Suspicious feature from 16S rRNA gene analysis using archaeal primers

Question

[will.wcb]

One of the top features in our 16S sequencing is very suspicious. It was not even classified to domain level using sklearn in QIIME2 on the Silva 132 database. When I blast the sequence there are no hits except with quite low scores, ~48, and high E-vales. It is the exact length of the other, assignable features.

Any ideas what kind of artifact this could be? Or how we can look more into it?

Here is the sequence TAAAAGAGTTGCTGGCGAACGAAGGGCGTCCCGAAGCGACAGTAGATCCTGTTATCGAGGAAATATCGGCAACCGCCGTGGGCCTTACCTTCAAGATCGTAGAGGGTCCCCGGTTCAGAGTCGCCGACATAGAGTTTGAAGGCAACACGGTCTTCTCGAGTTCTCACCTCAGAAAGAACATGAAGCTTGTGAAGAAAGTGGGTCTCCTGACCACCTTCAGCTCGAAGGACATCTACCACAAAGAAAAATTCGAAGCTGATCTTGATCGCCTCCGCGTGCTGGTATACGCCGATCAAGGCTATTTGAAAGCGAGGTTTGGAGAACCGCGAGTCGAGGAAGTAGGCAAAATCGGCAACTGGCTGCCGATCATCGGACACAAGGGCGAGGGGCTGAAGATCGTTGTTCCCGTCGAGGAAGGCCGCCAGTACCGCGCCGCAGAGGTGAAGGTTGAAGACAACACGGAGTTTACGGCCGAGGAAATCAAGGCAATCATTGGTCTCA

Edit: replaced sequence

[will.wcb]

Sorry, I placed the wrong sequence, here is the correct one

TAAAAGAGTTGCTGGCGAACGAAGGGCGTCCCGAAGCGACAGTAGATCCTGTTATCGAGGAAATATCGGCAACCGCCGTGGGCCTTACCTTCAAGATCGTAGAGGGTCCCCGGTTCAGAGTCGCCGACATAGAGTTTGAAGGCAACACGGTCTTCTCGAGTTCTCACCTCAGAAAGAACATGAAGCTTGTGAAGAAAGTGGGTCTCCTGACCACCTTCAGCTCGAAGGACATCTACCACAAAGAAAAATTCGAAGCTGATCTTGATCGCCTCCGCGTGCTGGTATACGCCGATCAAGGCTATTTGAAAGCGAGGTTTGGAGAACCGCGAGTCGAGGAAGTAGGCAAAATCGGCAACTGGCTGCCGATCATCGGACACAAGGGCGAGGGGCTGAAGATCGTTGTTCCCGTCGAGGAAGGCCGCCAGTACCGCGCCGCAGAGGTGAAGGTTGAAGACAACACGGAGTTTACGGCCGAGGAAATCAAGGCAATCATTGGTCTCA

[JC]

Blasting that with megablast don't have any significant hit, using blastn it gives the short hits that you described, so I guess is just contamination.

[GenoMax]

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Answer 1

[JC]

Blasting your sequence to NT, the best hit is a 16S from uncultured archaea (Score=641, Query cov=80%, E=6e-180, %identity=95.31%)