DADA2 for analysing metabarcoding data

As you saw in the previous sections, determining biodiversity from environmental samples involves sequencing small fragments of DNA using a technique called amplicon sequencing with Illumina technology. However, these DNA sequences can have errors, making it hard to tell which organisms are really there. Here we introduce DADA2, an open-source software package for modelling and correcting Illumina-sequenced amplicon errors.

DADA2 offers several advantages over other pipelines commonly used for analysing amplicon sequences.:

• Resolution: DADA2 infers amplicon sequence variants (ASVs) from amplicon data rather than operational taxonomic units (OTUs) clustering based methods.
• Accuracy: DADA2 reports fewer false positive sequence variants than other methods. It incorporates quality information, quantitative abundances, sequence differences and parameterises its error model using the data provided.
• Comparability: The ASVs output by DADA2 can be directly compared between studies, without the need to reprocess the pooled data.
• Computational Scaling: The compute time and memory requirements are lower than some other methods.

Click the tab below if you would like to learn more about the differences between OTU and ASV:

Now it’s your turn to gain hands-on experience with the DADA2 package for data analysis. Jump to the next page and follow the instructions to carry out the analysis.