Published: 08/01/20 15:34 Categories: Microbiology
The importance of biofilm formation in industry is evident when looking at the figures: One third of produce in the food chain is lost annually due to bacterial spoilage. And biofilms are a constant source of microbial contamination.
But do we really know what a biofilm is?
In the environment, bacteria can either be found in planktonic form, i.e. suspended in the environment, or in sessile form, adhered to surfaces. Specifically, biofilms are aggregates of microorganisms that are bound to each other and adhered to a surface, therefore, it can be said that they are in a sessile state.
In biofilms, microorganisms are immersed in an extracellular matrix composed of extracellular polymeric substances, proteins, and extracellular DNA. In turn, this matrix offers protection against external agents and enhance adhesion to different surfaces. The matrix performs other important functions in the following areas:
Nutrition: It concentrates the nutrients from the environment inside the biofilm.
Defense: It prevents or reduces the penetration and contact of antimicrobial agents with the microorganisms housed there.
Protection: It avoids desiccation.
Its structure is formed by numerous channels and capillaries that divide the biofilm into micro-colonies where water, nutrients, and oxygen are distributed. Substances or residues may also be expelled from the biofilm through these very channels. Transport to inner areas is more deficient, creating areas with lower nutritional levels and limited oxygen, generating an environment conducive to microaerophilic or anaerobic bacteria growth.
These types of bacterial communities can be found in nature, but they are also very common on industrial surfaces. Biofilms need environments with high hydration and nutrition levels, which can be found in meat industries or cosmetic manufacturers.
These industries require a large amount of water during production, favoring the hydration of the environment and causing hot spots leading to the appearance of this type of structures. Another factor to take into account is the high nutritional value of their raw materials and finished product, which would create possible contamination sources in the event of inadequate cleaning and disinfection protocols. Among these, biofilms.
Are biofilms formed by a single specie of microorganism?
These communities may consist of only one type of microorganism, but it is common for those found on work surfaces or in filling systems within the industry to consist of more than one bacterial species.
Multi-organism biofilms also generate a major problem for industry, as they have resistance mechanisms for biocides and disinfection, and can be a constant contamination source if not eliminated. And it's not an easy task as we shall see below.
Multispecies communities present greater structural complexity and, therefore, an improved extracellular matrix. These improvements are based on the exchange of information between bacteria, synergies and joint actions that can occur between different microorganisms. . Some species will produce enzymes that inactivate biocides, while other species will be producing metabolites that can be used by the community as a nutrient source.
Fuente: Microbial Cell, Vol. 6, No. 2, pp. 105 - 122; : 10.15698/mic2019.02.667
In addition, as we well know, bacteria are microorganisms with great genetic plasticity and are promiscuous when it comes to exchanging this material. These extra-chromosomal genetic transfer processes, through plasmids, are called conjugation. And it has been shown to be done at a higher speed in biofilms because they favor contact between cells. The plasmid material usually encodes resistance genes, causing that bacteria which would not be resistant to antimicrobial agents in their natural state, generate such resistance due to their presence in the biofilm.
Enemies or allies for industry?
Industry faces a huge struggle to ensure the disinfection of work surfaces and the control of biofilms. One of its main difficulties is to avoid the formation of these aggregations on surfaces, as well as to disable their resistance mechanisms against disinfectant agents. Its complex protection systems are mainly associated with the presence of the extracellular matrix, which makes it difficult for disinfectant agents to penetrate the innermost areas of the biofilm.
On the other hand, some authors propose another interesting approach, arguing that the strategy should not be aimed at the complete destruction of the biofilm. Rather, their reasoning is based on the presence of certain microorganisms that can generate competition for the adhesion of pathogenic microorganisms, in the same way they occur in our intestine; even a high or low count of certain microorganisms can have beneficial effects for industry, as for example in the fermentation of cold meats.
Therefore, there is still time to turn the situation around in order to benefit from the full potential of biofilm. Without ever forgetting or neglecting its current importance as a contamination source.
Would you like to know what the most common pathogenic microorganisms in industrial biofilms are? Don't forget to read our next article.