Rarefaction curves showing mean expected OTU number for Proteobacteria as a function of sample size. VosMichiel QuinceChristopher S. PijlAgata de HollanderMattias A. KowalchukGeorge 2012 <p>The 1% and 2.3% cut-offs for 16S rRNA and <i>rpoB</i> are chosen to reflect species definitions (see text).</p>