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Nitric Oxide Regulation of Biofilms

Invention Number: 
Bacterial biofilms cause industrial fouling, corrosion and severe illnesses such as Eepticaemia, Escherichia coli and Staphylococcus. This discovery will help control and combat biofilms.

In the last decade, there has been a paradigm shift in our understanding of how bacteria cause infections and persist in the environment.  It is now understood that most bacteria grow primarily as biofilms, whether in the natural environment, on Industrial surfaces or in the human body.  These biofilms are significantly recalcitrant to antimicrobials and antibiotics because they are covered by a self-produced slime or matrix that protects the underlying bacteria. The biofilms are also protected because the biofilm bacteria express unique genes while in the biofilm that are distinct from genes expressed when grown as planktonic, single cells. 

This increased resistance is one reason why biofilms are difficult to remove from surfaces or infection sites.  The formation of biofilms therefore calls for novel antimicrobials that are designed to target biofilm bacteria, which is not achieved by traditional antimicrobials.

The technology

UNSW researchers have made a seminal discovery that bacteria produce the signal molecule Nitric Oxide (NO).  One behaviour of bacteria that is controlled by NO is the dissolution of biofilms.  When bacteria in biofilms are exposed to the NO, they change gene expression and exit the biofilm as single cells or planktonic bacteria.  Not only does this remove the biofilm, but it converts the otherwise resistant biofilm cells into a form that are once again sensitive to antimicrobials.  The NO works through a non-biocidal mechanism and hence is likely to avoid the development of resistance seen for traditional toxic compounds that kill bacteria.  The NO can also be used in combination with antimicrobials, where the NO makes the biofilm sensitive to the effects of the antimicrobials and antibiotics.

The team has demonstrated that NO works against biofilms of a broad range of bacteria and yeast, including Pseudomonas aeruinosa, Escherichia coli, Vibrio cholerae, Staphylococcus aureus, Bacillus species and Candida albicans.  Further, they have shown that NO not only works against single species biofilms but also the more environmentally and clinical relevant mixed species biofilms. 

Key Benefits

• Good safety and ecotox profile for NO

• Can be used stand alone or in combination with antimicrobials

• Active against a broad range of microorganisms


• Biofilm control for liquid handling pipe systems, e.g. food industry, drinking water, liquids manufacturing

• Control of biofouling in membrane based water purification systems

• Infection control for chronic infections • Biomaterials compatible • Compatible with a range of formulations for optimisation of delivery