Natural coatings show antibacterial promise


CORVALLIS - Researchers at Oregon State University have discovered, analyzed and patented a way to use a natural protein to coat material surfaces and form an effective barrier to harmful bacteria.

Important applications in nursing, surgery, other aspects of medical care and food handling may all be possible with further research, experts say.

Such coatings may one day reduce the possibility of infection from catheters, create more sterile operating rooms or make food-handling countertops and instruments resist dangerous bacteria such as Listeria monocytogenes.

"Private industry is now interested in this technology for a variety of applications, ranging from suction catheters to surgical gowns and bacteria- resistant sponges," said Joseph McGuire, an OSU professor of bioresource engineering.

The technology is based on a greater understanding and use of the properties of nisin, McGuire said, which is in a class of proteins called bacteriocins. Nisin is naturally produced, active against gram-positive bacteria, and so safe it's already used as a food preservative.

But an OSU research team is exploring the fundamental ways in which nisin behaves on various surfaces, how it interacts with bacteria and how it can be more fully harnessed as a natural, non-toxic disinfectant.

A particular problem that nisin coatings may help address, McGuire said, is bacterial growth and infection associated with some medical devices needed during the process of surgical recovery or routine medical care. Any type of bodily fluid or blood can encourage rapid and potentially harmful bacterial growth on whatever it contacts - catheters, surgical gowns, tampons, tubes.

In medical care, the potential for infection from such bacterial growth is a real and constant concern. And many of the harsh anti-microbial agents that can be used in other areas are unsuitable for biological use.

OSU research, however, has found that coatings of nisin can effectively bind to different types of surfaces, be applied inexpensively to fabrics, plastics, and other materials, and form a safe, effective, temporary barrier to some types of bacteria.

"Our current approach is not intended for long-term applications, because eventually blood proteins and other components would likely displace nisin and set a course for bacterial growth," McGuire said.

"But for perhaps as much as several days the antimicrobial properties provided by nisin coatings might be sufficient for a number of circumstances," he said. "Medical and surgical practice would benefit considerably if we can avoid some of these problems."

Besides applications in biomedicine, such coatings may also find widespread use in commercial or home food handling, improving the bacteria resistance of surfaces.

The applications of nisin in such technology is an outgrowth of basic OSU research on protein-surface interactions, McGuire said.

Studies have been supported by the National Science Foundation, U.S. Dept. of Agriculture, Whitaker Foundation and Medical Research Foundation of Oregon. Scientists working on the projects include McGuire; Mark Daeschel, an OSU professor of food science and technology; and Cynthia Bower, an OSU research associate in bioresource engineering.