Specific gut microbiome's role in skin pigmentation: insights from SCARB1 mutants in Oujiang colour common carp.

Aims: Beyond the pivotal roles of the gut microbiome in initiating physiological processes and modulating genetic factors, a query persists: Can a single gene mutation alter the abundance of the gut microbiome community? Not only this, but the intricate impact of gut microbiome composition on skin pigmentation has been largely unexplored.

Methods and results: Based on these premises, our study examines the abundance of lipase-producing gut microbes about differential gene expression associated with bile acid synthesis and lipid metabolism-related blood metabolites in red (whole wild) and white (whole white wild and SCARB1-/- mutant) Oujiang colour common carp. Following the disruption of the SCARB1 gene in the resulting mutant fish with white body colour (SCARB1-/-), there is a notable decrease in the abundance of gut microbiomes (Bacillus, Staphylococcus, Pseudomonas, and Serratia) associated with lipase production. This reduction parallels the downregulation seen in wild-type white body colour fish (WW), as contrasting to the wild-type red body colour fish (WR). Meanwhile, in SCARB1-/- fish, there was a downregulation noted not only at the genetic and metabolic levels but also a decrease in lipase-producing bacteria. This consistency with WW contrasts significantly with WR. Similarly, genes involved in the bile acid synthesis pathway, along with blood metabolites related to lipid metabolism, exhibited downregulation in SCARB1-/- fish.

Conclusions: The SCARB1 knockout gene blockage led to significant alterations in the gut microbiome, potentially influencing the observed reduction in carotenoid-associated skin pigmentation. Our study emphasizes that skin pigmentation is not only impacted by genetic factors but also by the gut microbiome. Meanwhile, the gut microbiome's adaptability can be rapidly shaped and may be driven by specific single-gene variations.