Evaluating the Capacity of Human Gut Microorganisms to Colonize the Zebrafish Larvae (Danio rerio)

Abstract

In this study we evaluated if zebrafish larvae can be colonized by human gut microorganisms. We tested two strategies: (1) through transplantation of a human fecal microbiota and (2) by successively transplanting aerotolerant anaerobic microorganisms, similar to the colonization in the human intestine during early life. We used conventionally raised zebrafish larvae harboring their own aerobic microbiota to improve the colonization of anaerobic microorganisms. The results showed with the fecal transplant, that some members of the human gut microbiota were transferred to larvae. Bacillus, Roseburia, Prevotella, Oscillospira, one unclassified genus of the family Ruminococcaceae and Enterobacteriaceae were detected in 3 days post fertilization (dpf) larvae; however only Bacillus persisted to 7 dpf. Successive inoculation of Lactobacillus, Bifidobacterium and Clostridioides did not improve their colonization, compared to individual inoculation of each bacterial species. Interestingly, the sporulating bacteria Bacillus clausii and Clostridioides difficile were the most persistent microorganisms. Their endospores persisted at least 5 days after inoculating 3 dpf larvae. However, when 5 dpf larvae were inoculated, the proportion of vegetative cells in larvae increased, revealing proliferation of the inoculated bacteria and better colonization of the host. In conclusion, these results suggest that it is feasible to colonize zebrafish larvae with some human bacteria, such as C. difficile and Bacillus and open an interesting area to study interactions between these microorganisms and the host.

Commensal Microbiota Regulate Vertebrate Innate Immunity-Insights From the Zebrafish

“…Microbial consortia, strains, or their products can be added to the housing media to test their impact on host biology or their ecology in association with the host. Inoculation of GF zebrafish larvae with complex bacterial communities or defined strains demonstrated that even some mammalian commensal taxa, such as Escherichia, Enterococcus, Bacillus, Roseburia , and Prevotella , can colonize zebrafish larvae (22, 42), thus enabling the use of “humanized” zebrafish to for medium-throughput investigation of host-microbiota interactions. Furthermore, probiotic bacterial strains including several species of Lactobacilli , colonize zebrafish and can influence host immune responses and outcomes to bacterial infection (37–39, 43, 44).…”

The zebrafish as a model for gastrointestinal tract–microbe interactions

“…Valenzuela et al, 2018). The successful colonisation of the larval gut with anaerobic species, including Lactobacillus paracasei and strict anaerobes such as Eubacterium limosum and…”

Farm Animals are Important Biomedical Models

“…The gut microbiota of human and zebrafish are different. Valenzuela et al (2018) showed that germ-free zebrafish larvae can be colonized by human gut microorganisms, such as Clostridioides difficile and Bacillus. This result opened an interesting area to study interactions between these microorganisms and the host.…”