Friday, 2 February 2018

How one bacterium inhibits predators with poison

Microbiologists in South Korea report that the bacterium Chromobacterium piscinae produces cyanide when under attack from Bdellovibrio bacteriovorus HD100, a microbial predator found in rivers and soils that ingests its prey from the inside out. The researchers found that the prey produced levels of cyanide high enough to inhibit, but not kill, the B. bacteriovorus HD100.

Experiments showed that C. piscinae produced the protective cyanide in a nutrient-rich broth. In a medium devoid of nutrients, it didn't produce the cyanide and was consumed. The researchers suspect that the bacteria likely uses some ingredient in the broth to produce the cyanide. That observation implies that a bacteria's defenses may depend on location -- and, more generally, that bacteria may harbor protective mechanisms that are triggered in some environments, but not in others.

Studying such mechanisms may lead scientists to better understand how some pathogenic bacteria protect themselves against antibiotics, says microbiologist and study leader Robert Mitchell. His lab at the Ulsan National Institute of Science and Technology, in South Korea, focuses on understanding how microbial prey protect themselves from predators. They are investigating how bacterial predators like B. bacteriovorus HD100 might be optimized as "living antibiotics" that can target bacterial pathogens.

The study suggests microbes may have means for resisting predation that only show up in certain environs.


Wonsik Mun, Heeun Kwon, Hansol Im, Seong Yeol Choi, Ajay K. Monnappa, Robert J. Mitchell. Cyanide Production by Chromobacterium piscinae Shields It from Bdellovibrio bacteriovorus HD100 PredationmBio, December 2017 DOI: 10.1128/mBio.01370-17

Posted by Dr. Tim Sandle

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