# Taxonomy assignement issues

**URL:** https://forum.qiime2.org/t/taxonomy-assignement-issues/4365
**Category:** User Support
**Tags:** feature-classifier
**Created:** [May 30, 2018, 11:40am UTC](https://forum.qiime2.org/t/taxonomy-assignement-issues/4365 "2018-05-30T11:40:55Z")
**Posts on this page:** 1
**Showing post:** 7

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### Author: ![antgonza](https://forum.qiime2.org/user_avatar/forum.qiime2.org/antgonza/32/1236_2.png) [@antgonza](https://forum.qiime2.org/u/antgonza)
#### Post date: [June 1, 2018, 2:29pm UTC](https://forum.qiime2.org/t/taxonomy-assignement-issues/4365/7 "2018-06-01T14:29:24Z")

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Hi @BiOMan,

> [@BiOMan](#):
>
> greengenes is not appropriate as a database because it is used more for ecology

Just to add to @Nicholas_Bokulich reply. If you check [Extended Data Figure 2](https://www.nature.com/articles/nature24621/figures/6) from [A communal catalogue reveals Earth’s multiscale microbial diversity](https://www.nature.com/articles/nature24621); you will see in panel b a comparison of the 2 databases on how well they recover/match sequences when doing close reference; which could be used as a guideline to which database might be better for which kind of environment. Now, if you see panel c, you will see that Silva recruits more observed OTUs, while Greengenes more phylogenetic diversity; this is due to how these references are created; if you are interested, suggest reading more on how Silva and Greengenes are actually created.

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