E. faecalis releases DNA-damaging superoxide, which affects expression of up to 42 genes, according to study in the Journal of Medical Microbiology.



Scientists have discovered that a molecule produced by a common gut bacterium activates signaling pathways that are associated with inflammation, apoptosis, and cell-cycle regulation.


For several decades scientists have thought that some microbes living in the gut may play a role in the formation of sporadic colorectal cancer, but the exact mechanisms remained unknown. “We wanted to investigate how colon cells respond to normal gut bacteria that can damage DNA, like E. faecalis,” says Mark Huycke, M.D., professor at the Department of Veterans Affairs Medical Center.


“We found that superoxide from E. faecalis led to strong signaling in immune cells called macrophages. It also altered the way some cells in the gut grew and divided and even increased the productivity of genes that are associated with cancer.”


Unlike most gut bacteria, E. faecalis can survive using two different types of metabolism: respiration and fermentation. When the bacteria use fermentation, they release by-products. One of these by-products is superoxide, which harms DNA.


In their investigation, the researchers found that 42 genes in epithelial cells in the gut are involved in the regulation of the cell cycle, cell death, and signaling based on the unique metabolism of E. faecalis. This suggests that cells of the lining of the colon are rapidly affected when E. faecalis switches to fermentation. It also indicates that E. faecalis may have developed novel mechanisms to encourage colon cells to turn cancerous.


Scientists from the University of Oklahoma Health Sciences Center joined investigators from the Department of Veterans Affairs Medical Center. The research was published in the October issue of the Journal of Medical Microbiology.








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