I have run mothur pipeline for 16s amplicon sequencing data. I get made phyloseq object with phyloseq package in R now I want to visualize various plots like an abundance of taxa, and a comparison of taxa between different samples but I got stuck to writing R code when I made a bar plot it showed a black color-filled code is following. Anyone can modify this code for proper graphics.

plot_bar(pseq, x="Sample", y="Abundance", fill=NULL,
         title=NULL, facet_grid=NULL)