The Interactive Effect of Dietary Curcumin and Silver Nanoparticles on Gut Microbiota of Common Carp (Cyprinus carpio)

Discharge of silver nanoparticles (AgNPs) into aquatic ecosystems is inevitable due to their vast industrial applications. Thus, the present study aimed to evaluate the protective effect of dietary curcumin supplementation against AgNPs toxicity to the gut microbiota of common carp (Cyprinus carpio) including total bacteria count, mesophilic, lactic acid bacteria and Enterobacteriaceae. Nine different treatments including different combinations of dietary AgNPs (0, 0.05 and 0.15 g/kg feed) and curcumin (0, 0.75 and 1.5 g/kg feed) in three respective replicates were designed. The trial was conducted under natural photoperiod condition for 60 days. Samples were taken on days 20, 40 and 60. Our results showed that dietary AgNPs contamination resulted in reduced intestinal bacterial count in a dose dependent manner, however, dietary curcumin inclusion level of 0.75 g/kg remarkably reduced the toxicity of AgNPs to intestinal microflora of common carp at least at 0.05 g/kg AgNPs (p < 0.05). The results also indicated that there were highly significant relationships (p < 0.001) between intestinal microflora count and dietary curcumin and AgNPs concentrations which were dependent upon exposure time. Beta values for different terms of regression equations implied that AgNPs concentration had remarkable effects on different bacteria classes of gut microbiota (-0.75, -0.89, -0.73 and -0.84 for total bacteria, mesophilic bacteria, lactic acid bacteria and Enterobacteriaceae count, respectively). Conclusively, microflora population change might be assumed as an indication of environmental pollutions in aquatic ecosystems health assessment programs especially for newly emerging nano-materials. We also showed curcumin protected intestinal microflora against feed-born nanosilver particles.