Role of biochar-derived DOM compositions in enhanced biodegradation of sulfamethoxazole and chloramphenicol.

In the study, we investigated the different compositions of biochar-derived dissolved organic matter (BDOM) that play a key role in the biodegradation of sulfamethoxazole (SMX) and chloramphenicol (CAP) by P. stutzeri and S. putrefaciens, and found that aliphatic compounds in Group 4, fulvic acid like in Region III, and solid microbial byproduct like in region IV are key common factors. The growth and antibiotic degradation efficiency of P. stutzeri and S. putrefaciens are positively correlated with the content of Group 4 and Region III, and negatively correlated with Region IV. This is consistent with the optimal biodegradation results of BDOM700 with the highest content of Group 4 and Region III. Additionally, the degradation efficiency of SMX by Pseudomonas stutzeri is negatively correlated with the percentage of polycyclic aromatics in Group 1, but not with CAP. Similarly, the percentage of fatty acids in S. putrefaciens was positively correlated with Group 1, whereas P. stutzeri did not. This indicates that some components of BDOM have varying effects on different bacteria or types of antibiotics. This study provides new insights into enhancing antibiotic biodegradation by controlling the composition of BDOM.