Benzotriazole aerobic biodegradation by activated sludge and Bacillus sp. DH-12: Performance, community succession, and transformation products characterization

Understanding the biodegradation of benzotriazole compounds (BTs) is crucial for improving their removal from the environment. Experiments using activated sludge showed a 61.65 % removal rate for benzotriazole (BTA), primarily through biodegradation. Notably, microbial diversity changed significantly, especially within the class Bacilli , which increased from 0.17 % to 0.75 % over 21 days ( p < 0.05). A novel Bacillus strain, DH-12, was identified, capable of degrading over 85 % of BTA and 5-methylbenzotriazole (MBT) within 24 hours. During the degradation of three BTs, seven possible intermediates were detected. Strain DH-12 appears to use methylation and carboxylation pathways for transformation and shows aerobic dechlorination ability. Additionally, this strain helps reduce the toxicity of BTs. This research enhances our understanding of BTs biodegradation by both microbial communities and a specific bacterial strain, offering valuable insights for environmental biotransformation strategies.