Environmental sulfonamides pollution and microbial adaptation: Genome, transcriptome, and toxicology reveal Bacillus sp. HC-1 biotransformation and antibiotic resistance mechanisms.

Sulfonamides (SAs) residue in the environment presents significant challenges to both environmental safety and medical security. Currently, the reaction and transformation mechanisms of microorganisms in the presence of SAs remain unclear. This study employed multiomics to investigate the gene response and enzymatic transformation mechanisms of Bacillus sp. HC-1 under SAs exposure conditions. Strain HC-1 demonstrated the ability to transform sulfaquinoxaline (SQX), sulfamethoxazole (SMX), and sulfamethazine (SMZ) into their respective N4-acetylated products. Within 12 hours, the transformation rates of SQX, SMX, and SMZ reached 51.7 %, 44.7 %, and 42.70 % respectively. Transcriptome analysis revealed that differentially expressed genes (DEGs) related to cellular transport, membrane channel activity, and various metabolic pathways were significantly enriched in strain HC-1 exposed to SQX. Through genomic analysis, we identified three types of arylamine N-acetyltransferases (NATs), which were named BaNATA, BaNATB, and BaNATC. Their highest homologies with reported NATs were 35.29 %, 40.82 %, and 35.32 %, respectively. Resistance and toxicological assessments indicated that NATs functioned as resistance genes against SAs, and the toxicity of transformation products to microorganisms and plant seeds was diminished. This study offers a valuable reference for a more in-depth understanding of microbial reactions, potential resistance, and transformation mechanisms in antibiotic-contaminated environments.