What Are Microorganisms?
Since surfaces are exposed to the environment in which an object is located, they are the target of microbial contamination, attachment, survival and growth.
Microorganisms (or microbes) are microscopic organisms that exist as unicellular, multicellular, or cell clusters. Literally, the word “micro” means very small and “organism” means a form of life.
While microorganisms are widespread, abundant in nature, and beneficial to life, some can cause serious harm or illness. As a group, microorganisms that are commonly found on surfaces can be divided into major types: bacteria, fungi, algae, and viruses.
Microbes live everywhere on Earth. With respect to bacteria, their populations can increase quickly on surfaces because their cells are simple and can multiply easily. Some bacteria and fungi are beneficial microbes because they help to keep the environment in nutrient balance and they support food production, such as in the process of fermentation when they make wine, cheese, yogurt, and bread.
However, some microbes can be destructive such as when they cause diseases, staining, odors, and/or product degradation.
How Do Microbes Attach to Surfaces?
Since microbes are widespread in nature, they are likely to encounter exposed surfaces. These include animate, living surfaces (such as those found on animals and plants: skin, respiratory surfaces, fruits, vegetables) and nonliving surfaces (textiles, plastics, metals, wood, coatings).
Microbes will not always attach to surfaces that they contaminate. However, if certain chemical and physical conditions are met, microbes can attach and start multiplying.
Microbial attachment can happen within 5 to 30 seconds and occurs in 2 stages: reversible attachment followed by irreversible adhesion. Reversible attachment is initially weak, and microbes are easily removed by application of mild force.
Factors that support microbial attachment, survival, and growth on surfaces, and ultimately irreversible adhesion, include features of the microbial cell surface, chemical and physical properties of the surface, environmental factors (temperature, moisture, nutrients), and time.
There are chemical substances and physical structures that allow microbes to attach to surfaces. For example, bacterial glycocalyces and fimbriae. Glycocalyces (singular: glycocalyx) are gelatinous, sticky, sugary substances that are produced inside the cell and pushed out onto the cell’s surface.
In some bacteria, the glycocalyx forms a thick, fixed layer on the bacteria cell’s surface called a capsule. A loosely fitting layer is called a slime layer. Capsules and slime layers protect bacterial cells from drying out and improve the ability of bacterial cells to attach to surfaces.
Fimbriae are rod-like, sticky, bristle-like extensions that are built from proteins inside the bacteria and pushed out to allow bacteria to stick to one another and surfaces in the environment. Each bacterial cell may have hundreds of fimbriae on their surface.
What Are Biofilms?
When microorganisms are irreversibly attached to surfaces, they grow and form biofilms. Biofilms are a community of microorganisms that are embedded in a gel-like substance and anchored to surfaces. Traditionally, biofilms are associated with wet or damp surfaces.
Free moisture on a surface (e.g. water, blood) provides an ideal environment for microbial attachment and growth.
Biofilm Formation on Surfaces
Biofilm formation is commonly considered to occur in four main stages:
- INITIAL ATTACHMENT: A free-floating microbe attaches to a surface. Microbes can attach to a variety of surfaces (e.g. from woods, metals, and plastics to living tissues and stagnant water).
- MICROCOLONY FORMATION: As a biofilm grows and develops, the microbes multiply and produce sugar-based molecules which are forced out of the cells to form a matrix which is a gel-like substance around the cells.
- MATURATION: Recruitment of other cells and production of gel like substance to support attachment. Extra-cellular gel production and biofilm thickening.
- DETACHMENT: Also called dispersal. Biofilms release and disperse cells into the environment to colonize new areas.
Biofilms are highly organized three-dimensional structures that may include one type or multiple types of microorganisms that can grow together for protection from environmental stress (such as drying out, chemicals) and for access to nutrients. The gel-like substance contains many nutritional materials such as complex sugars, proteins, and nucleic acids.
One common example of a biofilm is dental plaque, a slimy buildup of bacteria that forms on the surfaces of teeth.
Biofilms on Antimicrobial Treated Surfaces
As with untreated surfaces, antimicrobial-treated surfaces are exposed and can be contaminated with microbes from the environment. However, when antimicrobials are incorporated into treated surfaces, they create unsuitable conditions making it less likely for microbial attachment, survival, and growth.
As the contaminating microbes attempt to attach and absorb nutrients from the surface environment, they are simultaneously absorbing the antimicrobial from the treated article as well. The imbibed antimicrobial will then have the opportunity to interrupt the microorganism’s metabolism and prevent attachment, survival, and/or growth.
Microban® antimicrobial technology does not prevent biofilm formation. However, it will work to protect a treated surface from microbially-induced product deterioration by delaying microbial attachment, survival, and growth. This means that if soil and dirt are wiped away from the treated article, the surface underneath will still be cleaner than an untreated surface.
Whilst incorporated antimicrobial treatments are not substitutes for normal cleaning and hygiene practices, they will continue to work in between cleaning to keep microbial populations low on exposed surfaces.
Ultimately, if microbes are able to persist on antimicrobial-treated surface and form biofilms, the biofilm effect will be delayed and reduced.
For more information on how you can treat your product range with built-in antimicrobial technology, contact a member of the team today.