Fecal virome transfer improves proliferation of commensal gut Akkermansia muciniphila and unexpectedly enhanced the fertility rate in laboratory mice. Prophages

Probiotics have been suggested as a nutritional supplement to prevent gut microbiome (GM) imbalances. However, the probiotics marketed today colonize the gut to a limited extent and thus have limited influence on the overall GM composition. The gut viral community is predominated by bacteriophages that attack bacteria in a host-specific manner. Fecal virome transplantation (FVT) have been shown to alter GM composition in the recipients. Here we investigate the use of FVT as a mean to alter GM composition to a degree, that could lead the way for persistent colonization of two types of probiotics. Namely Lacticaseibacillus rhamnosus GG (LGG) representing a well-established probiotic and Akkermansia muciniphila (AKM) representing a next-generation probiotic. Male and female C57BL/6NTac mice were cohoused in pairs at 4 weeks of age and grouped as: AKM+FVT, probiotic sham (Pro-sham)+FVT, LGG+Saline, AKM+Saline, and Pro-sham+Saline (control group). The FVT originated from donor mice with high relative abundance of A. muciniphila. The different treatments were performed twice, and all animals were terminated at age 9 weeks. The FVT treatment did not increase the abundance of the administered LGG or AKM. Instead FVT significantly (p < 0.05) increased the abundance of natural occurring A. muciniphila compared to the control group. This raise the potential of stimulating the commensal “probiotics” that already are permanent members of the gut. Unexpectedly, the FVT treated mice were observed with a significant (p < 0.05) increase in fertility rate that was independent of probiotic administration (LGG or AKM). These preliminary observations urge for supporting studies.