PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) is a tool for predicting functional abundances based only on marker gene sequences.
Read more about the tool: https://github.com/picrust/picrust2/wiki
Run sequence placement with EPA-NG and GAPPA to place study sequences (i.e. OTUs and ASVs) into a reference tree. Then runs hidden-state prediction with the castor R package to predict genome for each study sequence. Metagenome profiles are then generated, which can be optionally stratified by the contributing sequence. Finally, pathway abundances are predicted based on metagenome profiles. By default, output files include predictions for Enzyme Commission (EC) numbers, KEGG Orthologs (KOs), and MetaCyc pathway abundances. However, the tool enables users to use custom reference and trait tables to customize analyses.
The standard pipeline will generate metagenome predictions for 16S rRNA gene data.