Insightful approach for screening triclocarban-degrading microbes via enzyme-guided strategy: Detoxification regulation and energy metabolism by Diaphorobacter polyhydroxybutyrativorans

Biodegradation is critical for eliminating triclocarban (TCC) from polluted environments. However, few pure cultures capable of TCC degradation have been isolated, and the cytotoxicity and detoxification mechanisms involved remain poorly understood during degradation process. Conventional screening methods based on enrichment cultures are inefficient. This study explored the feasibility of high-throughput screening strategies of functional bacteria that could potentially degrade TCC using existing functional enzyme information, bioinformatics databases, microbial collections, and bioinformatics tools and systematically investigated TCC-induced cytotoxicity and detoxification responses. From over 5,000 candidate strains, eight representative isolates were selected, among which Diaphorobacter polyhydroxybutyrativorans (DP) degraded 26.0 ± 0.70% of 1 mg/L TCC within 48 h, along with its hydrolysates 3,4-dichloroaniline (3,4-DCA) and 4-chloroaniline (4-CA). Under TCC stress, DP maintained membrane integrity (TCC: 7.42% ± 1.36% vs Control: 4.75% ± 0.28%) and viability (TCC: 94.28% ± 0.53 vs Control: 95.15% ± 0.97%), despite elevated reactive oxygen species (ROS) levels. TCC exposure enhanced propionate metabolism, TCA cycle, and electron transport chain activity, redirecting energy allocation from biosynthesis to stress response and survival. Multiple detoxification mechanisms were employed, including lipopolysaccharide (LPS) modification, membrane permeability, efflux pumps and enzymatic catalysis. The concentrations of key energy metabolites, including fructose-1,6-bisphosphate, acetyl-CoA, and α-ketoglutarate, were reduced under TCC-induced stress. DP supplemented succinate and pyruvate through propionate metabolism via the methylcitrate cycle. This study provides a new perspective for screening emerging organic pollutant-degrading bacteria and new insights into regulation of metabolic network under stress of TCC. • It is feasible to screen functional bacteria by using enzyme-guided strategy. • DP effectively degraded triclocarban (TCC) and its hydrolysates (3,4-DCA and 4-CA). • TCC (1 mg/L) exposure did not exhibit significant lethal toxicity to DP cells. • TCC (1 mg/L) exposure elevated intracellular ROS levels in DP cells. • DP utilized propionate to sustain methylcitrate cycle for replenishing succinate and pyruvate.