CULTURE MEDIA WHAT IS?
What is... CULTURE MEDIA?
Angela Davies demystifies this key element of testing preservative systems
Angela Davies, CEO and founder, MSL Solution Providers
One of the battles we face as a
regulatory and testing house is assuring the safety of cosmetic products. As consumers use products, they introduce microorganisms which, if the preservative system is not effective, can result in contamination and spoilage, and risk consumer safety. To ensure their microbiological quality and establish that their preservative systems can withstand microbial contamination during use, cosmetics and personal care products must undergo a mandatory Preservative, Efficacy or Challenge Test (ISO 11930). These tests mimic contamination by introducing a known number of microorganisms into the product to ‘challenge’ the preservative system. This routine regulatory microbiology testing is performed using a variety of dehydrated culture media (DCM). But what exactly is dehydrated culture media? Used by all microbiology laboratories, dehydrated culture media is the key element in microbiological culturing of organisms. It consists of a dry mix of components. At the point of use, it is reconstituted with water and sterilised at high temperature and pressure. It is then used to facilitate the growth of microorganisms.
Each type of DCM is designed to have various characteristics that imitate the natural environment with nutrients that a specific organism may require, when incubated at the right temperature, for optimal growth. As a result, the DCM usually provides the essential nutrients or growth factors
an organism needs to survive, metabolise, and replicate.
DCM can be classified into six main types, which all have different properties, functions, and nutritional benefits: • Basal media is a general-purpose media that is used to culture organisms in a general way;
• Enriched media includes components, which provide the optimum growth factors that an organism may require or need to metabolise;
• Selective media has very specific components, such as antibiotics, which can be used to inhibit or facilitate growth;
• Indicator or differential media is used to distinguish between different organisms. It contains chemicals that produce a colour change, which can be seen either in the DCM itself or in the actual bacterial colony, depending on the mode of action;
• Transport media is designed specifically to protect organisms during transportation; and
• Storage media is used for storing bacteria for a long period of time; however, this should be chosen with the specific organism in mind.
WHAT IS DCM MADE FROM?
Standard culture media relies on enzymes, serums and proteins derived from animal by-products. Therefore, for brands and manufacturers of vegan cosmetics, assuring the microbiological safety of products without compromising their ethics, has historically posed a challenge. However, MSL Solution Providers can perform microbiological testing using non-animal derived culture media. Its pioneering VeganSure solution replaces all animal-derived ingredients with plant-based or synthetic alternatives, such as papaya-derived enzymes, soya bean, sugars from potatoes, cornmeal and plant peptones. It is registered with The Vegan Society’s
Trademark and is performed in an ISO/IEC 17025:2005 accredited testing laboratory at MSL Solution Providers, with separate workflows to avoid cross-contamination.
As consumers use products, they introduce microorganisms which, if the preservative system is not effective, can result in contamination
cosmeticsbusiness.com
DEVELOPING NEW CULTURE MEDIA Work to develop new culture media or improve its speed of recovery or selectivity is always going on behind the scenes. Formulation takes many hours of laboratory work and knowledge of each species to obtain optimum growth conditions depending on the application and reason for isolating or identifying the organism. It’s a forever-improving area with rapid techniques and novel formulations available. This not only enhances our knowledge and understanding of this fascinating essential world of microscopic organisms but also benefits public health. For example, whenever there are instances of contamination or infection, scientists develop DCM to encourage the growth of these microorganisms. This is an important step in developing vaccines, treatments and cures. After all, understanding the problem is half the solution
November 2021 43
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