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Medium- and long-term effects of the veterinary antibiotic sulfadiazine on soil microorganisms in a rice field
Received:February 04, 2020  
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KeyWord:sulfamethazine;degradation products;soil microorganisms;community composition
Author NameAffiliationE-mail
XU Jia-ying College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China  
ZHOU Jin-rong College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China  
WU Jie College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China  
WANG Jue College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China  
CHENG Su-yu College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China  
ZHAO Ge College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China  
JIANG Jing-yan College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China lilacjjy@njau.edu.cn 
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Abstract:
      The veterinary antibiotic sulfamethazine(SMZ)can enter into paddy soil with animal excrement, where it subsequently has a long biological half-life. In order to investigate the medium-and long-term effects of SMZ on soil microorganisms, HPLC-MS and Illumina MiSeq with high-throughput sequencing techniques were used to analyze the degradation products of SMZ and the effects on soil microorganisms after 47 d and 61 d of SMZ(30 mg·kg-1)being synchronous applied to paddy soil with different basal fertilizers(pig manure and compound fertilizer). The corresponding indoor pure incubation study of the single degradation products of SMZ was also carried out. The results showed that two degradation products, 2-amino-4, 6-dimethylpyrimidine and 4-(2-imino4, 6-dimethylpyrimidine-1(2H)-base)aniline, were produced after 47 d and 61 d of SMZ application, with the former being the dominant intermediate product regardless of which basal fertilizer was used. At the two sampling time points, SMZ had no significant effect on the diversity and richness of the soil microbial community for both basal fertilizers(P>0.05). However, in terms of the microbial dominant community composition, the soil treated with SMZ and pig manure significantly decreased the relative abundances of Gemmatimonadetes and Gemmatimonadaceae by 0.81% and 0.70%(P<0.05), respectively, and significantly increased the relative abundance of Subgroup6_norank by 0.54%(P<0.05)after 47 d in comparison to the pure manure control. This indicated that SMZ had a significant inhibitory effect on Gemmatimonadetes and Gemmatimonadaceae, but a significant promoting effect on Subgroup6_norank bacteria. The incubation experiment confirmed that these effects mainly related to the SMZ degradation product 2-amino-4, 6-dimethylpyrimidine. Moreover, in comparison to the pure fertilizer control, the soil treated with SMZ and manure significantly promoted the relative abundances of Actinobacteria, Firmicutes(P<0.05), and Burkholderiaceae(P<0.01)by 2.66%, 0.71%, and 0.25%, respectively, after 61 d of SMZ application. In contrast, the soil treated with SMZ and compound fertilizer significantly decreased the relative abundance of Thermodesul fovibrionia(P<0.05) by 0.43% after 61 d. Therefore, the medium-and long-term effect of veterinary antibiotics in soil, especially sulfonamides, should not be ignored.