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Breaching Bacteria’s Tough Outer Membrane Could Be Path to New Antibiotics

By August 6, 2018No Comments

A discovery about bacterial physics could point to a new way to develop antibiotics. The finding is likely to apply to approximately half of the world’s bacteria — potentially including antibiotic-resistant strains — said K.C. Huang, Ph.D., senior author on the study, which was published today in the journal Nature.

Huang and his colleagues found that the outer layer of E. coli behaves very differently than scientists had previously believed. This microbe is what is known as a Gram-negative bacterium, one of two broad classes of bacteria that also includes the disease-causing microbes Salmonella typhae and Pseudomonas aeruginosa.

All species of bacteria have a thick cell wall surrounding them that helps them maintain their shape in harsh environments such as the soil, bloodstream or human gut; Gram-negative bacteria also have a thin, outer membrane on top of that cell wall.

Most scientists thought that the outer membrane functioned like shrink wrap, Huang said, keeping important molecules inside the cell and toxic chemicals out, and that the cell wall acted more as armor or exoskeleton to physically protect the cells. But the study led by Huang, who is an associate professor of bioengineering and a member of the Allen Discovery Center at Stanford University, found that the outer membrane is far tougher than it appeared.

“The outer membrane is actually even more stiff than the cell wall,” Huang said. “It makes a larger contribution to cell mechanics than the object that had been thought for decades to be the only thing that matters for bacterial mechanics.”

That’s important not only for scientists like Huang who are trying to understand cellular biophysics, but because current antibiotics focus on targeting the bacterial cell wall — and new antibiotic strategies are sorely needed. Due in part to overuse of antibiotics, resistant strains of bacteria are on the rise. In the U.S. alone, at least 23,000 people die every year because of infections with antibiotic-resistant bacteria.