Fig. 1

Overview of techniques to detect bacterial microbiota. To detect which bacterial species there are in a sample, there are three options: 1) use quantitative polymerase chain reaction (qPCR) to detect total bacterial 16S rRNA gene and/or in combination with a specific qPCR for a bacterial group or species; 2) use 16S rRNA gene for amplicon multiplex sequencing to get information on the taxonomic distribution in a sample; 3) use total DNA of a sample for shot-gun sequencing of the metagenomics content to get information on taxonomic distribution and functions, examples of which are indicated in the box, to show that you have functional information within a taxonomic group, in this case butyrate kinase and glycoside hydrolase. The dollar sign below the different techniques is an indicator of the price: depending on the sample type and information depth, prices are variable, but, roughly, a one-dollar sign is around 5–10 dollars per sample; the two-dollar sign is 50–150 dollars per sample, and the three-dollar sign is 300–1000 dollars per sample