Directional lactic acid production could mitigate antibiotic and ARGs pollution.

The technology of directional lactic acid production (DLAP) for animal manure is an innovative way of value-added utilization, but the influence of residual antibiotics in animal manure on the DLAP is still unclear, especially the degradation rate and degradation pathways of antibiotic with residues lactic acid bacteria (LAB). In this study, the most common residual antibiotic (Sulfachloropyridazine, SCP) and LAB (Lactobacillus bulgaricus, Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus casei) were employed as the research objects, the SCP degradation, degradation pathways and antibiotic resistance genes (ARGs) with different LAB were investigated in pure culture. Results showed that LAB has a positive effect on the reduction in ARGs (sul1, sul2, sul3, sulA, intI1 and tnp A). The SCP degradation rates were 90.3 %, 85.1 %, 86.1 % and 84.0 % with the growth of Lactobacillus bulgaricus, Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus casei at 50 mg/L, respectively. And the SCP degradation pathway is different for LAB, but the main decomposition functions, including S-N bond cleavage, CH3 release, SO2 release, nitration, hydroxylation, NH2 release and C-N bond cleavage, are similar. And most of intermediate products of SCP were lower toxicity compared to the parent compound. The findings proved the DLAP process as a guidance for a potential solution for reducing antibiotic and ARGs contamination.