Development of a Microbially-Derived Therapy Against Fusobacterium Nucleatum, a Bacterial Pathogen Linked with Colorectal Cancer

Background. Specific bacterial species have been linked to several intestinal diseases, including colorectal cancer (CRC). In recent years, high abundances of an emerging pathogen, Fusobacterium nucleatum, have been identified in tumors and stool samples of CRC patients and it has been suggested that F. nucleatum contributes to CRC initiation and development. The possibility of suppressing the growth of F. nucleatum in the GI tract using antimicrobial-producing probiotic bacteria may reduce the overall risk of CRC development. Methods. Here, we screen a collection of faecal samples from healthy donors against F. nucleatum in an effort to discover an antimicrobial-producing isolate capable of selectively inhibiting this emerging human pathogen. Potential isolates with anti-Fusobacterial activity were then further analysed for the ability to inhibit the pathogen in cell culture and in a faecal fermentation system, which simulates the dynamic conditions of the human colon. Results. Culture-based screening of over 16,000 colonies of gastrointestinal origin resulted in the identification of one faecal isolate with probiotic potential displaying significant antagonistic activity against F. nucleatum initially in cell culture media and subsequently inhibition was confirmed in the simulated intestinal model. Conclusion. This study reveals that, a novel gut isolate demonstrates inhibition against the CRC-associated F. nucleatum in vitro and suppresses its growth in a model of the human distal colon. This is an important finding, suggesting the potential of a natural gut bacterium to supress the growth of a bacterial pathogen associated with CRC, which may contribute to reducing the overall risk of developing the disease.