Plasmid DNA contaminant in molecular reagents

Area of Science:

• Molecular Biology
• Metagenomics
• Bioinformatics

Background:

• Background noise in metagenomic studies is a significant challenge, often requiring extensive bioinformatics filtering.
• Low signal-to-noise ratios can lead to the loss of important biological signals.
• The potential for plasmid residues in reagents to cause bias has not been previously investigated.

Purpose of the Study:

• To investigate the prevalence and impact of plasmid DNA contamination in molecular biology reagents.
• To identify sources of plasmid contamination within the reagent production and handling chain.
• To assess the influence of plasmid contamination on metagenomic data analysis and interpretation.

Main Methods:

• Utilized a metagenomic approach to identify plasmid sequences in various samples and reagents.
• Traced identified plasmid sequences back to their potential sources, including expression plasmids.
• Conducted retrospective analyses of published metagenomic studies to evaluate signal-to-noise differentiation.

Main Results:

• Plasmid sequences, including fragments of the equine infectious anemia virus (pol) gene, were found to be omnipresent in molecular biology reagents.
• Identified contamination from expression plasmids in human samples and commercial polymerase preparations.
• Demonstrated that contamination can originate from reagent production, environmental sources, or sample handling.

Conclusions:

• Plasmid DNA contamination in molecular biology reagents is a widespread issue that can significantly bias metagenomic datasets.
• Inaccurate differentiation of signal from noise in existing studies may be attributed to this contamination.
• Critical assessment of metagenomic data for plasmid background noise is essential for reliable genomic and clinical interpretations.