Crop Biotech Update

Scripps Scientists Solve Mystery of Bacterial Growth and Resistance

May 4, 2012

Scientists from The Scripps Research Institute are able to explain the chemical pathway that allows bacteria to form clusters known as biofilms. This could lead to the development of new treatments that will block biofilm formation which are involved in several forms of human infection and help bacteria resist antibiotics.

Scripps Research President and CEO Michael Marletta said that there are about 80 percent of human pathogens that form biofilms during some part of its life cycle. "In this study, we have detailed for the first time the signaling pathway from nitric oxide to the sensor through cellular regulators and on the biological output, biofilm formation," he added. Biofilm formation makes the cells in the interior relatively protected from the effects of natural or pharmaceutical antibiotics, thus difficult to kill with conventional treatments. In sufficient quantity, nitric oxide is toxic to bacteria and it could set off the bacteria to enter in its ‘defensive state', as in the biofilm. The Marletta lab focused on how to pull nitric oxide's trigger.

Interactive genes for proteins are often found adjacent to each other, which is why the researchers were able to infer that there is a connection between bacterial Haeme-Nitric Oxide/Oxygen (H-NOX) domain and an enzyme called histidine kinase.

The experiments revealed that histidine kinase transfers a phosphate group to response regulators. These work together to control the biofilm formation. Each regulator has a complementary role, which makes for an oddly complex system. These roles involve activating of gene expression, controlling of the activity of an enzyme producing a bacterial messenger molecule critical in biofilm formation, and lastly, tuning of the degree of activity of the second regulator.

For more details regarding this study's findings, read a news release at