July 24, 2017

Biofilms—Pesky and Risky

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David R. Cronier, BSc Biotechnology

We often hear about the problems associated with drug resistant bacteria in hospitals. Canadian data estimate that 2,890 patients are infected with drug resistant bacteria. Bacteria can develop resilience over time and can be fatal when least expected.  One way they build resilience is to form what we call biofilms. Biofilms can be present almost anywhere—especially where there is water and nutrients.

dental plaque

Micro-organisms thriving in biofilms

Did you know that dental plaque is a form of biofilm?

But hospitals are not the only place we can find resilient bacteria and biofilms. Another area of high risk is in the food industry. And this was the topic of discussion at the October 2013 Innovation Breakfast on Microbiology/Sanitation Issues in Food Safety, hosted by NSF-GFTC.

Dr. Ruby Lee’s (Lee Food Microbiologists Inc) took us on the “bac trail”—to help us better understand biofilms, their detection, removal and how we might prevent the proliferation of threatening micro-beasts.  According to Dr Lee, biofilms can develop resilience against chemicals, antibiotics and desiccation (drying out).  When food production is in full effect, they can reduce heat transfer, increase flow resistance, cause corrosion in industrial equipment and lead to food spoilage and contamination. Furthermore, these microbial communities can contain pathogens responsible for serious illnesses.

But what is a biofilm? Well, in the bacterial world a biofilm is very much like an apartment complex. It is a nice little community of micro-organisms living together, sheltering themselves from the elements and helping each other out when needed. Except instead of being protected by an external concrete structure, the bacteria protect themselves by excreting EPS (ExoPolymeric Substances—made up mainly of polysaccharides (sugar) and proteins. Channels or tunnels are created to allow the flow of nutrients and oxygen.

Biofilmdevelopment

Formation of a biofilm

Bacteria start off in their free form (called planktonic cells). These cells attach themselves tightly to each other and onto a surface. At the beginning the attachment is reversible, but in a matter of seconds the cells proliferate and the attachment becomes permanent. Now it is considered a biofilm. Biofilms continue to grow and mature as more micro-organisms join in. Biofilms are more resistant to sanitizers than individual planktonic cells because of their tight knit, gene expression and EPS.

These biofilms are imminent threats in the food processing industry. In order to ensure food safety, the industry takes a number of critical steps to ward off microbial contamination. We’ve simplified the process to 3 critical steps.

Agitation—also known as a giving a surface a “good scrub” is considered one effective way to evict microscopic squatters. The 17th century term “elbow-grease” also applies here. When it comes to cleaning industrial equipment and surfaces there is no substitute for hard rubbing to disrupt biofilms.

Microbiological Detection—Now that you have scrubbed and scrubbed, you might think your job is done and call it a day. “Not so,” according to Dr Lee, who reminds us that early biofilms may not be visible to the human eye, so we may not even think of cleaning what we don’t see. And she adds, “Some equipment is just hard to clean—by design, which may include cracks and crevasses, hidden components, etc. That’s where ATP bioluminescence and other environmental microbiological testing come in. They help us see the invisible”.

Cleaning solutions—When detected, biofilms are best removed by using hydrogen peroxide/peroxyacetic acid-based compounds as part of the washing treatment. Like other oxidizing disinfectants, hydrogen peroxide and peroxyacetic acids can penetrate biofilms and they disinfect by oxidizing the cell membranes and inner cell structures of pathogens, destroying them.

You may now wonder how industrial sanitation applies to your own household. Well, this is our take-away from Dr Lee’s presentation.

Household appliances such as food processors, juicers, bread making machines and food preparation surfaces can pose similar risks at home. Household appliances and surfaces come in contact with moisture and food nutrients all the time. They’re grefight bacat party venues for bacteria lurking around in search a feast.

Giving your pots, pans, appliances and food preparation surfaces a good scrub with a good cleaner is a great step in the right direction.  Sounds basic, doesn’t it? Yet these simple steps are often overlooked and neglected.

Looking for more tips on how to be food safe at home, follow this link

To view a short clip on Dr Lee’s presentations, see below.

David Cronier, BSc, Biotechnology is currently a Consultant at nufoods international. He is responsible for articles related to new developments in food safety, microbiology and biotech.