利用漆酶-天然介体系统高效降解土霉素

Efficient degradation of oxytetracycline using a laccase-natural mediator system

土霉素作为兽用抗生素在禽、畜养殖业中应用广泛,严重危害环境和人体健康。采用漆酶对土霉素进行降解研究,通过介体筛选(丁香醛、香草醛、阿魏酸、对香豆酸、香草酮、ABTS、HBT),发现天然介体丁香醛和香草醛可有效促进漆酶对土霉素的降解,且效果要优于常用的人工合成介体ABTS和HBT。进一步研究表明:在相同介体浓度条件下(0.3 mmol·L^-1),复合介体的效果优于单一介体,其中由双天然介体丁香醛和香草醛配比而成的Syr/Van复合物对漆酶的作用显著。对漆酶-双天然介体系统降解土霉素的反应条件进行优化,在漆酶用量0.1 IU·mL^-1、50℃、120r·min^-1、pH 4.0的条件下反应4 h,漆酶-Syr/Van复合系统对土霉素的降解率高达95.14%。丁香醛、香草醛都是木质素降解过程的中间产物,采用此类廉价的天然介体替代人工合成介体ABTS、HBT,在经济和环保方面都具有明显的优势,该研究结果在环境治理方面具有良好的实际应用价值。

Oxytetracycline is widely used in poultry and animal husbandry as a veterinary antibiotic,which harms environment and human health.In this study,the effects of mediators(syringaldehyde,vanillin,ferulic acid,p-coumaric acid,vanillone,ABTS,HBT) on oxytetracycline degradation were investigated using laccase.The results show that syringaldehyde and vanillin could effectively promote laccase-catalyzed degradation of oxytetracycline,which is better than the commonly used synthetic mediators ABTS and HBT.Further studies indicate that mixed mediators are better than single mediators with same mediator concentration(0.3 mmol·L^-1),and the dual natural mediators syringaldehyde and vanillin(named Syr/Van) are the most effective.The reaction conditions for the degradation of oxytetracycline by the laccase-dual natural mediators system were optimized.When the reaction was performed at 50℃,120 r·min^-1,pH 4.0 with laccase dosage of 0.1 IU·mL^-1 for 4 h,degradation rate of oxytetracycline reached 95.14 %.Syringaldehyde and vanillin were both intermediates produced during the degradation of lignin.Replacing the synthetic mediators ABTS and HBT with inexpensive natural mediators has obvious advantages in cost saving and environmental protection.The results have great practical application in environmental treatment.