mouse microbiome with E coli and other gut bacteria labeled
tweaking microbiome composition reduces colorectal tumor growth in mice

Image of the Day: Tamed Gut Bacteria

Curbing the growth of harmful bacteria in mouse microbiomes reduces the animals’ incidence of inflammation-related colorectal cancer.

Nicoletta Lanese
Aug 8, 2019

ABOVE: Interior of mouse large intestine, with E. coli stained red, other bacteria green, and host cells purple. After tungsten treatment (right), the E. coli population is significantly reduced.

Tweaking the composition of gut bacteria in mice stymies inflammation and the growth of tumors in their colons, researchers reported July 29 in the Journal of Experimental Medicine

Inflammatory bowel disease, which affects more than 1.6 million Americans, is tied to an imbalance of certain bacterial populations in the gut and an increased risk of colorectal cancer. Scientists aimed to subdue these harmful microbes in mice, specifically modifying the function of a subset of E. coli that produce a DNA-damaging toxin and incite tumor growth in animal models. By administering water-soluble tungsten salt to model mice, the scientists suppressed the bacteria’s ability to generate energy.  

“Restricting the growth of these bacteria decreased intestinal inflammation and reduced the incidence of tumors in two models of colorectal cancer,” coauthor Sebastian Winter, a microbiologist at the University of Texas Southwestern Medical Center in Dallas, says in an announcement. The new study adds to a mounting pile of research focused on uncovering the link between the gut microbiome and immune responses in cancer cells.

The researchers took cross-sections of the large intestines of mice, untreated (left) and treated (right) with tungsten salt. Several tumors (purple masses) are visible at the center of the untreated intestine, while tumor numbers are reduced in the treated mouse.

W. Zhu et al., “Editing of the gut microbiota reduces carcinogenesis in mouse models of colitis-associated colorectal cancer,” doi:10.1084/jem.20181939, Journal of Experimental Medicine, 2019. 

Nicoletta Lanese is an intern at The Scientist. Email her at