Understanding how Mycobacterium tuberculosis, the bacterium responsible for tuberculosis (TB), responds to drugs at the molecular level is key to developing better treatments. A new research protocol developed by researchers from the National Microbiology Laboratory at the Public Health Agency of Canada offers a valuable solution for scientists studying the transcriptome of this difficult-to-work-with pathogen.

In this work, the team designed a detailed RNA sequencing (RNA-seq) workflow that is both efficient and reproducible. It starts with extracting high-quality RNA from small culture volumes using a combination of mechanical disruption, TRIzol™ phase separation, and column purification. Once purified, the RNA undergoes rRNA depletion and is converted into cDNA for sequencing. The researchers tested this method on 132 samples from 11 different clinical strains of M. tuberculosis, both with and without exposure to the TB drug pyrazinamide.

The team found that sequencing at a depth of 15 million reads was enough to reliably detect unique transcripts. Importantly, the method could detect changes in RNA expression in response to drug treatment. This means researchers can now use RNA-seq more confidently to investigate how M. tuberculosis responds to antibiotics or adapts in different environments.

This protocol represents a practical advance for microbiology labs working on TB and could help accelerate research into drug resistance and pathogen biology.