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LotuS2 is a amplicon sequencing pipeline, that is programmed to be lightweight, easy to use, fast without comprimising the quality of reconstructing microbial communitites. It supports 16S, 18S and ITS amplicons, and support for other amplicon targets is available. Currently five different sequence clustering algorithms (DADA2, uparse, unoise3, cd-hit, vsearch) are supported as well as multiple options to assigning taxonomic annotations. LotuS2 output can be imported directly into R or as text file into other programs. Full documentation on


LotuS2 requires a perl installation and sdm requires a fairly recent C++ compiler (like gcc or clang) that supports C++11. Lambda currently only works under linux, the option to use lambda is not available on mac os. Instead, Blast, vsearch or usearch can be used.


LotuS2 can be installed via conda

conda install -c bioconda lotus2

If there should be problems with the conda solver, try:

conda create -c conda-forge -c bioconda --strict-channel-priority -n lotus2 lotus2
conda activate lotus2

Alternatively, often the github contains pre-release versions and can be installed via:

git clone

All required software will be downloaded and installed in this directory.

If you want to install software and databases to other locations, follow installation instructions on:

LotuS2 packs a static compiled linux sdm binary, this should be useable out of the box. However, to manually compile sdm (the autoinstaller can also do this) go to the lotus subdirectory sdm_src and run make to compile the sdm binary. Next copy the binary into the lotus directory using cp. For using MACs and LotuS2, this would be a requirement as the static binary will only work Linux systems.

cd sdm_src
cp sdm ../sdm


If you installed LotuS2 via "git clone", you can get the latest release via "git pull". LotuS2 has a built in mechanism to upgrade LotuS2, so that properitary programs & databases (once installed) don't have to be downloaded again. To use this feature a) install LotuS2 for the first time using the autoinstaller. Once you know or want to check for new updates, simply excecute the autoinstaller again and you will be prompted if LotuS2 should be updated. In case no new updates are available, the autoinstaller will exit without making changes, so this function can be used frequently. New updates will be avaialble from the LotuS2 webpage ( or from github (


To test your installation, run a minimal example:

./lotus2 -i Example/ -m Example/ -o myTestRun

LotuS2 will try to choose default options. However, note that you should have seen a warning that no PCR primers were provided.

In the next example, we will explicitly configure the read filtering by providing sdm_miSeq2.txt, explicitly defining this to be 16S data from an illumina miSeq machine, to remove PCR primers used in this experiment, to use DADA2 instead of UPARSE clustering algorithm, to use alginments of ASVs against SILVA reference database instead of RDPclassifier taxonomic annotations:

./lotus2 -i Example/ -m Example/ -o myTestRun2 -s configs/sdm_miSeq2.txt -p miSeq -amplicon_type SSU -forwardPrimer GTGYCAGCMGCCGCGGTAA -reversePrimer GGACTACNVGGGTWTCTAAT -CL dada2 -refDB SLV -taxAligner lambda

Building the lambda formatted SILVA reference database will take a long time the first time you run this. Please ensure that during installation you selected that the SILVA database will be installed (otherwise this example will not work).

There are >60 flags with which you can further customize each LotuS2 run, but we try to optimize LotuS2 to work pretty well with just default options. Please run ./lotus2 to see these options.

Publications related to LotuS2


offtarget removal:



(c) Falk.Hildebrand {at}

Please cite LotuS2 with:

Pipeline - Özkurt E, Fritscher J, et al. (2022) LotuS2: An ultrafast and highly accurate tool for amplicon sequencing analysis. Microbiome 10:176 doi:10.1186/s40168-022-01365-1.

offtarget removal - Bedarf JR, Beraza N, Khazneh H, Özkurt E, et al (2021) Much ado about nothing? Off-target amplification can lead to false-positive bacterial brain microbiome detection in healthy and Parkinson’s disease individuals. Microbiome ;9:75.

We would like to acknowledge the following proprietary software, that is used in LotuS2. Please acknowledge these if your LotuS2 run was using them (listed in LotuSLogS/citations.txt for each LotuS2 run):

  • DADA2 - Callahan, B., McMurdie, P., Rosen, M. et al. 2016. DADA2: High resolution sample inference from Illumina amplicon data. Nat Methods, 13. 581–583 (2016).

  • UPARSE - Edgar RC. 2013. UPARSE: highly accurate OTU sequences from microbial amplicon reads. Nat Methods, 10, 996–998 (2013).

  • VSEARCH - Rognes T, Flouri T, Nichols B, Quince C, Mahé F.2016. VSEARCH: a versatile open source tool for metagenomics PeerJ. vol. 4 e2584.

  • swarm - Mahé F, Rognes T, Quince C, de Vargas C, Dunthorn M. 2014. Swarm: robust and fast clustering method for amplicon-based studies. PeerJ 2: e593.

  • CD-HIT - Fu L, Niu B, Zhu Z, Wu S, Li W. 2012. CD-HIT: Accelerated for clustering the next-generation sequencing data. Bioinformatics 28: 3150–3152.

  • uchime - Edgar RC, Haas BJ, Clemente JC, Quince C, Knight R. 2011. UCHIME improves sensitivity and speed of chimera detection. Bioinformatics 27: 2194–200.

  • RDP classifier - Wang Q, Garrity GM, Tiedje JM, Cole JR. 2007. Naive Bayesian classifier for rapid assignment of rRNA sequences into the new bacterial taxonomy. Appl Env Microbiol 73: 5261–5267; DOI: 10.1128/AEM.00062-07.

  • lambda aligner - Hauswedell H, Singer J, Reinert K. 2014. Lambda: the local aligner for massive biological data. Bioinformatics 30: i349–i355.

  • Blast+ - Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ. 1990. Basic local alignment search tool. J Mol Biol 215: 403–10.

  • Clustal Omega - Sievers F, Wilm A, Dineen D, Gibson TJ, Karplus K, Li W, Lopez R, McWilliam H, Remmert M, Söding J, et al. 2011. Fast, scalable generation of high-quality protein multiple sequence alignments using Clustal Omega. Mol Syst Biol 7: 539.

  • MAFFT - Katoh K, Standley DM. MAFFT multiple sequence alignment software version 7: improvements in performance and usability. Mol Biol Evol. 2013;30:772–80.

  • fasttree2 - Price MN, Dehal PS, Arkin AP. 2010. FastTree 2--approximately maximum-likelihood trees for large alignments. ed. A.F.Y. Poon. PLoS One 5: e9490.

  • IQ-TREE 2 - Nguyen L-T, Schmidt HA, von Haeseler A, Minh BQ. IQ-TREE: A Fast and Effective Stochastic Algorithm for Estimating Maximum-Likelihood Phylogenies. Mol Biol Evol. 2015;32:268–74.


  • Greengenes - McDonald D, Price MN, Goodrich J, Nawrocki EP, DeSantis TZ, Probst A, Andersen GL, Knight R, Hugenholtz P. 2012. An improved Greengenes taxonomy with explicit ranks for ecological and evolutionary analyses of bacteria and archaea. ISME J 6: 610–8.

  • SILVA - Yilmaz P, Parfrey LW, Yarza P, Gerken J, Pruesse E, Quast C, Schweer T, Peplies J, Ludwig W, Glockner FO (2014) The SILVA and "All-species Living Tree Project (LTP)" taxonomic frameworks. Nucleic Acid Res. 42:D643-D648

  • HITdb - Ritari J, Salojärvi J, Lahti L & de Vos WM. Improved taxonomic assignment of human intestinal 16S rRNA sequences by a dedicated reference database. BMC Genomics. 2015 Dec 12;16(1):1056.

  • beetax - Jones, JC, Fruciano, C, Hildebrand, F, et al. Gut microbiota composition is associated with environmental landscape in honey bees. Ecol Evol. 2018; 8: 441– 451.

  • PR2 - Guillou L, Bachar D, Audic S, et al. The Protist Ribosomal Reference database (PR2): a catalog of unicellular eukaryote small sub-unit rRNA sequences with curated taxonomy. Nucleic Acids Res. 2013;41(Database issue):D597-D604

ITS specific

  • UNITE ITS chimera DB - Nilsson et al. 2015. A comprehensive, automatically updated fungal ITS sequence dataset for reference-based chimera control in environmental sequencing efforts. Microbes and Environments

  • UNITE ITS taxonomical refDB - Koljalg, Urmas, et al. "Towards a unified paradigm for sequence-based identification of fungi." Molecular Ecology 22.21 (2013): 5271-5277.

  • ITSx - Bengtsson‐Palme, J., Ryberg, M., Hartmann, M., Branco, S., Wang, Z., Godhe, A., De Wit, P., Sánchez‐García, M., Ebersberger, I., de Sousa, F., Amend, A., Jumpponen, A., Unterseher, M., Kristiansson, E., Abarenkov, K., Bertrand, Y.J.K., Sanli, K., Eriksson, K.M., Vik, U., Veldre, V. and Nilsson, R.H. 2013. Improved software detection and extraction of ITS1 and ITS 2 from ribosomal ITS sequences of fungi and other eukaryotes for analysis of environmental sequencing data. Methods in Ecology and Evolution

Mathematical models

  • Puente-Sánchez 2016 - A novel conceptual approach to read-filtering in high-throughput amplicon sequencing studies. Nucleic Acids Res. 2016;44(4):e40.

C++ libraries