DNA Extraction from Biochar Amended Soils.

Molecular techniques are frequently used to evaluate microbial responses to biochar. Hence, it is important to determine whether the presence of biochar interferes with soil DNA extraction efficiency or purity. Here, we evaluated a traditional method for soil DNA extraction as well as a commercial kit that was employed with or without an additional step using phenol:chloroform:isoamyl (PCI). DNA extractions were carried out on soils amended with four different types of biochar with individual materials added to either clay or loam soils at a rate of 3% (w/w). Prior to DNA extraction, all of the soils were spiked with an internal standard using bacteria carry plasmids encoding green fluorescent protein (GFP) genes. DNA purity and yield were assessed spectrophotometrically for all extractions. To assess downstream applicability of the DNA extracts, quantitative PCR (qPCR) was used to enumerate GFP copy numbers per gram soil.  Results showed that use of the PCI modification to the extraction procedure allowed efficient extraction of DNA at a purity level sufficient for qPCR quantification of target genes.