Dietary Copper and Silver Nanoparticles Fail to Alter the Gut Microbiota of Rainbow Trout
Strange, R. J., T. B. Henry, and N. Brand-Lavridsen.  2018.  American Fisheries Society, Annual Meeting of the American Fisheries Society, August 19-23, Atlantic City, NJ.

Silver and copper nanoparticles (AgNP and CuNP) are widely used and may be expelled via wastewater into the habitats of river-dwelling fish such as Oncorhynchus mykiss, rainbow trout. Hatchery-raised rainbow trout were fed food amended with the following treatments: nanoparticles (AgNP and CuNP), material controls (CuSO4 and AgNO3) at a concentration of 50 mg/kg, and metal-free controls. Prior to and following the introduction of Y. ruckeri (causative agent of enteric redmouth disease) to one half of the sample population, the gut microbiota was examined at intervals. 16s rRNA gene amplicon sequencing and analysis in Mothur was used to determine the presence of different bacteria orders. There were large differences in the abundance of the different microorganisms in the intestine of individual fish, even within treatment groups. Treatment with the nanoparticles and metal bulk did not have any significant effects on the composition of microbiota. However, exposure and/or infection with Y. ruckeri did change the abundance of several orders of bacteria, primarily an increase in members of the order Burkholderiales, and a reduction in the orders unclassified Bacilli, Lactobacillales, Baccillales, Enterobaciteriales, Betaproteobacteria unclassified, Clostridiales and Xanthomonadales. Y. ruckeri exposure/infection generally significantly reduced the number of bacterial orders present in the gut.