8.8.2. Sample preparation
Both RNA and DNA destined for metagenomic surveys can be extracted using the means described in sections 3 and 4 (e.g., Trizol® extractions for RNA and CTAB extractions for DNA). For more recalcitrant samples (e.g., spore stages, or samples of organisms with impermeable coats, common to bacterial species and fungi) it is important to use mechanical or enzymatic rupturing of the cell coat via proteinase K, as described in the above CTAB DNA extraction protocol (section 3.2.1.), or prolonged shaking with a suspension of low-affinity silica particles or other inert solids.