Observed and estimated richness of the 27F&1492R and 63F&M1387R 16S rRNA gene libraries.

<p>Gray columns represent richness as estimated by the Chao1 estimator. Black and white columns represent observed richness. The ratio observed: Estimated, i.e. the coverage, is given within each column. The taxonomic levels were approximated by DNA similarities of 98.7%, 95%, 90% and 80%, for species, genera, family/class and phylum, respectively.