Comparative transcriptomic analysis of o-TA, Na-o-TA and K-o-TA against Escherichia coli, Aspergillus brasiliensis and Candida albicans
This study investigates the antimicrobial mechanisms of o-toluic acid (o-TA) and its sodium (Na-o-TA) and potassium (K-o-TA) salts through comparative transcriptomic analysis. Three representative microorganisms were examined: the Gram-negative bacterium Escherichia coli ATCC 8739, the filamentous fungus Aspergillus brasiliensis ATCC 16404, and the yeast Candida albicans ATCC 10231. Cell or spore suspensions (OD600 0.1-0.2) were treated with the test compounds and harvested after 24 h and 48 h for transcriptomic analysis. For E. coli ATCC 8739 and C. albicans ATCC 10231, the treatment concentrations were 0.25 mg/mL o-TA (with ethanol solvent control, C-E) or 2 mg/mL Na-o-TA and K-o-TA (with distilled-water solvent control, C-W). For A. brasiliensis ATCC 16404, the concentrations were 0.25 mg/mL o-TA (C-E) or 0.25 mg/mL Na-o-TA and K-o-TA (C-W). Three biological replicates were included per group. Total RNA was extracted and transcriptomic analysis was performed by RNA-seq, including library construction and cDNA sequencing on the Illumina NovaSeq 6000 platform. Differential expression analysis was performed using DESeq2. Genes were annotated against the NCBI taxonomy, NR, GO and KEGG databases.