BIOFILMS 3: Formation and Growth

How do biofilms form?

Bacteria, fungi and other microbes have existed in nature for thousands of years. They generally ensure survival and growth by attaching to different types of surfaces, animate and inanimate surfaces including soil, hard surface such metals, plastics, living tissues and in aquatic environments.

The microbes generally require wet environment or moisture to thrive in.

What factors can impact on formation and growth of biofilms?

The nature of the surfaces is a critical factor for the growth of biofilms and growth will differ between water repelling (hydrophobic) such as plastic, latex, and silicone surfaces and highly charged, hydrophilic surfaces such glass and metals. Smooth materials like in the silicone and plastic materials or rough in texture such as some environmental surfaces and water pipes, also make a difference to the type and rate of development of biofilms.

Some surfaces may be pre-treated with an antimicrobial agent such as copper or silver and the alloys to inhibit attachment to the surfaces and formation of biofilms. In general, rougher and more hydrophobic surfaces tend to develop biofilms more rapidly than the opposite.

The type of the microbial cell surface is as well important to the attachment and development of biofilms. Some microorganisms are thought to have specifically develop special appendages to enable and enhance their ability to attached onto surfaces, which is also linkage to their survival in or on their hosts. The possession of microbial flagella, pili, fimbriae, or glycocalyx have been shown to enhance attachment and ecosystem matrix, and linked to specific pathogenicity of the microbe.   

Human have since learnt to live in communities and collaborate in order to be more efficient, increase productivity and their defences against enemies, hence the chances of survival. Microorganisms have similar ability to live in communities of different ecosystems for the same reasons. The formation of these ecosystems on different surfaces is particularly significant to human in the case of pathogenic microbes, diseases and public health.    

Pathogenic bacteria and fungi in both healthcare settings and food production irreversibly attach to surfaces and grow. The microbial cells produce extracellular polymers to help hold the community together into a complex matrix. The new ecosystem enforces changes in the genetic makeup and behaviours (including pathogenicity and reproduction) of microorganism. New strains of a specific microbial type may develop in the biofilm with a different disease expression.

Importantly, biofilms render antimicrobial agents less effective against the microbial community, making medicinal antibiotics or surface disinfectants less effective. It has been indicated that these advantageous changes in the microbes may be natural or intrinsic due to the biofilm formation or acquired because of transfer of extra-genetic or chromosomal materials within individual cells the biofilm community.

Understanding how biofilms are formed and growth will assist in devising good related public health policies, control measures and treatment regime in healthcare settings and in the food industry.

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