Hi,

Could you explain briefly what's the goal of the "dereplication" process in a metagenomics analysis ? 
I think I understood the purpose ! 
Derepliaction is not a filtering process ! This step is used to compute the abundance of reads.   
For instance, I have the following fasta file : 

    > seq1 
    ACGT
    > seq2 
    ACGT
    > seq3 
    TCGA
    > seq4 
    GGAC

After dereplication I will have : 

    > seq1_2
    ACGT
    > seq3_1
    TCGA
    > seq4_1
    GGAC

Note that abondance value are written in the name of sequence

