim 9, wherein said hydro-soluble polymer means comprises polyvinylic alcohol (PVOH) . 11. A packaging unit according to any one of claims 8 to 10, and further comprising further package means externally of said package means. 12. A packaging unit according to claim 11, wherein said further package means are made of hydro-repellent material. 13. A packaging unit according to any one of claims 8 to 12, wherein said package means and/or said further package means are made of sheet material.

Inventors: MURGIA SERGIO, MURGIA, SERGIO
Applicants: MURGIA SERGIO, MURGIA, SERGIO
Application year: 1999
Main classification: C12N1
IPC codes: C12M1, C12N1