Comparison of four DNA extraction methods for comprehensive assessment of 16S rRNA bacterial diversity in marine biofilms using high-throughput sequencing

High-throughput DNA sequencing technologies are increasingly used for the metagenomic characterisation of microbial biodiversity. However, basic issues, such as the choice of an appropriate DNA extraction method, are still not resolved for non-model microbial communities. This study evaluates four commonly used DNA extraction methods for marine periphyton biofilms in terms of DNA yield, efficiency, purity, integrity and resulting 16S rRNA bacterial diversity. Among the tested methods, the Plant DNAzol (R) Reagent (PlantDNAzol) and the FastDNA (R) SPIN Kit for Soil (FastDNA Soil) methods were best suited to extract high quantities of DNA (77-130 mu g g wet wt(-1)). Lower amounts of DNA were obtained (<37 mu g g wet wt(-1)) with the Power Plant (R) Pro DNA Isolation Kit (PowerPlant) and the Power Biofilm (R) DNA Isolation Kit (PowerBiofilm) methods, but integrity and purity of the extracted DNA were higher. Results from 16S rRNA amplicon sequencing demonstrate that the choice of a DNA extraction method significantly influences the bacterial community profiles generated. A higher number of bacterial OTUs were detected when DNA was extracted with the PowerBiofilm and the PlantDNAzol methods. Overall, this study demonstrates the potential bias in metagenomic diversity estimates associated with different DNA extraction methods.