Evaluation of an adapted semi-automated DNA extraction for human salivary shotgun metagenomics

Abstract

The importance of oral microbiota has been recently highlighted in human health, such as in Parkinson disease, notably using shotgun metagenomics. One key aspect for efficient shotgun metagenomic analysis relies on optimal microbial sampling and DNA extraction, generally implementing commercial solutions developed to improve sample collection and preservation and provide high DNA quality and quantity for downstream analysis. Because metagenomic studies are today performed on a large number of samples, the next evolution to increase study throughput is with DNA extraction automation. In this study, we proposed a semi-automated DNA extraction protocol for human salivary samples collected with a commercial kit, and compared the outcomes with the DNA extraction recommended by the manufacturer. While similar DNA yields were observed between the protocols, our semi-automated DNA protocol significantly generated higher DNA fragment sizes. Moreover, we showed that the oral microbiome composition was equivalent between DNA extraction methods, even at the species level. This study demonstrates that our semi-automated protocol is suitable for shotgun metagenomic analysis, while allowing for a better sample treatment logistic with reduced technical variability and without compromising the structure of the oral microbiome.