model to study genetic effects on the microbiota
The interest in understanding and elucidating host-microbiota interactions is ever increasing. The focus of studying such interactions has long been on the well-established effects the microbiota has on its host. In contrast, little focus has been allocated toput on the participation ofpart the host plays in these intricate interactions. Understanding the role of the host in these interactions may well be an essential  key to understand the complexity of the relationship between the host and its microbiota. In this study, we utilize a model in which the effects of host genes on the microbiota can be elucidated and how such effects potentially shape the host-associated microbiota. We apply a hologenomic approach by implementing the CRISPR/Cas system in the zebrafish model to combine effects of host genotype with 16S metabarcoding and metabolomics data. We show that a knockout of the gene coding for the rate-limiting enzyme in melanogenesis, Tyrosinase (tyr), results in changes in the intestinal microbiota of zebrafish and differences in the abundance of specific metabolites, providing evidence of the impact of a single host gene on the composition and function of the intestinal microbiota.