Combined Transcriptomics and Proteomics Analysis to Reveal the Mechanism underlying the Degradation of TSNAs by Bacillus pumilus 05–5402

Tobacco-specific N-nitrosamines (TSNAs) present in tobacco and tobacco products cause serious diseases and, therefore, effective measures to reduce the levels of TSNAs in tobacco are necessary for tobacco harm reduction. Various bacteria have demonstrated the ability to degrade TSNAs, although their degradation efficiency is often affected by fermentation conditions. Therefore, optimizing the fermentation process is essential to improve the efficiency of the microbial degradation of TSNAs. However, the mechanisms involved in the microbial degradation of TSNAs remain unknown to date. In this context, the present study involved utilizing a combined transcriptomics and proteomics analysis to reveal the mechanism underlying the degradation of TSNAs by Bacillus pumilus strain 05–5402. The TSNAs in flue-cured tobacco were degraded, and the fermentation process was optimized to determine the best conditions for the functioning of strain 05–5402. A TSNA degradation rate of 31.99% was reached at 28°C and a water content of 100%. The combined transcriptomics and proteomics analysis revealed the involvement of diverse mechanisms in the degradation of TSNAs by strain 05–5402, among which amino acid biosynthesis, carbon metabolism, glycolysis/gluconeogenesis, starch and sucrose metabolism, and metabolism of multiple amino acids were the most prominent ones. These findings would serve as a reference for the degradation of TSNAs using Bacillus fermentation at the industrial scale.