Preservative Effectiveness: Why Can Microorganisms Still Survive in Products?
Preservatives are often used to protect products from microbial growth, but does the presence of preservatives always mean that microorganisms will be killed immediately? In fact, Preservative Effectiveness can be influenced by various factors, while some microorganisms can survive and adapt to preservative exposure through different defense mechanisms that are important to understand.
Table of Content:
Why Can Microorganisms Survive Preservatives?
Preservatives are used in cosmetic products to inhibit microbial growth and help keep products safe during use. However, Preservative Effectiveness can be influenced by the concentration used in the formulation.
Since preservative levels must also consider consumer safety, some more tolerant microorganisms may still be able to survive under these conditions. This microbial resistance or tolerance can affect Preservative Effectiveness, particularly when microorganisms can inactivate preservative compounds, reduce their susceptibility to them, or survive despite continued exposure.
The level of resistance can be influenced by several factors, including the type and number of microorganisms, preservative concentration, temperature, environmental conditions, and contact time. These factors can also affect Preservative Effectiveness, as different microorganisms may show varying levels of tolerance to a preservative system.
Not all microorganisms have the same level of resistance to preservatives. In general, bacterial endospores such as Bacillus and Clostridium are highly resistant forms, while mycobacteria also show relatively high resistance due to the characteristics of their cell walls.
The sensitivity of Gram-positive bacteria can vary depending on the type of preservative and testing conditions. Resistance or tolerance to preservatives is a concern because it can reduce Preservative Effectiveness and compromise the performance of a product's preservation system.
Therefore, research continues to explore new antimicrobial agents and alternative preservation systems, including the use of natural ingredients, to support Preservative Effectiveness. Understanding the interactions between microorganisms and their environment is also important for maintaining effective microbial control within a product.
Read Also:
Preservative Effectiveness Test: An Important Step to Keep Products Clean and Safe
How Do Microorganisms Survive Preservatives?
Microorganisms can use various mechanisms to survive exposure to preservatives, and these mechanisms depend on the type of preservative they encounter. For example, when exposed to organic acids, microorganisms may break down or degrade certain preservatives, such as sorbic acid and benzoic acid, reducing their effectiveness.
Some microorganisms can also adapt to acidic environments by maintaining the pH balance inside their cells, which may influence Preservative Effectiveness. For alcohols and phenolic compounds, such as triclosan and parabens, microorganisms may use different defense mechanisms to tolerate preservative exposure.
Bacteria can modify the cellular target of triclosan or increase the activity of efflux pumps to remove unwanted compounds from the cell. In the case of parabens, microorganisms may inactivate them through enzymatic processes or increase the expression of efflux pump genes.
Meanwhile, microorganisms exposed to aldehydes and formaldehyde-releasing preservatives may survive by reducing cell permeability, making it more difficult for the preservative to enter the cell. Bacteria may also use enzymes such as formaldehyde dehydrogenase to help break down formaldehyde, making the compound less effective.
For biguanides and quaternary ammonium compounds (QACs), the structure of the cell surface is an important factor in determining microbial resistance. Gram-negative bacteria, for example, have lipopolysaccharides in their outer membrane that can act as a barrier to the entry of chlorhexidine or QACs.
Changes in porins and increased efflux pump activity can also help reduce the amount of antimicrobial compounds inside the cell.
Microorganisms can also respond to heavy metal compounds by enzymatically inactivating them or removing them through efflux pumps. Therefore, microbial survival is not caused by a single mechanism.
It may involve changes in cell structure, enzyme activity, efflux pumps, and adaptation to environmental conditions. For this reason, the use of preservatives should take into account both the types of microorganisms present and the characteristics of the preservatives being used.
Verify Your Product's Preservative System Effectiveness Through Testing
Using preservatives does not automatically mean a product is adequately protected against microbial growth. Verify your preservative system's effectiveness through Challenge Testing!
IML Testing & Research provides Efficacy Testing services to help companies evaluate the ability of preservative systems to control microorganisms within product formulations.
Don't rely solely on the presence of preservatives in your formulation. Contact IML Testing & Research today and discuss your Challenge Test or Preservative Efficacy Test requirements with our team!
Author: Dherika
Editor: Lina
References
Halla, N., Fernandes, I. P., Heleno, S. A., Costa, P., Boucherit-Otmani, Z., Boucherit, K., Rodrigues, A. E., Ferreira, I. C. F. R., & Barreiro, M. F. (2018). Cosmetics Preservation: A Review on Present Strategies. Molecules, 23(7), 1571. https://doi.org/10.3390/molecules23071571.
Ortega Morente, E., Fernández-Fuentes, M. A., Grande Burgos, M. J., Abriouel, H., Pérez Pulido, R., & Gálvez, A. (2013). Biocide tolerance in bacteria. International journal of food microbiology, 162(1), 13–25. https://doi.org/10.1016/j.ijfoodmicro.2012.12.028.
