In a single cell of bacteria, the 16S gene copy number can vary as much as up to 15 times among bacterial strains.
NGS reads obtained from 16S amplicon samples are assigned to known taxa, and the number of 16S reads can be used to calculate the relative taxonomic abundance.
However, to get the true relative taxonomic abundance, the number of 16S reads should be normalized by 16S gene copy number and we finally get the number of cells for each species.
EzBioCloud includes 16S gene copy number information for over 3,200 species and the predicted 16S copy number by PICRUSt is provided for the remaining species.
To read more about 16S copy number correction, please refer to here.