Against this background, the fast-moving consumer goods (FMCG) world has also begun to explore the use of bacteria — including probiotics — in its skincare products. However, creams, gels and lotions are not the usual habitat in which these bacteria find themselves … and this leads to certain manufacturing challenges that have not been highlighted to date.
Before we start looking at the challenges facing industry’s ability to manufacture products with bacteria, let’s define terms. Probiotics are live micro-organisms that, when administered in adequate amounts, provide a health benefit. Some products claim they have probiotics included, but this is only correct if the micro-organism is still live.
Usually, probiotic organisms are species of bacteria such as Lactobacillus or Bifidobacteria. Normally found in the gut, the food industry has had the dual challenge for years of ensuring that these bacteria can first survive within the food/beverage into which they have been incorporated and, secondly, survive passage through the hostile environment of the stomach to exert their beneficial effects on the gut.
Consequently, many probiotics manufactured for therapeutic effect need to be encapsulated and then administered at very high levels to ensure the required number survive to reach the desired part of the gut. When it comes to using bacteria topically, the situation is even more complicated.
First, creams, gels and lotions, etc., are not “friendly to bacteria,” and it is highly unlikely that bacteria survive in these formulations. Secondly, the skin is not the usual habitat for these organisms. This is why some laboratories, including my own, have been looking for a different way forward with respect to a friendly bacteria answer to use in skin health.
At the Centre for Dermatology at The University of Manchester, we have demonstrated that lactobacilli do not need to be alive to provide skin benefits. Working with dead extracts, we have shown that specific species of lactobacilli can improve skin as a barrier, promote the healing of skin and inhibit the attachment of pathogens to models of skin.
Indeed, we consider working with dead bacteria or bacterial extracts to be the preferred option as it also circumvents any potential safety concerns associated with applying live bacteria on potentially broken skin.
Nevertheless, even though the bacteria do not necessarily need to be alive to exert their beneficial effects, the molecules within them that promote these effects do need to survive the manufacturing and formulation procedures. As probiotic bacteria live in the hostile environment of the gut, there is a view that these bacteria are extremely robust and can withstand common manufacturing processes. However, evidence from my laboratory suggests that this is probably not the case.
Processes generating temperatures greater than 40 °C need to be avoided. This is because the molecules within bacteria that promote their effects appear to be, by and large, proteins. As proteins are especially heat labile, processes such as tyndallisation (heating the substance being sterilised to 121 °C for 15 minutes in a pressured system) can potentially destroy the active molecules. The chemical lysis of bacteria is also to be approached with caution for the same reasons.
Similarly, formulations need to be designed with the active molecules in mind; as such, the use of strong surfactants that can destroy the activity of proteins needs to be avoided.
Of course, this may not be true for every species of bacterium and this is why it is important to have robust assays to test that the manufacturing and formulation processes have not compromised the activity of the bacteria. It is well worth investing the time to get these processes right as bacteria offer incredible potential for use on skin — dead or alive!
Bibliography
- W. Mohammedsaeed, et al., “Lactobacillus rhamnosus GG Lysate Increases Re-Epithelialization of Keratinocyte Scratch Assays by Promoting Migration,” Scientific Reports 5(5), 16147 (2015).
- W. Mohammedsaeed, et al., “Lactobacillus rhamnosus GG Inhibits the Toxic Effects of Staphylococcus aureus on Epidermal Keratinocytes,” Appl. Environ. Microbiol. 80(18), 5773–5781 (2014).
- R. Sultanna, A. McBain C.A. O’Neill, “Lysates of Lactobacillus and Bifidobacterium Augment Tight Junction Barrier Function in Human Primary Epidermal Keratinocytes in a Strain Dependent Manner,” Appl. Environ. Microbiol. 79(16), 4887–4894 (2013).
- T. Prince, A. McBain and C.A. O’Neill, “L. reuteri Protects Human Keratinocytes from the Effects of the Skin Pathogen S. aureus,” Appl. Environ. Microbial. 78(15), 5119–5126 (2011).
