Sea squirt from which a bacteria can be derived.

The sea squirt Ecteinascidia turbinata harbours a bacterium that helped to make a new antibiotic. Credit: Josie B. Ruiz/NPL

Microbiology

Two microbes are better than one for making an antibiotic

A bacterial pairing leads to a compound bad for germs, but not apparently for DNA.

Growing two microbes together has yielded an antibiotic with a potential new way of killing bacteria.

The rise of antibiotic resistance has researchers trying new strategies for unlocking useful compounds hidden in the genes of microbes — the source of most antibiotics used today. Tim Bugni of the University of Wisconsin–Madison and his colleagues grew Rhodococcus and Micromonospora bacteria, isolated from marine invertebrates, in the same culture, in the hope that doing so would trigger the expression of antibiotic genes that are silent when each microbe is grown singly. 

This yielded an antibiotic called keyicin, which is produced by a Micromonospora species but only in the presence of Rhodococcus. Keyicin can inhibit the growth of ‘Gram-positive’ bacteria, including an antibiotic-resistant strain of the pathogen Staphylococcus aureus. And, unlike other antibiotics of similar structure, keyicin does not seem to damage DNA.