Environmental hexavalent chromium exposure induces gut microbial dysbiosis in chickens

Hexavalent chromium [Cr (VI)] is a hazardous heavy metal that pollutes soil, water and crops. Moreover, its prolonged exposure can harm the gastrointestinal system, liver and respiratory tract in different species, but knowledge regarding Cr (VI) influence on gut microbiota in chickens remains scarce. Therefore, this study was performed to investigate the impact of Cr (VI) on gut microbiota in chickens. Results revealed that the gut microbiota in Cr (VI)-induced chickens exhibited a distinct reduction in alpha diversity, accompanied by significant shifts in microbial composition. Specifically, Firmicutes and Bacteroidetes were the most dominant phyla in the control chickens, whereas Firmicutes and Actinobacteria were observed to be predominant in the Cr (VI)-induced populations. Moreover, the types and relative abundances of predominant bacterial genus in control and Cr (VI)-induced chickens were also different. Bacterial taxonomic analysis revealed that the relative abundances of 3 phyla and 7 genera obviously increased, whereas 8 phyla and 30 genera dramatically decreased during Cr (VI) induction. Among them, 1 phylum (Deferribacteres) and 5 genera (Butyricicoccus, Butyricimonas, Intestinimonas, Lachnospiraceae_FCS020_group and Ruminococcaceae_V9D2013_group) even could not be found in the gut microbial community of Cr (VI)-induced chickens. Taken together, our study indicated that the long-term exposure to Cr (VI) dramatically alter the gut microbial diversity and composition in chickens. Notably, it represents a breakthrough in understanding the impact of Cr (VI) on the intestinal microbiota of chickens.