The biogas slurry produced by anaerobic fermentation process contained a large amount of dissolved organic matter (DOM). In this study, the reason for the effect of sulfanilamide antibiotics (SAs) on DOM components was revealed by analyzing the interaction between microbial community structure and DOM composition in the biogas slurry. Four components of DOM, including tyrosine-like, tryptophan-like or xenobiotic-like, Ultraviolet A (UVA) humic-like and UVA marine humic-like substances, were identified from all the samples through fluorescence excitation emission matrix-parallel factor (EEMPARAFAC) analysis. The most abundant phyla in biogas slurry were identified to be Firmicutes (60.99 %), Bacteroidetes (19.65 %), Proteobacteria (15.33 %) and Actinobacteria (3.15 %). The contents of soluble microbial byproduct-like substances were related to the growth and metabolism of high abundance of bacterial phyla. Firmicutes could lead to the content change of tyrosine-like substance. The content of the xenobiotic-like substance was negatively correlated with the abundances of Bacteroidetes and Proteobacteria. The addition of high concentration SAs inhibited the growth and reproduction of Firmicutes, resulting in the decrease of the content of tyrosine-like substance. The addition of 100 mg/L sulfaquinoxaline and sulfamethoxydiazine reduced the content of tyrosine-like by 47.5 % and 41.2 %, respectively. The change of tryptophan-like groups was opposite to that of the tyrosine-like. However, the addition of sulfamethoxazole had little effect on the content of all the abovementioned substances. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.