Abstract
Assessment of genomic DNA (gDNA) extraction efficiency is required for accurate bacterial quantification by qPCR. Exogenous DNA molecules are often added after bacterial cultures are lysed, but before DNA purification steps, to determine extraction efficiency. Herein we found that different exogenous DNA controls have different recovery rates, suggesting distinct DNA extraction efficiencies. Recovery rates are also affected by the gDNA extraction method being more affected in silica-based columns than in phenol-chloroform extraction. Overall, we determined that the use of long DNA fragments, such as gDNA, as exogenous controls have a higher recovery rate than use of smaller size DNA molecules.