磺胺二甲嘧啶对稻田土壤微生物的中长期效应

为了研究兽用抗生素磺胺二甲嘧啶(SMZ)对稻田土壤微生物的中长期效应,本文采用HPLC-MS和Illumina Miseq高通量测序技术,对比分析了磺胺二甲嘧啶(30 mg·kg-1)与不同基肥(猪粪和复合肥)同步输入稻田土壤47 d和61 d后,其在土壤中的降解情况和对土壤微生物的影响,并开展了磺胺二甲嘧啶单一降解产物相应室内纯培养验证研究。结果表明:无论基肥是猪粪还是复合肥,磺胺二甲嘧啶输入土壤47 d和61 d后均降解产生了2-氨基-4,6-二甲基嘧啶和4-2-亚氨基-4,6-二甲基嘧啶-1(2H)-基]苯胺这两种降解产物,且以前者为主。在两个研究时间点,无论肥源是猪粪还是复合肥,磺胺二甲嘧啶对土壤微生物群落多样性和丰富度变化均无显著影响(P0.05)。但从微生物优势群落组成上来看,磺胺二甲嘧啶输入47 d后,相对于猪粪对照,猪粪+SMZ处理中芽单胞菌门和芽单胞菌属相对丰度显著降低了0.81%和0.70%(P0.05),Subgroup6_norank菌属相对丰度显著增加了0.54%(P0.05),表明此时猪粪+SMZ处理对芽单胞菌门和芽单胞菌属有显著抑制作用,对Subgroup6_norank菌属有显著促进作用,培养试验证实了此作用效果主要来自于磺胺二甲嘧啶的降解产物2-氨基-4,6-二甲基嘧啶;磺胺二甲嘧啶输入61 d后,猪粪+SMZ处理对放线菌门和厚壁菌门有显著促进作用(P0.05),对伯克氏菌属有极显著促进作用(P0.01),复合肥+SMZ处理对热脱硫杆菌属起显著抑制作用(P0.05),相对于同种肥源对照,猪粪+SMZ处理中放线菌门、厚壁菌门和伯克氏菌属相对丰度分别提高了2.66%、0.71%和0.25%,复合肥+SMZ处理中热脱硫杆菌属相对丰度降低了0.43%。因此,磺胺类兽用抗生素在土壤中的中长期效应不可忽视。

Medium- and long-term effects of the veterinary antibiotic sulfadiazine on soil microorganisms in a rice field

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.