Sulfamethoxazole degradation by Aeromonas caviae and co-metabolism by the mixed bacteria

Sulfamethoxazole (SMX) is a frequently detected antibiotic in the environment and has attracted much attention. Aeromonas caviae strain GLB-10 was isolated, which could degrade SMX to Aniline and 3-Amino-5-methylisoxazole. Compared to the single bacteria, the mixed bacteria including stain GLB-10, Vibrio diabolicus strain L2-2, Zobellella taiwanensis, Microbacterium testaceum, Methylobacterium, etc, had an ultrahigh degradation efficiency to SMX, with 250 mg/L SMX being degraded in 3 days. In addition to bioproducts of single bacteria, SMX bioproducts by the mixed bacteria also included acetanilide and hydroquinone which were not detected in the single bacteria. The SMX degradation mechanism of the mixed bacteria was more complicated including acetylation, sulfur reduction 4S pathway, and ipso-hydrolysis. The molecular mechanism of the mixed bacteria degrading SMX was also investigated, revealing that the resistance mechanism related to protein outer membrane protein and catalase peroxidase were overexpressed, meanwhile, 6-hydroxynicotinate 3-monooxygenase

Automated summary

Sulfamethoxazole (SMX), a commonly found antibiotic in the environment, is efficiently degraded by a mixed bacteria community including Aeromonas caviae strain GLB-10. In addition to the bioproducts generated by single bacteria, the mixed bacteria produce acetanilide and hydroquinone during SMX degradation. The degradation mechanism of the mixed bacteria is more complex and involves acetylation, sulfur reduction 4S pathway, and ipso-hydrolysis. The molecular mechanism reveals the overexpression of outer membrane proteins and catalase peroxidase, as well as the involvement of 6-hydroxynicotinate 3-monooxygenase.