How mechanical killing works on bacteria, viruses and mould.

Across hygiene, food safety, animal health and crop production, it is common for a treatment that once performed to become gradually less effective, and the usual cause is resistance. Bacteria, viruses and mould are highly capable of adapting to the treatments used against them (read more on resistance in our article “The Rising Threat of Disinfectant Resistance”), although how readily they can depends largely on the way a treatment kills them in the first place.

There are two broad ways to destroy harmful microorganisms. The first is to interfere with a specific biological process, such as how they produce essential materials, grow or reproduce. The second is to physically damage their structure, disrupting the protective outer layers that keep them intact.

This article explains how bacteria, viruses and moulds are structured, how different antimicrobial approaches work, and why microorganisms generally find it more difficult to develop resistance to agents that physically disrupt their structures.

Why targeted treatments lead to resistance

Many conventional antimicrobial treatments work by targeting a specific function that a germ needs to survive or multiply. Over time, some microorganisms can adapt, making these treatments less effective.

This is how antimicrobial resistance develops. Bacteria and moulds can become harder to control, particularly when the same treatments are used repeatedly.

But what happens when, instead of targeting one function, a treatment physically damages the microorganism itself? This presents a very different challenge for the germ.

How bacteria, viruses and mould are built

Bacteria are single-celled organisms protected by an outer wall and a delicate membrane. Damage the membrane sufficiently, and the bacterium cannot survive.

Viruses contain genetic material inside a protective protein shell. Many also have a fatty outer coating that, if damaged, prevents them from infecting cells. Viruses without this coating are generally harder to destroy.

Moulds are fungi made up of cells protected by a membrane and a tough outer wall. They reproduce through spores, many of which can survive harsh conditions, making them particularly difficult to eliminate.

What mechanical killing does

Rather than targeting a single function inside a microorganism, some antimicrobial treatments work by physically disrupting its protective outer layers. This can damage the membrane of bacteria and mould cells, or the fatty outer coating of viruses such as influenza and coronaviruses.

When this damage is severe enough, bacteria and mould cells lose their ability to survive, while enveloped viruses lose their ability to infect cells.

Why physical destruction can't be adapted to

Physical disruption presents a different challenge for microorganisms. Unlike treatments that target a single biological function, membrane-disrupting agents attack structures that are essential for survival or infection.

Because these protective layers are so important, microorganisms may find it harder to develop resistance, particularly when a treatment damages them in several ways at once.

This is one of the key advantages of physical disruption: rather than relying on a single target, it attacks the fundamental structures that bacteria, moulds and many viruses depend on.

What this means day to day

Physical disruption still depends on contact. The treatment has to reach the germ to damage it, so a few practical points matter.

• Clean before you disinfect. Dirt, grease, manure and food scraps can shield germs. Removing them first lets the treatment get to the germs underneath.
• Watch out for slime build-up. Bacteria on surfaces such as drains, water lines and processing equipment often form slimy layers, known as biofilms, that protect the germs inside. This is primarily about access, rather than genetic resistance. Scrubbing or breaking up the slime helps the treatment get through.
• Give it enough time. Keep the surface wet for as long as the product label says, because the treatment needs sufficient contact time to work effectively.

Expect tougher germs to need more. Viruses without a fatty coat and mould spores are generally harder to inactivate or eliminate than enveloped viruses or actively growing mould. This natural toughness comes from how they're built, rather than resistance developed in response to a particular treatment.

Where our products fit in

Our natural L42 and L44 formulations are designed to disrupt the protective structures of microorganisms, rather than targeting a single biological function. This approach may make resistance more difficult to develop.

L42 focuses on surface disinfection, while L44 covers applications including food shelf-life extension and animal health. Our team can help identify the right product for your needs and provide supporting technical information.

Talk to us

If you'd like to talk about how our solutions apply to your premises, facility, processing plant or practice, contact the Aussan Laboratories team on +61 3 9125 8330, email info@aussan.com.au or visit aussan.com.au.