Fig. 2.

Prevotellaceae replaces Ruminococcaceae: a An LEfSe analysis showed significant differences between the morphine and saline controls. Many of the taxonomic differences contained or were contained by the two largest families in our analysis Prevotellaceae and Ruminococcaceae. b The relative abundance of Ruminococcaceae was lower in the morphine-treated group (p = 0.0317) and trended higher (p = 0.0556). c Linear regression analysis gave a Pearson correlation r = (p = < 0.0001) which was maintained at r = −0.9641 (p = 0.0081) and r = −0.9908 (p = 0.011) for the saline and morphine groups separated, respectively