FIG 1.

Experimental design. The resilience and resistance of gut microbiota were investigated using the same batch of adult zebrafish, which were subjected to exposure to three concentrations of AgNPs (i.e, 10, 33, and 100 μg/liter) for 15 days. They were then randomly assigned to continued-exposure (red) or recovery (green) groups for 30 and 60 days, respectively. The continued-exposure and recovery groups were used to test microbial resistance and resilience, respectively. The controls (black) without AgNP exposure were also sampled at each sampling time. L, M, and H indicate exposure to low (10 μg/liter), medium (33 μg/liter), and high (100 μg/liter) concentrations of AgNPs, respectively.