Mycobacteria, a bacterial group that causes killer diseases such as tuberculosis (TB), leprosy, and Buruli ulcer depend on carbon monoxide to survive when other nutrients are not available, suggests a new study.

The study was published in 'ISME Journal'. "When microbial cells are starved of their preferred energy sources, one way they subsist is by scavenging gases such as carbon monoxide," said Paul Cordero, the co-lead author of the study. "They breakdown this gas into its fundamental components that provide the cells just enough energy to persist," Cordero added. 

The researchers showed that an enzyme called carbon monoxide dehydrogenase is what allows mycobacteria to obtain energy from this gas. While the energy gained is not enough to allow for growth, the researchers found that carbon monoxide consumption allowed mycobacteria to survive for longer periods of time. The group's findings suggested that Mycobacterium tuberculosis might be able to survive inside the human host by using carbon monoxide. 

"It has been known for years that Mycobacterium tuberculosis can use carbon monoxide, but nobody knew why," said fellow study co-first author, Katie Bayly. "Based on these findings, we predict that it uses this gas to its advantage to persist inside human lungs," she said. "Our immune cells actually make small amounts of carbon monoxide, which the bacterium may be able to use as an energy supply while dormant." 

Dormancy allows Mycobacterium tuberculosis to stay alive inside patients for years. This dormant infection usually has no symptoms, but can advance into full-blown TB, for example when people become immuno-compromised. This new discovery on the survival mechanism of mycobacteria could pave the way for new strategies to better fight communicable diseases such as tuberculosis.