# Are the sequences in the QIIME2 database of SILVA reverse-complement

**URL:** https://forum.qiime2.org/t/are-the-sequences-in-the-qiime2-database-of-silva-reverse-complement/21634
**Category:** User Support
**Tags:** feature-classifier, feature-table
**Created:** [December 11, 2021, 3:18am UTC](https://forum.qiime2.org/t/are-the-sequences-in-the-qiime2-database-of-silva-reverse-complement/21634 "2021-12-11T03:18:44Z")
**Posts on this page:** 1
**Showing post:** 6

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### Author: ![Nicholas\_Bokulich](https://forum.qiime2.org/user_avatar/forum.qiime2.org/nicholas_bokulich/32/19937_2.png) [@Nicholas\_Bokulich](https://forum.qiime2.org/u/Nicholas_Bokulich)
#### Post date: [December 14, 2021, 6:49am UTC](https://forum.qiime2.org/t/are-the-sequences-in-the-qiime2-database-of-silva-reverse-complement/21634/6 "2021-12-14T06:49:53Z")

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Hi @nmgduan ,

> [@nmgduan](#):
>
> please check the following link of the QIIME2 reference database[QIIME in SILVA](https://www.arb-silva.de/no_cache/download/archive/qiime/).

That has not been updated for some time... the latest release there is 132, which is a few years old.

More up-to-date QIIME 2-formatted versions of the SILVA database are available on the QIIME 2 website:

> **[Data resources — QIIME 2 2021.11.0 documentation](https://docs.qiime2.org/2021.11/data-resources/)**

The original SILVA sequences consist of RNA, not DNA, so these are reverse transcribed to create the DNA sequence reference database available in the QIIME 2 resources (AAGGUUCC→AAGGTTCC).

You can see a full description of the steps used to create the QIIME 2 formatted versions of the SILVA database here (see the section "Getting SILVA data: Hard Mode" to see the full details):

> [@Processing, filtering, and evaluating the SILVA database (and other reference sequence data) with RESCRIPt](https://forum.qiime2.org/t/processing-filtering-and-evaluating-the-silva-database-and-other-reference-sequence-data-with-rescript/15494):
>
> construction Please consider this tutorial a living document, which may change based upon community feedback and ongoing plugin development. RESCRIPt [RESCRIPt](https://github.com/bokulich-lab/RESCRIPt) (REference Sequence annotation and CuRatIon Pipeline) is a python package and QIIME 2 plugin for formatting, managing, and manipulating sequence reference databases. This package was designed for compiling, manipulating, and evaluating sequence reference databases from SILVA, NCBI, Greengenes, GTDB, and other sources, and for construc…

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