A universal, high-quality, and high-yield DNA purification method for mycobacteria, including Mycobacterium tuberculosis : large-scale assessment of the chloroform-bead method

ABSTRACT Genomic analysis of mycobacteria has become increasingly crucial for understanding drug-resistance mechanisms, molecular epidemiology, and pathogenesis. However, efficient extraction of high-molecular-weight genomic DNA from these organisms remains challenging because of their thick mycolic acid-rich cell walls. In this study, we report the chloroform-bead method, a universal DNA extraction protocol that combines chemical and mechanical disruptions to overcome these challenges. Multi-laboratory evaluation (16 sites) demonstrated the chloroform-bead method’s superiority over conventional methods for Mycobacterium tuberculosis (DNA yield: 17.9 vs 1.9 µg, purity A260/A230: 1.86 vs 1.22, both P 32 nontuberculous mycobacterial species ( n = 1,058), showing performance comparable to M. tuberculosis ( n = 1,000), with both achieving median yields of 22.2 µg DNA and consistent quality metrics. The chloroform-bead method significantly reduced the processing time from 2 to 3 days to 2 h while ensuring complete sample sterilization, eliminating the need for species-specific optimization. This streamlined and universally applicable protocol represents a practical advancement in mycobacterial DNA extraction methodology, ideal for high-throughput genomic studies and routine clinical diagnostics. IMPORTANCE Mycobacterial genomics is crucial for understanding pathogenesis and drug resistance; however, DNA extraction remains a significant challenge because of its unique cell wall. Traditional methods rely on enzymatic treatments, resulting in complex and time-consuming protocols with variable results. The chloroform-bead method introduces a paradigm shift by chemically and mechanically disrupting the mycolic acid layer and eliminating the need for enzymatic treatment. This standardized approach ensures consistent, high-quality DNA extraction across diverse mycobacterial species, thereby enhancing research capabilities and clinical applications.