Abstract:

The use of green, efficient, and inexpensive microbial agents to eliminate antibiotic residues in fishery wastewater is important for ensuring the quality and ecological environment of aquatic products. To obtain erythromycin-degrading microbes that can be applied to fishery aquaculture wastewater, an erythromycin-degrading fungus was isolated using traditional methods and identified by morphological observation and internal transcribed spacer (ITS) sequence analysis. The optimal temperature and pH for erythromycin degradation were determined using single-factor tests, with the degradation rate as the indicator. The degradation metabolites of erythromycin were identified using ultra-high-performance liquid chromatography-tandem high-resolution electrospray ionization mass spectrometry. A zebrafish challenge test was performed to evaluate the biological safety of the strain. An ecological agent capable of degrading erythromycin was prepared through solid-state fermentation using the optimized parameters. This agent has been used to remediate erythromycin residues in aquaculture wastewaters. The results showed that strain ERY-1 is a member of Penicillium. The optimal conditions for erythromycin degradation by the strain ERY-1 were 20-35 ℃ and pH 5-7. Under these conditions, over 97% of erythromycin with an initial concentration of 1.0 mg·L^-1 was degraded. Five potential erythromycin degradation products were identified in this study. Erythromycin gradually loses its antibacterial activity due to dehydration, cladinose removal, and ring cleavage. Strain ERY-1 is relatively safe for aquatic organisms. The mass ratio of rice husk, wheat bran, and corn flour (m꞉m꞉m) was 1꞉1꞉1, which was used as the substrate for fermentation. The ratio of material to water was 1 g:1 L, and the initial inoculation ratio was 0.75%. Under such circumstances, a microbial ecological agent with a spore yield of approximately 9.14 × 10⁹ cfu·g^-1 was obtained after 13 days of fermentation at 25 ℃. The concentration of residual erythromycin is undetectable (below the detection limit of 0.2 ng·L^-1) after 3 days since application of this microbiological ecological agent into the erythromycin-contaminated aquaculture wastewater. The results showed that strain ERY-1 could effectively remediate erythromycin-contaminated aquaculture wastewater, and that the microbial ecological agent derived from this strain showed good application and promotion value.

Key words: erythromycin, microbial degradation, degradation characteristics, metabolites, solid-state fermentation, microbiol ecological agent application

摘要：

在渔业养殖过程中，使用绿色环保、高效低廉的微生物菌剂解决渔业废水中的抗生素残留，对保障水产品质量安全和生态环境有重要意义。为获得可应用于渔业养殖废水的红霉素降解菌剂，采用梯度富集驯化的方法从养殖污染底泥样品中分离筛选红霉素降解菌株，通过形态学特征和ITS（Internal Transcribed Spaces）序列分析进行微生物分类鉴定；采用单因素试验确定最适降解温度和pH；利用超高效液相色谱串联高分辨率电喷雾电离质谱仪鉴定降解产物，并据此推测降解途径，通过斑马鱼攻毒试验初步评估菌株的生物安全性；优化菌株固态发酵参数，制备红霉素降解菌剂，并初探降解菌剂对红霉素污染的养殖废水的修复效果。结果显示，获得一株红霉素降解菌株ERY-1并鉴定其为青霉菌属（Penicillium sp.）；菌株ERY-1在温度20－35 ℃、pH 5－7的环境中具有较好的降解率，在该条件下，菌株对质量浓度为1.0 mg·L^-1的红霉素的降解率在97%以上；鉴定了5种降解中间产物，并据此推测菌株ERY-1通过脱水、脱红霉支糖和开环逐渐使红霉素失去抗菌活性；斑马鱼攻毒试验初步表明菌株ERY-1对水生生物具有较高的安全性；以稻壳：麦麸：玉米粉质量比（m꞉m꞉m）为1꞉1꞉1作为固态培养基配方，初始料水比为1 g:1 L，接种量为0.75%，在温度为25 ℃，发酵13 d后获得产孢量约9.14×10⁹ cfu·g^-1的降解菌剂。将制备的降解菌剂投撒到有红霉素残留的养殖废水中，3 d后水中的红霉素未达到方法的检出质量浓度（0.2 ng·L^-1）。结果表明，菌株ERY-1可有效的解决渔业养殖废水中的红霉素残留，由其制备的降解菌剂具有良好的应用和推广价值。

关键词: 红霉素, 微生物降解, 降解特性, 代谢产物, 固态发酵, 菌剂应用