The Effect of Increased Dietary Iron on the Gut Microbiome of Zebrafish

The crocodile icefish in Antarctica naturally lacks hemoglobin but consumes an iron-rich diet. Iron is an essential nutrient that controls important biological functions. The gut microbiome of fish produces specific enzymes that catabolize the diet (including absorption). It is not known what role the microbes play in iron metabolism, or how the fishes use the excess iron. Zebrafish were used because they are a great model species and a close cousin to the icefish. The goal of this study was to test the effect increased iron has on the gut microbiome of zebrafish. 18 fish were separated into two tanks and fed a normal diet for 2 weeks. Then a tank of four fish began their diet of high iron (15g of ferrous sulfate to 50g of normal fish food), while a tank of ten fish remained on the control diet. After 3 1/2 weeks, the fish were harvested to obtain the gut contents. Gut contents were used for 1) DNA extraction 2) Colony Forming Units counts of culturable bacteria and 3) examination of carbon source utilization via Biolog Ecoplates. After analyzing the sequences of both the control and the experimental data, we found that the increased iron changed the gut microbiome composition. We also found that exposure to high iron makes the gut microbiome more uniform between the fish harvested, dietary iron, in the form of ferrous sulfate, increased diversity and uniformity of the gut microbiome composition in zebrafish