Extracting high-molecular weight DNA from cyanobacteria using Promega's Wizard^Ⓡ HMW DNA extraction kit with a...

Area of Science:

• Microbiology
• Molecular Biology
• Genomics

Background:

• Extracting high molecular weight (HMW) DNA from cyanobacteria is challenging due to fragmentation and purity issues.
• Existing methods often yield DNA unsuitable for sensitive downstream applications like long-read sequencing.
• Cyanobacterial mucilage complicates DNA extraction and can lead to contamination.

Purpose of the Study:

• To present a modified DNA extraction protocol for obtaining high-purity, high-molecular-weight DNA from cyanobacteria.
• To optimize DNA extraction for long-read sequencing applications.
• To reduce DNA fragmentation and improve yield for genomic assembly.

Main Methods:

• Utilized Promega's Wizard® HMW DNA Extraction Kit, adapting the Gram-Positive and Gram-Negative Bacteria protocol.
• Introduced a key modification, METIS (Maximizing Extraction, Transfer Isopropanol Step), between steps 11 and 12.
• Focused on removing residual cellular debris, particularly the mucilage layer, to prevent DNA pellet contamination.

Main Results:

• The METIS modification significantly reduced mucilage remnants, preventing contamination of the DNA pellet.
• Successfully extracted high molecular weight DNA with minimal fragmentation and high purity from cyanobacterial species (Synechococcus sp., Microcystis aeruginosa) and a gram-negative bacterium (Lacibacter).
• The protocol enabled rapid HMW DNA extraction without toxic chemicals like phenol.

Conclusions:

• The METIS protocol is effective for obtaining high-quality HMW DNA from cyanobacteria and other bacteria.
• This method is suitable for sensitive downstream applications, including PacBio sequencing and whole-genome assembly.
• The modified protocol offers a rapid, efficient, and safer alternative for HMW DNA extraction.